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Vila-Sanjurjo A, Mallo N, Elson JL, Smith PM, Blakely EL, Taylor RW. Structural analysis of mitochondrial rRNA gene variants identified in patients with deafness. Front Physiol 2023; 14:1163496. [PMID: 37362424 PMCID: PMC10285412 DOI: 10.3389/fphys.2023.1163496] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2023] [Accepted: 04/18/2023] [Indexed: 06/28/2023] Open
Abstract
The last few years have witnessed dramatic advances in our understanding of the structure and function of the mammalian mito-ribosome. At the same time, the first attempts to elucidate the effects of mito-ribosomal fidelity (decoding accuracy) in disease have been made. Hence, the time is right to push an important frontier in our understanding of mitochondrial genetics, that is, the elucidation of the phenotypic effects of mtDNA variants affecting the functioning of the mito-ribosome. Here, we have assessed the structural and functional role of 93 mitochondrial (mt-) rRNA variants thought to be associated with deafness, including those located at non-conserved positions. Our analysis has used the structural description of the human mito-ribosome of the highest quality currently available, together with a new understanding of the phenotypic manifestation of mito-ribosomal-associated variants. Basically, any base change capable of inducing a fidelity phenotype may be considered non-silent. Under this light, out of 92 previously reported mt-rRNA variants thought to be associated with deafness, we found that 49 were potentially non-silent. We also dismissed a large number of reportedly pathogenic mtDNA variants, 41, as polymorphisms. These results drastically update our view on the implication of the primary sequence of mt-rRNA in the etiology of deafness and mitochondrial disease in general. Our data sheds much-needed light on the question of how mt-rRNA variants located at non-conserved positions may lead to mitochondrial disease and, most notably, provide evidence of the effect of haplotype context in the manifestation of some mt-rRNA variants.
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Affiliation(s)
- Antón Vila-Sanjurjo
- Grupo GIBE. Departamento de Bioloxía e Centro Interdisciplinar de Química e Bioloxía (CICA), Universidade da Coruña (UDC), A Coruña, Spain
| | - Natalia Mallo
- Grupo GIBE. Departamento de Bioloxía e Centro Interdisciplinar de Química e Bioloxía (CICA), Universidade da Coruña (UDC), A Coruña, Spain
| | - Joanna L. Elson
- The Bioscience Institute, Newcastle University, Newcastle upon Tyne, United Kingdom
- Human Metabolomics, North-West University, Potchefstroom, South Africa
| | - Paul M. Smith
- Department of Paediatrics, Raigmore Hospital, Inverness, United Kingdom
| | - Emma L. Blakely
- Wellcome Centre for Mitochondrial Research, Translational and Clinical Research Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, United Kingdom
- NHS Highly Specialised Service for Rare Mitochondrial Disorders, Newcastle upon Tyne Hospitals NHS Foundation Trust, Newcastle upon Tyne, United Kingdom
| | - Robert W. Taylor
- Wellcome Centre for Mitochondrial Research, Translational and Clinical Research Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, United Kingdom
- NHS Highly Specialised Service for Rare Mitochondrial Disorders, Newcastle upon Tyne Hospitals NHS Foundation Trust, Newcastle upon Tyne, United Kingdom
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2
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Elwan M, Schaefer AM, Craig K, Hopton S, Falkous G, Blakely EL, Taylor RW, Warren N. Changing faces of mitochondrial disease: autosomal recessive POLG disease mimicking myasthenia gravis and progressive supranuclear palsy. BMJ Neurol Open 2022; 4:e000352. [PMCID: PMC9743281 DOI: 10.1136/bmjno-2022-000352] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/22/2022] [Indexed: 12/13/2022] Open
Abstract
Background Mitochondrial disorders are known to cause diverse neurological phenotypes which cause a diagnostic challenge to most neurologists. Pathogenic polymerase gamma (POLG) variants have been described as a cause of chronic progressive external ophthalmoplegia, which manifests with ptosis, horizontal and vertical eye movement restriction and myopathy. Autosomal dominant progressive external ophthalmoplegia is rarely associated with Parkinsonism responsive to levodopa. Methods We report a case of a 58-year-old man who presented with an eye movement disorder then Parkinsonism who made his way through the myasthenia then the movement disorder clinic. Results A diagnostic right tibialis anterior biopsy revealed classical hallmarks of mitochondrial disease, and genetic testing identified compound heterozygous pathogenic gene variants in the POLG gene. The patient was diagnosed with autosomal recessive POLG disease. Conclusions It is important to maintain a high index of suspicion of pathogenic POLG variants in patients presenting with atypical Parkinsonism and ophthalmoplegia. Patients with POLG-related disease will usually have ptosis, and downgaze is typically preserved until late in the disease. Accurate diagnosis is essential for appropriate prognosis and genetic counselling.
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Affiliation(s)
- Menatalla Elwan
- Department of Neurology, Royal Victoria Infirmary, Newcastle upon Tyne, UK
| | - Andrew M Schaefer
- Department of Neurology, Royal Victoria Infirmary, Newcastle upon Tyne, UK,Wellcome Centre for Mitochondrial Research, Translational and Clinical Research Institute, Faculty of Medical Sciences, Newcastle University, Newcastle Upon Tyne, UK
| | - Kate Craig
- Wellcome Centre for Mitochondrial Research, Translational and Clinical Research Institute, Faculty of Medical Sciences, Newcastle University, Newcastle Upon Tyne, UK
| | - Sila Hopton
- Wellcome Centre for Mitochondrial Research, Translational and Clinical Research Institute, Faculty of Medical Sciences, Newcastle University, Newcastle Upon Tyne, UK
| | - Gavin Falkous
- Wellcome Centre for Mitochondrial Research, Translational and Clinical Research Institute, Faculty of Medical Sciences, Newcastle University, Newcastle Upon Tyne, UK
| | - Emma L Blakely
- Wellcome Centre for Mitochondrial Research, Translational and Clinical Research Institute, Faculty of Medical Sciences, Newcastle University, Newcastle Upon Tyne, UK
| | - Robert W Taylor
- Wellcome Centre for Mitochondrial Research, Translational and Clinical Research Institute, Faculty of Medical Sciences, Newcastle University, Newcastle Upon Tyne, UK,NHS Highly Specialised Service for Rare Mitochondrial Disorders, Newcastle University, Newcastle upon Tyne, UK
| | - Naomi Warren
- Department of Neurology, Royal Victoria Infirmary, Newcastle upon Tyne, UK
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3
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Shintaku J, Pernice WM, Eyaid W, Gc JB, Brown ZP, Juanola-Falgarona M, Torres-Torronteras J, Sommerville EW, Hellebrekers DM, Blakely EL, Donaldson A, van de Laar IM, Leu CS, Marti R, Frank J, Tanji K, Koolen DA, Rodenburg RJ, Chinnery PF, Smeets HJM, Gorman GS, Bonnen PE, Taylor RW, Hirano M. RRM1 variants cause a mitochondrial DNA maintenance disorder via impaired de novo nucleotide synthesis. J Clin Invest 2022; 132:145660. [PMID: 35617047 PMCID: PMC9246377 DOI: 10.1172/jci145660] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2020] [Accepted: 05/19/2022] [Indexed: 11/17/2022] Open
Abstract
Mitochondrial DNA (mtDNA) depletion/deletions syndromes (MDDS) encompass a clinically and etiologically heterogenous group of mitochondrial disorders due to impaired mtDNA maintenance. Among the most frequent causes of MDDS are defects in nucleoside/nucleotide metabolism, which is critical for synthesis and homeostasis of the deoxynucleoside triphosphate (dNTP) substrates of mtDNA replication. A central enzyme for generating dNTPs is ribonucleotide reductase, a critical mediator of de novo nucleotide synthesis composed of catalytic RRM1 subunits in complex with RRM2 or p53R2. Here, we report five probands from four families who presented with ptosis and ophthalmoplegia, plus other manifestations and multiple mtDNA deletions in muscle. We identified three RRM1 loss-of-function variants, including a dominant catalytic site variant (NP_001024.1: p.N427K) and two homozygous recessive variants at p.R381, which has evolutionarily conserved interactions with the specificity site. Atomistic molecular dynamics simulations indicate mechanisms by which RRM1 variants affect protein structure. Cultured primary skin fibroblasts of probands manifested mtDNA depletion under cycling conditions, indicating impaired de novo nucleotide synthesis. Fibroblasts also exhibited aberrant nucleoside diphosphate and dNTP pools and mtDNA ribonucleotide incorporation. Our data reveal primary RRM1 deficiency and, by extension, impaired de novo nucleotide synthesis are causes of MDDS.
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Affiliation(s)
- Jonathan Shintaku
- Department of Neurology, Columbia University Irving Medical Center, New York, United States of America
| | - Wolfgang M Pernice
- Department of Neurology, Columbia University Irving Medical Center, New York, United States of America
| | - Wafaa Eyaid
- Department of Pediatrics, King Saud bin Abdulaziz University for Health Science, Riyadh, Saudi Arabia
| | - Jeevan B Gc
- Department of Biochemistry and Molecular Biophysics, Columbia University Irving Medical Center, New York, United States of America
| | - Zuben P Brown
- Department of Biochemistry and Molecular Biophysics, Columbia University Irving Medical Center, New York, United States of America
| | - Marti Juanola-Falgarona
- Department of Neurology, Columbia University Irving Medical Center, New York, United States of America
| | | | - Ewen W Sommerville
- Wellcome Trust Centre for Mitochondrial Research, Newcastle University, Newcastle, United Kingdom
| | - Debby Mei Hellebrekers
- Department of Clinical Genetics, Maastricht University Medical Center, Maastricht, Netherlands
| | - Emma L Blakely
- Wellcome Trust Centre for Mitochondrial Research, Newcastle University, Newcastle, United Kingdom
| | - Alan Donaldson
- Clinical Genetics Department, University of Bristol, Bristol, United Kingdom
| | - Ingrid Mbh van de Laar
- Department of Clinical Genetics, Erasmus Medical Center Rotterdam, Rotterdam, Netherlands
| | - Cheng-Shiun Leu
- Biostatistics, Columbia University, New York, United States of America
| | - Ramon Marti
- Laboratori de patologia neuromuscular i mitocondrial, Vall d'Hebron Research Institute, Barcelona, Spain
| | - Joachim Frank
- Department of Biochemistry and Molecular Biophysics, Columbia University Irving Medical Center, New York, United States of America
| | - Kurenai Tanji
- Department of Pathology and Cell Biology, Columbia University Irving Medical Center, New York, United States of America
| | - David A Koolen
- Department of Human Genetics, Radboud University Medical Center, Nijmegen, Netherlands
| | - Richard J Rodenburg
- Department of Laboratory Medicine, Radboud University Medical Center, Nijmegen, Netherlands
| | - Patrick F Chinnery
- Cambridge Biomedical Campus, University of Cambridge, Cambridge, United Kingdom
| | - H J M Smeets
- University of Maastricht, Maastricht, Netherlands
| | - Gráinne S Gorman
- Wellcome Trust Centre for Mitochondrial Research, Newcastle University, Newcastle, United Kingdom
| | - Penelope E Bonnen
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, United States of America
| | | | - Michio Hirano
- Department of Neurology, Columbia University Irving Medical Center, New York, United States of America
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4
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Ng YS, Lax NZ, Blain AP, Erskine D, Baker MR, Polvikoski T, Thomas RH, Morris CM, Lai M, Whittaker RG, Gebbels A, Winder A, Hall J, Feeney C, Farrugia ME, Hirst C, Roberts M, Lawthom C, Chrysostomou A, Murphy K, Baird T, Maddison P, Duncan C, Poulton J, Nesbitt V, Hanna MG, Pitceathly RDS, Taylor RW, Blakely EL, Schaefer AM, Turnbull DM, McFarland R, Gorman GS. Forecasting stroke-like episodes and outcomes in mitochondrial disease. Brain 2022; 145:542-554. [PMID: 34927673 PMCID: PMC9014738 DOI: 10.1093/brain/awab353] [Citation(s) in RCA: 20] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2021] [Revised: 07/16/2021] [Accepted: 08/06/2021] [Indexed: 12/03/2022] Open
Abstract
In this retrospective, multicentre, observational cohort study, we sought to determine the clinical, radiological, EEG, genetics and neuropathological characteristics of mitochondrial stroke-like episodes and to identify associated risk predictors. Between January 1998 and June 2018, we identified 111 patients with genetically determined mitochondrial disease who developed stroke-like episodes. Post-mortem cases of mitochondrial disease (n = 26) were identified from Newcastle Brain Tissue Resource. The primary outcome was to interrogate the clinico-radiopathological correlates and prognostic indicators of stroke-like episode in patients with mitochondrial encephalomyopathy, lactic acidosis and stroke-like episodes syndrome (MELAS). The secondary objective was to develop a multivariable prediction model to forecast stroke-like episode risk. The most common genetic cause of stroke-like episodes was the m.3243A>G variant in MT-TL1 (n = 66), followed by recessive pathogenic POLG variants (n = 22), and 11 other rarer pathogenic mitochondrial DNA variants (n = 23). The age of first stroke-like episode was available for 105 patients [mean (SD) age: 31.8 (16.1)]; a total of 35 patients (32%) presented with their first stroke-like episode ≥40 years of age. The median interval (interquartile range) between first and second stroke-like episodes was 1.33 (2.86) years; 43% of patients developed recurrent stroke-like episodes within 12 months. Clinico-radiological, electrophysiological and neuropathological findings of stroke-like episodes were consistent with the hallmarks of medically refractory epilepsy. Patients with POLG-related stroke-like episodes demonstrated more fulminant disease trajectories than cases of m.3243A>G and other mitochondrial DNA pathogenic variants, in terms of the frequency of refractory status epilepticus, rapidity of progression and overall mortality. In multivariate analysis, baseline factors of body mass index, age-adjusted blood m.3243A>G heteroplasmy, sensorineural hearing loss and serum lactate were significantly associated with risk of stroke-like episodes in patients with the m.3243A>G variant. These factors informed the development of a prediction model to assess the risk of developing stroke-like episodes that demonstrated good overall discrimination (area under the curve = 0.87, 95% CI 0.82-0.93; c-statistic = 0.89). Significant radiological and pathological features of neurodegeneration were more evident in patients harbouring pathogenic mtDNA variants compared with POLG: brain atrophy on cranial MRI (90% versus 44%, P < 0.001) and reduced mean brain weight (SD) [1044 g (148) versus 1304 g (142), P = 0.005]. Our findings highlight the often idiosyncratic clinical, radiological and EEG characteristics of mitochondrial stroke-like episodes. Early recognition of seizures and aggressive instigation of treatment may help circumvent or slow neuronal loss and abate increasing disease burden. The risk-prediction model for the m.3243A>G variant can help inform more tailored genetic counselling and prognostication in routine clinical practice.
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Affiliation(s)
- Yi Shiau Ng
- Wellcome Centre for Mitochondrial Research, Translational and Clinical Research Institute; NIHR Newcastle Biomedical Research Centre and Campus for Ageing and Vitality, Newcastle University, Newcastle upon Tyne NE2 4HH, UK
- Directorate of Neurosciences, Royal Victoria Infirmary, The Newcastle upon Tyne Hospitals NHS Foundation Trust, Newcastle upon Tyne NE1 4LP, UK
- Department of Neurosciences, NHS Highly Specialised Service for Rare Mitochondrial Disorders, Newcastle upon Tyne NE2 4HH, UK
| | - Nichola Z Lax
- Wellcome Centre for Mitochondrial Research, Translational and Clinical Research Institute; NIHR Newcastle Biomedical Research Centre and Campus for Ageing and Vitality, Newcastle University, Newcastle upon Tyne NE2 4HH, UK
| | - Alasdair P Blain
- Wellcome Centre for Mitochondrial Research, Translational and Clinical Research Institute; NIHR Newcastle Biomedical Research Centre and Campus for Ageing and Vitality, Newcastle University, Newcastle upon Tyne NE2 4HH, UK
| | - Daniel Erskine
- Wellcome Centre for Mitochondrial Research, Translational and Clinical Research Institute; NIHR Newcastle Biomedical Research Centre and Campus for Ageing and Vitality, Newcastle University, Newcastle upon Tyne NE2 4HH, UK
| | - Mark R Baker
- Directorate of Neurosciences, Royal Victoria Infirmary, The Newcastle upon Tyne Hospitals NHS Foundation Trust, Newcastle upon Tyne NE1 4LP, UK
- Campus for Ageing and Vitality, Newcastle Brain Tissue Resource, Newcastle University, Edwardson Building, Newcastle upon Tyne NE4 5PL, UK
| | - Tuomo Polvikoski
- Campus for Ageing and Vitality, Newcastle Brain Tissue Resource, Newcastle University, Edwardson Building, Newcastle upon Tyne NE4 5PL, UK
| | - Rhys H Thomas
- Wellcome Centre for Mitochondrial Research, Translational and Clinical Research Institute; NIHR Newcastle Biomedical Research Centre and Campus for Ageing and Vitality, Newcastle University, Newcastle upon Tyne NE2 4HH, UK
- Directorate of Neurosciences, Royal Victoria Infirmary, The Newcastle upon Tyne Hospitals NHS Foundation Trust, Newcastle upon Tyne NE1 4LP, UK
- Department of Neurosciences, NHS Highly Specialised Service for Rare Mitochondrial Disorders, Newcastle upon Tyne NE2 4HH, UK
| | - Christopher M Morris
- Campus for Ageing and Vitality, Newcastle Brain Tissue Resource, Newcastle University, Edwardson Building, Newcastle upon Tyne NE4 5PL, UK
| | - Ming Lai
- Directorate of Neurosciences, Royal Victoria Infirmary, The Newcastle upon Tyne Hospitals NHS Foundation Trust, Newcastle upon Tyne NE1 4LP, UK
| | - Roger G Whittaker
- Directorate of Neurosciences, Royal Victoria Infirmary, The Newcastle upon Tyne Hospitals NHS Foundation Trust, Newcastle upon Tyne NE1 4LP, UK
- Translational and Clinical Research Institute, Newcastle University, Newcastle upon Tyne NE2 4HH, UK
| | - Alasdair Gebbels
- Directorate of Neurosciences, Royal Victoria Infirmary, The Newcastle upon Tyne Hospitals NHS Foundation Trust, Newcastle upon Tyne NE1 4LP, UK
| | - Amy Winder
- Directorate of Neurosciences, Royal Victoria Infirmary, The Newcastle upon Tyne Hospitals NHS Foundation Trust, Newcastle upon Tyne NE1 4LP, UK
| | - Julie Hall
- Directorate of Neurosciences, Royal Victoria Infirmary, The Newcastle upon Tyne Hospitals NHS Foundation Trust, Newcastle upon Tyne NE1 4LP, UK
| | - Catherine Feeney
- Wellcome Centre for Mitochondrial Research, Translational and Clinical Research Institute; NIHR Newcastle Biomedical Research Centre and Campus for Ageing and Vitality, Newcastle University, Newcastle upon Tyne NE2 4HH, UK
- Directorate of Neurosciences, Royal Victoria Infirmary, The Newcastle upon Tyne Hospitals NHS Foundation Trust, Newcastle upon Tyne NE1 4LP, UK
- Department of Neurosciences, NHS Highly Specialised Service for Rare Mitochondrial Disorders, Newcastle upon Tyne NE2 4HH, UK
| | - Maria Elena Farrugia
- Institute of Neurological Sciences, Queen Elizabeth University Hospital, Glasgow G51 4TF, UK
| | - Claire Hirst
- Trust Headquarters, One Talbot Gateway, Baglan Energy Park, Baglan, Port Talbot SA12 7BR, UK
| | - Mark Roberts
- Greater Manchester Neuroscience Centre, Salford Royal NHS Foundation Trust, Manchester Academic Health Science Centre, Salford M6 8HD, UK
| | - Charlotte Lawthom
- Aneurin Bevan Epilepsy Specialist Team, Aneurin Bevan University Health Board, Newport, NP20 2UB, UK
| | - Alexia Chrysostomou
- Wellcome Centre for Mitochondrial Research, Translational and Clinical Research Institute; NIHR Newcastle Biomedical Research Centre and Campus for Ageing and Vitality, Newcastle University, Newcastle upon Tyne NE2 4HH, UK
| | - Kevin Murphy
- Department of Neurology, Sligo University Hospital, Sligo F91 H684, Ireland
| | - Tracey Baird
- Institute of Neurological Sciences, Queen Elizabeth University Hospital, Glasgow G51 4TF, UK
| | - Paul Maddison
- Department of Neurology, Queen’s Medical Centre, Nottingham NG7 2UH, UK
| | - Callum Duncan
- Department of Neurology, Aberdeen Royal Infirmary, NHS Grampian, Aberdeen AB25 2ZN, UK
| | - Joanna Poulton
- Nuffield Department of Women’s and Reproductive Health, University of Oxford, Oxford OX3 9DU, UK
| | - Victoria Nesbitt
- Department of Paediatrics, Medical Sciences Division, Oxford University, Oxford OX3 9DU, UK
- Department of Paediatrics, The Children's Hospital, Oxford, OX3 9DU, UK
| | - Michael G Hanna
- Department of Neuromuscular Diseases, University College London Queen Square Institute of Neurology and The National Hospital for Neurology and Neurosurgery, London WC1N 3BG, UK
| | - Robert D S Pitceathly
- Department of Neuromuscular Diseases, University College London Queen Square Institute of Neurology and The National Hospital for Neurology and Neurosurgery, London WC1N 3BG, UK
| | - Robert W Taylor
- Wellcome Centre for Mitochondrial Research, Translational and Clinical Research Institute; NIHR Newcastle Biomedical Research Centre and Campus for Ageing and Vitality, Newcastle University, Newcastle upon Tyne NE2 4HH, UK
- Department of Neurosciences, NHS Highly Specialised Service for Rare Mitochondrial Disorders, Newcastle upon Tyne NE2 4HH, UK
| | - Emma L Blakely
- Wellcome Centre for Mitochondrial Research, Translational and Clinical Research Institute; NIHR Newcastle Biomedical Research Centre and Campus for Ageing and Vitality, Newcastle University, Newcastle upon Tyne NE2 4HH, UK
- Department of Neurosciences, NHS Highly Specialised Service for Rare Mitochondrial Disorders, Newcastle upon Tyne NE2 4HH, UK
| | - Andrew M Schaefer
- Wellcome Centre for Mitochondrial Research, Translational and Clinical Research Institute; NIHR Newcastle Biomedical Research Centre and Campus for Ageing and Vitality, Newcastle University, Newcastle upon Tyne NE2 4HH, UK
- Directorate of Neurosciences, Royal Victoria Infirmary, The Newcastle upon Tyne Hospitals NHS Foundation Trust, Newcastle upon Tyne NE1 4LP, UK
- Department of Neurosciences, NHS Highly Specialised Service for Rare Mitochondrial Disorders, Newcastle upon Tyne NE2 4HH, UK
| | - Doug M Turnbull
- Wellcome Centre for Mitochondrial Research, Translational and Clinical Research Institute; NIHR Newcastle Biomedical Research Centre and Campus for Ageing and Vitality, Newcastle University, Newcastle upon Tyne NE2 4HH, UK
- Department of Neurosciences, NHS Highly Specialised Service for Rare Mitochondrial Disorders, Newcastle upon Tyne NE2 4HH, UK
| | - Robert McFarland
- Wellcome Centre for Mitochondrial Research, Translational and Clinical Research Institute; NIHR Newcastle Biomedical Research Centre and Campus for Ageing and Vitality, Newcastle University, Newcastle upon Tyne NE2 4HH, UK
- Department of Neurosciences, NHS Highly Specialised Service for Rare Mitochondrial Disorders, Newcastle upon Tyne NE2 4HH, UK
| | - Gráinne S Gorman
- Wellcome Centre for Mitochondrial Research, Translational and Clinical Research Institute; NIHR Newcastle Biomedical Research Centre and Campus for Ageing and Vitality, Newcastle University, Newcastle upon Tyne NE2 4HH, UK
- Directorate of Neurosciences, Royal Victoria Infirmary, The Newcastle upon Tyne Hospitals NHS Foundation Trust, Newcastle upon Tyne NE1 4LP, UK
- Department of Neurosciences, NHS Highly Specialised Service for Rare Mitochondrial Disorders, Newcastle upon Tyne NE2 4HH, UK
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5
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Baty K, Farrugia ME, Hopton S, Falkous G, Schaefer AM, Stewart W, Willison HJ, Reilly MM, Blakely EL, Taylor RW, Ng YS. A novel MT-CO2 variant causing cerebellar ataxia and neuropathy: The role of muscle biopsy in diagnosis and defining pathogenicity. Neuromuscul Disord 2021; 31:1186-1193. [PMID: 34325999 PMCID: PMC8708152 DOI: 10.1016/j.nmd.2021.05.014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2021] [Revised: 05/21/2021] [Accepted: 05/28/2021] [Indexed: 11/22/2022]
Abstract
Pathogenic variants in mitochondrial DNA (mtDNA) are associated with significant clinical heterogeneity with neuromuscular involvement commonly reported. Non-syndromic presentations of mtDNA disease continue to pose a diagnostic challenge and with genomic testing still necessitating a muscle biopsy in many cases. Here we describe an adult patient who presented with progressive ataxia, neuropathy and exercise intolerance in whom the application of numerous Mendelian gene panels had failed to make a genetic diagnosis. Muscle biopsy revealed characteristic mitochondrial pathology (cytochrome c oxidase deficient, ragged-red fibers) prompting a thorough investigation of the mitochondrial genome. Two heteroplasmic MT-CO2 gene variants (NC_012920.1: m.7887G>A and m.8250G>A) were identified, necessitating single fiber segregation and familial studies - including the biopsy of the patient's clinically-unaffected mother - to demonstrate pathogenicity of the novel m.7887G>A p.(Gly101Asp) variant and establishing this as the cause of the mitochondrial biochemical defects and clinical presentation. In the era of high throughput whole exome and genome sequencing, muscle biopsy remains a key investigation in the diagnosis of patients with non-syndromic presentations of adult-onset mitochondrial disease and fully defining the pathogenicity of novel mtDNA variants.
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Affiliation(s)
- Karen Baty
- Wellcome Centre for Mitochondrial Research, Translational and Clinical Research Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne NE2 4HH, UK; NHS Highly Specialised Services for Rare Mitochondrial Disorders, Newcastle upon Tyne Hospitals NHS Foundation Trust, Newcastle upon Tyne NE1 4LP, UK
| | - Maria E Farrugia
- Department of Neurology, Institute of Neurological Sciences, Queen Elizabeth University Hospital, Glasgow G51 4TF, UK
| | - Sila Hopton
- Wellcome Centre for Mitochondrial Research, Translational and Clinical Research Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne NE2 4HH, UK; NHS Highly Specialised Services for Rare Mitochondrial Disorders, Newcastle upon Tyne Hospitals NHS Foundation Trust, Newcastle upon Tyne NE1 4LP, UK
| | - Gavin Falkous
- Wellcome Centre for Mitochondrial Research, Translational and Clinical Research Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne NE2 4HH, UK; NHS Highly Specialised Services for Rare Mitochondrial Disorders, Newcastle upon Tyne Hospitals NHS Foundation Trust, Newcastle upon Tyne NE1 4LP, UK
| | - Andrew M Schaefer
- Wellcome Centre for Mitochondrial Research, Translational and Clinical Research Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne NE2 4HH, UK; NHS Highly Specialised Services for Rare Mitochondrial Disorders, Newcastle upon Tyne Hospitals NHS Foundation Trust, Newcastle upon Tyne NE1 4LP, UK; Directorate of Neurosciences, Royal Victoria Infirmary, Newcastle upon Tyne Hospitals NHS Foundation Trust, Newcastle upon Tyne NE1 4LP, UK
| | - William Stewart
- Department of Neuropathology, Queen Elizabeth University Hospital, Glasgow G51 4TF and Institute of Neuroscience and Psychology, University of Glasgow, G12 8QQ, UK
| | - Hugh J Willison
- Department of Neurology and Institute of Infection, Immunity and Inflammation, University of Glasgow, Glasgow G51 4TF, UK
| | - Mary M Reilly
- MRC Centre for Neuromuscular Diseases, Department of Neuromuscular Diseases, UCL Queen Square Institute of Neurology, London, WC1N 3BG, UK
| | - Emma L Blakely
- Wellcome Centre for Mitochondrial Research, Translational and Clinical Research Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne NE2 4HH, UK; NHS Highly Specialised Services for Rare Mitochondrial Disorders, Newcastle upon Tyne Hospitals NHS Foundation Trust, Newcastle upon Tyne NE1 4LP, UK
| | - Robert W Taylor
- Wellcome Centre for Mitochondrial Research, Translational and Clinical Research Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne NE2 4HH, UK; NHS Highly Specialised Services for Rare Mitochondrial Disorders, Newcastle upon Tyne Hospitals NHS Foundation Trust, Newcastle upon Tyne NE1 4LP, UK
| | - Yi Shiau Ng
- Wellcome Centre for Mitochondrial Research, Translational and Clinical Research Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne NE2 4HH, UK; NHS Highly Specialised Services for Rare Mitochondrial Disorders, Newcastle upon Tyne Hospitals NHS Foundation Trust, Newcastle upon Tyne NE1 4LP, UK; Directorate of Neurosciences, Royal Victoria Infirmary, Newcastle upon Tyne Hospitals NHS Foundation Trust, Newcastle upon Tyne NE1 4LP, UK.
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6
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Lim AZ, Ng YS, Blain A, Jiminez-Moreno C, Alston CL, Nesbitt V, Simmons L, Santra S, Wassmer E, Blakely EL, Turnbull DM, Taylor RW, Gorman GS, McFarland R. Natural History of Leigh Syndrome: A Study of Disease Burden and Progression. Ann Neurol 2021; 91:117-130. [PMID: 34716721 PMCID: PMC9534328 DOI: 10.1002/ana.26260] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2021] [Revised: 10/26/2021] [Accepted: 10/26/2021] [Indexed: 11/21/2022]
Abstract
Objective This observational cohort study aims to quantify disease burden over time, establish disease progression rates, and identify factors that may determine the disease course of Leigh syndrome. Methods Seventy‐two Leigh syndrome children who completed the Newcastle Paediatric Mitochondrial Disease Scale (NPMDS) at baseline at 3.7 years (interquartile range [IQR] = 2.0–7.6) and follow‐up assessments at 7.5 years (IQR = 3.7–11.0) in clinics were enrolled. Eighty‐two percent of this cohort had a confirmed genetic diagnosis, with pathogenic variants in the MT‐ATP6 and SURF1 genes being the most common cause. The total NPMDS scores denoted mild (0–14), moderate (15–25), and severe (>25) disease burden. Detailed clinical, neuroradiological, and molecular genetic findings were also analyzed. Results The median total NPMDS scores rose significantly (Z = −6.9, p < 0.001), and the percentage of children with severe disease burden doubled (22% → 42%) over 2.6 years of follow‐up. Poor function (especially mobility, self‐care, communication, feeding, and education) and extrapyramidal features contributed significantly to the disease burden (τb ≈ 0.45–0.68, p < 0.001). These children also deteriorated to wheelchair dependence (31% → 57%), exclusive enteral feeding (22% → 46%), and one‐to‐one assistance for self‐care (25% → 43%) during the study period. Twelve children (17%) died after their last NPMDS scores were recorded. These children had higher follow‐up NPMDS scores (disease burden; p < 0.001) and steeper increase in NPMDS score per annum (disease progression; p < 0.001). Other predictors of poor outcomes include SURF1 gene variants (p < 0.001) and bilateral caudate changes on neuroimaging (p < 0.01). Interpretation This study has objectively defined the disease burden and progression of Leigh syndrome. Our analysis has also uncovered potential influences on the trajectory of this neurodegenerative condition. ANN NEUROL 2022;91:117–130
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Affiliation(s)
- Albert Z Lim
- Wellcome Centre for Mitochondrial Research, Translational and Clinical Research Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, UK.,National Health Service Highly Specialised Services for Rare Mitochondrial Disorders, Newcastle upon Tyne Hospitals National Health Service Foundation Trust, Newcastle upon Tyne, UK
| | - Yi Shiau Ng
- Wellcome Centre for Mitochondrial Research, Translational and Clinical Research Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, UK.,National Health Service Highly Specialised Services for Rare Mitochondrial Disorders, Newcastle upon Tyne Hospitals National Health Service Foundation Trust, Newcastle upon Tyne, UK
| | - Alasdair Blain
- Wellcome Centre for Mitochondrial Research, Translational and Clinical Research Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, UK
| | - Cecilia Jiminez-Moreno
- Wellcome Centre for Mitochondrial Research, Translational and Clinical Research Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, UK
| | - Charlotte L Alston
- Wellcome Centre for Mitochondrial Research, Translational and Clinical Research Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, UK.,National Health Service Highly Specialised Services for Rare Mitochondrial Disorders, Newcastle upon Tyne Hospitals National Health Service Foundation Trust, Newcastle upon Tyne, UK
| | - Victoria Nesbitt
- National Health Service Highly Specialised Services for Rare Mitochondrial Disorders, Oxford University Hospitals National Health Service Foundation Trust, Oxford, UK
| | | | | | | | - Emma L Blakely
- Wellcome Centre for Mitochondrial Research, Translational and Clinical Research Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, UK.,National Health Service Highly Specialised Services for Rare Mitochondrial Disorders, Newcastle upon Tyne Hospitals National Health Service Foundation Trust, Newcastle upon Tyne, UK
| | - Doug M Turnbull
- Wellcome Centre for Mitochondrial Research, Translational and Clinical Research Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, UK.,National Health Service Highly Specialised Services for Rare Mitochondrial Disorders, Newcastle upon Tyne Hospitals National Health Service Foundation Trust, Newcastle upon Tyne, UK
| | - Robert W Taylor
- Wellcome Centre for Mitochondrial Research, Translational and Clinical Research Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, UK.,National Health Service Highly Specialised Services for Rare Mitochondrial Disorders, Newcastle upon Tyne Hospitals National Health Service Foundation Trust, Newcastle upon Tyne, UK
| | - Gráinne S Gorman
- Wellcome Centre for Mitochondrial Research, Translational and Clinical Research Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, UK.,National Health Service Highly Specialised Services for Rare Mitochondrial Disorders, Newcastle upon Tyne Hospitals National Health Service Foundation Trust, Newcastle upon Tyne, UK
| | - Robert McFarland
- Wellcome Centre for Mitochondrial Research, Translational and Clinical Research Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, UK.,National Health Service Highly Specialised Services for Rare Mitochondrial Disorders, Newcastle upon Tyne Hospitals National Health Service Foundation Trust, Newcastle upon Tyne, UK
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7
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Haumann S, Boix J, Knuever J, Bieling A, Vila Sanjurjo A, Elson JL, Blakely EL, Taylor RW, Riet N, Abken H, Kashkar H, Hornig-Do HT, Wiesner RJ. Mitochondrial DNA mutations induce mitochondrial biogenesis and increase the tumorigenic potential of Hodgkin and Reed-Sternberg cells. Carcinogenesis 2021; 41:1735-1745. [PMID: 32255484 DOI: 10.1093/carcin/bgaa032] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2019] [Revised: 03/17/2020] [Accepted: 04/06/2020] [Indexed: 11/14/2022] Open
Abstract
Functioning mitochondria are crucial for cancer metabolism, but aerobic glycolysis is still considered to be an important pathway for energy production in many tumor cells. Here we show that two well established, classic Hodgkin lymphoma (cHL) cell lines harbor deleterious variants within mitochondrial DNA (mtDNA) and thus exhibit reduced steady-state levels of respiratory chain complexes. However, instead of resulting in the expected bioenergetic defect, these mtDNA variants evoke a retrograde signaling response that induces mitochondrial biogenesis and ultimately results in increased mitochondrial mass as well as function and enhances proliferation in vitro as well as tumor growth in mice in vivo. When complex I assembly was impaired by knockdown of one of its subunits, this led to further increased mitochondrial mass and function and, consequently, further accelerated tumor growth in vivo. In contrast, inhibition of mitochondrial respiration in vivo by the mitochondrial complex I inhibitor metformin efficiently slowed down growth. We conclude that, as a new mechanism, mildly deleterious mtDNA variants in cHL cancer cells cause an increase of mitochondrial mass and enhanced function as a compensatory effect using a retrograde signaling pathway, which provides an obvious advantage for tumor growth.
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Affiliation(s)
- Sophie Haumann
- Center for Physiology and Pathophysiology, Institute of Vegetative Physiology, Medical Faculty, University of Cologne, Cologne, Germany.,Department of Pediatrics, Medical Faculty and University Hospital of Cologne, Cologne, Germany
| | - Julia Boix
- Center for Physiology and Pathophysiology, Institute of Vegetative Physiology, Medical Faculty, University of Cologne, Cologne, Germany
| | - Jana Knuever
- Center for Physiology and Pathophysiology, Institute of Vegetative Physiology, Medical Faculty, University of Cologne, Cologne, Germany.,Department of Dermatology, Medical Faculty and University Hospital of Cologne, Cologne, Germany
| | - Angela Bieling
- Center for Physiology and Pathophysiology, Institute of Vegetative Physiology, Medical Faculty, University of Cologne, Cologne, Germany
| | - Anton Vila Sanjurjo
- Grupo GIBE, Departamento de Bioloxía Celular e Molecular, Facultade de Ciencias, Universidade de A Coruña (UDC), A Coruña, Spain
| | - Joanna L Elson
- Institute of Genetic Medicine, Newcastle University, Newcastle upon Tyne, UK.,Human Metabolomics, North-West University, Potchefstroom, South Africa
| | - Emma L Blakely
- Wellcome Centre for Mitochondrial Research, Institute of Neuroscience, Newcastle University, Newcastle upon Tyne UK
| | - Robert W Taylor
- Wellcome Centre for Mitochondrial Research, Institute of Neuroscience, Newcastle University, Newcastle upon Tyne UK
| | - Nicole Riet
- Department I for Internal Medicine, Medical Faculty and University of Cologne, 50931 Cologne, Germany
| | - Hinrich Abken
- Department I for Internal Medicine, Medical Faculty and University of Cologne, 50931 Cologne, Germany.,Center for Molecular Medicine Cologne, 50931 Cologne (CMMC), University of Cologne, 50931 Cologne, Germany.,RCI, Regensburg Center for Interventional Immunology, Chair Gene-Immunotherapy, University Hospital Regensburg, Regensburg, Germany
| | - Hamid Kashkar
- Center for Molecular Medicine Cologne, 50931 Cologne (CMMC), University of Cologne, 50931 Cologne, Germany.,Institute of Medical Microbiology, Immunology and Hygiene, Medical Faculty and University Hospital of Cologne, Cologne, Germany.,Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, Cologne, Germany
| | - Hue-Tran Hornig-Do
- Center for Physiology and Pathophysiology, Institute of Vegetative Physiology, Medical Faculty, University of Cologne, Cologne, Germany
| | - Rudolf J Wiesner
- Center for Physiology and Pathophysiology, Institute of Vegetative Physiology, Medical Faculty, University of Cologne, Cologne, Germany.,Center for Molecular Medicine Cologne, 50931 Cologne (CMMC), University of Cologne, 50931 Cologne, Germany.,Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, Cologne, Germany
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8
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Horga A, Manole A, Mitchell AL, Bugiardini E, Hargreaves IP, Mowafi W, Bettencourt C, Blakely EL, He L, Polke JM, Woodward CE, Dalla Rosa I, Shah S, Pittman AM, Quinlivan R, Reilly MM, Taylor RW, Holt IJ, Hanna MG, Pitceathly RDS, Spinazzola A, Houlden H. Uniparental isodisomy of chromosome 2 causing MRPL44-related multisystem mitochondrial disease. Mol Biol Rep 2021; 48:2093-2104. [PMID: 33742325 DOI: 10.1007/s11033-021-06188-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2020] [Accepted: 01/28/2021] [Indexed: 12/15/2022]
Abstract
Mutations in nuclear-encoded protein subunits of the mitochondrial ribosome are an increasingly recognised cause of oxidative phosphorylation system (OXPHOS) disorders. Among them, mutations in the MRPL44 gene, encoding a structural protein of the large subunit of the mitochondrial ribosome, have been identified in four patients with OXPHOS defects and early-onset hypertrophic cardiomyopathy with or without additional clinical features. A 23-year-old individual with cardiac and skeletal myopathy, neurological involvement, and combined deficiency of OXPHOS complexes in skeletal muscle was clinically and genetically investigated. Analysis of whole-exome sequencing data revealed a homozygous mutation in MRPL44 (c.467 T > G), which was not present in the biological father, and a region of homozygosity involving most of chromosome 2, raising the possibility of uniparental disomy. Short-tandem repeat and genome-wide SNP microarray analyses of the family trio confirmed complete maternal uniparental isodisomy of chromosome 2. Mitochondrial ribosome assembly and mitochondrial translation were assessed in patient derived-fibroblasts. These studies confirmed that c.467 T > G affects the stability or assembly of the large subunit of the mitochondrial ribosome, leading to impaired mitochondrial protein synthesis and decreased levels of multiple OXPHOS components. This study provides evidence of complete maternal uniparental isodisomy of chromosome 2 in a patient with MRPL44-related disease, and confirms that MRLP44 mutations cause a mitochondrial translation defect that may present as a multisystem disorder with neurological involvement.
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Affiliation(s)
- Alejandro Horga
- MRC Centre for Neuromuscular Diseases, UCL Queen Square Institute of Neurology and the National Hospital for Neurology and Neurosurgery, Queen Square, London, WC1N 3BG, UK.
- Department of Neuromuscular Diseases, UCL Queen Square Institute of Neurology and the National Hospital for Neurology and Neurosurgery, Queen Square, London, WC1N 3BG, UK.
- Neuromuscular Diseases Unit, Department of Neurology, Hospital Clínico San Carlos and Instituto de Investigación Sanitaria San Carlos (IdISSC), 28040, Madrid, Spain.
| | - Andreea Manole
- MRC Centre for Neuromuscular Diseases, UCL Queen Square Institute of Neurology and the National Hospital for Neurology and Neurosurgery, Queen Square, London, WC1N 3BG, UK
- Department of Molecular Neuroscience, UCL Queen Square Institute of Neurology, Queen Square, London, WC1N 3BG, UK
| | - Alice L Mitchell
- Department of Clinical and Movement Neurosciences, UCL Queen Square Institute of Neurology, Royal Free Campus, London, NW3 2PF, UK
| | - Enrico Bugiardini
- MRC Centre for Neuromuscular Diseases, UCL Queen Square Institute of Neurology and the National Hospital for Neurology and Neurosurgery, Queen Square, London, WC1N 3BG, UK
- Department of Neuromuscular Diseases, UCL Queen Square Institute of Neurology and the National Hospital for Neurology and Neurosurgery, Queen Square, London, WC1N 3BG, UK
| | - Iain P Hargreaves
- Neurometabolic Unit, the National Hospital for Neurology and Neurosurgery, Queen Square, London, WC1N 3BG, UK
| | - Walied Mowafi
- Neurosciences Department, Calderdale Royal Hospital, Halifax, HX3 0PW, UK
| | - Conceição Bettencourt
- Queen Square Brain Bank for Neurological Disorders, Department of Clinical and Movement Neurosciences, UCL Queen Square Institute of Neurology, London, WC1N 1PJ, UK
| | - Emma L Blakely
- Institute of Neuroscience, Wellcome Centre for Mitochondrial Research, Newcastle University, Newcastle upon Tyne, NE2 4HH, UK
| | - Langping He
- Institute of Neuroscience, Wellcome Centre for Mitochondrial Research, Newcastle University, Newcastle upon Tyne, NE2 4HH, UK
| | - James M Polke
- Neurogenetic Unit, the National Hospital for Neurology and Neurosurgery, Queen Square, London, WC1N 3BG, UK
| | - Catherine E Woodward
- Neurogenetic Unit, the National Hospital for Neurology and Neurosurgery, Queen Square, London, WC1N 3BG, UK
| | - Ilaria Dalla Rosa
- Department of Clinical and Movement Neurosciences, UCL Queen Square Institute of Neurology, Royal Free Campus, London, NW3 2PF, UK
| | - Sachit Shah
- Lysholm Department of Neuroradiology, the National Hospital for Neurology and Neurosurgery, Queen Square, London, WC1N 3BG, UK
| | - Alan M Pittman
- Department of Molecular Neuroscience, UCL Queen Square Institute of Neurology, Queen Square, London, WC1N 3BG, UK
| | - Ros Quinlivan
- MRC Centre for Neuromuscular Diseases, UCL Queen Square Institute of Neurology and the National Hospital for Neurology and Neurosurgery, Queen Square, London, WC1N 3BG, UK
- Department of Neuromuscular Diseases, UCL Queen Square Institute of Neurology and the National Hospital for Neurology and Neurosurgery, Queen Square, London, WC1N 3BG, UK
| | - Mary M Reilly
- MRC Centre for Neuromuscular Diseases, UCL Queen Square Institute of Neurology and the National Hospital for Neurology and Neurosurgery, Queen Square, London, WC1N 3BG, UK
- Department of Neuromuscular Diseases, UCL Queen Square Institute of Neurology and the National Hospital for Neurology and Neurosurgery, Queen Square, London, WC1N 3BG, UK
| | - Robert W Taylor
- Institute of Neuroscience, Wellcome Centre for Mitochondrial Research, Newcastle University, Newcastle upon Tyne, NE2 4HH, UK
| | - Ian J Holt
- Department of Clinical and Movement Neurosciences, UCL Queen Square Institute of Neurology, Royal Free Campus, London, NW3 2PF, UK
- Biodonostia Health Research Institute, 20014, San Sebastián, Spain
- Ikerbasque, Basque Foundation for Science, 48013, Bilbao, Spain
| | - Michael G Hanna
- MRC Centre for Neuromuscular Diseases, UCL Queen Square Institute of Neurology and the National Hospital for Neurology and Neurosurgery, Queen Square, London, WC1N 3BG, UK
- Department of Neuromuscular Diseases, UCL Queen Square Institute of Neurology and the National Hospital for Neurology and Neurosurgery, Queen Square, London, WC1N 3BG, UK
| | - Robert D S Pitceathly
- MRC Centre for Neuromuscular Diseases, UCL Queen Square Institute of Neurology and the National Hospital for Neurology and Neurosurgery, Queen Square, London, WC1N 3BG, UK
- Department of Neuromuscular Diseases, UCL Queen Square Institute of Neurology and the National Hospital for Neurology and Neurosurgery, Queen Square, London, WC1N 3BG, UK
| | - Antonella Spinazzola
- MRC Centre for Neuromuscular Diseases, UCL Queen Square Institute of Neurology and the National Hospital for Neurology and Neurosurgery, Queen Square, London, WC1N 3BG, UK
- Department of Clinical and Movement Neurosciences, UCL Queen Square Institute of Neurology, Royal Free Campus, London, NW3 2PF, UK
| | - Henry Houlden
- MRC Centre for Neuromuscular Diseases, UCL Queen Square Institute of Neurology and the National Hospital for Neurology and Neurosurgery, Queen Square, London, WC1N 3BG, UK.
- Department of Neuromuscular Diseases, UCL Queen Square Institute of Neurology and the National Hospital for Neurology and Neurosurgery, Queen Square, London, WC1N 3BG, UK.
- Department of Molecular Neuroscience, UCL Queen Square Institute of Neurology, Queen Square, London, WC1N 3BG, UK.
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9
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Alston CL, Blakely EL, McFarland R, Taylor RW. The m.15043G > A MT-CYB variant is not a pathogenic mtDNA variant. J Neurol Sci 2020; 417:116950. [PMID: 32522371 PMCID: PMC7521199 DOI: 10.1016/j.jns.2020.116950] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2020] [Accepted: 05/25/2020] [Indexed: 12/01/2022]
Affiliation(s)
- Charlotte L Alston
- Wellcome Centre for Mitochondrial Research, Newcastle University, Framlington Place, Newcastle upon Tyne, NE2 4HH, UK; Translational and Clinical Research Institute, Faculty of Medical Sciences, Newcastle University, Framlington Place, Newcastle upon Tyne, NE2 4HH, UK; NHS Highly Specialised Service for Rare Mitochondrial Disorders, Royal Victoria Infirmary, Newcastle upon Tyne Hospitals NHS Foundation Trust, Queen Victoria Road, Newcastle upon Tyne, NE1 4LP, UK.
| | - Emma L Blakely
- NHS Highly Specialised Service for Rare Mitochondrial Disorders, Royal Victoria Infirmary, Newcastle upon Tyne Hospitals NHS Foundation Trust, Queen Victoria Road, Newcastle upon Tyne, NE1 4LP, UK
| | - Robert McFarland
- Wellcome Centre for Mitochondrial Research, Newcastle University, Framlington Place, Newcastle upon Tyne, NE2 4HH, UK; Translational and Clinical Research Institute, Faculty of Medical Sciences, Newcastle University, Framlington Place, Newcastle upon Tyne, NE2 4HH, UK; NHS Highly Specialised Service for Rare Mitochondrial Disorders, Royal Victoria Infirmary, Newcastle upon Tyne Hospitals NHS Foundation Trust, Queen Victoria Road, Newcastle upon Tyne, NE1 4LP, UK
| | - Robert W Taylor
- Wellcome Centre for Mitochondrial Research, Newcastle University, Framlington Place, Newcastle upon Tyne, NE2 4HH, UK; Translational and Clinical Research Institute, Faculty of Medical Sciences, Newcastle University, Framlington Place, Newcastle upon Tyne, NE2 4HH, UK; NHS Highly Specialised Service for Rare Mitochondrial Disorders, Royal Victoria Infirmary, Newcastle upon Tyne Hospitals NHS Foundation Trust, Queen Victoria Road, Newcastle upon Tyne, NE1 4LP, UK
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10
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Lujan SA, Longley MJ, Humble MH, Lavender CA, Burkholder A, Blakely EL, Alston CL, Gorman GS, Turnbull DM, McFarland R, Taylor RW, Kunkel TA, Copeland WC. Ultrasensitive deletion detection links mitochondrial DNA replication, disease, and aging. Genome Biol 2020; 21:248. [PMID: 32943091 PMCID: PMC7500033 DOI: 10.1186/s13059-020-02138-5] [Citation(s) in RCA: 36] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2020] [Accepted: 08/07/2020] [Indexed: 12/31/2022] Open
Abstract
BACKGROUND Acquired human mitochondrial genome (mtDNA) deletions are symptoms and drivers of focal mitochondrial respiratory deficiency, a pathological hallmark of aging and late-onset mitochondrial disease. RESULTS To decipher connections between these processes, we create LostArc, an ultrasensitive method for quantifying deletions in circular mtDNA molecules. LostArc reveals 35 million deletions (~ 470,000 unique spans) in skeletal muscle from 22 individuals with and 19 individuals without pathogenic variants in POLG. This nuclear gene encodes the catalytic subunit of replicative mitochondrial DNA polymerase γ. Ablation, the deleted mtDNA fraction, suffices to explain skeletal muscle phenotypes of aging and POLG-derived disease. Unsupervised bioinformatic analyses reveal distinct age- and disease-correlated deletion patterns. CONCLUSIONS These patterns implicate replication by DNA polymerase γ as the deletion driver and suggest little purifying selection against mtDNA deletions by mitophagy in postmitotic muscle fibers. Observed deletion patterns are best modeled as mtDNA deletions initiated by replication fork stalling during strand displacement mtDNA synthesis.
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Affiliation(s)
- Scott A Lujan
- Genome Integrity and Structural Biology Laboratory, DNA Replication Fidelity Group, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, NC, 27709, USA
| | - Matthew J Longley
- Genome Integrity and Structural Biology Laboratory, Mitochondrial DNA Replication Group, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, NC, 27709, USA
| | - Margaret H Humble
- Genome Integrity and Structural Biology Laboratory, Mitochondrial DNA Replication Group, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, NC, 27709, USA
| | - Christopher A Lavender
- Integrative Bioinformatics, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, NC, 27709, USA
| | - Adam Burkholder
- Integrative Bioinformatics, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, NC, 27709, USA
| | - Emma L Blakely
- Wellcome Centre for Mitochondrial Research, Translational and Clinical Research Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, NE2 4HH, UK
- NHS Highly Specialised Mitochondrial Diagnostic Laboratory, Newcastle upon Tyne Hospitals NHS Foundation Trust, Newcastle upon Tyne, NE1 4LP, UK
| | - Charlotte L Alston
- Wellcome Centre for Mitochondrial Research, Translational and Clinical Research Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, NE2 4HH, UK
- NHS Highly Specialised Mitochondrial Diagnostic Laboratory, Newcastle upon Tyne Hospitals NHS Foundation Trust, Newcastle upon Tyne, NE1 4LP, UK
| | - Grainne S Gorman
- Wellcome Centre for Mitochondrial Research, Translational and Clinical Research Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, NE2 4HH, UK
| | - Doug M Turnbull
- Wellcome Centre for Mitochondrial Research, Translational and Clinical Research Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, NE2 4HH, UK
| | - Robert McFarland
- Wellcome Centre for Mitochondrial Research, Translational and Clinical Research Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, NE2 4HH, UK
| | - Robert W Taylor
- Wellcome Centre for Mitochondrial Research, Translational and Clinical Research Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, NE2 4HH, UK
- NHS Highly Specialised Mitochondrial Diagnostic Laboratory, Newcastle upon Tyne Hospitals NHS Foundation Trust, Newcastle upon Tyne, NE1 4LP, UK
| | - Thomas A Kunkel
- Genome Integrity and Structural Biology Laboratory, DNA Replication Fidelity Group, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, NC, 27709, USA
| | - William C Copeland
- Genome Integrity and Structural Biology Laboratory, Mitochondrial DNA Replication Group, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, NC, 27709, USA.
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11
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Affiliation(s)
- Corina M Chilibeck
- Department of Ophthalmology, New Zealand National Eye Centre, Faculty of Medical and Health Science, The University of Auckland , Auckland, New Zealand.,Eye Department, Greenlane Clinical Centre, Auckland District Health Board , Auckland, New Zealand
| | - Emma E Glamuzina
- Adult and Paediatric National Metabolic Service, Starship Children's Hospital, Auckland District Health Board , Auckland, New Zealand
| | - Casey Y-J Ung
- Department of Ophthalmology, Southern District Health Board , Dunedin, New Zealand
| | - Emma L Blakely
- Translational and Clinical Research Institute, Newcastle University , Newcastle upon Tyne, UK.,NHS Highly Specialised Rare Mitochondrial Disorders Service, Newcastle upon Tyne Hospitals, NHS Foundation Trust , Newcastle upon Tyne, UK
| | - Robert W Taylor
- Translational and Clinical Research Institute, Newcastle University , Newcastle upon Tyne, UK.,NHS Highly Specialised Rare Mitochondrial Disorders Service, Newcastle upon Tyne Hospitals, NHS Foundation Trust , Newcastle upon Tyne, UK
| | - Andrea L Vincent
- Department of Ophthalmology, New Zealand National Eye Centre, Faculty of Medical and Health Science, The University of Auckland , Auckland, New Zealand.,Eye Department, Greenlane Clinical Centre, Auckland District Health Board , Auckland, New Zealand
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12
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Kipper K, Hecht M, Antunes NJ, Fairbanks LD, Levene M, Kalkan Uçar S, Schaefer A, Blakely EL, Bax BE. Quantification of Plasma and Urine Thymidine and 2'-Deoxyuridine by LC-MS/MS for the Pharmacodynamic Evaluation of Erythrocyte Encapsulated Thymidine Phosphorylase in Patients with Mitochondrial Neurogastrointestinal Encephalomyopathy. J Clin Med 2020; 9:jcm9030788. [PMID: 32183169 PMCID: PMC7141342 DOI: 10.3390/jcm9030788] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2020] [Revised: 03/05/2020] [Accepted: 03/11/2020] [Indexed: 02/05/2023] Open
Abstract
Mitochondrial neurogastrointestinal encephalomyopathy (MNGIE) is an ultra-rare disorder caused by mutations in TYMP, leading to a deficiency in thymidine phosphorylase and a subsequent systemic accumulation of thymidine and 2'-deoxyuridine. Erythrocyte-encapsulated thymidine phosphorylase (EE-TP) is under clinical development as an enzyme replacement therapy for MNGIE. Bioanalytical methods were developed according to regulatory guidelines for the quantification of thymidine and 2'-deoxyuridine in plasma and urine using liquid chromatography-tandem mass spectrometry (LC-MS/MS) for supporting the pharmacodynamic evaluation of EE-TP. Samples were deproteinized with 5% perchloric acid (v/v) and the supernatants analyzed using a Hypercarb column (30 × 2.1 mm, 3 µm), with mobile phases of 0.1% formic acid in methanol and 0.1% formic acid in deionized water. Detection was conducted using an ion-spray interface running in positive mode. Isotopically labelled thymidine and 2'-deoxyuridine were used as internal standards. Calibration curves for both metabolites showed linearity (r > 0.99) in the concentration ranges of 10-10,000 ng/mL for plasma, and 1-50 µg/mL for urine, with method analytical performances within the acceptable criteria for quality control samples. The plasma method was successfully applied to the diagnosis of two patients with MNGIE and the quantification of plasma metabolites in three patients treated with EE-TP.
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Affiliation(s)
- Karin Kipper
- Analytical Services International Ltd., St George’s University of London, Cranmer Terrace, London SW17 0RE, UK; (K.K.); (M.H.); (N.J.A.)
- University of Tartu, Institute of Chemistry, 14a Ravila Street, 50411 Tartu, Estonia
| | - Max Hecht
- Analytical Services International Ltd., St George’s University of London, Cranmer Terrace, London SW17 0RE, UK; (K.K.); (M.H.); (N.J.A.)
- University of Tartu, Institute of Chemistry, 14a Ravila Street, 50411 Tartu, Estonia
| | - Natalicia J. Antunes
- Analytical Services International Ltd., St George’s University of London, Cranmer Terrace, London SW17 0RE, UK; (K.K.); (M.H.); (N.J.A.)
- Department of Pharmacology, Faculty of Medical Sciences, State University of Campinas (UNICAMP), Campinas, SP 13083-881, Brazil
- Clinical Pharmacology, William Harvey Research Institute, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London EC1M 6BQ, UK
| | | | - Michelle Levene
- Molecular and Clinical Sciences, St George’s University of London, London SW17 0RE, UK;
| | - Sema Kalkan Uçar
- Division of Inborn Error of Metabolism, Ege University Medical Faculty, 35100 Izmir, Turkey;
| | - Andrew Schaefer
- The NHS Highly Specialised Service for Rare Mitochondrial Disorders, Newcastle upon Tyne NE2 4HH, UK; (A.S.); (E.L.B.)
| | - Emma L. Blakely
- The NHS Highly Specialised Service for Rare Mitochondrial Disorders, Newcastle upon Tyne NE2 4HH, UK; (A.S.); (E.L.B.)
| | - Bridget E. Bax
- Molecular and Clinical Sciences, St George’s University of London, London SW17 0RE, UK;
- Correspondence: ; Tel.: +0044(0)208-266-6836
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13
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Joshi PR, Baty K, Hopton S, Cordts I, Falkous G, Schoser B, Blakely EL, Taylor RW, Deschauer M. Progressive external ophthalmoplegia due to a recurrent de novo m.15990C>T MT-TP (mt-tRNA Pro) gene variant. Neuromuscul Disord 2020; 30:346-350. [PMID: 32305257 DOI: 10.1016/j.nmd.2020.02.020] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2019] [Revised: 02/11/2020] [Accepted: 02/27/2020] [Indexed: 11/25/2022]
Abstract
Progressive external ophthalmoplegia is typically associated with single or multiple mtDNA deletions but occasionally mtDNA single nucleotide variants within mitochondrial transfer RNAs (mt-tRNAs) are identified. We report a 34-year-old female sporadic patient with progressive external ophthalmoplegia accompanied by exercise intolerance but neither fixed weakness nor multisystemic involvement. Histopathologically, abundant COX-deficient fibres were present in muscle with immunofluorescence analysis confirming the loss of mitochondrial complex I and IV proteins. Molecular genetic analysis identified a rare heteroplasmic m.15990C>T mt-tRNAPro variant reported previously in a single patient with childhood-onset myopathy. The variant in our patient was restricted to muscle. Single muscle fibre analysis identified higher heteroplasmy load in COX-deficient fibres than COX-normal fibres, confirming segregation of high heteroplasmic load with a biochemical defect. Our case highlights the phenotypic variability typically observed with pathogenic mt-tRNA mutations, whilst the identification of a second case with the m.15990C>T mutation not only confirms pathogenicity but shows that de novo mt-tRNA point mutations can arise in multiple, unrelated patients.
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Affiliation(s)
- Pushpa Raj Joshi
- Department of Neurology, Martin-Luther-University Halle-Wittenberg, Germany.
| | - Karen Baty
- Wellcome Centre for Mitochondrial Research, Newcastle University, Newcastle upon Tyne, United Kingdom; NHS Highly Specialised Mitochondrial Diagnostic Laboratory, Newcastle upon Tyne Hospitals NHS Foundation Trust, Newcastle upon Tyne, United Kingdom
| | - Sila Hopton
- Wellcome Centre for Mitochondrial Research, Newcastle University, Newcastle upon Tyne, United Kingdom; NHS Highly Specialised Mitochondrial Diagnostic Laboratory, Newcastle upon Tyne Hospitals NHS Foundation Trust, Newcastle upon Tyne, United Kingdom
| | - Isabell Cordts
- Department of Neurology, Technical University Munich, School of Medicine, Munich, Germany
| | - Gavin Falkous
- Wellcome Centre for Mitochondrial Research, Newcastle University, Newcastle upon Tyne, United Kingdom; NHS Highly Specialised Mitochondrial Diagnostic Laboratory, Newcastle upon Tyne Hospitals NHS Foundation Trust, Newcastle upon Tyne, United Kingdom
| | - Benedikt Schoser
- Department of Neurology, Friedrich-Baur-Institute, University of Munich, Munich, Germany
| | - Emma L Blakely
- Wellcome Centre for Mitochondrial Research, Newcastle University, Newcastle upon Tyne, United Kingdom; NHS Highly Specialised Mitochondrial Diagnostic Laboratory, Newcastle upon Tyne Hospitals NHS Foundation Trust, Newcastle upon Tyne, United Kingdom
| | - Robert W Taylor
- Wellcome Centre for Mitochondrial Research, Newcastle University, Newcastle upon Tyne, United Kingdom; NHS Highly Specialised Mitochondrial Diagnostic Laboratory, Newcastle upon Tyne Hospitals NHS Foundation Trust, Newcastle upon Tyne, United Kingdom; Translational and Clinical Research Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Marcus Deschauer
- Department of Neurology, Technical University Munich, School of Medicine, Munich, Germany
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14
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Sommerville EW, Dalla Rosa I, Rosenberg MM, Bruni F, Thompson K, Rocha M, Blakely EL, He L, Falkous G, Schaefer AM, Yu‐Wai‐Man P, Chinnery PF, Hedstrom L, Spinazzola A, Taylor RW, Gorman GS. Identification of a novel heterozygous guanosine monophosphate reductase (GMPR) variant in a patient with a late-onset disorder of mitochondrial DNA maintenance. Clin Genet 2020; 97:276-286. [PMID: 31600844 PMCID: PMC7004030 DOI: 10.1111/cge.13652] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2019] [Revised: 09/18/2019] [Accepted: 09/27/2019] [Indexed: 12/18/2022]
Abstract
Autosomal dominant progressive external ophthalmoplegia (adPEO) is a late-onset, Mendelian mitochondrial disorder characterised by paresis of the extraocular muscles, ptosis, and skeletal-muscle restricted multiple mitochondrial DNA (mtDNA) deletions. Although dominantly inherited, pathogenic variants in POLG, TWNK and RRM2B are among the most common genetic defects of adPEO, identification of novel candidate genes and the underlying pathomechanisms remains challenging. We report the clinical, genetic and molecular investigations of a patient who presented in the seventh decade of life with PEO. Oxidative histochemistry revealed cytochrome c oxidase-deficient fibres and occasional ragged red fibres showing subsarcolemmal mitochondrial accumulation in skeletal muscle, while molecular studies identified the presence of multiple mtDNA deletions. Negative candidate screening of known nuclear genes associated with PEO prompted diagnostic exome sequencing, leading to the prioritisation of a novel heterozygous c.547G>C variant in GMPR (NM_006877.3) encoding guanosine monophosphate reductase, a cytosolic enzyme required for maintaining the cellular balance of adenine and guanine nucleotides. We show that the novel c.547G>C variant causes aberrant splicing, decreased GMPR protein levels in patient skeletal muscle, proliferating and quiescent cells, and is associated with subtle changes in nucleotide homeostasis protein levels and evidence of disturbed mtDNA maintenance in skeletal muscle. Despite confirmation of GMPR deficiency, demonstrating marked defects of mtDNA replication or nucleotide homeostasis in patient cells proved challenging. Our study proposes that GMPR is the 19th locus for PEO and highlights the complexities of uncovering disease mechanisms in late-onset PEO phenotypes.
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Affiliation(s)
- Ewen W. Sommerville
- Wellcome Centre for Mitochondrial Research, Institute of NeuroscienceNewcastle UniversityNewcastle upon TyneUK
| | - Ilaria Dalla Rosa
- Department of Clinical and Movement Neurosciences, UCL Queens Square Institute of Neurology, Royal Free CampusUniversity College LondonLondonUK
| | | | - Francesco Bruni
- Wellcome Centre for Mitochondrial Research, Institute of NeuroscienceNewcastle UniversityNewcastle upon TyneUK
- Department of Biosciences, Biotechnologies and BiopharmaceuticsUniversity of Bari “ldo Moro”BariItaly
| | - Kyle Thompson
- Wellcome Centre for Mitochondrial Research, Institute of NeuroscienceNewcastle UniversityNewcastle upon TyneUK
| | - Mariana Rocha
- Wellcome Centre for Mitochondrial Research, Institute of NeuroscienceNewcastle UniversityNewcastle upon TyneUK
| | - Emma L. Blakely
- Wellcome Centre for Mitochondrial Research, Institute of NeuroscienceNewcastle UniversityNewcastle upon TyneUK
| | - Langping He
- Wellcome Centre for Mitochondrial Research, Institute of NeuroscienceNewcastle UniversityNewcastle upon TyneUK
| | - Gavin Falkous
- Wellcome Centre for Mitochondrial Research, Institute of NeuroscienceNewcastle UniversityNewcastle upon TyneUK
| | - Andrew M. Schaefer
- Wellcome Centre for Mitochondrial Research, Institute of NeuroscienceNewcastle UniversityNewcastle upon TyneUK
| | - Patrick Yu‐Wai‐Man
- NIHR Biomedical Research Centre at Moorfields Eye Hospital and UCL Institute of OphthalmologyLondonUK
- MRC Mitochondrial Biology UnitUniversity of CambridgeCambridgeUK
- Cambridge Centre for Brain Repair, Department of Clinical NeurosciencesUniversity of CambridgeCambridgeUK
| | - Patrick F. Chinnery
- Department of Clinical Neuroscience & Medical Research Council Mitochondrial Biology UnitSchool of Clinical Medicine, University of CambridgeCambridgeUK
| | - Lizbeth Hedstrom
- Department of BiologyBrandeis UniversityWalthamMA
- Department of ChemistryBrandeis University, 415 South St.WalthamMA
| | - Antonella Spinazzola
- Department of Clinical and Movement Neurosciences, UCL Queens Square Institute of Neurology, Royal Free CampusUniversity College LondonLondonUK
- MRC Centre for Neuromuscular DiseasesUCL Institute of Neurology and National Hospital for Neurology and NeurosurgeryLondonUK
| | - Robert W. Taylor
- Wellcome Centre for Mitochondrial Research, Institute of NeuroscienceNewcastle UniversityNewcastle upon TyneUK
| | - Gráinne S. Gorman
- Wellcome Centre for Mitochondrial Research, Institute of NeuroscienceNewcastle UniversityNewcastle upon TyneUK
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15
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O'Donnell L, Blakely EL, Baty K, Alexander M, Bogdanova-Mihaylova P, Craig J, Walsh R, Brett F, Taylor RW, Murphy SM. Chronic Progressive External Ophthalmoplegia due to a Rare de novo m.12334G>A MT-TL2 Mitochondrial DNA Variant1. J Neuromuscul Dis 2020; 7:355-360. [PMID: 32310184 DOI: 10.3233/jnd-200486] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
We describe a patient with chronic progressive external ophthalmoplegia (CPEO) due to a rare mitochondrial genetic variant. Muscle biopsy revealed numerous cytochrome c oxidase (COX)-deficient fibres, prompting sequencing of the entire mitochondrial genome in muscle which revealed a rare m.12334G>A variant in the mitochondrial (mt-) tRNALeu(CUN)(MT-TL2) gene. Analysis of several tissues showed this to be a de novo mutational event. Single fibre studies confirmed the segregation of high m.12334G>A heteroplasmy levels with the COX histochemical defect, confirming pathogenicity of the m.12334G>A MT-TL2 variant. This case illustrates the importance of pursuing molecular genetic analysis in clinically-affected tissues when mitochondrial disease is suspected.
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Affiliation(s)
- Luke O'Donnell
- Department of Neurology, Tallaght University Hospital, Tallaght, Dublin, Ireland
| | - Emma L Blakely
- Wellcome Centre for Mitochondrial Research, Translational and Clinical Research Institute, Newcastle University, Newcastle upon Tyne, United Kingdom
- NHS Highly Specialised Mitochondrial Diagnostic Laboratory, Newcastle upon Tyne Hospitals NHS Foundation Trust, Newcastle upon Tyne, United Kingdom
| | - Karen Baty
- Wellcome Centre for Mitochondrial Research, Translational and Clinical Research Institute, Newcastle University, Newcastle upon Tyne, United Kingdom
- NHS Highly Specialised Mitochondrial Diagnostic Laboratory, Newcastle upon Tyne Hospitals NHS Foundation Trust, Newcastle upon Tyne, United Kingdom
| | - Michael Alexander
- Department of Neurophysiology, Tallaght University Hospital, Tallaght, Dublin, Ireland
- Academic Unit of Neurology, Trinity College Dublin, The University of Dublin, Dublin, Ireland
| | | | - John Craig
- Department of Neurology, Belfast Health and Social Care Trust, Belfast, United Kingdom
| | - Ronan Walsh
- Department of Neurology, Hermitage Medical Clinic, Dublin, Ireland
| | - Francesca Brett
- Department of Neuropathology, Beaumont Hospital, Dublin, Ireland
| | - Robert W Taylor
- Wellcome Centre for Mitochondrial Research, Translational and Clinical Research Institute, Newcastle University, Newcastle upon Tyne, United Kingdom
- NHS Highly Specialised Mitochondrial Diagnostic Laboratory, Newcastle upon Tyne Hospitals NHS Foundation Trust, Newcastle upon Tyne, United Kingdom
| | - Sinead M Murphy
- Department of Neurology, Tallaght University Hospital, Tallaght, Dublin, Ireland
- Academic Unit of Neurology, Trinity College Dublin, The University of Dublin, Dublin, Ireland
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16
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Thompson K, Collier JJ, Glasgow RIC, Robertson FM, Pyle A, Blakely EL, Alston CL, Oláhová M, McFarland R, Taylor RW. Recent advances in understanding the molecular genetic basis of mitochondrial disease. J Inherit Metab Dis 2020; 43:36-50. [PMID: 31021000 PMCID: PMC7041634 DOI: 10.1002/jimd.12104] [Citation(s) in RCA: 94] [Impact Index Per Article: 23.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/21/2019] [Revised: 04/03/2019] [Accepted: 04/24/2019] [Indexed: 12/22/2022]
Abstract
Mitochondrial disease is hugely diverse with respect to associated clinical presentations and underlying genetic causes, with pathogenic variants in over 300 disease genes currently described. Approximately half of these have been discovered in the last decade due to the increasingly widespread application of next generation sequencing technologies, in particular unbiased, whole exome-and latterly, whole genome sequencing. These technologies allow more genetic data to be collected from patients with mitochondrial disorders, continually improving the diagnostic success rate in a clinical setting. Despite these significant advances, some patients still remain without a definitive genetic diagnosis. Large datasets containing many variants of unknown significance have become a major challenge with next generation sequencing strategies and these require significant functional validation to confirm pathogenicity. This interface between diagnostics and research is critical in continuing to expand the list of known pathogenic variants and concomitantly enhance our knowledge of mitochondrial biology. The increasing use of whole exome sequencing, whole genome sequencing and other "omics" techniques such as transcriptomics and proteomics will generate even more data and allow further interrogation and validation of genetic causes, including those outside of coding regions. This will improve diagnostic yields still further and emphasizes the integral role that functional assessment of variant causality plays in this process-the overarching focus of this review.
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Affiliation(s)
- Kyle Thompson
- Wellcome Centre for Mitochondrial Research, Institute of NeuroscienceNewcastle UniversityNewcastle upon TyneUK
| | - Jack J. Collier
- Wellcome Centre for Mitochondrial Research, Institute of NeuroscienceNewcastle UniversityNewcastle upon TyneUK
| | - Ruth I. C. Glasgow
- Wellcome Centre for Mitochondrial Research, Institute of NeuroscienceNewcastle UniversityNewcastle upon TyneUK
| | - Fiona M. Robertson
- Wellcome Centre for Mitochondrial Research, Institute of NeuroscienceNewcastle UniversityNewcastle upon TyneUK
| | - Angela Pyle
- Wellcome Centre for Mitochondrial Research, Institute of Genetic MedicineNewcastle UniversityNewcastle upon TyneUK
| | - Emma L. Blakely
- Wellcome Centre for Mitochondrial Research, Institute of NeuroscienceNewcastle UniversityNewcastle upon TyneUK
- NHS Highly Specialised Mitochondrial Diagnostic LaboratoryNewcastle upon Tyne Hospitals NHS Foundation TrustNewcastle upon TyneUK
| | - Charlotte L. Alston
- Wellcome Centre for Mitochondrial Research, Institute of NeuroscienceNewcastle UniversityNewcastle upon TyneUK
- NHS Highly Specialised Mitochondrial Diagnostic LaboratoryNewcastle upon Tyne Hospitals NHS Foundation TrustNewcastle upon TyneUK
| | - Monika Oláhová
- Wellcome Centre for Mitochondrial Research, Institute of NeuroscienceNewcastle UniversityNewcastle upon TyneUK
| | - Robert McFarland
- Wellcome Centre for Mitochondrial Research, Institute of NeuroscienceNewcastle UniversityNewcastle upon TyneUK
| | - Robert W. Taylor
- Wellcome Centre for Mitochondrial Research, Institute of NeuroscienceNewcastle UniversityNewcastle upon TyneUK
- NHS Highly Specialised Mitochondrial Diagnostic LaboratoryNewcastle upon Tyne Hospitals NHS Foundation TrustNewcastle upon TyneUK
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17
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Ng YS, Martikainen MH, Gorman GS, Blain A, Bugiardini E, Bunting A, Schaefer AM, Alston CL, Blakely EL, Sharma S, Hughes I, Lim A, de Goede C, McEntagart M, Spinty S, Horrocks I, Roberts M, Woodward CE, Chinnery PF, Horvath R, Nesbitt V, Fratter C, Poulton J, Hanna MG, Pitceathly RDS, Taylor RW, Turnbull DM, McFarland R. Pathogenic variants in MT-ATP6: A United Kingdom-based mitochondrial disease cohort study. Ann Neurol 2019; 86:310-315. [PMID: 31187502 PMCID: PMC6771528 DOI: 10.1002/ana.25525] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2019] [Revised: 06/06/2019] [Accepted: 06/07/2019] [Indexed: 12/20/2022]
Abstract
Distinct clinical syndromes have been associated with pathogenic MT-ATP6 variants. In this cohort study, we identified 125 individuals (60 families) including 88 clinically affected individuals and 37 asymptomatic carriers. Thirty-one individuals presented with Leigh syndrome and 7 with neuropathy ataxia retinitis pigmentosa. The remaining 50 patients presented with variable nonsyndromic features including ataxia, neuropathy, and learning disability. We confirmed maternal inheritance in 39 families and demonstrated that tissue segregation patterns and phenotypic threshold are variant dependent. Our findings suggest that MT-ATP6-related mitochondrial DNA disease is best conceptualized as a mitochondrial disease spectrum disorder and should be routinely included in genetic ataxia and neuropathy gene panels. ANN NEUROL 2019;86:310-315.
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Affiliation(s)
- Yi Shiau Ng
- Wellcome Centre for Mitochondrial ResearchNewcastle UniversityNewcastle upon TyneUnited Kingdom
| | - Mika H. Martikainen
- Wellcome Centre for Mitochondrial ResearchNewcastle UniversityNewcastle upon TyneUnited Kingdom
- Faculty of MedicineUniversity of Turku, and Division of Clinical Neurosciences, Turku University HospitalTurkuFinland
| | - Gráinne S. Gorman
- Wellcome Centre for Mitochondrial ResearchNewcastle UniversityNewcastle upon TyneUnited Kingdom
| | - Alasdair Blain
- Wellcome Centre for Mitochondrial ResearchNewcastle UniversityNewcastle upon TyneUnited Kingdom
| | - Enrico Bugiardini
- Medical Research Council Centre for Neuromuscular DiseasesUniversity College London Queen Square Institute of Neurology and National Hospital for Neurology and NeurosurgeryLondonUnited Kingdom
- Department of Neuromuscular DiseasesUniversity College London Queen Square Institute of NeurologyLondonUnited Kingdom
| | - Apphia Bunting
- Nuffield Department of Obstetrics and GynaecologyUniversity of OxfordOxfordUnited Kingdom
| | - Andrew M. Schaefer
- Wellcome Centre for Mitochondrial ResearchNewcastle UniversityNewcastle upon TyneUnited Kingdom
| | - Charlotte L. Alston
- Wellcome Centre for Mitochondrial ResearchNewcastle UniversityNewcastle upon TyneUnited Kingdom
| | - Emma L. Blakely
- Wellcome Centre for Mitochondrial ResearchNewcastle UniversityNewcastle upon TyneUnited Kingdom
| | - Sunil Sharma
- Wellcome Centre for Mitochondrial ResearchNewcastle UniversityNewcastle upon TyneUnited Kingdom
| | - Imelda Hughes
- Royal Manchester Children's HospitalCentral Manchester University Hospitals National Health Service Foundation TrustManchesterUnited Kingdom
| | - Albert Lim
- Wellcome Centre for Mitochondrial ResearchNewcastle UniversityNewcastle upon TyneUnited Kingdom
| | - Christian de Goede
- Department of Paediatric NeurologyRoyal Preston HospitalPrestonUnited Kingdom
| | - Meriel McEntagart
- South West Thames Regional Genetics ServiceSt. George's HospitalLondonUnited Kingdom
| | - Stefan Spinty
- Alder Hey Children's National Health Service Foundation TrustLiverpoolUnited Kingdom
| | - Iain Horrocks
- Greater Glasgow and Clyde National Health Service Yorkhill HospitalGlasgowUnited Kingdom
| | - Mark Roberts
- Greater Manchester Neuroscience CentreSalford Royal National Health Service Foundation Trust, Manchester Academic Health Science CentreSalfordUnited Kingdom
| | - Cathy E. Woodward
- Neurogenetics UnitNational Hospital for Neurology and NeurosurgeryLondonUnited Kingdom
| | - Patrick F. Chinnery
- Department of Clinical NeurosciencesUniversity of Cambridge, Cambridge Biomedical CampusCambridgeUnited Kingdom
- MRC Mitochondrial Biology UnitUniversity of CambridgeCambridgeUnited Kingdom
| | - Rita Horvath
- Wellcome Centre for Mitochondrial ResearchNewcastle UniversityNewcastle upon TyneUnited Kingdom
- Department of Clinical NeurosciencesUniversity of Cambridge, Cambridge Biomedical CampusCambridgeUnited Kingdom
| | - Victoria Nesbitt
- Department of PaediatricsThe Children's HospitalOxfordUnited Kingdom
| | - Carl Fratter
- Oxford Medical Genetics LaboratoriesOxford University Hospitals National Health Service Foundation TrustOxfordUnited Kingdom
| | - Joanna Poulton
- Nuffield Department of Obstetrics and GynaecologyUniversity of OxfordOxfordUnited Kingdom
| | - Michael G. Hanna
- Medical Research Council Centre for Neuromuscular DiseasesUniversity College London Queen Square Institute of Neurology and National Hospital for Neurology and NeurosurgeryLondonUnited Kingdom
- Department of Neuromuscular DiseasesUniversity College London Queen Square Institute of NeurologyLondonUnited Kingdom
| | - Robert D. S. Pitceathly
- Medical Research Council Centre for Neuromuscular DiseasesUniversity College London Queen Square Institute of Neurology and National Hospital for Neurology and NeurosurgeryLondonUnited Kingdom
- Department of Neuromuscular DiseasesUniversity College London Queen Square Institute of NeurologyLondonUnited Kingdom
| | - Robert W. Taylor
- Wellcome Centre for Mitochondrial ResearchNewcastle UniversityNewcastle upon TyneUnited Kingdom
| | - Doug M. Turnbull
- Wellcome Centre for Mitochondrial ResearchNewcastle UniversityNewcastle upon TyneUnited Kingdom
| | - Robert McFarland
- Wellcome Centre for Mitochondrial ResearchNewcastle UniversityNewcastle upon TyneUnited Kingdom
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18
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Lim AZ, Blakely EL, Baty K, He L, Hopton S, Falkous G, McWilliam K, Cozens A, McFarland R, Taylor RW. A novel pathogenic m.4412G>A MT-TM mitochondrial DNA variant associated with childhood-onset seizures, myopathy and bilateral basal ganglia changes. Mitochondrion 2019; 47:18-23. [PMID: 31022467 PMCID: PMC6617384 DOI: 10.1016/j.mito.2019.04.007] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2019] [Revised: 04/18/2019] [Accepted: 04/19/2019] [Indexed: 12/03/2022]
Abstract
Mitochondrial DNA variants in the MT-TM (mt-tRNAMet) gene are rare, typically associated with myopathic phenotypes. We identified a novel MT-TM variant resulting in prolonged seizures with childhood-onset myopathy, retinopathy, short stature and elevated CSF lactate associated with bilateral basal ganglia changes on neuroimaging. Muscle biopsy confirmed multiple respiratory chain deficiencies and focal cytochrome c oxidase (COX) histochemical abnormalities. Next-generation sequencing of the mitochondrial genome revealed a novel m.4412G>A variant at high heteroplasmy levels in muscle that fulfils all accepted criteria for pathogenicity including segregation within single muscle fibres, thus broadening the genotypic and phenotypic landscape of mitochondrial tRNA-related disease.
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Affiliation(s)
- Albert Z Lim
- Wellcome Centre for Mitochondrial Research, Institute of Neuroscience, Newcastle University, Newcastle upon Tyne NE2 4HH, UK
| | - Emma L Blakely
- Wellcome Centre for Mitochondrial Research, Institute of Neuroscience, Newcastle University, Newcastle upon Tyne NE2 4HH, UK; NHS Highly Specialised Service for Rare Mitochondrial Disorders of Adults and Children, Newcastle upon Tyne Hospitals NHS Foundation Trust, Newcastle upon Tyne NE2 4HH, UK
| | - Karen Baty
- Wellcome Centre for Mitochondrial Research, Institute of Neuroscience, Newcastle University, Newcastle upon Tyne NE2 4HH, UK; NHS Highly Specialised Service for Rare Mitochondrial Disorders of Adults and Children, Newcastle upon Tyne Hospitals NHS Foundation Trust, Newcastle upon Tyne NE2 4HH, UK
| | - Langping He
- Wellcome Centre for Mitochondrial Research, Institute of Neuroscience, Newcastle University, Newcastle upon Tyne NE2 4HH, UK; NHS Highly Specialised Service for Rare Mitochondrial Disorders of Adults and Children, Newcastle upon Tyne Hospitals NHS Foundation Trust, Newcastle upon Tyne NE2 4HH, UK
| | - Sila Hopton
- Wellcome Centre for Mitochondrial Research, Institute of Neuroscience, Newcastle University, Newcastle upon Tyne NE2 4HH, UK; NHS Highly Specialised Service for Rare Mitochondrial Disorders of Adults and Children, Newcastle upon Tyne Hospitals NHS Foundation Trust, Newcastle upon Tyne NE2 4HH, UK
| | - Gavin Falkous
- Wellcome Centre for Mitochondrial Research, Institute of Neuroscience, Newcastle University, Newcastle upon Tyne NE2 4HH, UK; NHS Highly Specialised Service for Rare Mitochondrial Disorders of Adults and Children, Newcastle upon Tyne Hospitals NHS Foundation Trust, Newcastle upon Tyne NE2 4HH, UK
| | - Kenneth McWilliam
- Department of Paediatric Neurology, Royal Hospital for Sick Children, Edinburgh EH9 1LF, UK
| | - Alison Cozens
- Inherited Metabolic Disorders Scotland, NHS National Services Scotland, Glasgow G2 6QE, UK
| | - Robert McFarland
- Wellcome Centre for Mitochondrial Research, Institute of Neuroscience, Newcastle University, Newcastle upon Tyne NE2 4HH, UK
| | - Robert W Taylor
- Wellcome Centre for Mitochondrial Research, Institute of Neuroscience, Newcastle University, Newcastle upon Tyne NE2 4HH, UK; NHS Highly Specialised Service for Rare Mitochondrial Disorders of Adults and Children, Newcastle upon Tyne Hospitals NHS Foundation Trust, Newcastle upon Tyne NE2 4HH, UK.
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19
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Zierz CM, Baty K, Blakely EL, Hopton S, Falkous G, Schaefer AM, Hadjivassiliou M, Sarrigiannis PG, Ng YS, Taylor RW. A Novel Pathogenic Variant in MT-CO2 Causes an Isolated Mitochondrial Complex IV Deficiency and Late-Onset Cerebellar Ataxia. J Clin Med 2019; 8:jcm8060789. [PMID: 31167410 PMCID: PMC6617079 DOI: 10.3390/jcm8060789] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2019] [Revised: 05/28/2019] [Accepted: 05/30/2019] [Indexed: 01/03/2023] Open
Abstract
Both nuclear and mitochondrial DNA defects can cause isolated cytochrome c oxidase (COX; complex IV) deficiency, leading to the development of the mitochondrial disease. We report a 52-year-old female patient who presented with a late-onset, progressive cerebellar ataxia, tremor and axonal neuropathy. No family history of neurological disorder was reported. Although her muscle biopsy demonstrated a significant COX deficiency, there was no clinical and electromyographical evidence of myopathy. Electrophysiological studies identified low frequency sinusoidal postural tremor at 3 Hz, corroborating the clinical finding of cerebellar dysfunction. Complete sequencing of the mitochondrial DNA genome in muscle identified a novel MT-CO2 variant, m.8163A>G predicting p.(Tyr193Cys). We present several lines of evidence, in proving the pathogenicity of this heteroplasmic mitochondrial DNA variant, as the cause of her clinical presentation. Our findings serve as an important reminder that full mitochondrial DNA analysis should be included in the diagnostic pipeline for investigating individuals with spinocerebellar ataxia.
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Affiliation(s)
- Charlotte M Zierz
- Wellcome Centre for Mitochondrial Research, Institute of Neuroscience, Newcastle University, Newcastle upon Tyne NE2 4HH, UK.
| | - Karen Baty
- Wellcome Centre for Mitochondrial Research, Institute of Neuroscience, Newcastle University, Newcastle upon Tyne NE2 4HH, UK.
- NHS Highly Specialised Mitochondrial Diagnostic Laboratory, Newcastle upon Tyne Hospitals NHS Foundation Trust, Newcastle upon Tyne NE2 4HH, UK.
| | - Emma L Blakely
- Wellcome Centre for Mitochondrial Research, Institute of Neuroscience, Newcastle University, Newcastle upon Tyne NE2 4HH, UK.
- NHS Highly Specialised Mitochondrial Diagnostic Laboratory, Newcastle upon Tyne Hospitals NHS Foundation Trust, Newcastle upon Tyne NE2 4HH, UK.
| | - Sila Hopton
- Wellcome Centre for Mitochondrial Research, Institute of Neuroscience, Newcastle University, Newcastle upon Tyne NE2 4HH, UK.
- NHS Highly Specialised Mitochondrial Diagnostic Laboratory, Newcastle upon Tyne Hospitals NHS Foundation Trust, Newcastle upon Tyne NE2 4HH, UK.
| | - Gavin Falkous
- Wellcome Centre for Mitochondrial Research, Institute of Neuroscience, Newcastle University, Newcastle upon Tyne NE2 4HH, UK.
- NHS Highly Specialised Mitochondrial Diagnostic Laboratory, Newcastle upon Tyne Hospitals NHS Foundation Trust, Newcastle upon Tyne NE2 4HH, UK.
| | - Andrew M Schaefer
- Wellcome Centre for Mitochondrial Research, Institute of Neuroscience, Newcastle University, Newcastle upon Tyne NE2 4HH, UK.
- Department of Neurology, Royal Victoria Infirmary, Newcastle upon Tyne Hospitals NHS Foundation Trust, Newcastle upon Tyne NE1 4LP, UK.
| | - Marios Hadjivassiliou
- Academic Directorate of Neurosciences, Sheffield Teaching Hospitals NHS Foundation Trust, Royal Hallamshire Hospital, Sheffield S10 2JF, UK.
| | - Ptolemaios G Sarrigiannis
- Academic Directorate of Neurosciences, Sheffield Teaching Hospitals NHS Foundation Trust, Royal Hallamshire Hospital, Sheffield S10 2JF, UK.
- Department of Clinical Neurophysiology, Sheffield Teaching Hospitals NHS Foundation Trust, Royal Hallamshire Hospital, Sheffield S10 2JF, UK.
| | - Yi Shiau Ng
- Wellcome Centre for Mitochondrial Research, Institute of Neuroscience, Newcastle University, Newcastle upon Tyne NE2 4HH, UK.
- Department of Neurology, Royal Victoria Infirmary, Newcastle upon Tyne Hospitals NHS Foundation Trust, Newcastle upon Tyne NE1 4LP, UK.
| | - Robert W Taylor
- Wellcome Centre for Mitochondrial Research, Institute of Neuroscience, Newcastle University, Newcastle upon Tyne NE2 4HH, UK.
- NHS Highly Specialised Mitochondrial Diagnostic Laboratory, Newcastle upon Tyne Hospitals NHS Foundation Trust, Newcastle upon Tyne NE2 4HH, UK.
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20
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Grady JP, Pickett SJ, Ng YS, Alston CL, Blakely EL, Hardy SA, Feeney CL, Bright AA, Schaefer AM, Gorman GS, McNally RJ, Taylor RW, Turnbull DM, McFarland R. mtDNA heteroplasmy level and copy number indicate disease burden in m.3243A>G mitochondrial disease. EMBO Mol Med 2019; 10:emmm.201708262. [PMID: 29735722 PMCID: PMC5991564 DOI: 10.15252/emmm.201708262] [Citation(s) in RCA: 168] [Impact Index Per Article: 33.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Mitochondrial disease associated with the pathogenic m.3243A>G variant is a common, clinically heterogeneous, neurogenetic disorder. Using multiple linear regression and linear mixed modelling, we evaluated which commonly assayed tissue (blood N = 231, urine N = 235, skeletal muscle N = 77) represents the m.3243A>G mutation load and mitochondrial DNA (mtDNA) copy number most strongly associated with disease burden and progression. m.3243A>G levels are correlated in blood, muscle and urine (R2 = 0.61–0.73). Blood heteroplasmy declines by ~2.3%/year; we have extended previously published methodology to adjust for age. In urine, males have higher mtDNA copy number and ~20% higher m.3243A>G mutation load; we present formulas to adjust for this. Blood is the most highly correlated mutation measure for disease burden and progression in m.3243A>G‐harbouring individuals; increasing age and heteroplasmy contribute (R2 = 0.27, P < 0.001). In muscle, heteroplasmy, age and mtDNA copy number explain a higher proportion of variability in disease burden (R2 = 0.40, P < 0.001), although activity level and disease severity are likely to affect copy number. Whilst our data indicate that age‐corrected blood m.3243A>G heteroplasmy is the most convenient and reliable measure for routine clinical assessment, additional factors such as mtDNA copy number may also influence disease severity.
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Affiliation(s)
- John P Grady
- Wellcome Centre for Mitochondrial Research, Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, UK
| | - Sarah J Pickett
- Wellcome Centre for Mitochondrial Research, Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, UK
| | - Yi Shiau Ng
- Wellcome Centre for Mitochondrial Research, Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, UK
| | - Charlotte L Alston
- Wellcome Centre for Mitochondrial Research, Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, UK.,NHS Highly Specialised Mitochondrial Diagnostic Laboratory, Newcastle upon Tyne Hospitals NHS Foundation Trust, Newcastle upon Tyne, UK
| | - Emma L Blakely
- Wellcome Centre for Mitochondrial Research, Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, UK.,NHS Highly Specialised Mitochondrial Diagnostic Laboratory, Newcastle upon Tyne Hospitals NHS Foundation Trust, Newcastle upon Tyne, UK
| | - Steven A Hardy
- Wellcome Centre for Mitochondrial Research, Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, UK.,NHS Highly Specialised Mitochondrial Diagnostic Laboratory, Newcastle upon Tyne Hospitals NHS Foundation Trust, Newcastle upon Tyne, UK
| | - Catherine L Feeney
- Wellcome Centre for Mitochondrial Research, Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, UK
| | - Alexandra A Bright
- Wellcome Centre for Mitochondrial Research, Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, UK
| | - Andrew M Schaefer
- Wellcome Centre for Mitochondrial Research, Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, UK
| | - Gráinne S Gorman
- Wellcome Centre for Mitochondrial Research, Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, UK
| | - Richard Jq McNally
- Institute of Health and Society, Newcastle University, Newcastle upon Tyne, UK
| | - Robert W Taylor
- Wellcome Centre for Mitochondrial Research, Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, UK.,NHS Highly Specialised Mitochondrial Diagnostic Laboratory, Newcastle upon Tyne Hospitals NHS Foundation Trust, Newcastle upon Tyne, UK
| | - Doug M Turnbull
- Wellcome Centre for Mitochondrial Research, Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, UK
| | - Robert McFarland
- Wellcome Centre for Mitochondrial Research, Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, UK
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21
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Rocha MC, Rosa HS, Grady JP, Blakely EL, He L, Romain N, Haller RG, Newman J, McFarland R, Ng YS, Gorman GS, Schaefer AM, Tuppen HA, Taylor RW, Turnbull DM. Pathological mechanisms underlying single large-scale mitochondrial DNA deletions. Ann Neurol 2019; 83:115-130. [PMID: 29283441 PMCID: PMC5893934 DOI: 10.1002/ana.25127] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2017] [Revised: 12/01/2017] [Accepted: 12/21/2017] [Indexed: 12/17/2022]
Abstract
OBJECTIVE Single, large-scale deletions in mitochondrial DNA (mtDNA) are a common cause of mitochondrial disease. This study aimed to investigate the relationship between the genetic defect and molecular phenotype to improve understanding of pathogenic mechanisms associated with single, large-scale mtDNA deletions in skeletal muscle. METHODS We investigated 23 muscle biopsies taken from adult patients (6 males/17 females with a mean age of 43 years) with characterized single, large-scale mtDNA deletions. Mitochondrial respiratory chain deficiency in skeletal muscle biopsies was quantified by immunoreactivity levels for complex I and complex IV proteins. Single muscle fibers with varying degrees of deficiency were selected from 6 patient biopsies for determination of mtDNA deletion level and copy number by quantitative polymerase chain reaction. RESULTS We have defined 3 "classes" of single, large-scale deletion with distinct patterns of mitochondrial deficiency, determined by the size and location of the deletion. Single fiber analyses showed that fibers with greater respiratory chain deficiency harbored higher levels of mtDNA deletion with an increase in total mtDNA copy number. For the first time, we have demonstrated that threshold levels for complex I and complex IV deficiency differ based on deletion class. INTERPRETATION Combining genetic and immunofluorescent assays, we conclude that thresholds for complex I and complex IV deficiency are modulated by the deletion of complex-specific protein-encoding genes. Furthermore, removal of mt-tRNA genes impacts specific complexes only at high deletion levels, when complex-specific protein-encoding genes remain. These novel findings provide valuable insight into the pathogenic mechanisms associated with these mutations. Ann Neurol 2018;83:115-130.
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Affiliation(s)
- Mariana C Rocha
- Wellcome Centre for Mitochondrial Research, Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Hannah S Rosa
- Wellcome Centre for Mitochondrial Research, Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - John P Grady
- Wellcome Centre for Mitochondrial Research, Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Emma L Blakely
- Wellcome Centre for Mitochondrial Research, Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, United Kingdom.,National Health Service Highly Specialised Mitochondrial Diagnostic Laboratory, Newcastle upon Tyne Hospitals, National Health Service Foundation Trust, Newcastle upon Tyne, United Kingdom
| | - Langping He
- Wellcome Centre for Mitochondrial Research, Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, United Kingdom.,National Health Service Highly Specialised Mitochondrial Diagnostic Laboratory, Newcastle upon Tyne Hospitals, National Health Service Foundation Trust, Newcastle upon Tyne, United Kingdom
| | - Nadine Romain
- Department of Neurology and Neurotherapeutics, University of Texas Southwestern Medical Center, Dallas, TX.,Institute for Exercise and Environmental Medicine of Texas Health Presbyterian Hospital, Dallas, TX
| | - Ronald G Haller
- Department of Neurology and Neurotherapeutics, University of Texas Southwestern Medical Center, Dallas, TX.,Institute for Exercise and Environmental Medicine of Texas Health Presbyterian Hospital, Dallas, TX
| | - Jane Newman
- Wellcome Centre for Mitochondrial Research, Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Robert McFarland
- Wellcome Centre for Mitochondrial Research, Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Yi Shiau Ng
- Wellcome Centre for Mitochondrial Research, Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Grainne S Gorman
- Wellcome Centre for Mitochondrial Research, Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Andrew M Schaefer
- Wellcome Centre for Mitochondrial Research, Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Helen A Tuppen
- Wellcome Centre for Mitochondrial Research, Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Robert W Taylor
- Wellcome Centre for Mitochondrial Research, Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, United Kingdom.,National Health Service Highly Specialised Mitochondrial Diagnostic Laboratory, Newcastle upon Tyne Hospitals, National Health Service Foundation Trust, Newcastle upon Tyne, United Kingdom
| | - Doug M Turnbull
- Wellcome Centre for Mitochondrial Research, Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, United Kingdom
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22
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Kozak I, Oystreck DT, Abu-Amero KK, Nowilaty SR, Alkhalidi H, Elkhamary SM, Mohamed S, Hamad MHA, Salih MA, Blakely EL, Taylor RW, Bosley TM. NEW OBSERVATIONS REGARDING THE RETINOPATHY OF GENETICALLY CONFIRMED KEARNS-SAYRE SYNDROME. Retin Cases Brief Rep 2018; 12:349-358. [PMID: 28296806 DOI: 10.1097/icb.0000000000000503] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
PURPOSE To report novel retinal findings in Kearns-Sayre syndrome and correlate degree of retinopathy with other clinical findings. METHODS Observational case series of patients from Saudi Arabia with retinal and neuroophthalmologic examinations, medical chart review, and mitochondrial genetic evaluation. RESULTS The three unrelated patients had progressive external ophthalmoplegia and pigmentary retinopathy bilaterally. Muscle biopsy in two of the cases revealed mitochondrial myopathy. All three had abnormal findings on neuroimaging and modestly reduced visual acuity in both eyes with a variable pigmentary retinopathy. One of the patients had bilateral subretinal fibrosis with a full-thickness macular hole in the right eye. All three patients had single, large-scale mitochondrial DNA (mtDNA) deletions (5.0-7.6 kb in size) with blood mtDNA heteroplasmy levels ranging from below 20% to 57%. Severity of pigmentary retinopathy did not correlate with severity of progressive external ophthalmoplegia, but did correspond grossly with electroretinographic abnormalities, just as the degree of ocular motility restriction and ptosis in each patient correlated with the size of their extraocular muscles on neuroimaging. In addition, the size of the single, large-scale mtDNA deletion and level of mtDNA heteroplasmy corresponded with degree of ocular motility restriction but not with severity of retinopathy. CONCLUSION Subretinal fibrosis and macular hole are novel retinal observations which expand clinical profile in Kearns-Sayre syndrome. Genetic testing for mtDNA deletions and heteroplasmy in blood, muscle biopsy, careful ocular and retinal examination including electroretinography, and imaging are indispensable tests for this condition.
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Affiliation(s)
- Igor Kozak
- King Khaled Eye Specialist Hospital, Riyadh, Saudi Arabia
| | - Darren T Oystreck
- Department of Ophthalmology, College of Medicine, King Saud University, Riyadh, Saudi Arabia
- The Division of Ophthalmology, Faculty of Health Sciences, University of Stellenbosch, Tygerberg, South Africa
| | - Khaled K Abu-Amero
- Department of Ophthalmology, College of Medicine, King Saud University, Riyadh, Saudi Arabia
- Department of Ophthalmology, College of Medicine, University of Florida, Jacksonville, Florida
| | | | | | | | - Sarar Mohamed
- Pediatrics, College of Medicine, King Saud University Riyadh, Saudi Arabia
| | | | - Mustafa A Salih
- Pediatrics, College of Medicine, King Saud University Riyadh, Saudi Arabia
| | - Emma L Blakely
- The Wellcome Trust Centre for Mitochondrial Research, Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Robert W Taylor
- The Wellcome Trust Centre for Mitochondrial Research, Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Thomas M Bosley
- Department of Ophthalmology, College of Medicine, King Saud University, Riyadh, Saudi Arabia
- The Wilmer Eye Institute, Johns Hopkins University, Baltimore, Maryland
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23
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Ng YS, Lax NZ, Maddison P, Alston CL, Blakely EL, Hepplewhite PD, Riordan G, Meldau S, Chinnery PF, Pierre G, Chronopoulou E, Du A, Hughes I, Morris AA, Kamakari S, Chrousos G, Rodenburg RJ, Saris CGJ, Feeney C, Hardy SA, Sakakibara T, Sudo A, Okazaki Y, Murayama K, Mundy H, Hanna MG, Ohtake A, Schaefer AM, Champion MP, Turnbull DM, Taylor RW, Pitceathly RDS, McFarland R, Gorman GS. MT-ND5 Mutation Exhibits Highly Variable Neurological Manifestations at Low Mutant Load. EBioMedicine 2018; 30:86-93. [PMID: 29506874 PMCID: PMC5952215 DOI: 10.1016/j.ebiom.2018.02.010] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2018] [Revised: 02/03/2018] [Accepted: 02/12/2018] [Indexed: 01/06/2023] Open
Abstract
Mutations in the m.13094T>C MT-ND5 gene have been previously described in three cases of Leigh Syndrome (LS). In this retrospective, international cohort study we identified 20 clinically affected individuals (13 families) and four asymptomatic carriers. Ten patients were deceased at the time of analysis (median age of death was 10years (range: 5·4months-37years, IQR=17·9years). Nine patients manifested with LS, one with mitochondrial encephalomyopathy, lactic acidosis and stroke-like episodes (MELAS), and one with Leber hereditary optic neuropathy. The remaining nine patients presented with either overlapping syndromes or isolated neurological symptoms. Mitochondrial respiratory chain activity analysis was normal in five out of ten muscle biopsies. We confirmed maternal inheritance in six families, and demonstrated marked variability in tissue segregation, and phenotypic expression at relatively low blood mutant loads. Neuropathological studies of two patients manifesting with LS/MELAS showed prominent capillary proliferation, microvacuolation and severe neuronal cell loss in the brainstem and cerebellum, with conspicuous absence of basal ganglia involvement. These findings suggest that whole mtDNA genome sequencing should be considered in patients with suspected mitochondrial disease presenting with complex neurological manifestations, which would identify over 300 known pathogenic variants including the m.13094T>C.
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Affiliation(s)
- Yi Shiau Ng
- Wellcome Centre for Mitochondrial Research, Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, UK
| | - Nichola Z Lax
- Wellcome Centre for Mitochondrial Research, Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, UK
| | - Paul Maddison
- Department of Neurology, Queen's Medical Centre, Nottingham, UK
| | - Charlotte L Alston
- Wellcome Centre for Mitochondrial Research, Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, UK
| | - Emma L Blakely
- Wellcome Centre for Mitochondrial Research, Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, UK
| | - Philippa D Hepplewhite
- Wellcome Centre for Mitochondrial Research, Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, UK
| | - Gillian Riordan
- Paediatric Neurology Department, Red Cross War Memorial Children's Hospital, Cape Town, South Africa
| | - Surita Meldau
- Division of Chemical Pathology, Faculty of Health Sciences, University of Cape Town, South Africa; National Health Laboratory Service, Cape Town, South Africa
| | - Patrick F Chinnery
- Wellcome Centre for Mitochondrial Research, Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, UK; Medical Research Council Mitochondrial Biology Unit, Cambridge Biomedical Campus, Cambridge, UK
| | - Germaine Pierre
- Department of Inherited Metabolic Disease, Division of Women's and Children's Services, University Hospitals Bristol NHS Foundation Trust, Bristol, UK
| | - Efstathia Chronopoulou
- Department of Inherited Metabolic Disease, Division of Women's and Children's Services, University Hospitals Bristol NHS Foundation Trust, Bristol, UK
| | - Ailian Du
- Tongren Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, China
| | - Imelda Hughes
- Royal Manchester Children's Hospital, Central Manchester University Hospitals NHS Foundation Trust, UK
| | - Andrew A Morris
- Institute of Human Development, University of Manchester, Manchester M13 9WL, UK; Central Manchester University Hospitals NHS Foundation Trust, Manchester Academic Health Science Centre, Manchester M13 9WL, UK
| | - Smaragda Kamakari
- Ophthalmic Genetics Unit, OMMA, Institute of Ophthalmology, Athens, Greece
| | - Georgia Chrousos
- Pediatric Ophthalmology Department, MITERA Children's Hospital, Athens, Greece
| | - Richard J Rodenburg
- Radboud Center for Mitochondrial Medicine, Department of Pediatrics, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Christiaan G J Saris
- Department of Neurology, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Catherine Feeney
- Wellcome Centre for Mitochondrial Research, Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, UK
| | - Steven A Hardy
- Wellcome Centre for Mitochondrial Research, Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, UK
| | - Takafumi Sakakibara
- Department of Pediatrics, Nara Medical University Hospital, Nara 634-8522, Japan
| | - Akira Sudo
- Department of Pediatrics, Sapporo City General Hospital, Sapporo 060-8604, Japan
| | - Yasushi Okazaki
- Diagnostics and Therapeutics of Intractable Diseases, Intractable Disease Research Center, Graduate School of Medicine, Juntendo University, Tokyo 113-8421, Japan
| | - Kei Murayama
- Department of Metabolism, Chiba Children's Hospital, Chiba 266-0007, Japan
| | - Helen Mundy
- Evelina London Children's Hospital, Guy's & St Thomas' NHS Foundation Trust, London, UK
| | - Michael G Hanna
- MRC Centre for Neuromuscular Diseases, UCL Institute of Neurology and National Hospital for Neurology and Neurosurgery, London, UK
| | - Akira Ohtake
- Department of Pediatrics, Faculty of Medicine, Saitama Medical University, Saitama 350-0495, Japan
| | - Andrew M Schaefer
- Wellcome Centre for Mitochondrial Research, Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, UK
| | - Mike P Champion
- Evelina London Children's Hospital, Guy's & St Thomas' NHS Foundation Trust, London, UK
| | - Doug M Turnbull
- Wellcome Centre for Mitochondrial Research, Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, UK
| | - Robert W Taylor
- Wellcome Centre for Mitochondrial Research, Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, UK
| | - Robert D S Pitceathly
- MRC Centre for Neuromuscular Diseases, UCL Institute of Neurology and National Hospital for Neurology and Neurosurgery, London, UK
| | - Robert McFarland
- Wellcome Centre for Mitochondrial Research, Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, UK
| | - Gráinne S Gorman
- Wellcome Centre for Mitochondrial Research, Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, UK.
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24
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Sommerville EW, Jones RL, Hardy SA, Blakely EL, Pyle A, Schaefer AM, Chinnery PF, Turnbull DM, Gorman GS, Taylor RW. Opening One's Eyes to Mosaicism in Progressive External Ophthalmoplegia. Neurol Genet 2017; 3:e202. [PMID: 29264394 PMCID: PMC5732003 DOI: 10.1212/nxg.0000000000000202] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/08/2017] [Accepted: 08/27/2017] [Indexed: 11/24/2022]
Affiliation(s)
- Ewen W Sommerville
- Wellcome Centre for Mitochondrial Research (E.W.S., R.L.J., S.A.H., E.L.B., A.M.S., D.M.T., G.S.G., R.W.T.), Institute of Neuroscience, The Medical School, Newcastle University, United Kingdom; Department of Molecular and Human Genetics (E.W.S.), Baylor College of Medicine, Houston, TX; NHS Highly Specialised Mitochondrial Diagnostic Laboratory (R.L.J., S.A.H., E.L.B., R.W.T.), Newcastle upon Tyne Hospitals NHS Foundation Trust, United Kingdom; Wellcome Centre for Mitochondrial Research (A.P.), Institute of Genetic Medicine, Newcastle University, United Kingdom; and Department of Clinical Neurosciences (P.F.C.), School of Clinical Medicine, and MRC Mitochondrial Biology Unit (P.F.C.), University of Cambridge, United Kingdom
| | - Rachel L Jones
- Wellcome Centre for Mitochondrial Research (E.W.S., R.L.J., S.A.H., E.L.B., A.M.S., D.M.T., G.S.G., R.W.T.), Institute of Neuroscience, The Medical School, Newcastle University, United Kingdom; Department of Molecular and Human Genetics (E.W.S.), Baylor College of Medicine, Houston, TX; NHS Highly Specialised Mitochondrial Diagnostic Laboratory (R.L.J., S.A.H., E.L.B., R.W.T.), Newcastle upon Tyne Hospitals NHS Foundation Trust, United Kingdom; Wellcome Centre for Mitochondrial Research (A.P.), Institute of Genetic Medicine, Newcastle University, United Kingdom; and Department of Clinical Neurosciences (P.F.C.), School of Clinical Medicine, and MRC Mitochondrial Biology Unit (P.F.C.), University of Cambridge, United Kingdom
| | - Steven A Hardy
- Wellcome Centre for Mitochondrial Research (E.W.S., R.L.J., S.A.H., E.L.B., A.M.S., D.M.T., G.S.G., R.W.T.), Institute of Neuroscience, The Medical School, Newcastle University, United Kingdom; Department of Molecular and Human Genetics (E.W.S.), Baylor College of Medicine, Houston, TX; NHS Highly Specialised Mitochondrial Diagnostic Laboratory (R.L.J., S.A.H., E.L.B., R.W.T.), Newcastle upon Tyne Hospitals NHS Foundation Trust, United Kingdom; Wellcome Centre for Mitochondrial Research (A.P.), Institute of Genetic Medicine, Newcastle University, United Kingdom; and Department of Clinical Neurosciences (P.F.C.), School of Clinical Medicine, and MRC Mitochondrial Biology Unit (P.F.C.), University of Cambridge, United Kingdom
| | - Emma L Blakely
- Wellcome Centre for Mitochondrial Research (E.W.S., R.L.J., S.A.H., E.L.B., A.M.S., D.M.T., G.S.G., R.W.T.), Institute of Neuroscience, The Medical School, Newcastle University, United Kingdom; Department of Molecular and Human Genetics (E.W.S.), Baylor College of Medicine, Houston, TX; NHS Highly Specialised Mitochondrial Diagnostic Laboratory (R.L.J., S.A.H., E.L.B., R.W.T.), Newcastle upon Tyne Hospitals NHS Foundation Trust, United Kingdom; Wellcome Centre for Mitochondrial Research (A.P.), Institute of Genetic Medicine, Newcastle University, United Kingdom; and Department of Clinical Neurosciences (P.F.C.), School of Clinical Medicine, and MRC Mitochondrial Biology Unit (P.F.C.), University of Cambridge, United Kingdom
| | - Angela Pyle
- Wellcome Centre for Mitochondrial Research (E.W.S., R.L.J., S.A.H., E.L.B., A.M.S., D.M.T., G.S.G., R.W.T.), Institute of Neuroscience, The Medical School, Newcastle University, United Kingdom; Department of Molecular and Human Genetics (E.W.S.), Baylor College of Medicine, Houston, TX; NHS Highly Specialised Mitochondrial Diagnostic Laboratory (R.L.J., S.A.H., E.L.B., R.W.T.), Newcastle upon Tyne Hospitals NHS Foundation Trust, United Kingdom; Wellcome Centre for Mitochondrial Research (A.P.), Institute of Genetic Medicine, Newcastle University, United Kingdom; and Department of Clinical Neurosciences (P.F.C.), School of Clinical Medicine, and MRC Mitochondrial Biology Unit (P.F.C.), University of Cambridge, United Kingdom
| | - Andrew M Schaefer
- Wellcome Centre for Mitochondrial Research (E.W.S., R.L.J., S.A.H., E.L.B., A.M.S., D.M.T., G.S.G., R.W.T.), Institute of Neuroscience, The Medical School, Newcastle University, United Kingdom; Department of Molecular and Human Genetics (E.W.S.), Baylor College of Medicine, Houston, TX; NHS Highly Specialised Mitochondrial Diagnostic Laboratory (R.L.J., S.A.H., E.L.B., R.W.T.), Newcastle upon Tyne Hospitals NHS Foundation Trust, United Kingdom; Wellcome Centre for Mitochondrial Research (A.P.), Institute of Genetic Medicine, Newcastle University, United Kingdom; and Department of Clinical Neurosciences (P.F.C.), School of Clinical Medicine, and MRC Mitochondrial Biology Unit (P.F.C.), University of Cambridge, United Kingdom
| | - Patrick F Chinnery
- Wellcome Centre for Mitochondrial Research (E.W.S., R.L.J., S.A.H., E.L.B., A.M.S., D.M.T., G.S.G., R.W.T.), Institute of Neuroscience, The Medical School, Newcastle University, United Kingdom; Department of Molecular and Human Genetics (E.W.S.), Baylor College of Medicine, Houston, TX; NHS Highly Specialised Mitochondrial Diagnostic Laboratory (R.L.J., S.A.H., E.L.B., R.W.T.), Newcastle upon Tyne Hospitals NHS Foundation Trust, United Kingdom; Wellcome Centre for Mitochondrial Research (A.P.), Institute of Genetic Medicine, Newcastle University, United Kingdom; and Department of Clinical Neurosciences (P.F.C.), School of Clinical Medicine, and MRC Mitochondrial Biology Unit (P.F.C.), University of Cambridge, United Kingdom
| | - Douglass M Turnbull
- Wellcome Centre for Mitochondrial Research (E.W.S., R.L.J., S.A.H., E.L.B., A.M.S., D.M.T., G.S.G., R.W.T.), Institute of Neuroscience, The Medical School, Newcastle University, United Kingdom; Department of Molecular and Human Genetics (E.W.S.), Baylor College of Medicine, Houston, TX; NHS Highly Specialised Mitochondrial Diagnostic Laboratory (R.L.J., S.A.H., E.L.B., R.W.T.), Newcastle upon Tyne Hospitals NHS Foundation Trust, United Kingdom; Wellcome Centre for Mitochondrial Research (A.P.), Institute of Genetic Medicine, Newcastle University, United Kingdom; and Department of Clinical Neurosciences (P.F.C.), School of Clinical Medicine, and MRC Mitochondrial Biology Unit (P.F.C.), University of Cambridge, United Kingdom
| | - Gráinne S Gorman
- Wellcome Centre for Mitochondrial Research (E.W.S., R.L.J., S.A.H., E.L.B., A.M.S., D.M.T., G.S.G., R.W.T.), Institute of Neuroscience, The Medical School, Newcastle University, United Kingdom; Department of Molecular and Human Genetics (E.W.S.), Baylor College of Medicine, Houston, TX; NHS Highly Specialised Mitochondrial Diagnostic Laboratory (R.L.J., S.A.H., E.L.B., R.W.T.), Newcastle upon Tyne Hospitals NHS Foundation Trust, United Kingdom; Wellcome Centre for Mitochondrial Research (A.P.), Institute of Genetic Medicine, Newcastle University, United Kingdom; and Department of Clinical Neurosciences (P.F.C.), School of Clinical Medicine, and MRC Mitochondrial Biology Unit (P.F.C.), University of Cambridge, United Kingdom
| | - Robert W Taylor
- Wellcome Centre for Mitochondrial Research (E.W.S., R.L.J., S.A.H., E.L.B., A.M.S., D.M.T., G.S.G., R.W.T.), Institute of Neuroscience, The Medical School, Newcastle University, United Kingdom; Department of Molecular and Human Genetics (E.W.S.), Baylor College of Medicine, Houston, TX; NHS Highly Specialised Mitochondrial Diagnostic Laboratory (R.L.J., S.A.H., E.L.B., R.W.T.), Newcastle upon Tyne Hospitals NHS Foundation Trust, United Kingdom; Wellcome Centre for Mitochondrial Research (A.P.), Institute of Genetic Medicine, Newcastle University, United Kingdom; and Department of Clinical Neurosciences (P.F.C.), School of Clinical Medicine, and MRC Mitochondrial Biology Unit (P.F.C.), University of Cambridge, United Kingdom
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25
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Gill JS, Hardy SA, Blakely EL, Hopton S, Nemeth AH, Fratter C, Poulton J, Taylor RW, Downes SM. Pigmentary retinopathy, rod-cone dysfunction and sensorineural deafness associated with a rare mitochondrial tRNA Lys (m.8340G>A) gene variant. Br J Ophthalmol 2017; 101:1298-1302. [PMID: 28729369 PMCID: PMC5574396 DOI: 10.1136/bjophthalmol-2017-310370] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2017] [Revised: 05/23/2017] [Accepted: 06/01/2017] [Indexed: 12/04/2022]
Abstract
Background/Aim The rare mitochondrial DNA (mtDNA) variant m.8340G>A has been previously reported in the literature in a single, sporadic case of mitochondrial myopathy. In this report, we aim to investigate the case of a 39-year-old male patient with sensorineural deafness who presented to the eye clinic with nyctalopia, retinal pigmentary changes and bilateral cortical cataracts. Methods The patient was examined clinically and investigated with autofluorescence, full-field electroretinography, electro-oculogram and dark adaptometry. Sequencing of the mitochondrial genome in blood and muscle tissue was followed by histochemical and biochemical analyses together with single fibre studies of a muscle biopsy to confirm a mitochondrial aetiology. Results Electrophysiology, colour testing and dark adaptometry showed significant photoreceptor dysfunction with macular involvement. Sequencing the complete mitochondrial genome revealed a rare mitochondrial tRNALys (MTTK) gene variant—m.8340G>A—which was heteroplasmic in blood (11%) and skeletal muscle (65%) and cosegregated with cytochrome c oxidase-deficient fibres in single-fibre studies. Conclusion We confirm the pathogenicity of the rare mitochondrial m.8340G>A variant the basis of single-fibre segregation studies and its association with an expanded clinical phenotype. Our case expands the phenotypic spectrum of diseases associated with mitochondrial tRNA point mutations, highlighting the importance of considering a mitochondrial diagnosis in similar cases presenting to the eye clinic and the importance of further genetic testing if standard mutational analysis does not yield a result.
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Affiliation(s)
| | - Steven A Hardy
- Wellcome Trust Centre for Mitochondrial Research, Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, UK
| | - Emma L Blakely
- Wellcome Trust Centre for Mitochondrial Research, Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, UK
| | - Sila Hopton
- Wellcome Trust Centre for Mitochondrial Research, Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, UK
| | - Andrea H Nemeth
- Department of Clinical Genetics, Churchill Hospital, Oxford, UK.,Nuffield Department of Clinical Neuroscience, John Radcliffe Hospital, Oxford, UK
| | - Carl Fratter
- Oxford Medical Genetics Laboratory, Churchill Hospital, Oxford, UK
| | - Joanna Poulton
- Department of Clinical Genetics, Churchill Hospital, Oxford, UK
| | - Robert W Taylor
- Wellcome Trust Centre for Mitochondrial Research, Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, UK
| | - Susan M Downes
- John Radcliffe Hospital, Oxford, UK.,Nuffield Department of Clinical Neuroscience, John Radcliffe Hospital, Oxford, UK
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Martikainen MH, Ng YS, Gorman GS, Alston CL, Blakely EL, Schaefer AM, Chinnery PF, Burn DJ, Taylor RW, McFarland R, Turnbull DM. Clinical, Genetic, and Radiological Features of Extrapyramidal Movement Disorders in Mitochondrial Disease. JAMA Neurol 2017; 73:668-74. [PMID: 27111573 DOI: 10.1001/jamaneurol.2016.0355] [Citation(s) in RCA: 57] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
IMPORTANCE Extrapyramidal movement disorders associated with mitochondrial disease are difficult to treat and can lead to considerable disability. Moreover, potential new treatment trials on the horizon highlight the importance of genotype-phenotype associations and deep phenotyping of the movement disorders related to mitochondrial disease. OBJECTIVE To describe the phenotype, genetic etiology, and investigation of extrapyramidal movement disorders in a large and well-defined mitochondrial disease cohort. DESIGN, SETTING, AND PARTICIPANTS An observational cohort study at a single national referral center. Among 678 patients (87% adults) followed up at the Newcastle mitochondrial disease specialized referral center between January 1, 2000, and January 31, 2015, 42 patients (12 pediatric, 30 adult) with genetic or biochemical evidence of mitochondrial disease and with 1 or more predefined extrapyramidal movement disorders (parkinsonism, dystonia, tremor, chorea, and restless legs syndrome) were included. MAIN OUTCOMES AND MEASURES We investigated the prevalence and genetic causes of dystonia and parkinsonism as well as radiological findings in the context of movement disorders in mitochondrial disease. All patients were interviewed and examined. All available medical notes and clinical, radiological, and genetic investigations were reviewed. RESULTS Forty-two patients (mean [SD] age, 37 [25] years; 38% female) with mitochondrial disease (12 pediatric [age range, 4-14 years], 30 adult [age range, 20-81 years]) with extrapyramidal movement disorders were identified. Dystonia manifested in 11 pediatric patients (92%), often in the context of Leigh syndrome; parkinsonism predominated in 13 adult patients (43%), among whom 5 (38%) harbored either dominant (n = 1) or recessive (n = 4) mutations in POLG. Eleven adult patients (37%) manifested with either generalized or multifocal dystonia related to mutations in mitochondrial DNA, among which the most common were the m.11778G>A mutation and mutations in MT-ATP6 (3 of 11 patients [27%] each). Bilateral basal ganglia lesions were the most common finding in brain magnetic resonance imaging, usually associated with generalized dystonia or Leigh syndrome. CONCLUSIONS AND RELEVANCE Dystonia, often associated with Leigh syndrome, was the most common extrapyramidal movement disorder among pediatric patients with mitochondrial disease. Parkinsonism was the most prevalent extrapyramidal movement disorder in adults and was commonly associated with POLG mutations; dystonia was predominantly associated with mitochondrial DNA mutations. These findings may help direct genetic screening in a busy neurology outpatient setting.
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Affiliation(s)
- Mika H Martikainen
- Division of Clinical Neurosciences, University of Turku and Turku University Hospital, Turku, Finland2Wellcome Trust Centre for Mitochondrial Research and Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, England
| | - Yi Shiau Ng
- Wellcome Trust Centre for Mitochondrial Research and Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, England
| | - Gráinne S Gorman
- Wellcome Trust Centre for Mitochondrial Research and Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, England
| | - Charlotte L Alston
- Wellcome Trust Centre for Mitochondrial Research and Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, England
| | - Emma L Blakely
- Wellcome Trust Centre for Mitochondrial Research and Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, England
| | - Andrew M Schaefer
- Wellcome Trust Centre for Mitochondrial Research and Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, England
| | - Patrick F Chinnery
- Wellcome Trust Centre for Mitochondrial Research and Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, England3Department of Clinical Neuroscience, School of Clinical Medicine, University of Cambridge, Cambridge, England4Medical Resear
| | - David J Burn
- Wellcome Trust Centre for Mitochondrial Research and Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, England
| | - Robert W Taylor
- Wellcome Trust Centre for Mitochondrial Research and Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, England
| | - Robert McFarland
- Wellcome Trust Centre for Mitochondrial Research and Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, England
| | - Doug M Turnbull
- Wellcome Trust Centre for Mitochondrial Research and Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, England
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Van Maldergem L, Besse A, De Paepe B, Blakely EL, Appadurai V, Humble MM, Piard J, Craig K, He L, Hella P, Debray FG, Martin JJ, Gaussen M, Laloux P, Stevanin G, Van Coster R, Taylor RW, Copeland WC, Mormont E, Bonnen PE. POLG2 deficiency causes adult-onset syndromic sensory neuropathy, ataxia and parkinsonism. Ann Clin Transl Neurol 2016; 4:4-14. [PMID: 28078310 PMCID: PMC5221457 DOI: 10.1002/acn3.361] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2016] [Revised: 08/09/2016] [Accepted: 08/12/2016] [Indexed: 01/06/2023] Open
Abstract
Objective Mitochondrial dysfunction plays a key role in the pathophysiology of neurodegenerative disorders such as ataxia and Parkinson's disease. We describe an extended Belgian pedigree where seven individuals presented with adult‐onset cerebellar ataxia, axonal peripheral ataxic neuropathy, and tremor, in variable combination with parkinsonism, seizures, cognitive decline, and ophthalmoplegia. We sought to identify the underlying molecular etiology and characterize the mitochondrial pathophysiology of this neurological syndrome. Methods Clinical, neurophysiological, and neuroradiological evaluations were conducted. Patient muscle and cultured fibroblasts underwent extensive analyses to assess mitochondrial function. Genetic studies including genome‐wide sequencing were conducted. Results Hallmarks of mitochondrial dysfunction were present in patients’ tissues including ultrastructural anomalies of mitochondria, mosaic cytochrome c oxidase deficiency, and multiple mtDNA deletions. We identified a splice acceptor variant in POLG2, c.970‐1G>C, segregating with disease in this family and associated with a concomitant decrease in levels of POLG2 protein in patient cells. Interpretation This work extends the clinical spectrum of POLG2 deficiency to include an overwhelming, adult‐onset neurological syndrome that includes cerebellar syndrome, peripheral neuropathy, tremor, and parkinsonism. We therefore suggest to include POLG2 sequencing in the evaluation of ataxia and sensory neuropathy in adults, especially when it is accompanied by tremor or parkinsonism with white matter disease. The demonstration that deletions of mtDNA resulting from autosomal‐dominant POLG2 variant lead to a monogenic neurodegenerative multicomponent syndrome provides further evidence for a major role of mitochondrial dysfunction in the pathomechanism of nonsyndromic forms of the component neurodegenerative disorders.
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Affiliation(s)
- Lionel Van Maldergem
- Centre de génétique humaine Université de Franche-Comté Besançon France; Metabolic Unit Centre of Human Genetics University Hospital Liège Belgium
| | - Arnaud Besse
- Department of Molecular and Human Genetics Baylor College of Medicine Houston Texas
| | - Boel De Paepe
- Department of Pediatrics Division of Child Neurology & Metabolism Ghent University Hospital Belgium
| | - Emma L Blakely
- Wellcome Trust Centre for Mitochondrial Research Institute of Neuroscience Newcastle University Newcastle upon Tyne United Kingdom
| | - Vivek Appadurai
- Department of Molecular and Human Genetics Baylor College of Medicine Houston Texas
| | - Margaret M Humble
- Mitochondrial DNA Replication Group National Institute of Environmental Health Sciences Durham North Carolina
| | - Juliette Piard
- Centre de génétique humaine Université de Franche-Comté Besançon France
| | - Kate Craig
- Wellcome Trust Centre for Mitochondrial Research Institute of Neuroscience Newcastle University Newcastle upon Tyne United Kingdom
| | - Langping He
- Wellcome Trust Centre for Mitochondrial Research Institute of Neuroscience Newcastle University Newcastle upon Tyne United Kingdom
| | - Pierre Hella
- Department of Neurology Sambre and Meuse Regional Hospital Namur Belgium
| | | | | | - Marion Gaussen
- Inserm U1127 CNRS UMR 7225 Sorbonne Universités UPMC Paris France; Institut du Cerveau et de la Moelle épinière Hopital Pitié-Salpêtrière Paris France; Ecole Pratique des Hautes Etudes PSL Université Laboratoire de neurogénétique F-75013 Paris France
| | - Patrice Laloux
- Université catholique de Louvain CHU UCL Namur Department of Neurology B5530 Yvoir Belgium; UCL Institute of Neuroscience (IoNS) B1200 Brussels Belgium
| | - Giovanni Stevanin
- Inserm U1127 CNRS UMR 7225 Sorbonne Universités UPMC Paris France; Institut du Cerveau et de la Moelle épinière Hopital Pitié-Salpêtrière Paris France; Ecole Pratique des Hautes Etudes PSL Université Laboratoire de neurogénétique F-75013 Paris France
| | - Rudy Van Coster
- Department of Pediatrics Division of Child Neurology & Metabolism Ghent University Hospital Belgium
| | - Robert W Taylor
- Wellcome Trust Centre for Mitochondrial Research Institute of Neuroscience Newcastle University Newcastle upon Tyne United Kingdom
| | - William C Copeland
- Mitochondrial DNA Replication Group National Institute of Environmental Health Sciences Durham North Carolina
| | - Eric Mormont
- Université catholique de Louvain CHU UCL Namur Department of Neurology B5530 Yvoir Belgium; UCL Institute of Neuroscience (IoNS) B1200 Brussels Belgium
| | - Penelope E Bonnen
- Department of Molecular and Human Genetics Baylor College of Medicine Houston Texas
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Gupta A, Colmenero I, Ragge NK, Blakely EL, He L, McFarland R, Taylor RW, Vogt J, Milford DV. Compound heterozygous RMND1 gene variants associated with chronic kidney disease, dilated cardiomyopathy and neurological involvement: a case report. BMC Res Notes 2016; 9:325. [PMID: 27350610 PMCID: PMC4924262 DOI: 10.1186/s13104-016-2131-2] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2016] [Accepted: 06/18/2016] [Indexed: 01/02/2023] Open
Abstract
Background Nuclear gene mutations are being increasingly recognised as causes of mitochondrial disease. The nuclear gene RMND1 has recently been implicated in mitochondrial disease, but the spectrum of pathogenic variants and associated phenotype for this gene, has not been fully elucidated. Case presentation An 11-month-old boy presented with renal impairment associated with a truncal ataxia, bilateral sensorineural hearing loss, hypotonia, delayed visual maturation and global developmental delay. Over a 9-year period, he progressed to chronic kidney disease stage V and developed a dilated cardiomyopathy. Abnormalities in renal and muscle biopsy as well as cytochrome c oxidase activity prompted genetic testing. After exclusion of mitochondrial DNA defects, nuclear genetic studies identified compound heterozygous RMND1 (c.713A>G, p. Asn238Ser and c.565C>T, p.Gln189*) variants. Conclusion We report RMND1 gene variants associated with end stage renal failure, dilated cardiomyopathy, deafness and neurological involvement due to mitochondrial disease. This case expands current knowledge of mitochondrial disease secondary to mutation of the RMND1 gene by further delineating renal manifestations including histopathology. To our knowledge dilated cardiomyopathy has not been reported with renal failure in mitochondrial disease due to mutations of RMND1. The presence of this complication was important in this case as it precluded renal transplantation.
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Affiliation(s)
- Asheeta Gupta
- Birmingham Childrens Hospital, Steelhouse Lane, Birmingham, B4 6NH, UK
| | - Isabel Colmenero
- Birmingham Childrens Hospital, Steelhouse Lane, Birmingham, B4 6NH, UK
| | - Nicola K Ragge
- Clinical Genetics Unit, West Midlands Regional Genetics Service, Birmingham Women's Hospital, Birmingham, B15 2TG, UK.,Faculty of Health and Life Sciences, Oxford Brookes University, Oxford, OX3 0BP, UK
| | - Emma L Blakely
- Wellcome Trust Centre for Mitochondrial Research, Institute of Neuroscience, The Medical School, Newcastle University, Newcastle upon Tyne, NE2 4HH, UK
| | - Langping He
- Wellcome Trust Centre for Mitochondrial Research, Institute of Neuroscience, The Medical School, Newcastle University, Newcastle upon Tyne, NE2 4HH, UK
| | - Robert McFarland
- Wellcome Trust Centre for Mitochondrial Research, Institute of Neuroscience, The Medical School, Newcastle University, Newcastle upon Tyne, NE2 4HH, UK
| | - Robert W Taylor
- Wellcome Trust Centre for Mitochondrial Research, Institute of Neuroscience, The Medical School, Newcastle University, Newcastle upon Tyne, NE2 4HH, UK
| | - Julie Vogt
- Clinical Genetics Unit, West Midlands Regional Genetics Service, Birmingham Women's Hospital, Birmingham, B15 2TG, UK
| | - David V Milford
- Birmingham Childrens Hospital, Steelhouse Lane, Birmingham, B4 6NH, UK.
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Hardy SA, Blakely EL, Purvis AI, Rocha MC, Ahmed S, Falkous G, Poulton J, Rose MR, O'Mahony O, Bermingham N, Dougan CF, Ng YS, Horvath R, Turnbull DM, Gorman GS, Taylor RW. Pathogenic mtDNA mutations causing mitochondrial myopathy: The need for muscle biopsy. Neurol Genet 2016; 2:e82. [PMID: 27536729 PMCID: PMC4972142 DOI: 10.1212/nxg.0000000000000082] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/22/2016] [Accepted: 05/16/2016] [Indexed: 11/26/2022]
Affiliation(s)
- Steven A Hardy
- Wellcome Trust Centre for Mitochondrial Research, Institute of Neuroscience (S.A.H., E.L.B., A.I.P., M.C.R., S.A., G.F., Y.S.N., D.M.T., G.S.G., R.W.T.), The Medical School, Institute of Genetic Medicine (R.H.), Newcastle University; Nuffield Department of Obstetrics and Gynaecology (J.P.), University of Oxford; Department of Neurology (M.R.R.), King's College Hospital NHS Foundation Trust, London; Departments of Neurology and Neuropathology (O.O., N.B.), Cork University Hospital, Ireland; and The Walton Centre for Neurology and Neurosurgery (C.F.D.), Liverpool, UK
| | - Emma L Blakely
- Wellcome Trust Centre for Mitochondrial Research, Institute of Neuroscience (S.A.H., E.L.B., A.I.P., M.C.R., S.A., G.F., Y.S.N., D.M.T., G.S.G., R.W.T.), The Medical School, Institute of Genetic Medicine (R.H.), Newcastle University; Nuffield Department of Obstetrics and Gynaecology (J.P.), University of Oxford; Department of Neurology (M.R.R.), King's College Hospital NHS Foundation Trust, London; Departments of Neurology and Neuropathology (O.O., N.B.), Cork University Hospital, Ireland; and The Walton Centre for Neurology and Neurosurgery (C.F.D.), Liverpool, UK
| | - Andrew I Purvis
- Wellcome Trust Centre for Mitochondrial Research, Institute of Neuroscience (S.A.H., E.L.B., A.I.P., M.C.R., S.A., G.F., Y.S.N., D.M.T., G.S.G., R.W.T.), The Medical School, Institute of Genetic Medicine (R.H.), Newcastle University; Nuffield Department of Obstetrics and Gynaecology (J.P.), University of Oxford; Department of Neurology (M.R.R.), King's College Hospital NHS Foundation Trust, London; Departments of Neurology and Neuropathology (O.O., N.B.), Cork University Hospital, Ireland; and The Walton Centre for Neurology and Neurosurgery (C.F.D.), Liverpool, UK
| | - Mariana C Rocha
- Wellcome Trust Centre for Mitochondrial Research, Institute of Neuroscience (S.A.H., E.L.B., A.I.P., M.C.R., S.A., G.F., Y.S.N., D.M.T., G.S.G., R.W.T.), The Medical School, Institute of Genetic Medicine (R.H.), Newcastle University; Nuffield Department of Obstetrics and Gynaecology (J.P.), University of Oxford; Department of Neurology (M.R.R.), King's College Hospital NHS Foundation Trust, London; Departments of Neurology and Neuropathology (O.O., N.B.), Cork University Hospital, Ireland; and The Walton Centre for Neurology and Neurosurgery (C.F.D.), Liverpool, UK
| | - Syeda Ahmed
- Wellcome Trust Centre for Mitochondrial Research, Institute of Neuroscience (S.A.H., E.L.B., A.I.P., M.C.R., S.A., G.F., Y.S.N., D.M.T., G.S.G., R.W.T.), The Medical School, Institute of Genetic Medicine (R.H.), Newcastle University; Nuffield Department of Obstetrics and Gynaecology (J.P.), University of Oxford; Department of Neurology (M.R.R.), King's College Hospital NHS Foundation Trust, London; Departments of Neurology and Neuropathology (O.O., N.B.), Cork University Hospital, Ireland; and The Walton Centre for Neurology and Neurosurgery (C.F.D.), Liverpool, UK
| | - Gavin Falkous
- Wellcome Trust Centre for Mitochondrial Research, Institute of Neuroscience (S.A.H., E.L.B., A.I.P., M.C.R., S.A., G.F., Y.S.N., D.M.T., G.S.G., R.W.T.), The Medical School, Institute of Genetic Medicine (R.H.), Newcastle University; Nuffield Department of Obstetrics and Gynaecology (J.P.), University of Oxford; Department of Neurology (M.R.R.), King's College Hospital NHS Foundation Trust, London; Departments of Neurology and Neuropathology (O.O., N.B.), Cork University Hospital, Ireland; and The Walton Centre for Neurology and Neurosurgery (C.F.D.), Liverpool, UK
| | - Joanna Poulton
- Wellcome Trust Centre for Mitochondrial Research, Institute of Neuroscience (S.A.H., E.L.B., A.I.P., M.C.R., S.A., G.F., Y.S.N., D.M.T., G.S.G., R.W.T.), The Medical School, Institute of Genetic Medicine (R.H.), Newcastle University; Nuffield Department of Obstetrics and Gynaecology (J.P.), University of Oxford; Department of Neurology (M.R.R.), King's College Hospital NHS Foundation Trust, London; Departments of Neurology and Neuropathology (O.O., N.B.), Cork University Hospital, Ireland; and The Walton Centre for Neurology and Neurosurgery (C.F.D.), Liverpool, UK
| | - Michael R Rose
- Wellcome Trust Centre for Mitochondrial Research, Institute of Neuroscience (S.A.H., E.L.B., A.I.P., M.C.R., S.A., G.F., Y.S.N., D.M.T., G.S.G., R.W.T.), The Medical School, Institute of Genetic Medicine (R.H.), Newcastle University; Nuffield Department of Obstetrics and Gynaecology (J.P.), University of Oxford; Department of Neurology (M.R.R.), King's College Hospital NHS Foundation Trust, London; Departments of Neurology and Neuropathology (O.O., N.B.), Cork University Hospital, Ireland; and The Walton Centre for Neurology and Neurosurgery (C.F.D.), Liverpool, UK
| | - Olivia O'Mahony
- Wellcome Trust Centre for Mitochondrial Research, Institute of Neuroscience (S.A.H., E.L.B., A.I.P., M.C.R., S.A., G.F., Y.S.N., D.M.T., G.S.G., R.W.T.), The Medical School, Institute of Genetic Medicine (R.H.), Newcastle University; Nuffield Department of Obstetrics and Gynaecology (J.P.), University of Oxford; Department of Neurology (M.R.R.), King's College Hospital NHS Foundation Trust, London; Departments of Neurology and Neuropathology (O.O., N.B.), Cork University Hospital, Ireland; and The Walton Centre for Neurology and Neurosurgery (C.F.D.), Liverpool, UK
| | - Niamh Bermingham
- Wellcome Trust Centre for Mitochondrial Research, Institute of Neuroscience (S.A.H., E.L.B., A.I.P., M.C.R., S.A., G.F., Y.S.N., D.M.T., G.S.G., R.W.T.), The Medical School, Institute of Genetic Medicine (R.H.), Newcastle University; Nuffield Department of Obstetrics and Gynaecology (J.P.), University of Oxford; Department of Neurology (M.R.R.), King's College Hospital NHS Foundation Trust, London; Departments of Neurology and Neuropathology (O.O., N.B.), Cork University Hospital, Ireland; and The Walton Centre for Neurology and Neurosurgery (C.F.D.), Liverpool, UK
| | - Charlotte F Dougan
- Wellcome Trust Centre for Mitochondrial Research, Institute of Neuroscience (S.A.H., E.L.B., A.I.P., M.C.R., S.A., G.F., Y.S.N., D.M.T., G.S.G., R.W.T.), The Medical School, Institute of Genetic Medicine (R.H.), Newcastle University; Nuffield Department of Obstetrics and Gynaecology (J.P.), University of Oxford; Department of Neurology (M.R.R.), King's College Hospital NHS Foundation Trust, London; Departments of Neurology and Neuropathology (O.O., N.B.), Cork University Hospital, Ireland; and The Walton Centre for Neurology and Neurosurgery (C.F.D.), Liverpool, UK
| | - Yi Shiau Ng
- Wellcome Trust Centre for Mitochondrial Research, Institute of Neuroscience (S.A.H., E.L.B., A.I.P., M.C.R., S.A., G.F., Y.S.N., D.M.T., G.S.G., R.W.T.), The Medical School, Institute of Genetic Medicine (R.H.), Newcastle University; Nuffield Department of Obstetrics and Gynaecology (J.P.), University of Oxford; Department of Neurology (M.R.R.), King's College Hospital NHS Foundation Trust, London; Departments of Neurology and Neuropathology (O.O., N.B.), Cork University Hospital, Ireland; and The Walton Centre for Neurology and Neurosurgery (C.F.D.), Liverpool, UK
| | - Rita Horvath
- Wellcome Trust Centre for Mitochondrial Research, Institute of Neuroscience (S.A.H., E.L.B., A.I.P., M.C.R., S.A., G.F., Y.S.N., D.M.T., G.S.G., R.W.T.), The Medical School, Institute of Genetic Medicine (R.H.), Newcastle University; Nuffield Department of Obstetrics and Gynaecology (J.P.), University of Oxford; Department of Neurology (M.R.R.), King's College Hospital NHS Foundation Trust, London; Departments of Neurology and Neuropathology (O.O., N.B.), Cork University Hospital, Ireland; and The Walton Centre for Neurology and Neurosurgery (C.F.D.), Liverpool, UK
| | - Doug M Turnbull
- Wellcome Trust Centre for Mitochondrial Research, Institute of Neuroscience (S.A.H., E.L.B., A.I.P., M.C.R., S.A., G.F., Y.S.N., D.M.T., G.S.G., R.W.T.), The Medical School, Institute of Genetic Medicine (R.H.), Newcastle University; Nuffield Department of Obstetrics and Gynaecology (J.P.), University of Oxford; Department of Neurology (M.R.R.), King's College Hospital NHS Foundation Trust, London; Departments of Neurology and Neuropathology (O.O., N.B.), Cork University Hospital, Ireland; and The Walton Centre for Neurology and Neurosurgery (C.F.D.), Liverpool, UK
| | - Grainne S Gorman
- Wellcome Trust Centre for Mitochondrial Research, Institute of Neuroscience (S.A.H., E.L.B., A.I.P., M.C.R., S.A., G.F., Y.S.N., D.M.T., G.S.G., R.W.T.), The Medical School, Institute of Genetic Medicine (R.H.), Newcastle University; Nuffield Department of Obstetrics and Gynaecology (J.P.), University of Oxford; Department of Neurology (M.R.R.), King's College Hospital NHS Foundation Trust, London; Departments of Neurology and Neuropathology (O.O., N.B.), Cork University Hospital, Ireland; and The Walton Centre for Neurology and Neurosurgery (C.F.D.), Liverpool, UK
| | - Robert W Taylor
- Wellcome Trust Centre for Mitochondrial Research, Institute of Neuroscience (S.A.H., E.L.B., A.I.P., M.C.R., S.A., G.F., Y.S.N., D.M.T., G.S.G., R.W.T.), The Medical School, Institute of Genetic Medicine (R.H.), Newcastle University; Nuffield Department of Obstetrics and Gynaecology (J.P.), University of Oxford; Department of Neurology (M.R.R.), King's College Hospital NHS Foundation Trust, London; Departments of Neurology and Neuropathology (O.O., N.B.), Cork University Hospital, Ireland; and The Walton Centre for Neurology and Neurosurgery (C.F.D.), Liverpool, UK
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Kullar P, Alston CL, Ball S, Blakely EL, Differ AM, Fratter C, Sweeney MG, Taylor RW, Chinnery PF. The frequency of the m.1555A>G ( MTRNR1) variant in UK patients with suspected mitochondrial deafness. Hearing Balance Commun 2016; 14:101-102. [PMID: 27257558 DOI: 10.3109/21695717.2016.1151124] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Affiliation(s)
- Peter Kullar
- Wellcome Trust Centre for Mitochondrial Research, Institute of Genetic Medicine, Newcastle University, Newcastle upon Tyne, NE1 3BZ, UK
| | - Charlotte L Alston
- Wellcome Trust Centre for Mitochondrial Research, Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, NE2 4HH, UK
| | - Sarah Ball
- Micropathology Ltd, University of Warwick Science Park, Venture Centre, Sir William Lyons Road, Coventry, CV4 7EZ, UK
| | - Emma L Blakely
- Wellcome Trust Centre for Mitochondrial Research, Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, NE2 4HH, UK
| | - Ann-Marie Differ
- Department of Molecular Genetics, great Ormond Street for Children NHS Trust and UCL Institute of Child Health, London, WC1N 3JH
| | - Carl Fratter
- Oxford Medical Genetics Laboratories, Oxford University Hospitals NHS Trust, Oxford, OX3 7LE, UK
| | - Mary G Sweeney
- Neurogenetics Unit, National Hospital for Neurology and Neurosurgery, London, WC1N3BG, UK
| | - Robert W Taylor
- Wellcome Trust Centre for Mitochondrial Research, Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, NE2 4HH, UK
| | - Patrick F Chinnery
- Wellcome Trust Centre for Mitochondrial Research, Institute of Genetic Medicine, Newcastle University, Newcastle upon Tyne, NE1 3BZ, UK
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Rygiel KA, Tuppen HA, Grady JP, Vincent A, Blakely EL, Reeve AK, Taylor RW, Picard M, Miller J, Turnbull DM. Complex mitochondrial DNA rearrangements in individual cells from patients with sporadic inclusion body myositis. Nucleic Acids Res 2016; 44:5313-29. [PMID: 27131788 PMCID: PMC4914118 DOI: 10.1093/nar/gkw382] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2016] [Accepted: 04/26/2016] [Indexed: 01/26/2023] Open
Abstract
Mitochondrial DNA (mtDNA) rearrangements are an important cause of mitochondrial disease and age related mitochondrial dysfunction in tissues including brain and skeletal muscle. It is known that different mtDNA deletions accumulate in single cells, but the detailed nature of these rearrangements is still unknown. To evaluate this we used a complementary set of sensitive assays to explore the mtDNA rearrangements in individual cells from patients with sporadic inclusion body myositis, a late-onset inflammatory myopathy with prominent mitochondrial changes. We identified large-scale mtDNA deletions in individual muscle fibres with 20% of cytochrome c oxidase-deficient myofibres accumulating two or more mtDNA deletions. The majority of deletions removed only the major arc but ∼10% of all deletions extended into the minor arc removing the origin of light strand replication (OL) and a variable number of genes. Some mtDNA molecules contained two deletion sites. Additionally, we found evidence of mitochondrial genome duplications allowing replication and clonal expansion of these complex rearranged molecules. The extended spectrum of mtDNA rearrangements in single cells provides insight into the process of clonal expansion which is fundamental to our understanding of the role of mtDNA mutations in ageing and disease.
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Affiliation(s)
- Karolina A Rygiel
- Wellcome Trust Centre for Mitochondrial Research, Institute of Neuroscience, Medical School, Newcastle University, Newcastle upon Tyne NE2 4HH, UK Newcastle University Centre for Ageing and Vitality, Institute of Neuroscience, Medical School, Newcastle University, Newcastle upon Tyne, NE2 4HH, UK
| | - Helen A Tuppen
- Wellcome Trust Centre for Mitochondrial Research, Institute of Neuroscience, Medical School, Newcastle University, Newcastle upon Tyne NE2 4HH, UK
| | - John P Grady
- Wellcome Trust Centre for Mitochondrial Research, Institute of Neuroscience, Medical School, Newcastle University, Newcastle upon Tyne NE2 4HH, UK
| | - Amy Vincent
- Wellcome Trust Centre for Mitochondrial Research, Institute of Neuroscience, Medical School, Newcastle University, Newcastle upon Tyne NE2 4HH, UK Newcastle University Centre for Ageing and Vitality, Institute of Neuroscience, Medical School, Newcastle University, Newcastle upon Tyne, NE2 4HH, UK
| | - Emma L Blakely
- Wellcome Trust Centre for Mitochondrial Research, Institute of Neuroscience, Medical School, Newcastle University, Newcastle upon Tyne NE2 4HH, UK
| | - Amy K Reeve
- Wellcome Trust Centre for Mitochondrial Research, Institute of Neuroscience, Medical School, Newcastle University, Newcastle upon Tyne NE2 4HH, UK Newcastle University Centre for Ageing and Vitality, Institute of Neuroscience, Medical School, Newcastle University, Newcastle upon Tyne, NE2 4HH, UK
| | - Robert W Taylor
- Wellcome Trust Centre for Mitochondrial Research, Institute of Neuroscience, Medical School, Newcastle University, Newcastle upon Tyne NE2 4HH, UK
| | - Martin Picard
- Division of Behavioral Medicine, Department of Psychiatry, Department of Neurology and CTNI, College of Physicians and Surgeons, Columbia University Medical Center, New York, NY 10032, USA
| | - James Miller
- Department of Neurology, Newcastle upon Tyne Hospitals NHS Foundation Trust Royal Victoria Infirmary, Newcastle upon Tyne, NE1 4LP, UK
| | - Doug M Turnbull
- Wellcome Trust Centre for Mitochondrial Research, Institute of Neuroscience, Medical School, Newcastle University, Newcastle upon Tyne NE2 4HH, UK Newcastle University Centre for Ageing and Vitality, Institute of Neuroscience, Medical School, Newcastle University, Newcastle upon Tyne, NE2 4HH, UK
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Dombi E, Diot A, Morten K, Carver J, Lodge T, Fratter C, Ng YS, Liao C, Muir R, Blakely EL, Hargreaves I, Al-Dosary M, Sarkar G, Hickman SJ, Downes SM, Jayawant S, Yu-Wai-Man P, Taylor RW, Poulton J. The m.13051G>A mitochondrial DNA mutation results in variable neurology and activated mitophagy. Neurology 2016; 86:1921-3. [PMID: 27164671 PMCID: PMC4873683 DOI: 10.1212/wnl.0000000000002688] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2015] [Accepted: 01/25/2016] [Indexed: 01/30/2023] Open
Affiliation(s)
- Eszter Dombi
- From the University of Oxford (E.D., A.D., K.M., J.C., T.L., C.L., R.M., S.M.D., J.P.); Churchill Hospital (C.F.), Oxford; Newcastle University (Y.S.N., E.L.B., M.A.-D., P.Y.-W.-M., R.W.T.), Newcastle upon Tyne; National Hospital for Neurology and Neurosurgery (I.H.), UCLH, Queen Square, London; Stoke Mandeville Hospital (G.S.), Aylesbury; Royal Hallamshire Hospital (S.J.H.), Sheffield; John Radcliffe Hospital (S.J.), Oxford; Royal Victoria Infirmary (P.Y.-W.-M.), Newcastle upon Tyne; and Moorfields Eye Hospital and UCL Institute of Ophthalmology (P.Y.-W.-M.), London, UK
| | - Alan Diot
- From the University of Oxford (E.D., A.D., K.M., J.C., T.L., C.L., R.M., S.M.D., J.P.); Churchill Hospital (C.F.), Oxford; Newcastle University (Y.S.N., E.L.B., M.A.-D., P.Y.-W.-M., R.W.T.), Newcastle upon Tyne; National Hospital for Neurology and Neurosurgery (I.H.), UCLH, Queen Square, London; Stoke Mandeville Hospital (G.S.), Aylesbury; Royal Hallamshire Hospital (S.J.H.), Sheffield; John Radcliffe Hospital (S.J.), Oxford; Royal Victoria Infirmary (P.Y.-W.-M.), Newcastle upon Tyne; and Moorfields Eye Hospital and UCL Institute of Ophthalmology (P.Y.-W.-M.), London, UK
| | - Karl Morten
- From the University of Oxford (E.D., A.D., K.M., J.C., T.L., C.L., R.M., S.M.D., J.P.); Churchill Hospital (C.F.), Oxford; Newcastle University (Y.S.N., E.L.B., M.A.-D., P.Y.-W.-M., R.W.T.), Newcastle upon Tyne; National Hospital for Neurology and Neurosurgery (I.H.), UCLH, Queen Square, London; Stoke Mandeville Hospital (G.S.), Aylesbury; Royal Hallamshire Hospital (S.J.H.), Sheffield; John Radcliffe Hospital (S.J.), Oxford; Royal Victoria Infirmary (P.Y.-W.-M.), Newcastle upon Tyne; and Moorfields Eye Hospital and UCL Institute of Ophthalmology (P.Y.-W.-M.), London, UK
| | - Janet Carver
- From the University of Oxford (E.D., A.D., K.M., J.C., T.L., C.L., R.M., S.M.D., J.P.); Churchill Hospital (C.F.), Oxford; Newcastle University (Y.S.N., E.L.B., M.A.-D., P.Y.-W.-M., R.W.T.), Newcastle upon Tyne; National Hospital for Neurology and Neurosurgery (I.H.), UCLH, Queen Square, London; Stoke Mandeville Hospital (G.S.), Aylesbury; Royal Hallamshire Hospital (S.J.H.), Sheffield; John Radcliffe Hospital (S.J.), Oxford; Royal Victoria Infirmary (P.Y.-W.-M.), Newcastle upon Tyne; and Moorfields Eye Hospital and UCL Institute of Ophthalmology (P.Y.-W.-M.), London, UK
| | - Tiffany Lodge
- From the University of Oxford (E.D., A.D., K.M., J.C., T.L., C.L., R.M., S.M.D., J.P.); Churchill Hospital (C.F.), Oxford; Newcastle University (Y.S.N., E.L.B., M.A.-D., P.Y.-W.-M., R.W.T.), Newcastle upon Tyne; National Hospital for Neurology and Neurosurgery (I.H.), UCLH, Queen Square, London; Stoke Mandeville Hospital (G.S.), Aylesbury; Royal Hallamshire Hospital (S.J.H.), Sheffield; John Radcliffe Hospital (S.J.), Oxford; Royal Victoria Infirmary (P.Y.-W.-M.), Newcastle upon Tyne; and Moorfields Eye Hospital and UCL Institute of Ophthalmology (P.Y.-W.-M.), London, UK
| | - Carl Fratter
- From the University of Oxford (E.D., A.D., K.M., J.C., T.L., C.L., R.M., S.M.D., J.P.); Churchill Hospital (C.F.), Oxford; Newcastle University (Y.S.N., E.L.B., M.A.-D., P.Y.-W.-M., R.W.T.), Newcastle upon Tyne; National Hospital for Neurology and Neurosurgery (I.H.), UCLH, Queen Square, London; Stoke Mandeville Hospital (G.S.), Aylesbury; Royal Hallamshire Hospital (S.J.H.), Sheffield; John Radcliffe Hospital (S.J.), Oxford; Royal Victoria Infirmary (P.Y.-W.-M.), Newcastle upon Tyne; and Moorfields Eye Hospital and UCL Institute of Ophthalmology (P.Y.-W.-M.), London, UK
| | - Yi Shiau Ng
- From the University of Oxford (E.D., A.D., K.M., J.C., T.L., C.L., R.M., S.M.D., J.P.); Churchill Hospital (C.F.), Oxford; Newcastle University (Y.S.N., E.L.B., M.A.-D., P.Y.-W.-M., R.W.T.), Newcastle upon Tyne; National Hospital for Neurology and Neurosurgery (I.H.), UCLH, Queen Square, London; Stoke Mandeville Hospital (G.S.), Aylesbury; Royal Hallamshire Hospital (S.J.H.), Sheffield; John Radcliffe Hospital (S.J.), Oxford; Royal Victoria Infirmary (P.Y.-W.-M.), Newcastle upon Tyne; and Moorfields Eye Hospital and UCL Institute of Ophthalmology (P.Y.-W.-M.), London, UK
| | - Chunyan Liao
- From the University of Oxford (E.D., A.D., K.M., J.C., T.L., C.L., R.M., S.M.D., J.P.); Churchill Hospital (C.F.), Oxford; Newcastle University (Y.S.N., E.L.B., M.A.-D., P.Y.-W.-M., R.W.T.), Newcastle upon Tyne; National Hospital for Neurology and Neurosurgery (I.H.), UCLH, Queen Square, London; Stoke Mandeville Hospital (G.S.), Aylesbury; Royal Hallamshire Hospital (S.J.H.), Sheffield; John Radcliffe Hospital (S.J.), Oxford; Royal Victoria Infirmary (P.Y.-W.-M.), Newcastle upon Tyne; and Moorfields Eye Hospital and UCL Institute of Ophthalmology (P.Y.-W.-M.), London, UK
| | - Rebecca Muir
- From the University of Oxford (E.D., A.D., K.M., J.C., T.L., C.L., R.M., S.M.D., J.P.); Churchill Hospital (C.F.), Oxford; Newcastle University (Y.S.N., E.L.B., M.A.-D., P.Y.-W.-M., R.W.T.), Newcastle upon Tyne; National Hospital for Neurology and Neurosurgery (I.H.), UCLH, Queen Square, London; Stoke Mandeville Hospital (G.S.), Aylesbury; Royal Hallamshire Hospital (S.J.H.), Sheffield; John Radcliffe Hospital (S.J.), Oxford; Royal Victoria Infirmary (P.Y.-W.-M.), Newcastle upon Tyne; and Moorfields Eye Hospital and UCL Institute of Ophthalmology (P.Y.-W.-M.), London, UK
| | - Emma L Blakely
- From the University of Oxford (E.D., A.D., K.M., J.C., T.L., C.L., R.M., S.M.D., J.P.); Churchill Hospital (C.F.), Oxford; Newcastle University (Y.S.N., E.L.B., M.A.-D., P.Y.-W.-M., R.W.T.), Newcastle upon Tyne; National Hospital for Neurology and Neurosurgery (I.H.), UCLH, Queen Square, London; Stoke Mandeville Hospital (G.S.), Aylesbury; Royal Hallamshire Hospital (S.J.H.), Sheffield; John Radcliffe Hospital (S.J.), Oxford; Royal Victoria Infirmary (P.Y.-W.-M.), Newcastle upon Tyne; and Moorfields Eye Hospital and UCL Institute of Ophthalmology (P.Y.-W.-M.), London, UK
| | - Iain Hargreaves
- From the University of Oxford (E.D., A.D., K.M., J.C., T.L., C.L., R.M., S.M.D., J.P.); Churchill Hospital (C.F.), Oxford; Newcastle University (Y.S.N., E.L.B., M.A.-D., P.Y.-W.-M., R.W.T.), Newcastle upon Tyne; National Hospital for Neurology and Neurosurgery (I.H.), UCLH, Queen Square, London; Stoke Mandeville Hospital (G.S.), Aylesbury; Royal Hallamshire Hospital (S.J.H.), Sheffield; John Radcliffe Hospital (S.J.), Oxford; Royal Victoria Infirmary (P.Y.-W.-M.), Newcastle upon Tyne; and Moorfields Eye Hospital and UCL Institute of Ophthalmology (P.Y.-W.-M.), London, UK
| | - Mazhor Al-Dosary
- From the University of Oxford (E.D., A.D., K.M., J.C., T.L., C.L., R.M., S.M.D., J.P.); Churchill Hospital (C.F.), Oxford; Newcastle University (Y.S.N., E.L.B., M.A.-D., P.Y.-W.-M., R.W.T.), Newcastle upon Tyne; National Hospital for Neurology and Neurosurgery (I.H.), UCLH, Queen Square, London; Stoke Mandeville Hospital (G.S.), Aylesbury; Royal Hallamshire Hospital (S.J.H.), Sheffield; John Radcliffe Hospital (S.J.), Oxford; Royal Victoria Infirmary (P.Y.-W.-M.), Newcastle upon Tyne; and Moorfields Eye Hospital and UCL Institute of Ophthalmology (P.Y.-W.-M.), London, UK
| | - Gopa Sarkar
- From the University of Oxford (E.D., A.D., K.M., J.C., T.L., C.L., R.M., S.M.D., J.P.); Churchill Hospital (C.F.), Oxford; Newcastle University (Y.S.N., E.L.B., M.A.-D., P.Y.-W.-M., R.W.T.), Newcastle upon Tyne; National Hospital for Neurology and Neurosurgery (I.H.), UCLH, Queen Square, London; Stoke Mandeville Hospital (G.S.), Aylesbury; Royal Hallamshire Hospital (S.J.H.), Sheffield; John Radcliffe Hospital (S.J.), Oxford; Royal Victoria Infirmary (P.Y.-W.-M.), Newcastle upon Tyne; and Moorfields Eye Hospital and UCL Institute of Ophthalmology (P.Y.-W.-M.), London, UK
| | - Simon J Hickman
- From the University of Oxford (E.D., A.D., K.M., J.C., T.L., C.L., R.M., S.M.D., J.P.); Churchill Hospital (C.F.), Oxford; Newcastle University (Y.S.N., E.L.B., M.A.-D., P.Y.-W.-M., R.W.T.), Newcastle upon Tyne; National Hospital for Neurology and Neurosurgery (I.H.), UCLH, Queen Square, London; Stoke Mandeville Hospital (G.S.), Aylesbury; Royal Hallamshire Hospital (S.J.H.), Sheffield; John Radcliffe Hospital (S.J.), Oxford; Royal Victoria Infirmary (P.Y.-W.-M.), Newcastle upon Tyne; and Moorfields Eye Hospital and UCL Institute of Ophthalmology (P.Y.-W.-M.), London, UK
| | - Susan M Downes
- From the University of Oxford (E.D., A.D., K.M., J.C., T.L., C.L., R.M., S.M.D., J.P.); Churchill Hospital (C.F.), Oxford; Newcastle University (Y.S.N., E.L.B., M.A.-D., P.Y.-W.-M., R.W.T.), Newcastle upon Tyne; National Hospital for Neurology and Neurosurgery (I.H.), UCLH, Queen Square, London; Stoke Mandeville Hospital (G.S.), Aylesbury; Royal Hallamshire Hospital (S.J.H.), Sheffield; John Radcliffe Hospital (S.J.), Oxford; Royal Victoria Infirmary (P.Y.-W.-M.), Newcastle upon Tyne; and Moorfields Eye Hospital and UCL Institute of Ophthalmology (P.Y.-W.-M.), London, UK
| | - Sandeep Jayawant
- From the University of Oxford (E.D., A.D., K.M., J.C., T.L., C.L., R.M., S.M.D., J.P.); Churchill Hospital (C.F.), Oxford; Newcastle University (Y.S.N., E.L.B., M.A.-D., P.Y.-W.-M., R.W.T.), Newcastle upon Tyne; National Hospital for Neurology and Neurosurgery (I.H.), UCLH, Queen Square, London; Stoke Mandeville Hospital (G.S.), Aylesbury; Royal Hallamshire Hospital (S.J.H.), Sheffield; John Radcliffe Hospital (S.J.), Oxford; Royal Victoria Infirmary (P.Y.-W.-M.), Newcastle upon Tyne; and Moorfields Eye Hospital and UCL Institute of Ophthalmology (P.Y.-W.-M.), London, UK
| | - Patrick Yu-Wai-Man
- From the University of Oxford (E.D., A.D., K.M., J.C., T.L., C.L., R.M., S.M.D., J.P.); Churchill Hospital (C.F.), Oxford; Newcastle University (Y.S.N., E.L.B., M.A.-D., P.Y.-W.-M., R.W.T.), Newcastle upon Tyne; National Hospital for Neurology and Neurosurgery (I.H.), UCLH, Queen Square, London; Stoke Mandeville Hospital (G.S.), Aylesbury; Royal Hallamshire Hospital (S.J.H.), Sheffield; John Radcliffe Hospital (S.J.), Oxford; Royal Victoria Infirmary (P.Y.-W.-M.), Newcastle upon Tyne; and Moorfields Eye Hospital and UCL Institute of Ophthalmology (P.Y.-W.-M.), London, UK
| | - Robert W Taylor
- From the University of Oxford (E.D., A.D., K.M., J.C., T.L., C.L., R.M., S.M.D., J.P.); Churchill Hospital (C.F.), Oxford; Newcastle University (Y.S.N., E.L.B., M.A.-D., P.Y.-W.-M., R.W.T.), Newcastle upon Tyne; National Hospital for Neurology and Neurosurgery (I.H.), UCLH, Queen Square, London; Stoke Mandeville Hospital (G.S.), Aylesbury; Royal Hallamshire Hospital (S.J.H.), Sheffield; John Radcliffe Hospital (S.J.), Oxford; Royal Victoria Infirmary (P.Y.-W.-M.), Newcastle upon Tyne; and Moorfields Eye Hospital and UCL Institute of Ophthalmology (P.Y.-W.-M.), London, UK
| | - Joanna Poulton
- From the University of Oxford (E.D., A.D., K.M., J.C., T.L., C.L., R.M., S.M.D., J.P.); Churchill Hospital (C.F.), Oxford; Newcastle University (Y.S.N., E.L.B., M.A.-D., P.Y.-W.-M., R.W.T.), Newcastle upon Tyne; National Hospital for Neurology and Neurosurgery (I.H.), UCLH, Queen Square, London; Stoke Mandeville Hospital (G.S.), Aylesbury; Royal Hallamshire Hospital (S.J.H.), Sheffield; John Radcliffe Hospital (S.J.), Oxford; Royal Victoria Infirmary (P.Y.-W.-M.), Newcastle upon Tyne; and Moorfields Eye Hospital and UCL Institute of Ophthalmology (P.Y.-W.-M.), London, UK.
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Bargiela D, Shanmugarajah P, Lo C, Blakely EL, Taylor RW, Horvath R, Wharton S, Chinnery PF, Hadjivassiliou M. Mitochondrial pathology in progressive cerebellar ataxia. Cerebellum Ataxias 2015; 2:16. [PMID: 26640698 PMCID: PMC4670505 DOI: 10.1186/s40673-015-0035-x] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 08/01/2015] [Accepted: 12/02/2015] [Indexed: 12/16/2022]
Abstract
BACKGROUND Mitochondrial disease can manifest as multi-organ disorder, often with neurological dysfunction. Cerebellar ataxia in isolation or in combination with other features can result from mitochondrial disease yet genetic testing using blood DNA is not sufficient to exclude this as a cause of ataxia. Muscle biopsy is a useful diagnostic tool for patients with ataxia suspected of mitochondrial disease. Our aim was to determine specific patient selection criteria for muscle biopsy to see how frequent mitochondrial mutations are responsible for progressive ataxia. We performed a two centre retrospective review of patients with unexplained progressive ataxia who underwent muscle biopsy for suspected mitochondrial disease between 2004 and 2014 (Sheffield and Newcastle Ataxia Centres). RESULTS A total of 126 patients were identified; 26 assessed in Newcastle and 100 in Sheffield. Twenty-four patients had pure ataxia and 102 had ataxia with additional features. The total number of patients with histologically suspected and/or genetically confirmed mitochondrial disease was 29/126 (23 %). CONCLUSIONS A large proportion of patients (23 %) with progressive ataxia who underwent muscle biopsy were found to have features of mitochondrial dysfunction, with molecular confirmation in some. Muscle biopsy is a helpful diagnostic tool for mitochondrial disease in patients with progressive ataxia.
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Affiliation(s)
- David Bargiela
- Institute of Genetic Medicine, Newcastle University, Newcastle upon Tyne, UK
| | - Priya Shanmugarajah
- Academic Department of Neurosciences, Royal Hallamshire Hospital, Glossop Road, Sheffield, S10 2JF UK
| | - Christine Lo
- Academic Department of Neurosciences, Royal Hallamshire Hospital, Glossop Road, Sheffield, S10 2JF UK
| | - Emma L Blakely
- Wellcome Trust Centre for Mitochondrial Research, Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, UK
| | - Robert W Taylor
- Wellcome Trust Centre for Mitochondrial Research, Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, UK
| | - Rita Horvath
- Institute of Human Genetics, Newcastle University, Newcastle upon Tyne, UK
| | - Stephen Wharton
- Department of Histopathology, Royal Hallamshire Hospital, Sheffield, UK
| | - Patrick F Chinnery
- Institute of Genetic Medicine, Newcastle University, Newcastle upon Tyne, UK
| | - Marios Hadjivassiliou
- Academic Department of Neurosciences, Royal Hallamshire Hospital, Glossop Road, Sheffield, S10 2JF UK
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Payne BAI, Gardner K, Blakely EL, Maddison P, Horvath R, Taylor RW, Chinnery PF. Clinical and pathological features of mitochondrial DNA deletion disease following antiretroviral treatment. JAMA Neurol 2015; 72:603-5. [PMID: 25961175 DOI: 10.1001/jamaneurol.2015.0150] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Affiliation(s)
- Brendan A I Payne
- Wellcome Trust Centre for Mitochondrial Research, Institute of Genetic Medicine, Newcastle University, Newcastle-upon-Tyne, England2Department of Infection and Tropical Medicine, Royal Victoria Infirmary, Newcastle-upon-Tyne, England
| | - Kristian Gardner
- Wellcome Trust Centre for Mitochondrial Research, Institute of Genetic Medicine, Newcastle University, Newcastle-upon-Tyne, England
| | - Emma L Blakely
- Wellcome Trust Centre for Mitochondrial Research, Institute of Neuroscience, Newcastle University, Newcastle-upon-Tyne, England
| | | | - Rita Horvath
- Wellcome Trust Centre for Mitochondrial Research, Institute of Genetic Medicine, Newcastle University, Newcastle-upon-Tyne, England
| | - Robert W Taylor
- Wellcome Trust Centre for Mitochondrial Research, Institute of Neuroscience, Newcastle University, Newcastle-upon-Tyne, England
| | - Patrick F Chinnery
- Wellcome Trust Centre for Mitochondrial Research, Institute of Genetic Medicine, Newcastle University, Newcastle-upon-Tyne, England
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Alston CL, Ceccatelli Berti C, Blakely EL, Oláhová M, He L, McMahon CJ, Olpin SE, Hargreaves IP, Nolli C, McFarland R, Goffrini P, O'Sullivan MJ, Taylor RW. A recessive homozygous p.Asp92Gly SDHD mutation causes prenatal cardiomyopathy and a severe mitochondrial complex II deficiency. Hum Genet 2015; 134:869-79. [PMID: 26008905 PMCID: PMC4495259 DOI: 10.1007/s00439-015-1568-z] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2015] [Accepted: 05/16/2015] [Indexed: 01/15/2023]
Abstract
Succinate dehydrogenase (SDH) is a crucial metabolic enzyme complex that is involved in ATP production, playing roles in both the tricarboxylic cycle and the mitochondrial respiratory chain (complex II). Isolated complex II deficiency is one of the rarest oxidative phosphorylation disorders with mutations described in three structural subunits and one of the assembly factors; just one case is attributed to recessively inherited SDHD mutations. We report the pathological, biochemical, histochemical and molecular genetic investigations of a male neonate who had left ventricular hypertrophy detected on antenatal scan and died on day one of life. Subsequent postmortem examination confirmed hypertrophic cardiomyopathy with left ventricular non-compaction. Biochemical analysis of his skeletal muscle biopsy revealed evidence of a severe isolated complex II deficiency and candidate gene sequencing revealed a novel homozygous c.275A>G, p.(Asp92Gly) SDHD mutation which was shown to be recessively inherited through segregation studies. The affected amino acid has been reported as a Dutch founder mutation p.(Asp92Tyr) in families with hereditary head and neck paraganglioma. By introducing both mutations into Saccharomyces cerevisiae, we were able to confirm that the p.(Asp92Gly) mutation causes a more severe oxidative growth phenotype than the p.(Asp92Tyr) mutant, and provides functional evidence to support the pathogenicity of the patient’s SDHD mutation. This is only the second case of mitochondrial complex II deficiency due to inherited SDHD mutations and highlights the importance of sequencing all SDH genes in patients with biochemical and histochemical evidence of isolated mitochondrial complex II deficiency.
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Affiliation(s)
- Charlotte L Alston
- Wellcome Trust Centre for Mitochondrial Research, Institute of Neuroscience, The Medical School, Newcastle University, Newcastle upon Tyne, NE2 4HH, UK
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Lehmann D, Schubert K, Joshi PR, Hardy SA, Tuppen HAL, Baty K, Blakely EL, Bamberg C, Zierz S, Deschauer M, Taylor RW. Pathogenic mitochondrial mt-tRNA(Ala) variants are uniquely associated with isolated myopathy. Eur J Hum Genet 2015; 23:1735-8. [PMID: 25873012 PMCID: PMC4519577 DOI: 10.1038/ejhg.2015.73] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2015] [Accepted: 03/12/2015] [Indexed: 11/09/2022] Open
Abstract
Pathogenic mitochondrial DNA (mtDNA) point mutations are associated with a wide range of clinical phenotypes, often involving multiple organ systems. We report two patients with isolated myopathy owing to novel mt-tRNA(Ala) variants. Muscle biopsy revealed extensive histopathological findings including cytochrome c oxidase (COX)-deficient fibres. Pyrosequencing confirmed mtDNA heteroplasmy for both mutations (m.5631G>A and m.5610G>A) whilst single-muscle fibre segregation studies (revealing statistically significant higher mutation loads in COX-deficient fibres than in COX-positive fibres), hierarchical mutation segregation within patient tissues and decreased steady-state mt-tRNA(Ala) levels all provide compelling evidence of pathogenicity. Interestingly, both patients showed very high-mutation levels in all tissues, inferring that the threshold for impairment of oxidative phosphorylation, as evidenced by COX deficiency, appears to be extremely high for these mt-tRNA(Ala) variants. Previously described mt-tRNA(Ala) mutations are also associated with a pure myopathic phenotype and demonstrate very high mtDNA heteroplasmy thresholds, inferring at least some genotype:phenotype correlation for mutations within this particular mt-tRNA gene.
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Affiliation(s)
- Diana Lehmann
- Department of Neurology, University of Halle-Wittenberg, Halle (Saale), Germany
| | - Kathrin Schubert
- Department of Neurology, University of Halle-Wittenberg, Halle (Saale), Germany
| | - Pushpa R Joshi
- Department of Neurology, University of Halle-Wittenberg, Halle (Saale), Germany
| | - Steven A Hardy
- Wellcome Trust Centre for Mitochondrial Research, Institute of Neuroscience, The Medical School, Newcastle University, Framlington Place, Newcastle upon Tyne, UK
| | - Helen A L Tuppen
- Wellcome Trust Centre for Mitochondrial Research, Institute of Neuroscience, The Medical School, Newcastle University, Framlington Place, Newcastle upon Tyne, UK
| | - Karen Baty
- Wellcome Trust Centre for Mitochondrial Research, Institute of Neuroscience, The Medical School, Newcastle University, Framlington Place, Newcastle upon Tyne, UK
| | - Emma L Blakely
- Wellcome Trust Centre for Mitochondrial Research, Institute of Neuroscience, The Medical School, Newcastle University, Framlington Place, Newcastle upon Tyne, UK
| | | | - Stephan Zierz
- Department of Neurology, University of Halle-Wittenberg, Halle (Saale), Germany
| | - Marcus Deschauer
- Department of Neurology, University of Halle-Wittenberg, Halle (Saale), Germany
| | - Robert W Taylor
- Wellcome Trust Centre for Mitochondrial Research, Institute of Neuroscience, The Medical School, Newcastle University, Framlington Place, Newcastle upon Tyne, UK
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Gorman GS, Schaefer AM, Ng Y, Gomez N, Blakely EL, Alston CL, Feeney C, Horvath R, Yu-Wai-Man P, Chinnery PF, Taylor RW, Turnbull DM, McFarland R. Prevalence of nuclear and mitochondrial DNA mutations related to adult mitochondrial disease. Ann Neurol 2015; 77:753-9. [PMID: 25652200 PMCID: PMC4737121 DOI: 10.1002/ana.24362] [Citation(s) in RCA: 574] [Impact Index Per Article: 63.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2014] [Revised: 11/30/2014] [Accepted: 01/08/2015] [Indexed: 01/17/2023]
Abstract
OBJECTIVE The prevalence of mitochondrial disease has proven difficult to establish, predominantly as a result of clinical and genetic heterogeneity. The phenotypic spectrum of mitochondrial disease has expanded significantly since the original reports that associated classic clinical syndromes with mitochondrial DNA (mtDNA) rearrangements and point mutations. The revolution in genetic technologies has allowed interrogation of the nuclear genome in a manner that has dramatically improved the diagnosis of mitochondrial disorders. We comprehensively assessed the prevalence of all forms of adult mitochondrial disease to include pathogenic mutations in both nuclear and mtDNA. METHODS Adults with suspected mitochondrial disease in the North East of England were referred to a single neurology center from 1990 to 2014. For the midyear period of 2011, we evaluated the minimum prevalence of symptomatic nuclear DNA mutations and symptomatic and asymptomatic mtDNA mutations causing mitochondrial diseases. RESULTS The minimum prevalence rate for mtDNA mutations was 1 in 5,000 (20 per 100,000), comparable with our previously published prevalence rates. In this population, nuclear mutations were responsible for clinically overt adult mitochondrial disease in 2.9 per 100,000 adults. INTERPRETATION Combined, our data confirm that the total prevalence of adult mitochondrial disease, including pathogenic mutations of both the mitochondrial and nuclear genomes (≈1 in 4,300), is among the commonest adult forms of inherited neurological disorders. These figures hold important implications for the evaluation of interventions, provision of evidence-based health policies, and planning of future services.
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Affiliation(s)
- Gráinne S Gorman
- Wellcome Centre for Mitochondrial Research, Newcastle University, Newcastle upon Tyne, United Kingdom; Institute of Neuroscience, Henry Wellcome Building for Neuroecology, Newcastle upon Tyne, United Kingdom
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Gorman GS, Pfeffer G, Griffin H, Blakely EL, Kurzawa-Akanbi M, Gabriel J, Sitarz K, Roberts M, Schoser B, Pyle A, Schaefer AM, McFarland R, Turnbull DM, Horvath R, Chinnery PF, Taylor RW. Clonal expansion of secondary mitochondrial DNA deletions associated with spinocerebellar ataxia type 28. JAMA Neurol 2015; 72:106-11. [PMID: 25420100 DOI: 10.1001/jamaneurol.2014.1753] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
IMPORTANCE Progressive external ophthalmoplegia (PEO) is a common feature in adults with mitochondrial (mt) DNA maintenance disorders associated with somatic mtDNA deletions in muscle, yet the causal genetic defect in many patients remains undetermined. OBSERVATIONS Whole-exome sequencing identified a novel, heterozygous p.(Gly671Trp) mutation in the AFG3L2 gene encoding an mt protease--previously associated with dominant spinocerebellar ataxia type 28 disease--in a patient with indolent ataxia and PEO. Targeted analysis of a larger, genetically undetermined cohort of patients with PEO with suspected mtDNA maintenance abnormalities identified a second unrelated patient with a similar phenotype and a novel, heterozygous p.(Tyr689His) AFG3L2 mutation. Analysis of patient fibroblasts revealed mt fragmentation and decreased AFG3L2 transcript expression. Western blotting of patient fibroblast and muscle showed decreased AFG3L2 protein levels. CONCLUSIONS AND RELEVANCE Our observations suggest that AFG3L2 mutations are another important cause, albeit rare, of a late-onset ataxic PEO phenotype due to a disturbance of mtDNA maintenance.
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Affiliation(s)
- Gráinne S Gorman
- Wellcome Centre for Mitochondrial Research, Newcastle University, Newcastle upon Tyne, England2Institute for Ageing and Health, National Institute for Health Research Biomedical Research Centre for Ageing, Newcastle University, Newcastle upon Tyne, Englan
| | - Gerald Pfeffer
- Wellcome Centre for Mitochondrial Research, Newcastle University, Newcastle upon Tyne, England3Institute of Genetic Medicine, Newcastle University, Newcastle upon Tyne, England
| | - Helen Griffin
- Wellcome Centre for Mitochondrial Research, Newcastle University, Newcastle upon Tyne, England3Institute of Genetic Medicine, Newcastle University, Newcastle upon Tyne, England
| | - Emma L Blakely
- Wellcome Centre for Mitochondrial Research, Newcastle University, Newcastle upon Tyne, England2Institute for Ageing and Health, National Institute for Health Research Biomedical Research Centre for Ageing, Newcastle University, Newcastle upon Tyne, Englan
| | - Marzena Kurzawa-Akanbi
- Wellcome Centre for Mitochondrial Research, Newcastle University, Newcastle upon Tyne, England3Institute of Genetic Medicine, Newcastle University, Newcastle upon Tyne, England
| | - Jessica Gabriel
- Wellcome Centre for Mitochondrial Research, Newcastle University, Newcastle upon Tyne, England
| | - Kamil Sitarz
- Wellcome Centre for Mitochondrial Research, Newcastle University, Newcastle upon Tyne, England3Institute of Genetic Medicine, Newcastle University, Newcastle upon Tyne, England
| | - Mark Roberts
- Department of Neurology, Hope Hospital, Salford, England
| | - Benedikt Schoser
- Friedrich-Baur Institut, Department of Neurology, Ludwig-Maximilians University, München, Germany
| | - Angela Pyle
- Wellcome Centre for Mitochondrial Research, Newcastle University, Newcastle upon Tyne, England3Institute of Genetic Medicine, Newcastle University, Newcastle upon Tyne, England
| | - Andrew M Schaefer
- Wellcome Centre for Mitochondrial Research, Newcastle University, Newcastle upon Tyne, England
| | - Robert McFarland
- Wellcome Centre for Mitochondrial Research, Newcastle University, Newcastle upon Tyne, England2Institute for Ageing and Health, National Institute for Health Research Biomedical Research Centre for Ageing, Newcastle University, Newcastle upon Tyne, Englan
| | - Douglass M Turnbull
- Wellcome Centre for Mitochondrial Research, Newcastle University, Newcastle upon Tyne, England2Institute for Ageing and Health, National Institute for Health Research Biomedical Research Centre for Ageing, Newcastle University, Newcastle upon Tyne, Englan
| | - Rita Horvath
- Wellcome Centre for Mitochondrial Research, Newcastle University, Newcastle upon Tyne, England3Institute of Genetic Medicine, Newcastle University, Newcastle upon Tyne, England
| | - Patrick F Chinnery
- Wellcome Centre for Mitochondrial Research, Newcastle University, Newcastle upon Tyne, England3Institute of Genetic Medicine, Newcastle University, Newcastle upon Tyne, England
| | - Robert W Taylor
- Wellcome Centre for Mitochondrial Research, Newcastle University, Newcastle upon Tyne, England2Institute for Ageing and Health, National Institute for Health Research Biomedical Research Centre for Ageing, Newcastle University, Newcastle upon Tyne, Englan
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Nesbitt V, Alston CL, Blakely EL, Fratter C, Feeney CL, Poulton J, Brown GK, Turnbull DM, Taylor RW, McFarland R. A national perspective on prenatal testing for mitochondrial disease. Eur J Hum Genet 2014; 22:1255-9. [PMID: 24642831 PMCID: PMC4200441 DOI: 10.1038/ejhg.2014.35] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2013] [Revised: 12/17/2013] [Accepted: 01/16/2014] [Indexed: 01/30/2023] Open
Abstract
Mitochondrial diseases affect >1 in 7500 live births and may be due to mutations in either mitochondrial DNA (mtDNA) or nuclear DNA (nDNA). Genetic counselling for families with mitochondrial diseases, especially those due to mtDNA mutations, provides unique and difficult challenges particularly in relation to disease transmission and prevention. We have experienced an increasing demand for prenatal diagnostic testing from families affected by mitochondrial disease since we first offered this service in 2007. We review the diagnostic records of the 62 prenatal samples (17 mtDNA and 45 nDNA) analysed since 2007, the reasons for testing, mutation investigated and the clinical outcome. Our findings indicate that prenatal testing for mitochondrial disease is reliable and informative for the nuclear and selected mtDNA mutations we have tested. Where available, the results of mtDNA heteroplasmy analyses from other family members are helpful in interpreting the prenatal mtDNA test result. This is particularly important when the mutation is rare or the mtDNA heteroplasmy is observed at intermediate levels. At least 11 cases of mitochondrial disease were prevented following prenatal testing, 3 of which were mtDNA disease. On the basis of our results, we believe that prenatal testing for mitochondrial disease is an important option for couples where appropriate genetic analyses and pre/post-test counselling can be provided.
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Affiliation(s)
- Victoria Nesbitt
- Wellcome Trust Centre for Mitochondrial Research, The Medical School, Institute for Ageing and Health, Newcastle University, Newcastle-upon-Tyne, UK
| | - Charlotte L Alston
- NHS Specialised Services for Rare Mitochondrial Disorders of Adults and Children UK, Oxford, UK
| | - Emma L Blakely
- NHS Specialised Services for Rare Mitochondrial Disorders of Adults and Children UK, Oxford, UK
| | - Carl Fratter
- NHS Specialised Services for Rare Mitochondrial Disorders of Adults and Children UK, Oxford, UK
- Oxford Medical Genetics Laboratories, Oxford University Hospitals NHS Trust, Oxford, UK
| | - Catherine L Feeney
- NHS Specialised Services for Rare Mitochondrial Disorders of Adults and Children UK, Oxford, UK
| | - Joanna Poulton
- NHS Specialised Services for Rare Mitochondrial Disorders of Adults and Children UK, Oxford, UK
- Nuffield Department of Obstetrics and Gynaecology, University of Oxford, John Radcliffe Hospital, Oxford, UK
| | - Garry K Brown
- NHS Specialised Services for Rare Mitochondrial Disorders of Adults and Children UK, Oxford, UK
- Department of Biochemistry, University of Oxford, Oxford, UK
| | - Doug M Turnbull
- Wellcome Trust Centre for Mitochondrial Research, The Medical School, Institute for Ageing and Health, Newcastle University, Newcastle-upon-Tyne, UK
- NHS Specialised Services for Rare Mitochondrial Disorders of Adults and Children UK, Oxford, UK
| | - Robert W Taylor
- Wellcome Trust Centre for Mitochondrial Research, The Medical School, Institute for Ageing and Health, Newcastle University, Newcastle-upon-Tyne, UK
- NHS Specialised Services for Rare Mitochondrial Disorders of Adults and Children UK, Oxford, UK
| | - Robert McFarland
- Wellcome Trust Centre for Mitochondrial Research, The Medical School, Institute for Ageing and Health, Newcastle University, Newcastle-upon-Tyne, UK
- NHS Specialised Services for Rare Mitochondrial Disorders of Adults and Children UK, Oxford, UK
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Lehmann D, Schubert K, Joshi PR, Baty K, Blakely EL, Zierz S, Taylor RW, Deschauer M. A novel m.7539C>T point mutation in the mt-tRNA(Asp) gene associated with multisystemic mitochondrial disease. Neuromuscul Disord 2014; 25:81-4. [PMID: 25447692 PMCID: PMC4317191 DOI: 10.1016/j.nmd.2014.09.008] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2014] [Revised: 09/03/2014] [Accepted: 09/17/2014] [Indexed: 11/18/2022]
Abstract
Mitochondrial transfer RNA (mt-tRNA) mutations are the commonest sub-type of mitochondrial (mtDNA) mutations associated with human disease. We report a patient with multisytemic disease characterised by myopathy, spinal ataxia, sensorineural hearing loss, cataract and cognitive impairment in whom a novel m.7539C>T mt-tRNA(Asp) transition was identified. Muscle biopsy revealed extensive histopathological findings including cytochrome c oxidase (COX)-deficient fibres. Pyrosequencing confirmed mtDNA heteroplasmy for the mutation whilst single muscle fibre segregation studies revealed statistically significant higher mutation loads in COX-deficient fibres than in COX-positive fibres. Absence from control databases, hierarchical mt-tRNA mutation segregation within tissues, and occurrence at conserved sequence positions, further confirm this novel mt-tRNA mutation to be pathogenic. To date only three mt-tRNA(Asp) gene mutations have been described with clear evidence of pathogenicity. The novel m.7539C>T mt-tRNA(Asp) gene mutation extends the spectrum of pathogenic mutations in this gene, further supporting the notion that mt-tRNA(Asp) gene mutations are associated with multisystemic disease presentations.
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Affiliation(s)
- Diana Lehmann
- Department of Neurology, University of Halle-Wittenberg, Ernst-Grube-Str. 40, Halle/Saale 06097, Germany
| | - Kathrin Schubert
- Department of Neurology, University of Halle-Wittenberg, Ernst-Grube-Str. 40, Halle/Saale 06097, Germany
| | - Pushpa R Joshi
- Department of Neurology, University of Halle-Wittenberg, Ernst-Grube-Str. 40, Halle/Saale 06097, Germany
| | - Karen Baty
- Wellcome Trust Centre for Mitochondrial Research, Institute of Neuroscience, The Medical School, Newcastle University, Framlington Place, Newcastle upon Tyne, UK
| | - Emma L Blakely
- Wellcome Trust Centre for Mitochondrial Research, Institute of Neuroscience, The Medical School, Newcastle University, Framlington Place, Newcastle upon Tyne, UK
| | - Stephan Zierz
- Department of Neurology, University of Halle-Wittenberg, Ernst-Grube-Str. 40, Halle/Saale 06097, Germany
| | - Robert W Taylor
- Wellcome Trust Centre for Mitochondrial Research, Institute of Neuroscience, The Medical School, Newcastle University, Framlington Place, Newcastle upon Tyne, UK
| | - Marcus Deschauer
- Department of Neurology, University of Halle-Wittenberg, Ernst-Grube-Str. 40, Halle/Saale 06097, Germany.
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Taylor RW, Pyle A, Griffin H, Blakely EL, Duff J, He L, Smertenko T, Alston CL, Neeve VC, Best A, Yarham JW, Kirschner J, Schara U, Talim B, Topaloglu H, Baric I, Holinski-Feder E, Abicht A, Czermin B, Kleinle S, Morris AA, Vassallo G, Gorman GS, Ramesh V, Turnbull DM, Santibanez-Koref M, McFarland R, Horvath R, Chinnery PF. Use of whole-exome sequencing to determine the genetic basis of multiple mitochondrial respiratory chain complex deficiencies. JAMA 2014; 312:68-77. [PMID: 25058219 PMCID: PMC6558267 DOI: 10.1001/jama.2014.7184] [Citation(s) in RCA: 251] [Impact Index Per Article: 25.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
IMPORTANCE Mitochondrial disorders have emerged as a common cause of inherited disease, but their diagnosis remains challenging. Multiple respiratory chain complex defects are particularly difficult to diagnose at the molecular level because of the massive number of nuclear genes potentially involved in intramitochondrial protein synthesis, with many not yet linked to human disease. OBJECTIVE To determine the molecular basis of multiple respiratory chain complex deficiencies. DESIGN, SETTING, AND PARTICIPANTS We studied 53 patients referred to 2 national centers in the United Kingdom and Germany between 2005 and 2012. All had biochemical evidence of multiple respiratory chain complex defects but no primary pathogenic mitochondrial DNA mutation. Whole-exome sequencing was performed using 62-Mb exome enrichment, followed by variant prioritization using bioinformatic prediction tools, variant validation by Sanger sequencing, and segregation of the variant with the disease phenotype in the family. RESULTS Presumptive causal variants were identified in 28 patients (53%; 95% CI, 39%-67%) and possible causal variants were identified in 4 (8%; 95% CI, 2%-18%). Together these accounted for 32 patients (60% 95% CI, 46%-74%) and involved 18 different genes. These included recurrent mutations in RMND1, AARS2, and MTO1, each on a haplotype background consistent with a shared founder allele, and potential novel mutations in 4 possible mitochondrial disease genes (VARS2, GARS, FLAD1, and PTCD1). Distinguishing clinical features included deafness and renal involvement associated with RMND1 and cardiomyopathy with AARS2 and MTO1. However, atypical clinical features were present in some patients, including normal liver function and Leigh syndrome (subacute necrotizing encephalomyelopathy) seen in association with TRMU mutations and no cardiomyopathy with founder SCO2 mutations. It was not possible to confidently identify the underlying genetic basis in 21 patients (40%; 95% CI, 26%-54%). CONCLUSIONS AND RELEVANCE Exome sequencing enhances the ability to identify potential nuclear gene mutations in patients with biochemically defined defects affecting multiple mitochondrial respiratory chain complexes. Additional study is required in independent patient populations to determine the utility of this approach in comparison with traditional diagnostic methods.
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Affiliation(s)
- Robert W. Taylor
- Wellcome Trust Centre for Mitochondrial Research, Institute for Ageing and Health, The Medical School, Newcastle University, Newcastle upon Tyne, NE2 4HH, UK
| | - Angela Pyle
- Wellcome Trust Centre for Mitochondrial Research, Institute of Genetic Medicine, Newcastle University, Central Parkway, Newcastle upon Tyne, NE1 3BZ, UK
| | - Helen Griffin
- Wellcome Trust Centre for Mitochondrial Research, Institute of Genetic Medicine, Newcastle University, Central Parkway, Newcastle upon Tyne, NE1 3BZ, UK
| | - Emma L. Blakely
- Wellcome Trust Centre for Mitochondrial Research, Institute for Ageing and Health, The Medical School, Newcastle University, Newcastle upon Tyne, NE2 4HH, UK
| | - Jennifer Duff
- Wellcome Trust Centre for Mitochondrial Research, Institute of Genetic Medicine, Newcastle University, Central Parkway, Newcastle upon Tyne, NE1 3BZ, UK
| | - Langping He
- Wellcome Trust Centre for Mitochondrial Research, Institute for Ageing and Health, The Medical School, Newcastle University, Newcastle upon Tyne, NE2 4HH, UK
| | - Tania Smertenko
- Wellcome Trust Centre for Mitochondrial Research, Institute of Genetic Medicine, Newcastle University, Central Parkway, Newcastle upon Tyne, NE1 3BZ, UK
| | - Charlotte L. Alston
- Wellcome Trust Centre for Mitochondrial Research, Institute for Ageing and Health, The Medical School, Newcastle University, Newcastle upon Tyne, NE2 4HH, UK
| | - Vivienne C. Neeve
- Wellcome Trust Centre for Mitochondrial Research, Institute of Genetic Medicine, Newcastle University, Central Parkway, Newcastle upon Tyne, NE1 3BZ, UK
| | - Andrew Best
- Wellcome Trust Centre for Mitochondrial Research, Institute of Genetic Medicine, Newcastle University, Central Parkway, Newcastle upon Tyne, NE1 3BZ, UK
| | - John W. Yarham
- Wellcome Trust Centre for Mitochondrial Research, Institute for Ageing and Health, The Medical School, Newcastle University, Newcastle upon Tyne, NE2 4HH, UK
| | - Janbernd Kirschner
- Division of Neuropediatrics and Muscle Disorders, University Medical Center Freiburg, Germany
| | - Ulrike Schara
- Department of Neuropediatrics, University of Essen, Essen, Germany
| | - Beril Talim
- Department of Pediatrics, Hacettepe University, Ankara, Turkey
| | - Haluk Topaloglu
- Department of Pediatrics, Hacettepe University, Ankara, Turkey
| | - Ivo Baric
- Department of Paediatrics, University Hospital Center Zagreb & University of Zagreb,School of Medicine, Zagreb, Croatia
| | | | | | | | | | - Andrew A.M. Morris
- Willink Biochemical Genetics Unit, Manchester Centre for Genomic Medicine, Central Manchester University Hospitals NHS Foundation Trust, Manchester, M13 9WL
| | - Grace Vassallo
- Department of Paediatric Neurology, Central Manchester University Hospitals NHS Foundation Trust, Manchester, M13 9WL
| | - Grainne S. Gorman
- Wellcome Trust Centre for Mitochondrial Research, Institute for Ageing and Health, The Medical School, Newcastle University, Newcastle upon Tyne, NE2 4HH, UK
| | - Venkateswaran Ramesh
- Department of Paediatric Neurology, Newcastle upon Tyne Hospitals NHS Trust, Newcastle upon Tyne, NE1 4LP
| | - Douglass M. Turnbull
- Wellcome Trust Centre for Mitochondrial Research, Institute for Ageing and Health, The Medical School, Newcastle University, Newcastle upon Tyne, NE2 4HH, UK
| | - Mauro Santibanez-Koref
- Wellcome Trust Centre for Mitochondrial Research, Institute of Genetic Medicine, Newcastle University, Central Parkway, Newcastle upon Tyne, NE1 3BZ, UK
| | - Robert McFarland
- Wellcome Trust Centre for Mitochondrial Research, Institute for Ageing and Health, The Medical School, Newcastle University, Newcastle upon Tyne, NE2 4HH, UK
- Department of Paediatric Neurology, Newcastle upon Tyne Hospitals NHS Trust, Newcastle upon Tyne, NE1 4LP
| | - Rita Horvath
- Wellcome Trust Centre for Mitochondrial Research, Institute of Genetic Medicine, Newcastle University, Central Parkway, Newcastle upon Tyne, NE1 3BZ, UK
| | - Patrick F. Chinnery
- Wellcome Trust Centre for Mitochondrial Research, Institute of Genetic Medicine, Newcastle University, Central Parkway, Newcastle upon Tyne, NE1 3BZ, UK
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Yarham JW, Lamichhane TN, Pyle A, Mattijssen S, Baruffini E, Bruni F, Donnini C, Vassilev A, He L, Blakely EL, Griffin H, Santibanez-Koref M, Bindoff LA, Ferrero I, Chinnery PF, McFarland R, Maraia RJ, Taylor RW. Defective i6A37 modification of mitochondrial and cytosolic tRNAs results from pathogenic mutations in TRIT1 and its substrate tRNA. PLoS Genet 2014; 10:e1004424. [PMID: 24901367 PMCID: PMC4046958 DOI: 10.1371/journal.pgen.1004424] [Citation(s) in RCA: 102] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2013] [Accepted: 04/20/2014] [Indexed: 01/10/2023] Open
Abstract
Identifying the genetic basis for mitochondrial diseases is technically challenging given the size of the mitochondrial proteome and the heterogeneity of disease presentations. Using next-generation exome sequencing, we identified in a patient with severe combined mitochondrial respiratory chain defects and corresponding perturbation in mitochondrial protein synthesis, a homozygous p.Arg323Gln mutation in TRIT1. This gene encodes human tRNA isopentenyltransferase, which is responsible for i6A37 modification of the anticodon loops of a small subset of cytosolic and mitochondrial tRNAs. Deficiency of i6A37 was previously shown in yeast to decrease translational efficiency and fidelity in a codon-specific manner. Modelling of the p.Arg323Gln mutation on the co-crystal structure of the homologous yeast isopentenyltransferase bound to a substrate tRNA, indicates that it is one of a series of adjacent basic side chains that interact with the tRNA backbone of the anticodon stem, somewhat removed from the catalytic center. We show that patient cells bearing the p.Arg323Gln TRIT1 mutation are severely deficient in i6A37 in both cytosolic and mitochondrial tRNAs. Complete complementation of the i6A37 deficiency of both cytosolic and mitochondrial tRNAs was achieved by transduction of patient fibroblasts with wild-type TRIT1. Moreover, we show that a previously-reported pathogenic m.7480A>G mt-tRNASer(UCN) mutation in the anticodon loop sequence A36A37A38 recognised by TRIT1 causes a loss of i6A37 modification. These data demonstrate that deficiencies of i6A37 tRNA modification should be considered a potential mechanism of human disease caused by both nuclear gene and mitochondrial DNA mutations while providing insight into the structure and function of TRIT1 in the modification of cytosolic and mitochondrial tRNAs. Mitochondrial disorders are clinically diverse, and identifying the underlying genetic mutations is technically challenging due to the large number of mitochondrial proteins. Using high-throughput sequencing technology, we identified a disease-causing mutation in the TRIT1 gene. This gene encodes an enzyme, tRNA isopentenyltransferase, that adds an N6-isopentenyl modification to adenosine-37 (i6A37) in a small number of tRNAs, enabling them to function correctly during the synthesis of essential mitochondrial proteins. We show that this mutation leads to severe deficiency of tRNA-i6A37 in the patient's cells that can be rescued by introduction of the wild-type TRIT1 protein. A deficiency in oxidative phosphorylation, the process by which energy (ATP) is generated in the mitochondria, leads to a mitochondrial disease presentation. Introducing the mutant protein into model yeast species and measuring the resulting impairment provided further evidence of the pathogenic effect of the mutation. Additional studies investigating a previously reported pathogenic mutation in a mitochondrial tRNA gene demonstrated that a mutation in a substrate of TRIT1 can also cause a loss of the modification, providing evidence of a new mechanism causing mitochondrial disease in humans.
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Affiliation(s)
- John W. Yarham
- Wellcome Trust Centre for Mitochondrial Research, Institute for Ageing and Health, The Medical School, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Tek N. Lamichhane
- Intramural Research Program, NICHD, NIH, Bethesda, Maryland, United States of America
| | - Angela Pyle
- Wellcome Trust Centre for Mitochondrial Research, Institute for Genetic Medicine, The Medical School, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Sandy Mattijssen
- Intramural Research Program, NICHD, NIH, Bethesda, Maryland, United States of America
| | | | - Francesco Bruni
- Wellcome Trust Centre for Mitochondrial Research, Institute for Ageing and Health, The Medical School, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Claudia Donnini
- Department of Life Sciences, University of Parma, Parma, Italy
| | - Alex Vassilev
- Intramural Research Program, NICHD, NIH, Bethesda, Maryland, United States of America
| | - Langping He
- Wellcome Trust Centre for Mitochondrial Research, Institute for Ageing and Health, The Medical School, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Emma L. Blakely
- Wellcome Trust Centre for Mitochondrial Research, Institute for Ageing and Health, The Medical School, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Helen Griffin
- Wellcome Trust Centre for Mitochondrial Research, Institute for Genetic Medicine, The Medical School, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Mauro Santibanez-Koref
- Wellcome Trust Centre for Mitochondrial Research, Institute for Genetic Medicine, The Medical School, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Laurence A. Bindoff
- Department of Neurology, Haukeland University Hospital, Bergen, Norway
- Department of Clinical Medicine, University of Bergen, Bergen, Norway
| | - Ileana Ferrero
- Department of Life Sciences, University of Parma, Parma, Italy
| | - Patrick F. Chinnery
- Wellcome Trust Centre for Mitochondrial Research, Institute for Genetic Medicine, The Medical School, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Robert McFarland
- Wellcome Trust Centre for Mitochondrial Research, Institute for Ageing and Health, The Medical School, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Richard J. Maraia
- Intramural Research Program, NICHD, NIH, Bethesda, Maryland, United States of America
- * E-mail: (RJM) (RM); (RWT) (RT)
| | - Robert W. Taylor
- Wellcome Trust Centre for Mitochondrial Research, Institute for Ageing and Health, The Medical School, Newcastle University, Newcastle upon Tyne, United Kingdom
- * E-mail: (RJM) (RM); (RWT) (RT)
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Pfeffer G, Gorman GS, Griffin H, Kurzawa-Akanbi M, Blakely EL, Wilson I, Sitarz K, Moore D, Murphy JL, Alston CL, Pyle A, Coxhead J, Payne B, Gorrie GH, Longman C, Hadjivassiliou M, McConville J, Dick D, Imam I, Hilton D, Norwood F, Baker MR, Jaiser SR, Yu-Wai-Man P, Farrell M, McCarthy A, Lynch T, McFarland R, Schaefer AM, Turnbull DM, Horvath R, Taylor RW, Chinnery PF. Mutations in the SPG7 gene cause chronic progressive external ophthalmoplegia through disordered mitochondrial DNA maintenance. Brain 2014; 137:1323-36. [PMID: 24727571 PMCID: PMC3999722 DOI: 10.1093/brain/awu060] [Citation(s) in RCA: 119] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2013] [Revised: 01/12/2014] [Accepted: 01/30/2014] [Indexed: 12/12/2022] Open
Abstract
Despite being a canonical presenting feature of mitochondrial disease, the genetic basis of progressive external ophthalmoplegia remains unknown in a large proportion of patients. Here we show that mutations in SPG7 are a novel cause of progressive external ophthalmoplegia associated with multiple mitochondrial DNA deletions. After excluding known causes, whole exome sequencing, targeted Sanger sequencing and multiplex ligation-dependent probe amplification analysis were used to study 68 adult patients with progressive external ophthalmoplegia either with or without multiple mitochondrial DNA deletions in skeletal muscle. Nine patients (eight probands) were found to carry compound heterozygous SPG7 mutations, including three novel mutations: two missense mutations c.2221G>A; p.(Glu741Lys), c.2224G>A; p.(Asp742Asn), a truncating mutation c.861dupT; p.Asn288*, and seven previously reported mutations. We identified a further six patients with single heterozygous mutations in SPG7, including two further novel mutations: c.184-3C>T (predicted to remove a splice site before exon 2) and c.1067C>T; p.(Thr356Met). The clinical phenotype typically developed in mid-adult life with either progressive external ophthalmoplegia/ptosis and spastic ataxia, or a progressive ataxic disorder. Dysphagia and proximal myopathy were common, but urinary symptoms were rare, despite the spasticity. Functional studies included transcript analysis, proteomics, mitochondrial network analysis, single fibre mitochondrial DNA analysis and deep re-sequencing of mitochondrial DNA. SPG7 mutations caused increased mitochondrial biogenesis in patient muscle, and mitochondrial fusion in patient fibroblasts associated with the clonal expansion of mitochondrial DNA mutations. In conclusion, the SPG7 gene should be screened in patients in whom a disorder of mitochondrial DNA maintenance is suspected when spastic ataxia is prominent. The complex neurological phenotype is likely a result of the clonal expansion of secondary mitochondrial DNA mutations modulating the phenotype, driven by compensatory mitochondrial biogenesis.
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Affiliation(s)
- Gerald Pfeffer
- 1 Wellcome Centre for Mitochondrial Research, Newcastle University, Newcastle upon Tyne, NE2 4HH, UK
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Blakely EL, Alston CL, Lecky B, Chakrabarti B, Falkous G, Turnbull DM, Taylor RW, Gorman GS. Distal weakness with respiratory insufficiency caused by the m.8344A > G "MERRF" mutation. Neuromuscul Disord 2014; 24:533-6. [PMID: 24792523 PMCID: PMC4047625 DOI: 10.1016/j.nmd.2014.03.011] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2014] [Revised: 03/07/2014] [Accepted: 03/20/2014] [Indexed: 12/02/2022]
Abstract
The m.8344A > G mutation in the mt-tRNALys gene, first described in myoclonic epilepsy and ragged red fibers (MERRF), accounts for approximately 80% of mutations in individuals with MERRF syndrome. Although originally described in families with a classical syndrome of myoclonus, ataxia, epilepsy and ragged red fibers in muscle biopsy, the m.8344A > G mutation is increasingly recognised to exhibit marked phenotypic heterogeneity. This paper describes the clinical, morphological and laboratory features of an unusual phenotype in a patient harboring the m.8344A > G ‘MERRF’ mutation. We present the case of a middle-aged woman with distal weakness since childhood who also had ptosis and facial weakness and who developed mid-life respiratory insufficiency necessitating non-invasive nocturnal ventilator support. Neurophysiological and acetylcholine receptor antibody analyses excluded myasthenia gravis whilst molecular genetic testing excluded myotonic dystrophy, prompting a diagnostic needle muscle biopsy. Mitochondrial histochemical abnormalities including subsarcolemmal mitochondrial accumulation (ragged-red fibers) and in excess of 90% COX-deficient fibers, was seen leading to sequencing of the mitochondrial genome in muscle. This identified the m.8344A > G mutation commonly associated with the MERRF phenotype. This case extends the evolving phenotypic spectrum of the m.8344A > G mutation and emphasizes that it may cause indolent distal weakness with respiratory insufficiency, with marked histochemical defects in muscle. Our findings support consideration of screening of this gene in cases of indolent myopathy resembling distal limb-girdle muscular dystrophy in which screening of the common genes prove negative.
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Affiliation(s)
- Emma L Blakely
- Wellcome Trust Centre for Mitochondrial Research, Institute for Ageing and Health, The Medical School, Newcastle University, Newcastle upon Tyne NE2 2HH, UK
| | - Charlotte L Alston
- Wellcome Trust Centre for Mitochondrial Research, Institute for Ageing and Health, The Medical School, Newcastle University, Newcastle upon Tyne NE2 2HH, UK
| | - Bryan Lecky
- The Walton Centre NHS Foundation Trust, Liverpool L9 7LJ, UK
| | | | - Gavin Falkous
- Wellcome Trust Centre for Mitochondrial Research, Institute for Ageing and Health, The Medical School, Newcastle University, Newcastle upon Tyne NE2 2HH, UK
| | - Douglass M Turnbull
- Wellcome Trust Centre for Mitochondrial Research, Institute for Ageing and Health, The Medical School, Newcastle University, Newcastle upon Tyne NE2 2HH, UK
| | - Robert W Taylor
- Wellcome Trust Centre for Mitochondrial Research, Institute for Ageing and Health, The Medical School, Newcastle University, Newcastle upon Tyne NE2 2HH, UK
| | - Grainne S Gorman
- Wellcome Trust Centre for Mitochondrial Research, Institute for Ageing and Health, The Medical School, Newcastle University, Newcastle upon Tyne NE2 2HH, UK.
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Blakely EL, Yarham JW, Alston CL, Craig K, Poulton J, Brierley C, Park SM, Dean A, Xuereb JH, Anderson KN, Compston A, Allen C, Sharif S, Enevoldson P, Wilson M, Hammans SR, Turnbull DM, McFarland R, Taylor RW. Pathogenic mitochondrial tRNA point mutations: nine novel mutations affirm their importance as a cause of mitochondrial disease. Hum Mutat 2014; 34:1260-8. [PMID: 23696415 PMCID: PMC3884772 DOI: 10.1002/humu.22358] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2013] [Accepted: 05/10/2013] [Indexed: 11/26/2022]
Abstract
Mutations in the mitochondrial genome, and in particular the mt-tRNAs, are an important cause of human disease. Accurate classification of the pathogenicity of novel variants is vital to allow accurate genetic counseling for patients and their families. The use of weighted criteria based on functional studies—outlined in a validated pathogenicity scoring system—is therefore invaluable in determining whether novel or rare mt-tRNA variants are pathogenic. Here, we describe the identification of nine novel mt-tRNA variants in nine families, in which the probands presented with a diverse range of clinical phenotypes including mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes, isolated progressive external ophthalmoplegia, epilepsy, deafness and diabetes. Each of the variants identified (m.4289T>C, MT-TI; m.5541C>T, MT-TW; m.5690A>G, MT-TN; m.7451A>T, MT-TS1; m.7554G>A, MT-TD; m.8304G>A, MT-TK; m.12206C>T, MT-TH; m.12317T>C, MT-TL2; m.16023G>A, MT-TP) was present in a different tRNA, with evidence in support of pathogenicity, and where possible, details of mutation transmission documented. Through the application of the pathogenicity scoring system, we have classified six of these variants as “definitely pathogenic” mutations (m.5541C>T, m.5690A>G, m.7451A>T, m.12206C>T, m.12317T>C, and m.16023G>A), whereas the remaining three currently lack sufficient evidence and are therefore classed as ‘possibly pathogenic’ (m.4289T>C, m.7554G>A, and m.8304G>A).
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Affiliation(s)
- Emma L Blakely
- Wellcome Trust Centre for Mitochondrial Research, Institute for Ageing and Health, Newcastle University, Newcastle upon Tyne, UK
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46
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Pyle A, Ramesh V, Bartsakoulia M, Boczonadi V, Gomez-Duran A, Herczegfalvi A, Blakely EL, Smertenko T, Duff J, Eglon G, Moore D, Yu-Wai-Man P, Douroudis K, Santibanez-Koref M, Griffin H, Lochmüller H, Karcagi V, Taylor RW, Chinnery PF, Horvath R. Behr's Syndrome is Typically Associated with Disturbed Mitochondrial Translation and Mutations in the C12orf65 Gene. J Neuromuscul Dis 2014; 1:55-63. [PMID: 26380172 PMCID: PMC4568311 DOI: 10.3233/jnd-140003] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
BACKGROUND Behr's syndrome is a classical phenotypic description of childhood-onset optic atrophy combined with various neurological symptoms, including ophthalmoparesis, nystagmus, spastic paraparesis, ataxia, peripheral neuropathy and learning difficulties. OBJECTIVE Here we describe 4 patients with the classical Behr's syndrome phenotype from 3 unrelated families who carry homozygous nonsense mutations in the C12orf65 gene encoding a protein involved in mitochondrial translation. METHODS Whole exome sequencing was performed in genomic DNA and oxygen consumption was measured in patient cell lines. RESULTS We detected 2 different homozygous C12orf65 nonsense mutations in 4 patients with a homogeneous clinical presentation matching the historical description of Behr's syndrome. The first symptom in all patients was childhood-onset optic atrophy, followed by spastic paraparesis, distal weakness, motor neuropathy and ophthalmoparesis. CONCLUSIONS We think that C12orf65 mutations are more frequent than previously suggested and screening of this gene should be considered not only in patients with mitochondrial respiratory chain deficiencies, but also in inherited peripheral neuropathies, spastic paraplegias and ataxias, especially with pre-existing optic atrophy.
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Affiliation(s)
- Angela Pyle
- Wellcome Trust Centre for Mitochondrial Research, Institute of Genetic Medicine, Newcastle University, Newcastle upon Tyne, UK
| | - Venkateswaran Ramesh
- Department of Pediatric Neurology, Royal Victoria Infirmary, Newcastle upon Tyne Hospitals NHS Trust, UK
| | - Marina Bartsakoulia
- Wellcome Trust Centre for Mitochondrial Research, Institute of Genetic Medicine, Newcastle University, Newcastle upon Tyne, UK
| | - Veronika Boczonadi
- Wellcome Trust Centre for Mitochondrial Research, Institute of Genetic Medicine, Newcastle University, Newcastle upon Tyne, UK
| | - Aurora Gomez-Duran
- Wellcome Trust Centre for Mitochondrial Research, Institute of Genetic Medicine, Newcastle University, Newcastle upon Tyne, UK
| | | | - Emma L. Blakely
- Wellcome Trust Mitochondrial Research Centre, Institute for Ageing and Health, Newcastle University, Newcastle upon Tyne, UK
| | - Tania Smertenko
- Wellcome Trust Centre for Mitochondrial Research, Institute of Genetic Medicine, Newcastle University, Newcastle upon Tyne, UK
| | - Jennifer Duff
- Wellcome Trust Centre for Mitochondrial Research, Institute of Genetic Medicine, Newcastle University, Newcastle upon Tyne, UK
| | - Gail Eglon
- Wellcome Trust Centre for Mitochondrial Research, Institute of Genetic Medicine, Newcastle University, Newcastle upon Tyne, UK
| | - David Moore
- Wellcome Trust Centre for Mitochondrial Research, Institute of Genetic Medicine, Newcastle University, Newcastle upon Tyne, UK
| | - Patrick Yu-Wai-Man
- Wellcome Trust Centre for Mitochondrial Research, Institute of Genetic Medicine, Newcastle University, Newcastle upon Tyne, UK
| | - Konstantinos Douroudis
- Wellcome Trust Centre for Mitochondrial Research, Institute of Genetic Medicine, Newcastle University, Newcastle upon Tyne, UK
| | | | - Helen Griffin
- Wellcome Trust Centre for Mitochondrial Research, Institute of Genetic Medicine, Newcastle University, Newcastle upon Tyne, UK
| | - Hanns Lochmüller
- Institute of Genetic Medicine, Newcastle University, Newcastle upon Tyne, UK
| | - Veronika Karcagi
- Department of Molecular Genetics and Diagnostics, NIEH, Budapest, Hungary
| | - Robert W. Taylor
- Wellcome Trust Mitochondrial Research Centre, Institute for Ageing and Health, Newcastle University, Newcastle upon Tyne, UK
| | - Patrick F. Chinnery
- Wellcome Trust Centre for Mitochondrial Research, Institute of Genetic Medicine, Newcastle University, Newcastle upon Tyne, UK
| | - Rita Horvath
- Wellcome Trust Centre for Mitochondrial Research, Institute of Genetic Medicine, Newcastle University, Newcastle upon Tyne, UK
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Alston CL, Schaefer AM, Raman P, Solaroli N, Krishnan KJ, Blakely EL, He L, Craig K, Roberts M, Vyas A, Nixon J, Horvath R, Turnbull DM, Karlsson A, Gorman GS, Taylor RW. Late-onset respiratory failure due to TK2 mutations causing multiple mtDNA deletions. Neurology 2013; 81:2051-3. [PMID: 24198295 PMCID: PMC3854830 DOI: 10.1212/01.wnl.0000436931.94291.e6] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2013] [Accepted: 08/20/2013] [Indexed: 11/15/2022] Open
Abstract
Mutations in nuclear genes involved in the maintenance of mitochondrial DNA (mtDNA) are associated with an extensive spectrum of clinical phenotypes, manifesting as either mtDNA depletion syndromes or multiple mtDNA deletion disorders.(1.)
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Affiliation(s)
- Charlotte L Alston
- From Newcastle University (C.L.A., A.M.S., P.R., K.J.K., E.L.B., L.H., K.C., R.H., D.M.T., G.S.G., R.W.T.), Newcastle upon Tyne, UK; Karolinska Institute (N.S., A.K.), Stockholm, Sweden; Hope Hospital (M.R.), Salford; and Royal Preston Hospital (A.V., J.N.), Preston, UK
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48
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Grady JP, Campbell G, Ratnaike T, Blakely EL, Falkous G, Nesbitt V, Schaefer AM, McNally RJ, Gorman GS, Taylor RW, Turnbull DM, McFarland R. Disease progression in patients with single, large-scale mitochondrial DNA deletions. Brain 2013; 137:323-34. [PMID: 24277717 PMCID: PMC3914470 DOI: 10.1093/brain/awt321] [Citation(s) in RCA: 77] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Single, large-scale deletions of mitochondrial DNA are a common cause of mitochondrial disease and cause a broad phenotypic spectrum ranging from mild myopathy to devastating multi-system syndromes such as Kearns-Sayre syndrome. Studies to date have been inconsistent on the value of putative predictors of clinical phenotype and disease progression such as mutation load and the size or location of the deletion. Using a cohort of 87 patients with single, large-scale mitochondrial DNA deletions we demonstrate that a variety of outcome measures such as COX-deficient fibre density, age-at-onset of symptoms and progression of disease burden, as measured by the Newcastle Mitochondrial Disease Adult Scale, are significantly (P < 0.05) correlated with the size of the deletion, the deletion heteroplasmy level in skeletal muscle, and the location of the deletion within the genome. We validate these findings with re-analysis of 256 cases from published data and clarify the previously conflicting information of the value of these predictors, identifying that multiple regression analysis is necessary to understand the effect of these interrelated predictors. Furthermore, we have used mixed modelling techniques to model the progression of disease according to these predictors, allowing a better understanding of the progression over time of this strikingly variable disease. In this way we have developed a new paradigm in clinical mitochondrial disease assessment and management that sidesteps the perennial difficulty of ascribing a discrete clinical phenotype to a broad multi-dimensional and progressive spectrum of disease, establishing a framework to allow better understanding of disease progression.
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Affiliation(s)
- John P Grady
- 1 Wellcome Trust Centre for Mitochondrial Research, Institute for Ageing and Health, Newcastle University, Newcastle upon Tyne, UK
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Baruffini E, Dallabona C, Invernizzi F, Yarham JW, Melchionda L, Blakely EL, Lamantea E, Donnini C, Santra S, Vijayaraghavan S, Roper HP, Burlina A, Kopajtich R, Walther A, Strom TM, Haack TB, Prokisch H, Taylor RW, Ferrero I, Zeviani M, Ghezzi D. MTO1 mutations are associated with hypertrophic cardiomyopathy and lactic acidosis and cause respiratory chain deficiency in humans and yeast. Hum Mutat 2013; 34:1501-9. [PMID: 23929671 PMCID: PMC4028987 DOI: 10.1002/humu.22393] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2013] [Revised: 07/10/2013] [Accepted: 07/19/2013] [Indexed: 11/10/2022]
Abstract
We report three families presenting with hypertrophic cardiomyopathy, lactic acidosis, and multiple defects of mitochondrial respiratory chain (MRC) activities. By direct sequencing of the candidate gene MTO1, encoding the mitochondrial-tRNA modifier 1, or whole exome sequencing analysis, we identified novel missense mutations. All MTO1 mutations were predicted to be deleterious on MTO1 function. Their pathogenic role was experimentally validated in a recombinant yeast model, by assessing oxidative growth, respiratory activity, mitochondrial protein synthesis, and complex IV activity. In one case, we also demonstrated that expression of wt MTO1 could rescue the respiratory defect in mutant fibroblasts. The severity of the yeast respiratory phenotypes partly correlated with the different clinical presentations observed in MTO1 mutant patients, although the clinical outcome was highly variable in patients with the same mutation and seemed also to depend on timely start of pharmacological treatment, centered on the control of lactic acidosis by dichloroacetate. Our results indicate that MTO1 mutations are commonly associated with a presentation of hypertrophic cardiomyopathy, lactic acidosis, and MRC deficiency, and that ad hoc recombinant yeast models represent a useful system to test the pathogenic potential of uncommon variants, and provide insight into their effects on the expression of a biochemical phenotype.
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50
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Spendiff S, Reza M, Murphy JL, Gorman G, Blakely EL, Taylor RW, Horvath R, Campbell G, Newman J, Lochmüller H, Turnbull DM. Mitochondrial DNA deletions in muscle satellite cells: implications for therapies. Hum Mol Genet 2013; 22:4739-47. [PMID: 23847047 PMCID: PMC3820134 DOI: 10.1093/hmg/ddt327] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Progressive myopathy is a major clinical feature of patients with mitochondrial DNA (mtDNA) disease. There is limited treatment available for these patients although exercise and other approaches to activate muscle stem cells (satellite cells) have been proposed. The majority of mtDNA defects are heteroplasmic (a mixture of mutated and wild-type mtDNA present within the muscle) with high levels of mutated mtDNA and low levels of wild-type mtDNA associated with more severe disease. The culture of satellite cell-derived myoblasts often reveals no evidence of the original mtDNA mutation although it is not known if this is lost by selection or simply not present in these cells. We have explored if the mtDNA mutation is present in the satellite cells in one of the commonest genotypes associated with mitochondrial myopathies (patients with single, large-scale mtDNA deletions). Analysis of satellite cells from eight patients showed that the level of mtDNA mutation in the satellite cells is the same as in the mature muscle but is most often subsequently lost during culture. We show that there are two periods of selection against the mutated form, one early on possibly during satellite cell activation and the other during the rapid replication phase of myoblast culture. Our data suggest that the mutations are also lost during rapid replication in vivo, implying that strategies to activate satellite cells remain a viable treatment for mitochondrial myopathies in specific patient groups.
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Affiliation(s)
- Sally Spendiff
- Wellcome Trust Centre for Mitochondrial Research, The Medical School, Newcastle University, Newcastle upon Tyne NE2 4HH, UK
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