1
|
Duan H, Pan C, Wu T, Peng J, Yang L. MT-TN mutations lead to progressive mitochondrial encephalopathy and promotes mitophagy. Biochim Biophys Acta Mol Basis Dis 2024; 1870:167043. [PMID: 38320662 DOI: 10.1016/j.bbadis.2024.167043] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2023] [Revised: 01/15/2024] [Accepted: 01/24/2024] [Indexed: 02/08/2024]
Abstract
Mitochondrial encephalopathy is a neurological disorder caused by impaired mitochondrial function and energy production. One of the genetic causes of this condition is the mutation of MT-TN, a gene that encodes the mitochondrial transfer RNA (tRNA) for asparagine. MT-TN mutations affect the stability and structure of the tRNA, resulting in reduced protein synthesis and complex enzymatic deficiency of the mitochondrial respiratory chain. Our patient cohort manifests with epileptic encephalopathy, ataxia, hypotonia, and bilateral basal ganglia calcification, which differs from previously reported cases. MT-TN mutation deficiency leads to decreased basal and maximal oxygen consumption rates, disrupted spare respiratory capacity, declined mitochondrial membrane potential, and impaired ATP production. Moreover, MT-TN mutations promote mitophagy, a process of selective degradation of damaged mitochondria by autophagy. Excessive mitophagy further leads to mitochondrial biogensis as a compensatory mechanism. In this study, we provided evidence of pathogenicity for two MT-TN mutations, m.5688 T > C and m.G5691A, explored the molecular mechanisms, and summarized the clinical manifestations of MT-TN mutations. Our study expanded the genotype and phenotypic spectrum and provided new insight into mt-tRNA (Asn)-associated mitochondrial encephalopathy.
Collapse
Affiliation(s)
- Haolin Duan
- Department of Pediatrics, Clinical Research Center of Children Neurodevelopmental Disabilities of Hunan Province, Xiangya Hospital, Central South University, Changsha 410008, China
| | - Cunhui Pan
- Department of Pediatrics, Clinical Research Center of Children Neurodevelopmental Disabilities of Hunan Province, Xiangya Hospital, Central South University, Changsha 410008, China
| | - Tenghui Wu
- Department of Pediatrics, Clinical Research Center of Children Neurodevelopmental Disabilities of Hunan Province, Xiangya Hospital, Central South University, Changsha 410008, China
| | - Jing Peng
- Department of Pediatrics, Clinical Research Center of Children Neurodevelopmental Disabilities of Hunan Province, Xiangya Hospital, Central South University, Changsha 410008, China..
| | - Li Yang
- Department of Pediatrics, Clinical Research Center of Children Neurodevelopmental Disabilities of Hunan Province, Xiangya Hospital, Central South University, Changsha 410008, China..
| |
Collapse
|
2
|
Ghirigato E, Terenzi F, Baglivo M, Zanetti N, Baldo F, Murru FM, Bobbo M, Barbi E, Zeviani M, Bruno I, Lamantea E. A new family with a case of severe early-onset muscle fatigue and a peculiar maternally inherited painful swelling in chewing muscles associated with homoplasmic m.15992A>T mutation in mitochondrial tRNA Pro. Neuromuscul Disord 2023; 33:972-977. [PMID: 38030461 DOI: 10.1016/j.nmd.2023.11.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2023] [Revised: 09/12/2023] [Accepted: 11/01/2023] [Indexed: 12/01/2023]
Abstract
A 16-year-old boy was evaluated for a history of exercise-induced fatigability associated with nausea even after minimal effort, lower limbs muscle hypotrophy, and swelling of the masseter muscles after chewing. Laboratory tests were remarkable for hyperlactatemia and metabolic acidosis after short physical activity. The muscle biopsy showed non-specific mitochondrial alterations and an increase in intrafibral lipids. Biochemical analysis showed reduced activity of the respiratory chain complexes. Mitochondrial DNA sequencing revealed the presence of a homoplasmic variant m.15992A>T in the MT-TP gene, coding for the mt-tRNAPro in the patient, in his mother and in his brother. Pathogenic or likely pathogenic variants in MT-TP gene are rare. They are responsible for different clinical presentation, almost ever involving the muscle tissue. We report the first family with exercise-induced muscle weakness and swelling of the chewing muscles due to m.15992A>T variant in absence of J1c10 haplogroup, confirming its pathogenicity.
Collapse
Affiliation(s)
| | | | - Mirko Baglivo
- Unit of Medical Genetics and Neurogenetics, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy
| | - Nadia Zanetti
- Unit of Medical Genetics and Neurogenetics, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy
| | - Francesco Baldo
- Institute for Maternal and Child Health IRCCS Burlo Garofolo, Trieste, Italy.
| | - Flora Maria Murru
- Institute for Maternal and Child Health IRCCS Burlo Garofolo, Trieste, Italy
| | - Marco Bobbo
- Institute for Maternal and Child Health IRCCS Burlo Garofolo, Trieste, Italy
| | - Egidio Barbi
- University of Trieste, Italy; Institute for Maternal and Child Health IRCCS Burlo Garofolo, Trieste, Italy
| | - Massimo Zeviani
- Institute for Maternal and Child Health IRCCS Burlo Garofolo, Trieste, Italy
| | - Irene Bruno
- Institute for Maternal and Child Health IRCCS Burlo Garofolo, Trieste, Italy
| | - Eleonora Lamantea
- Unit of Medical Genetics and Neurogenetics, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy
| |
Collapse
|
3
|
Anwar G, Mamut R, Wang J. Characterization of Complete Mitochondrial Genomes of the Five Peltigera and Comparative Analysis with Relative Species. J Fungi (Basel) 2023; 9:969. [PMID: 37888225 PMCID: PMC10607270 DOI: 10.3390/jof9100969] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2023] [Revised: 09/15/2023] [Accepted: 09/16/2023] [Indexed: 10/28/2023] Open
Abstract
In the present study, the complete mitochondrial genomes of five Peltigera species (Peltigera elisabethae, Peltigera neocanina, Peltigera canina, Peltigera ponojensis, Peltigera neckeri) were sequenced, assembled and compared with relative species. The five mitogenomes were all composed of circular DNA molecules, and their ranged from 58,132 bp to 69,325 bp. The mitochondrial genomes of the five Peltigera species contain 15 protein-coding genes (PCGs), 2 rRNAs, 26-27 tRNAs and an unidentified open reading frame (ORF). The PCG length, AT skew and GC skew varied among the 15 PCGs in the five mitogenomes. Among the 15 PCGs, cox2 had the least K2P genetic distance, indicating that the gene was highly conserved. The synteny analysis revealed that the coding regions were highly conserved in the Peltigera mitochondrial genomes, but gene rearrangement occurred in the intergenic regions. The phylogenetic analysis based on the 14 PCGs showed that the 11 Peltigera species formed well-supported topologies, indicating that the protein-coding genes in the mitochondrial genome may be used as a reliable molecular tool in the study of the phylogenetic relationship of Peltigera.
Collapse
Affiliation(s)
| | - Reyim Mamut
- College of Life Sciences and Technology, Xinjiang University, Urumchi 830017, China; (G.A.); (J.W.)
| | | |
Collapse
|
4
|
Wu G, Shen Y, Zhu F, Tao W, Zhou Y, Ke S, Jiang H. Comprehensive Diagnostic Criteria for MELAS Syndrome; a Case Study Involving an Elderly Patient With MT-TWm.5541C>T Mutation. Neurologist 2023; 28:190-194. [PMID: 36125978 PMCID: PMC10158598 DOI: 10.1097/nrl.0000000000000457] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
INTRODUCTION The mitochondrial encephalopathy, lactic acidosis, and stroke-like episodes (MELAS) syndrome is a matrilineal hereditary multisystem disease caused by mutations in the mitochondrial DNA. Although the initial diagnostic criteria correlate with a range of clinical phenotypes, including clinical onset after the age of 40, there is still lack of a unified single diagnostic standard for MELAS. CASE REPORT A 71-year-old female patient with recurrent stroke was reported. Magnetic resonance imaging showed a cerebral gyrus-like diffusion weighted imaging high signal lesion in the parietal-occipital lobe and the area of this lesion expanded with disease progression. The MRS result showed significantly inverted Lac/Lip peaks. The nucleic acid sequencing result displayed a MT-TWm.5541C>T mutation, and a 12.86% mutation rate in the blood sample. The patient had a 6-year history of type 2 diabetes. CONCLUSION Patients with the MELAS syndrome may present with a variety of clinical manifestations. Our data demonstrated that, for patients with atypical cerebral infarction and suspected MELAS syndrome, gene sequencing and muscle biopsy should be performed in time. This case provides a reference for the diagnostic criteria of MELAS syndrome.
Collapse
Affiliation(s)
- Gang Wu
- Department of Neurology
- Department of Pharmacy, Taizhou Hospital of Zhejiang Province affiliated to Wenzhou Medical University, Linhai, Zhejiang, China
| | | | | | | | | | | | | |
Collapse
|
5
|
The Mitochondrial tRNA Ser(UCN) Gene: A Novel m.7484A>G Mutation Associated with Mitochondrial Encephalomyopathy and Literature Review. Life (Basel) 2023; 13:life13020554. [PMID: 36836911 PMCID: PMC9963529 DOI: 10.3390/life13020554] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2023] [Revised: 01/26/2023] [Accepted: 02/14/2023] [Indexed: 02/18/2023] Open
Abstract
Mitochondrial tRNASer(UCN) is considered a hot-spot for non-syndromic and aminoglycoside-induced hearing loss. However, many patients have been described with more extensive neurological diseases, mainly including epilepsy, myoclonus, ataxia, and myopathy. We describe a novel homoplasmic m.7484A>G mutation in the tRNASer(UCN) gene affecting the third base of the anticodon triplet in a girl with profound intellectual disability, spastic tetraplegia, sensorineural hearing loss, a clinical history of epilepsia partialis continua and vomiting, typical of MELAS syndrome, leading to a myoclonic epilepticus status, and myopathy with severe COX deficiency at muscle biopsy. The mutation was also found in the homoplasmic condition in the mother who presented with mild cognitive deficit, cerebellar ataxia, myoclonic epilepsy, sensorineural hearing loss and myopathy with COX deficient ragged-red fibers consistent with MERRF syndrome. This is the first anticodon mutation in the tRNASer(UCN) and the second homoplasmic mutation in the anticodon triplet reported to date.
Collapse
|
6
|
Genetic testing for mitochondrial disease: the United Kingdom best practice guidelines. Eur J Hum Genet 2023; 31:148-163. [PMID: 36513735 PMCID: PMC9905091 DOI: 10.1038/s41431-022-01249-w] [Citation(s) in RCA: 18] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2022] [Revised: 11/12/2022] [Accepted: 11/16/2022] [Indexed: 12/15/2022] Open
Abstract
Primary mitochondrial disease describes a diverse group of neuro-metabolic disorders characterised by impaired oxidative phosphorylation. Diagnosis is challenging; >350 genes, both nuclear and mitochondrial DNA (mtDNA) encoded, are known to cause mitochondrial disease, leading to all possible inheritance patterns and further complicated by heteroplasmy of the multicopy mitochondrial genome. Technological advances, particularly next-generation sequencing, have driven a shift in diagnostic practice from 'biopsy first' to genome-wide analyses of blood and/or urine DNA. This has led to the need for a reference framework for laboratories involved in mitochondrial genetic testing to facilitate a consistent high-quality service. In the United Kingdom, consensus guidelines have been prepared by a working group of Clinical Scientists from the NHS Highly Specialised Service followed by national laboratory consultation. These guidelines summarise current recommended technologies and methodologies for the analysis of mtDNA and nuclear-encoded genes in patients with suspected mitochondrial disease. Genetic testing strategies for diagnosis, family testing and reproductive options including prenatal diagnosis are outlined. Importantly, recommendations for the minimum levels of mtDNA testing for the most common referral reasons are included, as well as guidance on appropriate referrals and information on the minimal appropriate gene content of panels when analysing nuclear mitochondrial genes. Finally, variant interpretation and recommendations for reporting of results are discussed, focussing particularly on the challenges of interpreting and reporting mtDNA variants.
Collapse
|
7
|
Abstract
Progressive external ophthalmoplegia (PEO), characterized by ptosis and impaired eye movements, is a clinical syndrome with an expanding number of etiologically distinct subtypes. Advances in molecular genetics have revealed numerous pathogenic causes of PEO, originally heralded in 1988 by the detection of single large-scale deletions of mitochondrial DNA (mtDNA) in skeletal muscle of people with PEO and Kearns-Sayre syndrome. Since then, multiple point variants of mtDNA and nuclear genes have been identified to cause mitochondrial PEO and PEO-plus syndromes, including mitochondrial neurogastrointestinal encephalomyopathy (MNGIE) and sensory ataxic neuropathy dysarthria ophthalmoplegia (SANDO). Intriguingly, many of those nuclear DNA pathogenic variants impair maintenance of the mitochondrial genome causing downstream mtDNA multiple deletions and depletion. In addition, numerous genetic causes of nonmitochondrial PEO have been identified.
Collapse
Affiliation(s)
- Michio Hirano
- H. Houston Merritt Neuromuscular Research Center, Neuromuscular Medicine Division, Department of Neurology, Columbia University Irving Medical Center, New York, NY, United States.
| | - Robert D S Pitceathly
- Department of Neuromuscular Diseases, UCL Queen Square Institute of Neurology, London, United Kingdom; NHS Highly Specialised Service for Rare Mitochondrial Disorders, Queen Square Centre for Neuromuscular Diseases, National Hospital for Neurology and Neurosurgery, London, United Kingdom
| |
Collapse
|
8
|
Yuen L, Sahai I, O'Grady L, Selig M, Walker MA, Shah U, Misdraji J. Hepatic histologic findings in a case of MEGDHEL syndrome due to SERAC1 deficiency. Am J Med Genet A 2022; 188:2760-2765. [PMID: 35781780 DOI: 10.1002/ajmg.a.62886] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2021] [Revised: 05/20/2022] [Accepted: 06/13/2022] [Indexed: 01/25/2023]
Abstract
MEGD(H)EL syndrome is a rare autosomal recessive disorder caused by mutations in SERAC1, a protein necessary for phosphatidylglycerol remodeling. It is characterized by 3-methylglutaconic aciduria, deafness-dystonia, (hepatopathy), encephalopathy, and Leigh-like syndrome, but has a wide spectrum of severity. Here, we present a case of a child with MEGD(H)EL syndrome with infantile hepatopathy, neurodevelopmental delays, characteristic biochemical abnormalities, and biallelic novel SERAC1 mutations: (1) deletion of (at least) exons 2-4, pathogenic; and (2) c.1601A>T (p.H534L), likely pathogenic. Her initial clinical presentation was notable for persistently elevated transaminases, speech delay, delayed motor milestones, and sensorineural hearing loss. However, her verbal and motor development has progressively improved and now, at 4 years of age, she has only speech and mild gross motor delays as compared to her unaffected peers and is exceeding clinical expectations. The histologic features of a liver biopsy are described, which has not previously been published in detail for this syndrome. Hepatocytes showed granular cytoplasm and fine intracytoplasmic lipid droplets. The ultrastructural findings included abnormal circular mitochondrial cristae. These findings are consistent with a mitochondrial disorder.
Collapse
Affiliation(s)
- Lisa Yuen
- Department of Pathology, Massachusetts General Hospital, Boston, Massachusetts, USA.,Harvard Medical School, Boston, Massachusetts, USA
| | - Inderneel Sahai
- Harvard Medical School, Boston, Massachusetts, USA.,Division of Medical Genetics and Metabolism, Massachusetts General Hospital for Children, Boston, Massachusetts, USA
| | - Lauren O'Grady
- Harvard Medical School, Boston, Massachusetts, USA.,Division of Medical Genetics and Metabolism, Massachusetts General Hospital for Children, Boston, Massachusetts, USA
| | - Martin Selig
- Department of Pathology, Massachusetts General Hospital, Boston, Massachusetts, USA.,Harvard Medical School, Boston, Massachusetts, USA
| | - Melissa Anne Walker
- Harvard Medical School, Boston, Massachusetts, USA.,Department of Neurology, Massachusetts General Hospital, Boston, Massachusetts, USA
| | - Uzma Shah
- Harvard Medical School, Boston, Massachusetts, USA.,Department of Pediatric Gastroenterology, Massachusetts General Hospital for Children, Boston, Massachusetts, USA
| | - Joseph Misdraji
- Department of Pathology, Yale University, New Haven, Connecticut, USA
| |
Collapse
|
9
|
A Novel MTTK Gene Variant m.8315A>C as a Cause of MERRF Syndrome. Genes (Basel) 2022; 13:genes13071245. [PMID: 35886028 PMCID: PMC9319148 DOI: 10.3390/genes13071245] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2022] [Revised: 07/11/2022] [Accepted: 07/11/2022] [Indexed: 02/01/2023] Open
Abstract
In this study, we report on a novel heteroplasmic pathogenic variant in mitochondrial DNA (mtDNA). The studied patient had myoclonus, epilepsy, muscle weakness, and hearing impairment and harbored a heteroplasmic m.8315A>C variant in the MTTK gene with a mutation load ranging from 71% to >96% in tested tissues. In muscle mitochondria, markedly decreased activities of respiratory chain complex I + III and complex IV were observed together with mildly reduced amounts of complex I and complex V (with the detection of V*- and free F1-subcomplexes) and a diminished level of complex IV holoenzyme. This pattern was previously seen in other MTTK pathogenic variants. The novel variant was not present in internal and publicly available control databases. Our report further expands the spectrum of MTTK variants associated with mitochondrial encephalopathies in adults.
Collapse
|
10
|
Wang J, Balciuniene J, Diaz-Miranda MA, McCormick EM, Aref-Eshghi E, Muir AM, Cao K, Troiani J, Moseley A, Fan Z, Zolkipli-Cunningham Z, Goldstein A, Ganetzky RD, Muraresku CC, Peterson JT, Spinner NB, Wallace DC, Dulik MC, Falk MJ. Advanced approach for comprehensive mtDNA genome testing in mitochondrial disease. Mol Genet Metab 2022; 135:93-101. [PMID: 34969639 PMCID: PMC8877466 DOI: 10.1016/j.ymgme.2021.12.006] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/17/2021] [Revised: 12/13/2021] [Accepted: 12/14/2021] [Indexed: 01/16/2023]
Abstract
Mitochondrial disease diagnosis requires interrogation of both nuclear and mitochondrial (mtDNA) genomes for single-nucleotide variants (SNVs) and copy number alterations, both in the proband and often maternal relatives, together with careful phenotype correlation. We developed a comprehensive mtDNA sequencing test ('MitoGenome') using long-range PCR (LR-PCR) to amplify the full length of the mtDNA genome followed by next generation sequencing (NGS) to accurately detect SNVs and large-scale mtDNA deletions (LSMD), combined with droplet digital PCR (ddPCR) for LSMD heteroplasmy quantification. Overall, MitoGenome tests were performed on 428 samples from 394 patients with suspected or confirmed mitochondrial disease. The positive yield was 11% (43/394), including 34 patients with pathogenic or likely pathogenic SNVs (the most common being m.3243A > G in 8/34 (24%) patients), 8 patients with single LSMD, and 3 patients with multiple LSMD exceeding 10% heteroplasmy levels. Two patients with both LSMD and pathogenic SNV were detected. Overall, this LR-PCR/NGS assay provides a highly accurate and comprehensive diagnostic method for simultaneous mtDNA SNV detection at heteroplasmy levels as low as 1% and LSMD detection at heteroplasmy levels below 10%. Inclusion of maternal samples for variant classification and ddPCR to quantify LSMD heteroplasmy levels further enables accurate pathogenicity assessment and clinical correlation interpretation of mtDNA genome sequence variants and copy number alterations.
Collapse
Affiliation(s)
- Jing Wang
- Division of Genomic Diagnostics, Department of Pathology, The Children's Hospital of Philadelphia, Philadelphia, PA, USA; Department of Pathology and Laboratory Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Jorune Balciuniene
- Division of Genomic Diagnostics, Department of Pathology, The Children's Hospital of Philadelphia, Philadelphia, PA, USA
| | - Maria Alejandra Diaz-Miranda
- Division of Genomic Diagnostics, Department of Pathology, The Children's Hospital of Philadelphia, Philadelphia, PA, USA
| | - Elizabeth M McCormick
- Mitochondrial Medicine Frontier Program, Division of Human Genetics, Department of Pediatrics, The Children's Hospital of Philadelphia, Philadelphia, PA, USA
| | - Erfan Aref-Eshghi
- Division of Genomic Diagnostics, Department of Pathology, The Children's Hospital of Philadelphia, Philadelphia, PA, USA
| | - Alison M Muir
- Division of Genomic Diagnostics, Department of Pathology, The Children's Hospital of Philadelphia, Philadelphia, PA, USA
| | - Kajia Cao
- Division of Genomic Diagnostics, Department of Pathology, The Children's Hospital of Philadelphia, Philadelphia, PA, USA
| | - Juliana Troiani
- Division of Genomic Diagnostics, Department of Pathology, The Children's Hospital of Philadelphia, Philadelphia, PA, USA
| | - Alicia Moseley
- Division of Genomic Diagnostics, Department of Pathology, The Children's Hospital of Philadelphia, Philadelphia, PA, USA
| | - Zhiqian Fan
- Division of Genomic Diagnostics, Department of Pathology, The Children's Hospital of Philadelphia, Philadelphia, PA, USA
| | - Zarazuela Zolkipli-Cunningham
- Mitochondrial Medicine Frontier Program, Division of Human Genetics, Department of Pediatrics, The Children's Hospital of Philadelphia, Philadelphia, PA, USA; Department of Pediatrics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Amy Goldstein
- Mitochondrial Medicine Frontier Program, Division of Human Genetics, Department of Pediatrics, The Children's Hospital of Philadelphia, Philadelphia, PA, USA; Department of Pediatrics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Rebecca D Ganetzky
- Mitochondrial Medicine Frontier Program, Division of Human Genetics, Department of Pediatrics, The Children's Hospital of Philadelphia, Philadelphia, PA, USA; Department of Pediatrics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Colleen C Muraresku
- Mitochondrial Medicine Frontier Program, Division of Human Genetics, Department of Pediatrics, The Children's Hospital of Philadelphia, Philadelphia, PA, USA
| | - James T Peterson
- Mitochondrial Medicine Frontier Program, Division of Human Genetics, Department of Pediatrics, The Children's Hospital of Philadelphia, Philadelphia, PA, USA
| | - Nancy B Spinner
- Division of Genomic Diagnostics, Department of Pathology, The Children's Hospital of Philadelphia, Philadelphia, PA, USA; Department of Pathology and Laboratory Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Douglas C Wallace
- Center for Mitochondrial and Epigenomic Medicine, Division of Human Genetics, Department of Pediatrics, The Children's Hospital of Philadelphia, USA; Department of Pediatrics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Matthew C Dulik
- Division of Genomic Diagnostics, Department of Pathology, The Children's Hospital of Philadelphia, Philadelphia, PA, USA; Department of Pathology and Laboratory Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA.
| | - Marni J Falk
- Mitochondrial Medicine Frontier Program, Division of Human Genetics, Department of Pediatrics, The Children's Hospital of Philadelphia, Philadelphia, PA, USA; Department of Pediatrics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA.
| |
Collapse
|
11
|
Wang S, Miao J, Feng J. Case Report: Mitochondrial Encephalomyopathy Presents as Epilepsy, Ataxia, and Dystonia With a Rare Mutation in MT-TW. Front Neurol 2021; 12:679302. [PMID: 34276539 PMCID: PMC8281247 DOI: 10.3389/fneur.2021.679302] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2021] [Accepted: 06/02/2021] [Indexed: 11/18/2022] Open
Abstract
Mitochondrial diseases are a group of common inherited disorders caused by mutations in nuclear DNA or mitochondrial DNA (mtDNA); the clinical phenotype of diseases caused by mutant mtDNA is challenging owing to heteroplasmy of mtDNA and may delay diagnosis and treatment. Herein, we report the case of an adult male who slowly developed epilepsy, ataxia, dystonia, impaired cognition, and hearing impairment over 14 years in the absence of clinical myopathy. His lactate level was normal. Brain computed tomography showed calcifications of the bilateral basal ganglia, thalamus, and cerebellar dentate nuclei. Magnetic resonance imaging revealed multiple lesions in the bilateral internal capsule and periventricular areas, which were hypointense on T1-weighted images and hyperintense on T2-weighted images. The first blood genetic test result was negative. Two years later, a muscle biopsy was performed. Succinate dehydrogenase (SDH) staining showed several ragged blue fibers and atypical strongly SDH-reactive vessels. Cytochrome C oxidase (COX) staining revealed abundant COX-deficient fibers. mtDNA testing of blood and muscle revealed a rare m.5549G>A mutation in the MT-TW gene. It was heteroplasmic, with 5.4% mutant mtDNA in the blood and 61.5% in the muscle. The patient was diagnosed with mitochondrial encephalomyopathy and treated with levetiracetam instead of valproate to reduce possible mitochondrial toxicity. After receiving anti-epileptic drugs and mitochondrial supplements, the patient remained clinically stable. For mitochondrial disease, when mutant mtDNA is not detected in blood, muscle biopsy should be performed in routine analysis, and it should be genetically tested, even if there are no manifestations of myopathy.
Collapse
Affiliation(s)
- Shuang Wang
- Department of Neurology, The First Hospital of Jilin University, Changchun, China
| | - Jing Miao
- Department of Neurology, The First Hospital of Jilin University, Changchun, China
| | - Jiachun Feng
- Department of Neurology, The First Hospital of Jilin University, Changchun, China
| |
Collapse
|
12
|
Pozzi A, Dowling DK. Small mitochondrial RNAs as mediators of nuclear gene regulation, and potential implications for human health. Bioessays 2021; 43:e2000265. [PMID: 33763872 DOI: 10.1002/bies.202000265] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2020] [Revised: 03/03/2021] [Accepted: 03/05/2021] [Indexed: 02/06/2023]
Abstract
Much research has focused on the effects of pathogenic mitochondrial mutations on health. Notwithstanding, the mechanisms regulating the link between these mutations and their effects remain elusive in several cases. Here, we propose that certain mitochondrial mutations may disrupt function of a set of mitochondrial-transcribed small RNAs, perturbing communication between mitochondria and nucleus, leading to disease. Our hypothesis synthesises two lines of supporting evidence. First, several mitochondrial mutations cannot be directly linked to effects on energy production or protein synthesis. Second, emerging studies have described the existence of small RNAs encoded by the mitochondria and proposed their involvement in RNA interference. We present a roadmap to testing this hypothesis.
Collapse
Affiliation(s)
- Andrea Pozzi
- School of Biological Sciences, Monash University, Melbourne, Victoria, Australia
| | - Damian K Dowling
- School of Biological Sciences, Monash University, Melbourne, Victoria, Australia
| |
Collapse
|
13
|
Loos MA, Gomez G, Mayorga L, Caraballo RH, Eiroa HD, Obregon MG, Rugilo C, Lubieniecki F, Taratuto AL, Saccoliti M, Alonso CN, Aráoz HV. Clinical and molecular characterization of mitochondrial DNA disorders in a group of Argentinian pediatric patients. Mol Genet Metab Rep 2021; 27:100733. [PMID: 33717984 PMCID: PMC7933530 DOI: 10.1016/j.ymgmr.2021.100733] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2020] [Revised: 02/04/2021] [Accepted: 02/05/2021] [Indexed: 11/02/2022] Open
Abstract
Objective To describe the clinical and molecular features of a group of Argentinian pediatric patients with mitochondrial DNA (mtDNA) disorders, and to evaluate the results of the implementation of a classical approach for the molecular diagnosis of mitochondrial diseases. Methods Clinical data from 27 patients with confirmed mtDNA pathogenic variants were obtained from a database of 89 patients with suspected mitochondrial disease, registered from 2014 to 2020. Clinical data, biochemical analysis, neuroimaging findings, muscle biopsy and molecular studies were analyzed. Results Patients were 18 females and 9 males, with ages at onset ranging from 1 week to 14 years (median = 4 years). The clinical phenotypes were: mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes (MELAS) syndrome (n = 11), Leigh syndrome (n = 5), Kearns-Sayre syndrome (n = 3), Chronic Progressive External Ophthalmoplegia (n = 2), Leber hereditary optic neuropathy (n = 2), myoclonic epilepsy associated with ragged-red fibers (n = 1) and reversible infantile myopathy with cytochrome-C oxidase deficiency (n = 3). Most of the patients harbored pathogenic single nucleotide variants, mainly involving mt-tRNA genes, such as MT-TL1, MT-TE and MT-TK. Other point variants were found in complex I subunits, like MT-ND6, MT-ND4, MT-ND5; or in MT-ATP6. The m.13513G > A variant in MT-ND5 and the m.9185 T > C variant in MT-ATP6 were apparently de novo. The rest of the patients presented large scale-rearrangements, either the "common" deletion or a larger deletion. Conclusions This study highlights the clinical and genetic heterogeneity of pediatric mtDNA disorders. All the cases presented with classical phenotypes, being MELAS the most frequent. Applying classical molecular methods, it was possible to achieve a genetic diagnosis in 30% of the cases, suggesting that this is an effective first approach, especially for those centers from low-middle income countries, leaving NGS studies for those patients with inconclusive results.
Collapse
Affiliation(s)
- Mariana Amina Loos
- Department of Neurology, Hospital de Pediatría "Juan P. Garrahan", Combate de los Pozos 1881, Buenos Aires 1245, Argentina
| | - Gimena Gomez
- Genomics Laboratory, Hospital de Pediatría "Juan P. Garrahan", Combate de los Pozos 1881, Buenos Aires 1245, Argentina
| | - Lía Mayorga
- Instituto de Histología y Embriología de Mendoza (IHEM, Universidad Nacional de Cuyo, CONICET), Centro Universitario UNCuyo, 5500 Mendoza, Argentina
| | - Roberto Horacio Caraballo
- Department of Neurology, Hospital de Pediatría "Juan P. Garrahan", Combate de los Pozos 1881, Buenos Aires 1245, Argentina
| | - Hernán Diego Eiroa
- Department of Inborn Errors of Metabolism, Hospital de Pediatría "Juan P. Garrahan", Combate de los Pozos 1881, Buenos Aires, 1245, Argentina
| | - María Gabriela Obregon
- Department of Medical Genetics, Hospital de Pediatría "Juan P. Garrahan", Combate de los Pozos 1881, Buenos Aires 1245, Argentina
| | - Carlos Rugilo
- Department of DiagnosticImaging, Hospital de Pediatría "Juan P. Garrahan", Combate de los Pozos 1881, Buenos Aires 1245, Argentina
| | - Fabiana Lubieniecki
- Department of Pathology, Hospital de Pediatría "Juan P. Garrahan", Combate de los Pozos 1881, Buenos Aires 1245, Argentina
| | - Ana Lía Taratuto
- Neuropathology and Neuromuscular Diseases Laboratory, Buenos Aires, Argentina
| | - María Saccoliti
- Neuropathology and Neuromuscular Diseases Laboratory, Buenos Aires, Argentina
| | - Cristina Noemi Alonso
- Genomics Laboratory, Hospital de Pediatría "Juan P. Garrahan", Combate de los Pozos 1881, Buenos Aires 1245, Argentina
| | - Hilda Verónica Aráoz
- Department of Medical Genetics, Hospital de Pediatría "Juan P. Garrahan", Combate de los Pozos 1881, Buenos Aires 1245, Argentina
| |
Collapse
|
14
|
Richter U, McFarland R, Taylor RW, Pickett SJ. The molecular pathology of pathogenic mitochondrial tRNA variants. FEBS Lett 2021; 595:1003-1024. [PMID: 33513266 PMCID: PMC8600956 DOI: 10.1002/1873-3468.14049] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2020] [Revised: 01/14/2021] [Accepted: 01/18/2021] [Indexed: 12/16/2022]
Abstract
Mitochondrial diseases are clinically and genetically heterogeneous disorders, caused by pathogenic variants in either the nuclear or mitochondrial genome. This heterogeneity is particularly striking for disease caused by variants in mitochondrial DNA‐encoded tRNA (mt‐tRNA) genes, posing challenges for both the treatment of patients and understanding the molecular pathology. In this review, we consider disease caused by the two most common pathogenic mt‐tRNA variants: m.3243A>G (within MT‐TL1, encoding mt‐tRNALeu(UUR)) and m.8344A>G (within MT‐TK, encoding mt‐tRNALys), which together account for the vast majority of all mt‐tRNA‐related disease. We compare and contrast the clinical disease they are associated with, as well as their molecular pathologies, and consider what is known about the likely molecular mechanisms of disease. Finally, we discuss the role of mitochondrial–nuclear crosstalk in the manifestation of mt‐tRNA‐associated disease and how research in this area not only has the potential to uncover molecular mechanisms responsible for the vast clinical heterogeneity associated with these variants but also pave the way to develop treatment options for these devastating diseases.
Collapse
Affiliation(s)
- Uwe Richter
- Wellcome Centre for Mitochondrial Research, The Medical School, Newcastle University, UK.,Molecular and Integrative Biosciences Research Programme, Faculty of Biological and Environmental Sciences, University of Helsinki, Finland.,Newcastle University Biosciences Institute, Newcastle University, UK
| | - Robert McFarland
- Wellcome Centre for Mitochondrial Research, The Medical School, Newcastle University, UK.,Newcastle University Translational and Clinical Research Institute, Newcastle University, UK
| | - Robert W Taylor
- Wellcome Centre for Mitochondrial Research, The Medical School, Newcastle University, UK.,Newcastle University Translational and Clinical Research Institute, Newcastle University, UK
| | - Sarah J Pickett
- Wellcome Centre for Mitochondrial Research, The Medical School, Newcastle University, UK.,Newcastle University Translational and Clinical Research Institute, Newcastle University, UK
| |
Collapse
|
15
|
Visuttijai K, Hedberg‐Oldfors C, Lindgren U, Nordström S, Elíasdóttir Ó, Lindberg C, Oldfors A. Progressive external ophthalmoplegia associated with novel MT-TN mutations. Acta Neurol Scand 2021; 143:103-108. [PMID: 32869280 PMCID: PMC7756270 DOI: 10.1111/ane.13339] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2020] [Revised: 07/22/2020] [Accepted: 08/21/2020] [Indexed: 11/28/2022]
Abstract
OBJECTIVES To describe two patients with progressive external ophthalmoplegia (PEO) and mitochondrial myopathy associated with mutations in mitochondrial DNA, encoding the tRNAAsn gene (MT-TN), which have not previously been published with clinical descriptions. MATERIALS & METHODS Two unrelated patients with PEO were clinically examined. Muscle biopsy was performed and investigated by exome sequencing, enzyme histochemistry, and immunohistochemistry. The level of heteroplasmy was investigated in single muscle fibers and in other tissues. RESULTS Patient 1 was a 52-year-old man with ptosis, PEO, and exercise intolerance since childhood. Muscle biopsy demonstrated mitochondrial myopathy with frequent cytochrome c oxidase (COX)-deficient fibers and a heteroplasmic mutation, m.5669G>A in the MT-TN gene, resulting in a substitution of a highly conserved C to T in the T stem of tRNAAsn . Patient 2 was a 66-year-old woman with ptosis, PEO, and exercise intolerance since many years. Muscle biopsy demonstrated mitochondrial myopathy with frequent COX-deficient fibers. She had a novel m.5702delA mutation in MT-TN, resulting in loss of a highly conserved U in the anticodon stem of tRNAAsn . Single fiber analysis in both cases showed highly significant differences in mutation load between COX-deficient and COX-normal fibers and a high threshold level for COX deficiency. The mutations were not found in blood, urine sediment or buccal cells. CONCLUSION We describe two MT-TN mutations associated with PEO and mitochondrial myopathy, and their pathogenicity was demonstrated. Together with previous reports, the results indicate that MT-TN is a hot spot for mutations causing sporadic PEO.
Collapse
Affiliation(s)
- Kittichate Visuttijai
- Department of Laboratory MedicineSahlgrenska AcademyUniversity of GothenburgGothenburgSweden
| | - Carola Hedberg‐Oldfors
- Department of Laboratory MedicineSahlgrenska AcademyUniversity of GothenburgGothenburgSweden
| | - Ulrika Lindgren
- Department of Laboratory MedicineSahlgrenska AcademyUniversity of GothenburgGothenburgSweden
| | - Sara Nordström
- Department of NeurologySahlgrenska University HospitalGothenburgSweden
| | - Ólöf Elíasdóttir
- Department of NeurologySahlgrenska University HospitalGothenburgSweden
| | | | - Anders Oldfors
- Department of Laboratory MedicineSahlgrenska AcademyUniversity of GothenburgGothenburgSweden
| |
Collapse
|
16
|
A mitochondrial myopathy-associated tRNA Ser(UCN) 7453G>A mutation alters tRNA metabolism and mitochondrial function. Mitochondrion 2020; 57:1-8. [PMID: 33279600 DOI: 10.1016/j.mito.2020.11.015] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2020] [Revised: 10/09/2020] [Accepted: 11/23/2020] [Indexed: 12/25/2022]
Abstract
BACKGROUND Mitochondrial disorders are a group of heterogeneous diseases characterized by biochemical disturbances in oxidative phosphorylation (OXPHOS). Mutations in mitochondrial transfer RNA (mt-tRNA) genes are the most frequently in mitochondrial disease. However, few studies have detailed the molecular mechanisms behind these mutations. METHODS We performed clinical evaluation, genetic analysis, muscle histochemistry, and molecular and biochemical investigations in muscle tissue and proband-derived cybrid cell lines. RESULTS We found a mitochondrial tRNASer(UCN) mutation (m.7453G>A) in a 15-year-old patient with severe mitochondrial myopathy. We demonstrated that this mutation caused impairment of mitochondrial translation, respiratory deficiency, overproduction of reactive oxygen species (ROS), and decreased mitochondrial membrane potential (MMP), which ultimately led to severe mitochondrial myopathy. CONCLUSION Our findings offer valuable new insights into the tRNASer(UCN) m.7453G>A mutation for both the pathogenic mechanism and functional consequences.
Collapse
|
17
|
Ji K, Lin Y, Xu X, Wang W, Wang D, Zhang C, Li W, Zhao Y, Yan C. MELAS-associated m.5541C>T mutation caused instability of mitochondrial tRNA Trp and remarkable mitochondrial dysfunction. J Med Genet 2020; 59:79-87. [PMID: 33208382 DOI: 10.1136/jmedgenet-2020-107323] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2020] [Revised: 10/13/2020] [Accepted: 10/24/2020] [Indexed: 11/04/2022]
Abstract
BACKGROUND Mitochondrial encephalomyopathy with lactic acidosis and stroke-like episode (MELAS) is a group of genetic diseases caused by mutations in mitochondrial DNA and nuclear DNA. The causative mutations of MELAS have drawn much attention, among them, mutations in mitochondrial tRNA genes possessing prominent status. However, the detailed molecular pathogenesis of these tRNA gene mutations remains unclear and there are very few effective therapies available to date. METHODS We performed muscle histochemistry, genetic analysis, molecular dynamic stimulation and measurement of oxygen consumption rate and respiratory chain complex activities to demonstrate the molecular pathomechanisms of m.5541C>T mutation. Moreover, we use cybrid cells to investigate the potential of taurine to rescue mitochondrial dysfunction caused by this mutation. RESULTS We found a pathogenic m.5541C>T mutation in the tRNATrp gene in a large MELAS family. This mutation first affected the maturation and stability of tRNATrp and impaired mitochondrial respiratory chain complex activities, followed by remarkable mitochondrial dysfunction. Surprisingly, we identified that the supplementation of taurine almost completely restored mitochondrial tRNATrp levels and mitochondrial respiration deficiency at the in vitro cell level. CONCLUSION The m.5541C>T mutation disturbed the translation machinery of mitochondrial tRNATrp and taurine supplementation may be a potential treatment for patients with m.5541C>T mutation. Further studies are needed to explore the full potential of taurine supplementation as therapy for patients with this mutation.
Collapse
Affiliation(s)
- Kunqian Ji
- Department of Neurology, Qilu Hospital of Shandong University, Jinan, Shandong, China.,Department of Neurology, Research Institute of Neuromuscular and Neurodegenerative Diseases of Shandong University, Jinan, China
| | - Yan Lin
- Department of Neurology, Qilu Hospital of Shandong University, Jinan, Shandong, China
| | - Xuebi Xu
- Department of Neurology, Wenzhou Medical University First Affiliated Hospital, Wenzhou, Zhejiang, China
| | - Wei Wang
- Department of Neurology, Qilu Hospital of Shandong University, Jinan, Shandong, China
| | - Dongdong Wang
- Department of Neurology, Qilu Hospital of Shandong University, Jinan, Shandong, China
| | - Chen Zhang
- Mitochondrial Medicine Laboratory, Qilu Hospital (Qingdao), Shandong University, Qingda, China
| | - Wei Li
- Department of Neurology, Qilu Hospital of Shandong University, Jinan, Shandong, China
| | - Yuying Zhao
- Department of Neurology, Qilu Hospital of Shandong University, Jinan, Shandong, China
| | - Chuanzhu Yan
- Department of Neurology, Qilu Hospital of Shandong University, Jinan, Shandong, China .,Department of Neurology, Research Institute of Neuromuscular and Neurodegenerative Diseases of Shandong University, Jinan, China.,Brain Science Research Institute of Shandong University, Jinan, China
| |
Collapse
|
18
|
Toncheva D, Serbezov D, Karachanak-Yankova S, Nesheva D. Ancient mitochondrial DNA pathogenic variants putatively associated with mitochondrial disease. PLoS One 2020; 15:e0233666. [PMID: 32970680 PMCID: PMC7514063 DOI: 10.1371/journal.pone.0233666] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2020] [Accepted: 08/09/2020] [Indexed: 11/18/2022] Open
Abstract
Mitochondrial DNA variants associated with diseases are widely studied in contemporary populations, but their prevalence has not yet been investigated in ancient populations. The publicly available AmtDB database contains 1443 ancient mtDNA Eurasian genomes from different periods. The objective of this study was to use this data to establish the presence of pathogenic mtDNA variants putatively associated with mitochondrial diseases in ancient populations. The clinical significance, pathogenicity prediction and contemporary frequency of mtDNA variants were determined using online platforms. The analyzed ancient mtDNAs contain six variants designated as being "confirmed pathogenic" in modern patients. The oldest of these, m.7510T>C in the MT-TS1 gene, was found in a sample from the Neolithic period, dated 5800-5400 BCE. All six have well established clinical association, and their pathogenic effect is corroborated by very low population frequencies in contemporary populations. Analysis of the geographic location of the ancient samples, contemporary epidemiological trends and probable haplogroup association indicate diverse spatiotemporal dynamics of these variants. The dynamics in the prevalence and distribution is conceivably result of de novo mutations or human migrations and subsequent evolutionary processes. In addition, ten variants designated as possibly or likely pathogenic were found, but the clinical effect of these is not yet well established and further research is warranted. All detected mutations putatively associated with mitochondrial disease in ancient mtDNA samples are in tRNA coding genes. Most of these mutations are in a mt-tRNA type (Model 2) that is characterized by loss of D-loop/T-loop interaction. Exposing pathogenic variants in ancient human populations expands our understanding of their origin and prevalence dynamics.
Collapse
Affiliation(s)
- Draga Toncheva
- Department of Medical Genetics, Medical University of Sofia, Bulgarian Academy of Science, Sofia, Bulgaria
- Bulgarian Academy of Sciences–BAS, Sofia, Bulgaria
- * E-mail:
| | - Dimitar Serbezov
- Department of Medical Genetics, Medical University of Sofia, Bulgarian Academy of Science, Sofia, Bulgaria
| | - Sena Karachanak-Yankova
- Department of Medical Genetics, Medical University of Sofia, Bulgarian Academy of Science, Sofia, Bulgaria
- Department of Genetics, Faculty of biology, Sofia University “St. Kliment Ohridski”, Sofia, Bulgaria
| | - Desislava Nesheva
- Department of Medical Genetics, Medical University of Sofia, Bulgarian Academy of Science, Sofia, Bulgaria
| |
Collapse
|
19
|
Barcia G, Assouline Z, Magen M, Pennisi A, Rötig A, Munnich A, Bonnefont JP, Steffann J. Improving post-natal detection of mitochondrial DNA mutations. Expert Rev Mol Diagn 2020; 20:1003-1008. [PMID: 32902337 DOI: 10.1080/14737159.2020.1820326] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
INTRODUCTION Currently, genetic testing of mitochondrial DNA mutations includes screening for single-nucleotide variants, several base pair insertions or deletions, large-scale deletions, or relative depletion of total mitochondrial DNA content. Within the last decade, next-generation sequencing (NGS) has resulted in remarkable advances in the field of mitochondrial diseases (MD) and has become a routine step of the diagnostic workup. AREAS COVERED We aimed to present an overview of current technologies employed in molecular diagnosis of mitochondrial DNA diseases. We report on the recent contributions of NGS testing to the diagnosis and understanding of MD. EXPERT OPINION The progress of NGS technologies allows the simultaneous detection of mutations and quantification of the heteroplasmy level, ensuring sensitivity and specificity requested for the detection of mitochondrial DNA point mutations. NGS protocols enabling the simultaneous analysis of mitochondrial and nuclear DNA are now efficient and cost-saving approaches, and have become the gold-standard technique in diagnostic laboratories.
Collapse
Affiliation(s)
- Giulia Barcia
- Université de Paris et Service de Génétique Moléculaire, Reference Center for Mitochondrial Diseases (CARAMMEL), Groupe Hospitalier Necker Enfants Malades, Assistance Publique-Hôpitaux de Paris , Paris, France
| | - Zahra Assouline
- Université de Paris et Service de Génétique Moléculaire, Reference Center for Mitochondrial Diseases (CARAMMEL), Groupe Hospitalier Necker Enfants Malades, Assistance Publique-Hôpitaux de Paris , Paris, France
| | - Maryse Magen
- Université de Paris et Service de Génétique Moléculaire, Reference Center for Mitochondrial Diseases (CARAMMEL), Groupe Hospitalier Necker Enfants Malades, Assistance Publique-Hôpitaux de Paris , Paris, France
| | - Alessandra Pennisi
- Université de Paris et Service de Génétique Moléculaire, Reference Center for Mitochondrial Diseases (CARAMMEL), Groupe Hospitalier Necker Enfants Malades, Assistance Publique-Hôpitaux de Paris , Paris, France.,Laboratory for Genetics of Mitochondrial Disorders, INSERM U1163, Université Paris Descartes-Sorbonne Paris Cité, Institut Imagine , Paris, France
| | - Agnès Rötig
- Laboratory for Genetics of Mitochondrial Disorders, INSERM U1163, Université Paris Descartes-Sorbonne Paris Cité, Institut Imagine , Paris, France
| | - Arnold Munnich
- Université de Paris et Service de Génétique Moléculaire, Reference Center for Mitochondrial Diseases (CARAMMEL), Groupe Hospitalier Necker Enfants Malades, Assistance Publique-Hôpitaux de Paris , Paris, France.,Laboratory for Genetics of Mitochondrial Disorders, INSERM U1163, Université Paris Descartes-Sorbonne Paris Cité, Institut Imagine , Paris, France
| | - Jean-Paul Bonnefont
- Université de Paris et Service de Génétique Moléculaire, Reference Center for Mitochondrial Diseases (CARAMMEL), Groupe Hospitalier Necker Enfants Malades, Assistance Publique-Hôpitaux de Paris , Paris, France.,Laboratory for Genetics of Mitochondrial Disorders, INSERM U1163, Université Paris Descartes-Sorbonne Paris Cité, Institut Imagine , Paris, France
| | - Julie Steffann
- Université de Paris et Service de Génétique Moléculaire, Reference Center for Mitochondrial Diseases (CARAMMEL), Groupe Hospitalier Necker Enfants Malades, Assistance Publique-Hôpitaux de Paris , Paris, France.,Laboratory for Genetics of Mitochondrial Disorders, INSERM U1163, Université Paris Descartes-Sorbonne Paris Cité, Institut Imagine , Paris, France
| |
Collapse
|
20
|
Lim AZ, McMacken G, Rastelli F, Oláhová M, Baty K, Hopton S, Falkous G, Töpf A, Lochmüller H, Marini-Bettolo C, McFarland R, Taylor RW. A novel, pathogenic dinucleotide deletion in the mitochondrial MT-TY gene causing myasthenia-like features. Neuromuscul Disord 2020; 30:661-668. [PMID: 32684384 PMCID: PMC7477489 DOI: 10.1016/j.nmd.2020.06.008] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2020] [Revised: 06/16/2020] [Accepted: 06/17/2020] [Indexed: 11/29/2022]
Abstract
Mitochondrial DNA (mtDNA)-related diseases often pose a diagnostic challenge and require rigorous clinical and laboratory investigation. Pathogenic variants in the mitochondrial tRNA gene MT-TY, which encodes the tRNATyr, are a rare cause of mitochondrial disease. Here we describe a novel m.5860delTA anticodon variant in the MT-TY gene in a patient who initially presented with features akin to a childhood onset myasthenic syndrome. Using histochemical, immunohistochemical and protein studies we demonstrate that this mutation leads to severe biochemical defects of mitochondrial translation, which is reflected in the early onset and progressive phenotype. This case highlights the clinical overlap between mtDNA-related diseases and other neuromuscular disorders, and demonstrates the potential pitfalls in analysis of next generation sequencing results, given whole exome sequencing of a blood DNA sample failed to make a genetics diagnosis. Muscle biopsy remains an important requirement in the diagnosis of mitochondrial disease and in establishing the pathogenicity of novel mtDNA variants.
Collapse
Affiliation(s)
- Albert Z Lim
- Wellcome Centre for Mitochondrial Research, The Medical School, Newcastle University, Newcastle upon Tyne, UK
| | - Grace McMacken
- The John Walton Muscular Dystrophy Research Centre, Newcastle University, Newcastle upon Tyne, UK; Department of Neurosciences, Royal Victoria Hospital, Belfast Health and Social Care Trust, Belfast, UK
| | - Francesca Rastelli
- Wellcome Centre for Mitochondrial Research, The Medical School, Newcastle University, Newcastle upon Tyne, UK
| | - Monika Oláhová
- Wellcome Centre for Mitochondrial Research, The Medical School, Newcastle University, Newcastle upon Tyne, UK; Biosciences Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, UK
| | - Karen Baty
- Wellcome Centre for Mitochondrial Research, The Medical School, Newcastle University, Newcastle upon Tyne, UK; NHS Highly Specialised Service for Rare Mitochondrial Disorders, Newcastle upon Tyne, UK
| | - Sila Hopton
- Wellcome Centre for Mitochondrial Research, The Medical School, Newcastle University, Newcastle upon Tyne, UK; NHS Highly Specialised Service for Rare Mitochondrial Disorders, Newcastle upon Tyne, UK
| | - Gavin Falkous
- Wellcome Centre for Mitochondrial Research, The Medical School, Newcastle University, Newcastle upon Tyne, UK; NHS Highly Specialised Service for Rare Mitochondrial Disorders, Newcastle upon Tyne, UK
| | - Ana Töpf
- The John Walton Muscular Dystrophy Research Centre, Newcastle University, Newcastle upon Tyne, UK
| | - Hanns Lochmüller
- Department of Neuropediatrics and Muscle Disorders, Medical Center, Faculty of Medicine, University of Freiburg, Freiburg, Germany; Centro Nacional de Análisis Genómico (CNAG-CRG), Center for Genomic Regulation, Barcelona Institute of Science and Technology (BIST), Barcelona, Spain; Research Institute, Children's Hospital of Eastern Ontario, Ottawa, Canada; Division of Neurology, Department of Medicine, Ottawa University, Ottawa, Canada
| | - Chiara Marini-Bettolo
- The John Walton Muscular Dystrophy Research Centre, Newcastle University, Newcastle upon Tyne, UK
| | - Robert McFarland
- Wellcome Centre for Mitochondrial Research, The Medical School, Newcastle University, Newcastle upon Tyne, UK; Translational and Clinical Research Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, United Kingdom.
| | - Robert W Taylor
- Wellcome Centre for Mitochondrial Research, The Medical School, Newcastle University, Newcastle upon Tyne, UK; NHS Highly Specialised Service for Rare Mitochondrial Disorders, Newcastle upon Tyne, UK; Translational and Clinical Research Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, United Kingdom
| |
Collapse
|
21
|
Boguszewska K, Szewczuk M, Kaźmierczak-Barańska J, Karwowski BT. The Similarities between Human Mitochondria and Bacteria in the Context of Structure, Genome, and Base Excision Repair System. Molecules 2020; 25:E2857. [PMID: 32575813 PMCID: PMC7356350 DOI: 10.3390/molecules25122857] [Citation(s) in RCA: 41] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2020] [Revised: 06/17/2020] [Accepted: 06/19/2020] [Indexed: 02/06/2023] Open
Abstract
Mitochondria emerged from bacterial ancestors during endosymbiosis and are crucial for cellular processes such as energy production and homeostasis, stress responses, cell survival, and more. They are the site of aerobic respiration and adenosine triphosphate (ATP) production in eukaryotes. However, oxidative phosphorylation (OXPHOS) is also the source of reactive oxygen species (ROS), which are both important and dangerous for the cell. Human mitochondria contain mitochondrial DNA (mtDNA), and its integrity may be endangered by the action of ROS. Fortunately, human mitochondria have repair mechanisms that allow protecting mtDNA and repairing lesions that may contribute to the occurrence of mutations. Mutagenesis of the mitochondrial genome may manifest in the form of pathological states such as mitochondrial, neurodegenerative, and/or cardiovascular diseases, premature aging, and cancer. The review describes the mitochondrial structure, genome, and the main mitochondrial repair mechanism (base excision repair (BER)) of oxidative lesions in the context of common features between human mitochondria and bacteria. The authors present a holistic view of the similarities of mitochondria and bacteria to show that bacteria may be an interesting experimental model for studying mitochondrial diseases, especially those where the mechanism of DNA repair is impaired.
Collapse
Affiliation(s)
| | | | | | - Bolesław T. Karwowski
- DNA Damage Laboratory of Food Science Department, Faculty of Pharmacy, Medical University of Lodz, ul. Muszynskiego 1, 90-151 Lodz, Poland; (K.B.); (M.S.); (J.K.-B.)
| |
Collapse
|
22
|
Infante-Rojas H, Marino-Ramirez L, Hernández-Fernández J. Structural analysis of leucine, lysine and tryptophan mitochondrial tRNA of nesting turtles Caretta caretta (Testudines: Chelonioidea) in the Colombian Caribbean. PeerJ 2020; 8:e9204. [PMID: 32596037 PMCID: PMC7306221 DOI: 10.7717/peerj.9204] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2019] [Accepted: 04/25/2020] [Indexed: 11/20/2022] Open
Abstract
The understanding of the functional properties of mitochondrial transfer RNA (mt tRNAs) depend on the knowledge of its structure. tRNA acts as an interface between polynucleotides and polypeptides thus, they are key molecules in protein biosynthesis. The tRNA molecule has a functional design and, given its importance in the translation of mitochondrial genes, it is plausible that modifications of the structure can affect the synthesis of proteins and the functional properties of the mitochondria. In a previous work, the mitochondrial genome of an individual of the nesting Caretta caretta of the Colombian Caribbean was obtained, where specific mutations were identified in the only tRNALeu (CUN), tRNATrp and tRNALys genes. In order to analyze the effect of these mutations on these three mt tRNAs, the prediction of 2D and 3D structures was performed. Genes were sequenced in 11 nesting loggerhead turtles from the Colombian Caribbean. Two-dimensional structures were inferred using the ARWEN program, and three-dimensional structures were obtained with the RNA Composer 3D program. Two polymorphisms were identified in tRNATrp and another one was located in tRNALys, both specific to C. caretta. The thymine substitution in nucleotide position 14 of tRNATrp could constitute an endemic polymorphism of the nesting colony of the Colombian Caribbean. Two 2D and three 3D patterns were obtained for tRNATrp. In the case of tRNALys and tRNALeu 2D and 3D structures were obtained respectively, which showed compliance to canonical structures, with 4 bp in the D-arm, 4-5 bp in the T-arm, and 5 bp in the anticodon arm. Moderate deviations were found, such as a change in the number of nucleotides, elongation in loops or stems and non-Watson-Crick base pairing: adenine-adenine in stem D of tRNATrp, uracil-uracil and adenine-cytosine in the acceptor arm of the tRNALys and cytosine-cytosine in the anticodon stem of the tRNALeu. In addition, distortions or lack of typical interactions in 3D structures gave them unique characteristics. According to the size of the variable region (4-5 nt), the three analyzed tRNAs belong to class I. The interactions in the three studied tRNAs occur mainly between D loop-variable region, and between spacer bases-variable region, which classifies them as tRNA of typology II. The polymorphisms and structural changes described can, apparently, be post-transcriptionally stabilized. It will be crucial to perform studies at the population and functional levels to elucidate the synthetic pathways affected by these genes. This article analyses for the first time the 1D, 2D and 3D structures of the mitochondrial tRNALys, tRNATrp and tRNALeu in the loggerhead turtle.
Collapse
Affiliation(s)
- Harvey Infante-Rojas
- Department of Natural and Environmental Sciences, Genetics, Molecular Biology and Bioinformatics Lab, Jorge Tadeo Lozano University, Bogotá, Cundinamarca, Colombia
| | | | - Javier Hernández-Fernández
- Department of Natural and Environmental Sciences, Genetics, Molecular Biology and Bioinformatics Lab, Jorge Tadeo Lozano University, Bogotá, Cundinamarca, Colombia
| |
Collapse
|
23
|
Decoux-Poullot AG, Bannwarth S, Procaccio V, Lebre AS, Jardel C, Vialettes B, Paquis-Flucklinger V, Chevalier N. Clinical phenotype of mitochondrial diabetes due to rare mitochondrial DNA mutations. ANNALES D'ENDOCRINOLOGIE 2020; 81:68-77. [PMID: 32409007 DOI: 10.1016/j.ando.2020.04.007] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/08/2020] [Revised: 04/08/2020] [Accepted: 04/08/2020] [Indexed: 11/18/2022]
Abstract
OBJECTIVE While the most frequent mutation responsible for mitochondrial diabetes is the point mutation m.3243 A>G of mitochondrial DNA (mtDNA), few data are available about the role of rare mtDNA mutations in the pathophysiology of diabetes. The main objective of our study was to describe the phenotypic characteristics of patients suffering from diabetes linked to rare mtDNA mutations. RESEARCH DESIGN AND METHODS We performed a post-hoc analysis of a prospective multicenter cohort of 743 patients with mitochondrial disorder (previously published by the French Network of Mitochondrial Diseases), associated to a literature review of the PubMed database from 1992 to May 2016. We extracted all reported patients with diabetes and identified rare mtDNA mutations and described their clinical and metabolic phenotypes. RESULTS The 50 identified patients (10 from the princeps study; 40 from the review of the literature) showed a heterogeneous metabolic phenotype in terms of age, symptoms prior to diagnosis, treatments, and associated clinical and biological signs. However, neurological symptoms were more frequent in case of rare mtDNA mutations compared to the classical m.3243 A>G mutation (P=0.024). In contrast, deafness (65% vs. 95%, P=3.7E-5), macular pattern dystrophy (20% vs. 86%, P=1.6E-10) and nephropathy (8% vs. 28%, P=0.018) were significantly less frequent than in case of the classical m.3243 A>G mutation. CONCLUSION Although no specific metabolic phenotype could be identified suggesting or eliminating implication of rare mtDNA mutations in diabetes, clinical phenotypes featured more frequent neurological signs.
Collapse
Affiliation(s)
- Anne-Gaëlle Decoux-Poullot
- Service d'endocrinologie, diabétologie et médecine de la reproduction, hôpital de l'Archet 2, université Côte d'Azur, CHU de Nice, Nice, France
| | - Sylvie Bannwarth
- Inserm, CNRS, IRCAN, Université Côte d'Azur, CHU de Nice, Nice, France
| | | | - Anne-Sophie Lebre
- Inserm U781, Service de génétique, Hôpital Necker-Enfants-Malades, Université Paris-Descartes, Paris, France
| | - Claude Jardel
- Biochimie métabolique, Centre de génétique moléculaire et chromosomique, Groupe Hospitalier Pitié-Salpêtrière, Paris, France
| | - Bernard Vialettes
- Service d'endocrinologie, diabète, maladies métaboliques, Hôpital de la Conception, CHU de Marseille, 13385 Marseille Cedex 5, France
| | | | - Nicolas Chevalier
- Service d'endocrinologie, diabétologie et médecine de la reproduction, hôpital de l'Archet 2, université Côte d'Azur, CHU de Nice, Nice, France; Institut national de la santé et de la recherche médicale (Inserm), UMR U1065/UNS, Centre méditerranéen de médecine moléculaire (C3M), équipe 5 « Cellular Basis and Signaling of Tumor Metabolism », Université Côte d'Azur, CHU de Nice, Nice, France.
| |
Collapse
|
24
|
Poole OV, Horga A, Hardy SA, Bugiardini E, Woodward CE, Hargreaves IP, Merve A, Quinlivan R, Taylor RW, Hanna MG, Pitceathly RDS. Multisystem mitochondrial disease caused by a rare m.10038G>A mitochondrial tRNA Gly ( MT-TG) variant. Neurol Genet 2020; 6:e413. [PMID: 32337339 PMCID: PMC7164964 DOI: 10.1212/nxg.0000000000000413] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2019] [Accepted: 01/23/2020] [Indexed: 11/15/2022]
Affiliation(s)
- Olivia V Poole
- Department of Neuromuscular Diseases (O.V.P., A.H., E.B., R.Q., M.G.H., R.D.S.P.), UCL Queen Square Institute of Neurology and The National Hospital for Neurology and Neurosurgery, London, United Kingdom; Wellcome Centre for Mitochondrial Research (S.A.H., R.W.T.), Translational and Clinical Research Institute, Newcastle University, Newcastle Upon Tyne; Neurogenetics Unit (C.E.W.), and Neurometabolic Unit (I.P.H.), The National Hospital for Neurology and Neurosurgery; Division of Neuropathology (A.M.), UCL Queen Square Institute of Neurology; Department of Histopathology (A.M.), Camelia Botnar Laboratory, Great Ormond Street Hospital; and Dubowitz Neuromuscular Centre (R.Q.), Great Ormond Street Hospital, London, United Kingdom
| | - Alejandro Horga
- Department of Neuromuscular Diseases (O.V.P., A.H., E.B., R.Q., M.G.H., R.D.S.P.), UCL Queen Square Institute of Neurology and The National Hospital for Neurology and Neurosurgery, London, United Kingdom; Wellcome Centre for Mitochondrial Research (S.A.H., R.W.T.), Translational and Clinical Research Institute, Newcastle University, Newcastle Upon Tyne; Neurogenetics Unit (C.E.W.), and Neurometabolic Unit (I.P.H.), The National Hospital for Neurology and Neurosurgery; Division of Neuropathology (A.M.), UCL Queen Square Institute of Neurology; Department of Histopathology (A.M.), Camelia Botnar Laboratory, Great Ormond Street Hospital; and Dubowitz Neuromuscular Centre (R.Q.), Great Ormond Street Hospital, London, United Kingdom
| | - Steven A Hardy
- Department of Neuromuscular Diseases (O.V.P., A.H., E.B., R.Q., M.G.H., R.D.S.P.), UCL Queen Square Institute of Neurology and The National Hospital for Neurology and Neurosurgery, London, United Kingdom; Wellcome Centre for Mitochondrial Research (S.A.H., R.W.T.), Translational and Clinical Research Institute, Newcastle University, Newcastle Upon Tyne; Neurogenetics Unit (C.E.W.), and Neurometabolic Unit (I.P.H.), The National Hospital for Neurology and Neurosurgery; Division of Neuropathology (A.M.), UCL Queen Square Institute of Neurology; Department of Histopathology (A.M.), Camelia Botnar Laboratory, Great Ormond Street Hospital; and Dubowitz Neuromuscular Centre (R.Q.), Great Ormond Street Hospital, London, United Kingdom
| | - Enrico Bugiardini
- Department of Neuromuscular Diseases (O.V.P., A.H., E.B., R.Q., M.G.H., R.D.S.P.), UCL Queen Square Institute of Neurology and The National Hospital for Neurology and Neurosurgery, London, United Kingdom; Wellcome Centre for Mitochondrial Research (S.A.H., R.W.T.), Translational and Clinical Research Institute, Newcastle University, Newcastle Upon Tyne; Neurogenetics Unit (C.E.W.), and Neurometabolic Unit (I.P.H.), The National Hospital for Neurology and Neurosurgery; Division of Neuropathology (A.M.), UCL Queen Square Institute of Neurology; Department of Histopathology (A.M.), Camelia Botnar Laboratory, Great Ormond Street Hospital; and Dubowitz Neuromuscular Centre (R.Q.), Great Ormond Street Hospital, London, United Kingdom
| | - Cathy E Woodward
- Department of Neuromuscular Diseases (O.V.P., A.H., E.B., R.Q., M.G.H., R.D.S.P.), UCL Queen Square Institute of Neurology and The National Hospital for Neurology and Neurosurgery, London, United Kingdom; Wellcome Centre for Mitochondrial Research (S.A.H., R.W.T.), Translational and Clinical Research Institute, Newcastle University, Newcastle Upon Tyne; Neurogenetics Unit (C.E.W.), and Neurometabolic Unit (I.P.H.), The National Hospital for Neurology and Neurosurgery; Division of Neuropathology (A.M.), UCL Queen Square Institute of Neurology; Department of Histopathology (A.M.), Camelia Botnar Laboratory, Great Ormond Street Hospital; and Dubowitz Neuromuscular Centre (R.Q.), Great Ormond Street Hospital, London, United Kingdom
| | - Iain P Hargreaves
- Department of Neuromuscular Diseases (O.V.P., A.H., E.B., R.Q., M.G.H., R.D.S.P.), UCL Queen Square Institute of Neurology and The National Hospital for Neurology and Neurosurgery, London, United Kingdom; Wellcome Centre for Mitochondrial Research (S.A.H., R.W.T.), Translational and Clinical Research Institute, Newcastle University, Newcastle Upon Tyne; Neurogenetics Unit (C.E.W.), and Neurometabolic Unit (I.P.H.), The National Hospital for Neurology and Neurosurgery; Division of Neuropathology (A.M.), UCL Queen Square Institute of Neurology; Department of Histopathology (A.M.), Camelia Botnar Laboratory, Great Ormond Street Hospital; and Dubowitz Neuromuscular Centre (R.Q.), Great Ormond Street Hospital, London, United Kingdom
| | - Ashirwad Merve
- Department of Neuromuscular Diseases (O.V.P., A.H., E.B., R.Q., M.G.H., R.D.S.P.), UCL Queen Square Institute of Neurology and The National Hospital for Neurology and Neurosurgery, London, United Kingdom; Wellcome Centre for Mitochondrial Research (S.A.H., R.W.T.), Translational and Clinical Research Institute, Newcastle University, Newcastle Upon Tyne; Neurogenetics Unit (C.E.W.), and Neurometabolic Unit (I.P.H.), The National Hospital for Neurology and Neurosurgery; Division of Neuropathology (A.M.), UCL Queen Square Institute of Neurology; Department of Histopathology (A.M.), Camelia Botnar Laboratory, Great Ormond Street Hospital; and Dubowitz Neuromuscular Centre (R.Q.), Great Ormond Street Hospital, London, United Kingdom
| | - Rosaline Quinlivan
- Department of Neuromuscular Diseases (O.V.P., A.H., E.B., R.Q., M.G.H., R.D.S.P.), UCL Queen Square Institute of Neurology and The National Hospital for Neurology and Neurosurgery, London, United Kingdom; Wellcome Centre for Mitochondrial Research (S.A.H., R.W.T.), Translational and Clinical Research Institute, Newcastle University, Newcastle Upon Tyne; Neurogenetics Unit (C.E.W.), and Neurometabolic Unit (I.P.H.), The National Hospital for Neurology and Neurosurgery; Division of Neuropathology (A.M.), UCL Queen Square Institute of Neurology; Department of Histopathology (A.M.), Camelia Botnar Laboratory, Great Ormond Street Hospital; and Dubowitz Neuromuscular Centre (R.Q.), Great Ormond Street Hospital, London, United Kingdom
| | - Robert W Taylor
- Department of Neuromuscular Diseases (O.V.P., A.H., E.B., R.Q., M.G.H., R.D.S.P.), UCL Queen Square Institute of Neurology and The National Hospital for Neurology and Neurosurgery, London, United Kingdom; Wellcome Centre for Mitochondrial Research (S.A.H., R.W.T.), Translational and Clinical Research Institute, Newcastle University, Newcastle Upon Tyne; Neurogenetics Unit (C.E.W.), and Neurometabolic Unit (I.P.H.), The National Hospital for Neurology and Neurosurgery; Division of Neuropathology (A.M.), UCL Queen Square Institute of Neurology; Department of Histopathology (A.M.), Camelia Botnar Laboratory, Great Ormond Street Hospital; and Dubowitz Neuromuscular Centre (R.Q.), Great Ormond Street Hospital, London, United Kingdom
| | - Michael G Hanna
- Department of Neuromuscular Diseases (O.V.P., A.H., E.B., R.Q., M.G.H., R.D.S.P.), UCL Queen Square Institute of Neurology and The National Hospital for Neurology and Neurosurgery, London, United Kingdom; Wellcome Centre for Mitochondrial Research (S.A.H., R.W.T.), Translational and Clinical Research Institute, Newcastle University, Newcastle Upon Tyne; Neurogenetics Unit (C.E.W.), and Neurometabolic Unit (I.P.H.), The National Hospital for Neurology and Neurosurgery; Division of Neuropathology (A.M.), UCL Queen Square Institute of Neurology; Department of Histopathology (A.M.), Camelia Botnar Laboratory, Great Ormond Street Hospital; and Dubowitz Neuromuscular Centre (R.Q.), Great Ormond Street Hospital, London, United Kingdom
| | - Robert D S Pitceathly
- Department of Neuromuscular Diseases (O.V.P., A.H., E.B., R.Q., M.G.H., R.D.S.P.), UCL Queen Square Institute of Neurology and The National Hospital for Neurology and Neurosurgery, London, United Kingdom; Wellcome Centre for Mitochondrial Research (S.A.H., R.W.T.), Translational and Clinical Research Institute, Newcastle University, Newcastle Upon Tyne; Neurogenetics Unit (C.E.W.), and Neurometabolic Unit (I.P.H.), The National Hospital for Neurology and Neurosurgery; Division of Neuropathology (A.M.), UCL Queen Square Institute of Neurology; Department of Histopathology (A.M.), Camelia Botnar Laboratory, Great Ormond Street Hospital; and Dubowitz Neuromuscular Centre (R.Q.), Great Ormond Street Hospital, London, United Kingdom
| |
Collapse
|
25
|
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] [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.
Collapse
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
| |
Collapse
|
26
|
Pula S, Urankar K, Norman A, Pierre G, Langton-Hewer S, Selby V, Mason F, Vijayakumar K, McFarland R, Taylor RW, Majumdar A. A novel de novo ACTA1 variant in a patient with nemaline myopathy and mitochondrial Complex I deficiency. Neuromuscul Disord 2020; 30:159-164. [PMID: 32005493 DOI: 10.1016/j.nmd.2019.11.014] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2019] [Revised: 11/23/2019] [Accepted: 11/28/2019] [Indexed: 12/30/2022]
Abstract
We describe the presentation and follow-up of a three-year-old girl with nemaline myopathy due to a de-novo variant in ACTA1 (encoding skeletal alpha actin) and moderately low enzyme level of Complex I of the mitochondrial respiratory chain. She presented in the neonatal period with hypotonia, followed by weakness in the facial, bulbar, respiratory and neck flexors muscles. A biopsy of her quadriceps muscle at the age of one year showed nemaline rods. Based on her clinical presentation of a congenital myopathy and histopathological features on a muscle biopsy, ACTA1 was sequenced, and this revealed a novel sequence variant, c.760 A>C p. (Asn254His). In addition, mitochondrial respiratory chain enzymatic activity of skeletal muscle biopsy showed a moderately low activity of complex I (nicotinamide adenine dinucleotide (NADH): ubiquinone oxidoreductase). Disturbances of Complex I of the respiratory chain have been reported in patients with nemaline myopathy, although the mechanism remains unclear.
Collapse
Affiliation(s)
- Shpresa Pula
- Department of Paediatric Neurology, University Hospitals Bristol NHS Foundation Trust, 6th Floor Education Centre, Upper Maudlin St, Bristol BS2 8BJ, United Kingdom
| | - Kathryn Urankar
- Department of Neuropathology, North Bristol Hospital NHS Foundation Trust, Bristol, United Kingdom
| | - Andrew Norman
- Department of Clinical Genetics, University Hospitals Bristol NHS Foundation Trust, Bristol, United Kingdom
| | - Germaine Pierre
- Department of Paediatric Neurology, University Hospitals Bristol NHS Foundation Trust, 6th Floor Education Centre, Upper Maudlin St, Bristol BS2 8BJ, United Kingdom
| | - Simon Langton-Hewer
- Department of Paediatric Respiratory Medicine, Bristol Royal Hospital for Children, University Hospitals Bristol NHS Foundation Trust, Bristol, United Kingdom
| | - Victoria Selby
- Department of Paediatric Neurology, University Hospitals Bristol NHS Foundation Trust, 6th Floor Education Centre, Upper Maudlin St, Bristol BS2 8BJ, United Kingdom
| | - Faye Mason
- Department of Paediatric Neurology, University Hospitals Bristol NHS Foundation Trust, 6th Floor Education Centre, Upper Maudlin St, Bristol BS2 8BJ, United Kingdom
| | - Kayal Vijayakumar
- Department of Paediatric Neurology, University Hospitals Bristol NHS Foundation Trust, 6th Floor Education Centre, Upper Maudlin St, Bristol BS2 8BJ, United Kingdom
| | - Robert McFarland
- Wellcome Centre for Mitochondrial Research, Institute of Neurosciences, Newcastle University, Newcastle, United Kingdom
| | - Robert W Taylor
- Wellcome Centre for Mitochondrial Research, Institute of Neurosciences, Newcastle University, Newcastle, United Kingdom
| | - Anirban Majumdar
- Department of Paediatric Neurology, University Hospitals Bristol NHS Foundation Trust, 6th Floor Education Centre, Upper Maudlin St, Bristol BS2 8BJ, United Kingdom.
| |
Collapse
|
27
|
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] [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.
Collapse
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
| |
Collapse
|
28
|
Chen C, Li Q, Fu R, Wang J, Xiong C, Fan Z, Hu R, Zhang H, Lu D. Characterization of the mitochondrial genome of the pathogenic fungus Scytalidium auriculariicola (Leotiomycetes) and insights into its phylogenetics. Sci Rep 2019; 9:17447. [PMID: 31768013 PMCID: PMC6877775 DOI: 10.1038/s41598-019-53941-5] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2019] [Accepted: 10/17/2019] [Indexed: 12/26/2022] Open
Abstract
Scytalidium auriculariicola is the causative pathogen of slippery scar disease in the cultivated cloud ear fungus, Auricularia polytricha. In the present study, the mitogenome of S. auriculariicola was sequenced and assembled by next-generation sequencing technology. The circular mitogenome is 96,857 bp long and contains 56 protein-coding genes, 2 ribosomal RNA genes, and 30 transfer RNA genes (tRNAs). The high frequency of A and T used in codons contributed to the high AT content (73.70%) of the S. auriculariicola mitogenome. Comparative analysis indicated that the base composition and the number of introns and protein-coding genes in the S. auriculariicola mitogenome varied from that of other Leotiomycetes mitogenomes, including a uniquely positive AT skew. Five distinct groups were found in the gene arrangements of Leotiomycetes. Phylogenetic analyses based on combined gene datasets (15 protein-coding genes) yielded well-supported (BPP = 1) topologies. A single-gene phylogenetic tree indicated that the nad4 gene may be useful as a molecular marker to analyze the phylogenetic relationships of Leotiomycetes species. This study is the first report on the mitochondrial genome of the genus Scytalidium, and it will contribute to our understanding of the population genetics and evolution of S. auriculariicola and related species.
Collapse
Affiliation(s)
- Cheng Chen
- Institute of plant protection, Sichuan Academy of Agricultural Sciences, Chengdu, 610066, Sichuan, P.R. China
- Key Laboratory of Integrated Pest Management on Crops in Southwest, Ministry of Agriculture, Chengdu, 610066, Sichuan, P.R. China
| | - Qiang Li
- College of Pharmacy and Biological Engineering, Chengdu University, Chengdu, 610106, Sichuan, P.R. China
| | - Rongtao Fu
- Institute of plant protection, Sichuan Academy of Agricultural Sciences, Chengdu, 610066, Sichuan, P.R. China
| | - Jian Wang
- Institute of plant protection, Sichuan Academy of Agricultural Sciences, Chengdu, 610066, Sichuan, P.R. China
| | - Chuan Xiong
- Biotechnology and Nuclear Technology Research Institute, Sichuan Academy of Agricultural Sciences, Chengdu, 610061, Sichuan, P.R. China
| | - Zhonghan Fan
- Institute of plant protection, Sichuan Academy of Agricultural Sciences, Chengdu, 610066, Sichuan, P.R. China
| | - Rongping Hu
- Institute of plant protection, Sichuan Academy of Agricultural Sciences, Chengdu, 610066, Sichuan, P.R. China
| | - Hong Zhang
- Institute of plant protection, Sichuan Academy of Agricultural Sciences, Chengdu, 610066, Sichuan, P.R. China
| | - Daihua Lu
- Institute of plant protection, Sichuan Academy of Agricultural Sciences, Chengdu, 610066, Sichuan, P.R. China.
- Sichuan Academy of Agricultural Sciences, 20 # Jingjusi Rd, Chengdu, 610066, Sichuan, P.R. China.
| |
Collapse
|
29
|
A novel mitochondrial m.4414T>C MT-TM gene variant causing progressive external ophthalmoplegia and myopathy. Neuromuscul Disord 2019; 29:693-697. [PMID: 31488384 DOI: 10.1016/j.nmd.2019.08.005] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2019] [Revised: 08/13/2019] [Accepted: 08/15/2019] [Indexed: 11/22/2022]
Abstract
We report a novel mitochondrial m.4414T>C variant in the mt-tRNAMet (MT-TM) gene in an adult patient with chronic progressive external ophthalmoplegia and myopathy whose muscle biopsy revealed focal cytochrome c oxidase (COX)-deficient and ragged red fibres. The m.4414T>C variant occurs at a strongly evolutionary conserved sequence position, disturbing a canonical base pair and disrupting the secondary and tertiary structure of the mt-tRNAMet. Definitive evidence of pathogenicity is provided by clear segregation of m.4414T>C mutant levels with COX deficiency in single muscle fibres. Interestingly, the variant is present in skeletal muscle at relatively low levels (30%) and undetectable in accessible, non-muscle tissues from the patient and her asymptomatic brother, emphasizing the continuing requirement for a diagnostic muscle biopsy as the preferred tissue for mtDNA genetic investigations of mt-tRNA variants leading to mitochondrial myopathy.
Collapse
|
30
|
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] [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.
Collapse
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
| |
Collapse
|
31
|
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] [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.
Collapse
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.
| |
Collapse
|
32
|
Kwon S, Kim SS, Nebeck HE, Ahn EH. Immortalization of Different Breast Epithelial Cell Types Results in Distinct Mitochondrial Mutagenesis. Int J Mol Sci 2019; 20:E2813. [PMID: 31181796 PMCID: PMC6600575 DOI: 10.3390/ijms20112813] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2019] [Revised: 05/27/2019] [Accepted: 06/02/2019] [Indexed: 11/16/2022] Open
Abstract
Different phenotypes of normal cells might influence genetic profiles, epigenetic profiles, and tumorigenicities of their transformed derivatives. In this study, we investigate whether the whole mitochondrial genome of immortalized cells can be attributed to the different phenotypes (stem vs. non-stem) of their normal epithelial cell originators. To accurately determine mutations, we employed Duplex Sequencing, which exhibits the lowest error rates among currently-available DNA sequencing methods. Our results indicate that the vast majority of the observed mutations of the whole mitochondrial DNA occur at low-frequency (rare mutations). The most prevalent rare mutation types are C→T/G→A and A→G/T→C transitions. Frequencies and spectra of homoplasmic point mutations are virtually identical between stem cell-derived immortalized (SV1) cells and non-stem cell-derived immortalized (SV22) cells, verifying that both cell types were derived from the same woman. However, frequencies of rare point mutations are significantly lower in SV1 cells (5.79 × 10-5) than in SV22 cells (1.16 × 10-4). The significantly lower frequencies of rare mutations are aligned with a finding of longer average distances to adjacent mutations in SV1 cells than in SV22 cells. Additionally, the predicted pathogenicity for rare mutations in the mitochondrial tRNA genes tends to be lower (by 2.5-fold) in SV1 cells than in SV22 cells. While four known/confirmed pathogenic mt-tRNA mutations (m.5650 G>A, m.5521 G>A, m.5690 A>G, m.1630 A>G) were identified in SV22 cells, no such mutations were observed in SV1 cells. Our findings suggest that the immortalization of normal cells with stem cell features leads to decreased mitochondrial mutagenesis, particularly in RNA gene regions. The mutation spectra and mutations specific to stem cell-derived immortalized cells (vs. non-stem cell derived) have implications in characterizing the heterogeneity of tumors and understanding the role of mitochondrial mutations in the immortalization and transformation of human cells.
Collapse
Affiliation(s)
- Sujin Kwon
- Department of Pathology, University of Washington, Seattle, WA 98195, USA.
| | - Susan S Kim
- Department of Biochemistry, University of Washington, Seattle, WA 98195, USA.
| | - Howard E Nebeck
- Department of Pathology, University of Washington, Seattle, WA 98195, USA.
| | - Eun Hyun Ahn
- Department of Pathology, University of Washington, Seattle, WA 98195, USA.
- Institute of Stem Cell and Regenerative Medicine, University of Washington, Seattle, WA 98109, USA.
| |
Collapse
|
33
|
Zhou Z, Sun B, Huang S, Jia W, Yu D. The tRNA-associated dysregulation in diabetes mellitus. Metabolism 2019; 94:9-17. [PMID: 30711570 DOI: 10.1016/j.metabol.2019.01.017] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/20/2018] [Revised: 01/26/2019] [Accepted: 01/30/2019] [Indexed: 12/26/2022]
Abstract
Diabetes mellitus (DM) is a complex endocrine and metabolic disorder for human health and well-being. Deregulated glucose and lipid metabolism are the primary underlying manifestations associated with this disease. Transfer RNAs (tRNAs) are considered to mainly participate in protein translation and may contribute to complex human pathologies. Although the molecular mechanisms remain, for the most part, unknown, accumulating evidence indicates that tRNAs play a vital role in the pathogenesis of DM. This paper reviews different aspects of tRNA-associated dysregulation in DM, such as tRNA mutations, tRNA modifications, tRNA aminoacylation and tRNA derivatives, aiming at a better understanding of the pathogenesis of DM and providing new ideas for the personalized treatment of this metabolism-associated disease.
Collapse
Affiliation(s)
- Zheng Zhou
- Department of Chinese Medicine, The First Affiliated Hospital of Zhengzhou University, Zhengzhou 450000, China
| | - Bao Sun
- Department of Clinical Pharmacology, Xiangya Hospital, Central South University, Changsha 410000, China; Hunan Key Laboratory of Pharmacogenetics, Institute of Clinical Pharmacology, Central South University, Changsha 410000, China
| | - Shiqiong Huang
- Department of Clinical Pharmacology, Xiangya Hospital, Central South University, Changsha 410000, China; Hunan Key Laboratory of Pharmacogenetics, Institute of Clinical Pharmacology, Central South University, Changsha 410000, China
| | - Wenrui Jia
- Department of Chinese Medicine, The First Affiliated Hospital of Zhengzhou University, Zhengzhou 450000, China
| | - Dongsheng Yu
- Department of Chinese Medicine, The First Affiliated Hospital of Zhengzhou University, Zhengzhou 450000, China.
| |
Collapse
|
34
|
Pan J, Wang L, Lu C, Zhu Y, Min Z, Dong X, Sha H. Matching Mitochondrial DNA Haplotypes for Circumventing Tissue-Specific Segregation Bias. iScience 2019; 13:371-379. [PMID: 30897510 PMCID: PMC6426714 DOI: 10.1016/j.isci.2019.03.002] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2018] [Revised: 01/13/2019] [Accepted: 03/01/2019] [Indexed: 02/01/2023] Open
Abstract
Mitochondrial DNA (mtDNA) segregation associated with donor-recipient mtDNA mismatch in mitochondria replacement therapy leads to unknown risks. Here, to explore whether matching mtDNA haplotypes contributes to ameliorating segregation, we reproduced various degrees of heteroplasmic mice with three single nucleotide polymorphisms to monitor segregation severity. “Segregation” presented in tissues of heteroplasmic mice containing low-level donor mtDNA heteroplasmy, and disappeared as donor mtDNA heteroplasmy levels ascended. Meanwhile, we found that distribution of donor mtDNA among the blastomeres of preimplantation embryos from the heteroplasmic mice shared the same tendency as that in adult tissues. Statistical analysis showed that no selective replication of donor mtDNA occurred during lifespan. Tracking donor mtDNA distribution showed that uneven distribution of donor mtDNA among embryonic blastomeres gradually became even as donor mtDNA heteroplasmy increased, indicating that the “segregation” in tissues was inherited from the uneven distribution. Our finding suggested that donor-recipient mtDNA matching could circumvent segregation in mitochondria replacement therapy. Matching mitochondrial DNA haplotypes make the nucleus treat different mtDNA the same Similar mtDNA haplotypes prevents tissue-specific segregation bias Low level of mtDNA heteroplasmy results in uneven inheritance rather than segregation
Collapse
Affiliation(s)
- Jianxin Pan
- Reproductive Medicine Center, Zhongshan Hospital, State Key Laboratory of Medical Neurobiology, Institutes of Brain Science, Shanghai Medical College, Fudan University, Shanghai 200032, China
| | - Li Wang
- Key Lab of Synthetic Biology of CAS, Shanghai Institute for Biological Sciences, Shanghai Research Center of Biotech., Chinese Academy of Sciences, 500 Caobao Road, Shanghai 200233, China
| | - Charles Lu
- Reproductive Medicine Center, Zhongshan Hospital, State Key Laboratory of Medical Neurobiology, Institutes of Brain Science, Shanghai Medical College, Fudan University, Shanghai 200032, China; Washington University in St. Louis, Saint Louis 63110, USA
| | - Yanming Zhu
- Reproductive Medicine Center, Zhongshan Hospital, State Key Laboratory of Medical Neurobiology, Institutes of Brain Science, Shanghai Medical College, Fudan University, Shanghai 200032, China
| | - Zhunyuan Min
- Reproductive Medicine Center, Zhongshan Hospital, State Key Laboratory of Medical Neurobiology, Institutes of Brain Science, Shanghai Medical College, Fudan University, Shanghai 200032, China
| | - Xi Dong
- Reproductive Medicine Center, Zhongshan Hospital, State Key Laboratory of Medical Neurobiology, Institutes of Brain Science, Shanghai Medical College, Fudan University, Shanghai 200032, China.
| | - Hongying Sha
- Reproductive Medicine Center, Zhongshan Hospital, State Key Laboratory of Medical Neurobiology, Institutes of Brain Science, Shanghai Medical College, Fudan University, Shanghai 200032, China.
| |
Collapse
|
35
|
Schlapakow E, Peeva V, Zsurka G, Jeub M, Wabbels B, Kornblum C, Kunz WS. Distinct segregation of the pathogenic m.5667G>A mitochondrial tRNA Asn mutation in extraocular and skeletal muscle in chronic progressive external ophthalmoplegia. Neuromuscul Disord 2019; 29:358-367. [PMID: 30962064 DOI: 10.1016/j.nmd.2019.02.009] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2018] [Revised: 01/08/2019] [Accepted: 02/19/2019] [Indexed: 12/13/2022]
Abstract
Chronic progressive external ophthalmoplegia (CPEO) is a frequent clinical manifestation of disorders caused by pathogenic mitochondrial DNA mutations. However, for diagnostic purposes skeletal muscle tissue is used, since extraocular muscle tissue is usually not available for work-up. In the present study we aimed to identify causative factors that are responsible for extraocular muscle to be primarily affected in CPEO. We performed comparative histochemical and molecular genetic analyses of extraocular muscle and skeletal muscle single fibers in a case of isolated CPEO caused by the heteroplasmic m.5667G>A mutation in the mitochondrial tRNAAsn gene (MT-TN). Histochemical analyses revealed higher proportion of cytochrome c oxidase deficient fibers in extraocular muscle (41%) compared to skeletal muscle (10%). However, genetic analyses of single fibers revealed no significant difference either in the mutation loads between extraocular muscle and skeletal muscle cytochrome c oxidase deficient single fibers (extraocular muscle 86% ± 4.6%; skeletal muscle 87.8 %± 5.7%, p = 0.246) nor in the mutation threshold (extraocular muscle 74% ± 3%; skeletal muscle 74% ± 4%). We hypothesize that higher proportion of cytochrome c oxidase deficient fibers in extraocular muscle compared to skeletal muscle might be due to facilitated segregation of the m.5667G>A mutation into extraocular muscle, which may explain the preferential ocular manifestation and clinically isolated CPEO.
Collapse
Affiliation(s)
- Elena Schlapakow
- Department of Neurology, University Hospital of Bonn, Germany; Center for Rare Diseases, University Hospital of Bonn, Germany
| | - Viktoriya Peeva
- Division of Neurochemistry, Institute of Experimental Epileptology and Cognition Research, University of Bonn, Sigmund-Freud-Str. 25, D-53105 Bonn, Germany
| | - Gábor Zsurka
- Division of Neurochemistry, Institute of Experimental Epileptology and Cognition Research, University of Bonn, Sigmund-Freud-Str. 25, D-53105 Bonn, Germany; Department of Epileptology, University of Bonn, Germany
| | - Monika Jeub
- Department of Neurology, University Hospital of Bonn, Germany
| | | | - Cornelia Kornblum
- Department of Neurology, University Hospital of Bonn, Germany; Center for Rare Diseases, University Hospital of Bonn, Germany
| | - Wolfram S Kunz
- Division of Neurochemistry, Institute of Experimental Epileptology and Cognition Research, University of Bonn, Sigmund-Freud-Str. 25, D-53105 Bonn, Germany; Department of Epileptology, University of Bonn, Germany.
| |
Collapse
|
36
|
Nadeem MS, Ahmad H, Mohammed K, Muhammad K, Ullah I, Baothman OAS, Ali N, Anwar F, Zamzami MA, Shakoori AR. Identification of variants in the mitochondrial lysine-tRNA (MT-TK) gene in myoclonic epilepsy-pathogenicity evaluation and structural characterization by in silico approach. J Cell Biochem 2018; 119:6258-6265. [PMID: 29663531 DOI: 10.1002/jcb.26857] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2018] [Accepted: 03/12/2018] [Indexed: 02/06/2023]
Abstract
Variations in mitochondrial genes have an established link with myoclonic epilepsy. In the present study we evaluated the nucleotide sequence of MT-TK gene of 52 individuals from 12 unrelated families and reported three variations in 2 of the 13 epileptic patients. The DNA sequences coding for MT-TK gene were sequenced and mutations were detected in all participants. The mutations were further analyzed by the in silico analysis and their structural and pathogenic effects were determined. All the investigated patients had symptoms of myoclonus, 61.5% were positive for ataxia, 23.07% were suffering from hearing loss, 15.38% were having mild to severe dementia, 69.23% were males, and 61.53% had cousin marriage in their family history. DNA extracted from saliva was used for the PCR amplification of a 440 bp DNA fragment encompassing complete MT-TK gene. The nucleotide sequence analysis revealed three mutations, m.8306T>C, m.8313G>C, and m.8362T>G that are divergent from available reports. The identified mutations designate the heteroplasmic condition. Furthermore, pathogenicity of the identified variants was predicted by in silico tools viz., PON-mt-tRNA and MitoTIP. Secondary structure of altered MT-TK was predicted by RNAStructure web server. Studies by MitoTIP and PON-mt-tRNA tools have provided strong evidences of pathogenic effects of these mutations. Single nucleotide variations resulted in disruptive secondary structure of mutant MT-TK models, as predicted by RNAStructure. In vivo confirmation of structural and pathogenic effects of identified mutations in the animal models can be prolonged on the basis of these findings.
Collapse
Affiliation(s)
- Muhammad S Nadeem
- Department of Biochemistry, Faculty of Science, King Abdul Aziz University, Jeddah, Saudi Arabia
| | - Habib Ahmad
- Department of Genetics, Faculty of Life Sciences, Hazara University, Mansehra, Pakistan
| | - Kaleemuddin Mohammed
- Department of Biochemistry, Faculty of Science, King Abdul Aziz University, Jeddah, Saudi Arabia
| | - Khushi Muhammad
- Department of Genetics, Faculty of Life Sciences, Hazara University, Mansehra, Pakistan
| | - Inam Ullah
- Department of Genetics, Faculty of Life Sciences, Hazara University, Mansehra, Pakistan
| | - Othman A S Baothman
- Department of Biochemistry, Faculty of Science, King Abdul Aziz University, Jeddah, Saudi Arabia
| | - Nasir Ali
- Department of Genetics, Faculty of Life Sciences, Hazara University, Mansehra, Pakistan
| | - Firoz Anwar
- Department of Biochemistry, Faculty of Science, King Abdul Aziz University, Jeddah, Saudi Arabia
| | - Mazin A Zamzami
- Department of Biochemistry, Faculty of Science, King Abdul Aziz University, Jeddah, Saudi Arabia
| | - Abdul Rauf Shakoori
- School of Biological Sciences, University of the Punjab, Quaid-i-Azam Campus, Lahore, Pakistan
| |
Collapse
|
37
|
Cardaioli E, Mignarri A, Cantisani TA, Malandrini A, Nesti C, Rubegni A, Funel N, Federico A, Santorelli FM, Dotti MT. Myoclonus epilepsy, retinitis pigmentosa, leukoencephalopathy and cerebral calcifications associated with a novel m.5513G>A mutation in the MT-TW gene. Biochem Biophys Res Commun 2018; 500:158-162. [PMID: 29625105 DOI: 10.1016/j.bbrc.2018.04.009] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2018] [Accepted: 04/02/2018] [Indexed: 12/13/2022]
Abstract
We sequenced the mitochondrial genome from a 40-year-old woman with myoclonus epilepsy, retinitis pigmentosa, leukoencephalopathy and cerebral calcifications. Histological and biochemical features of mitochondrial respiratory chain dysfunction were present. Direct sequencing showed a novel heteroplasmic mutation at nucleotide 5513 in the MT-TW gene that encodes tRNATrp. Restriction Fragment Length Polymorphism analysis confirmed that about 80% of muscle mtDNA harboured the mutation while it was present in minor percentages in mtDNA from other tissues. The mutation is predicted to disrupt a highly conserved base pair within the aminoacyl acceptor stem of the tRNA. This is the 17° mutation in MT-TW gene and expands the known causes of late-onset mitochondrial diseases.
Collapse
Affiliation(s)
- Elena Cardaioli
- Department of Medicine, Surgery and Neuroscience, University of Siena, Viale Bracci 2, 53100, Siena, Italy.
| | - Andrea Mignarri
- Department of Medicine, Surgery and Neuroscience, University of Siena, Viale Bracci 2, 53100, Siena, Italy
| | - Teresa Anna Cantisani
- Perugia Hospital, Neurophysiopathology Unit, Azienda Ospedaliera di Perugia, S. Andrea delle Fratte, 06156 Perugia, Italy
| | - Alessandro Malandrini
- Department of Medicine, Surgery and Neuroscience, University of Siena, Viale Bracci 2, 53100, Siena, Italy
| | - Claudia Nesti
- Molecular Medicine, IRCCS Stella Maris, Via dei Giacinti 2, 56128, Pisa, Italy
| | - Anna Rubegni
- Molecular Medicine, IRCCS Stella Maris, Via dei Giacinti 2, 56128, Pisa, Italy
| | - Niccola Funel
- Department of Translational Research & The New Technologies in Medicine & Surgery, University of Pisa, Via Paradisa 2, 56124, Pisa, Italy
| | - Antonio Federico
- Department of Medicine, Surgery and Neuroscience, University of Siena, Viale Bracci 2, 53100, Siena, Italy
| | | | - Maria Teresa Dotti
- Department of Medicine, Surgery and Neuroscience, University of Siena, Viale Bracci 2, 53100, Siena, Italy
| |
Collapse
|
38
|
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] [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.
Collapse
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.
| |
Collapse
|
39
|
Bacalhau M, Simões M, Rocha MC, Hardy SA, Vincent AE, Durães J, Macário MC, Santos MJ, Rebelo O, Lopes C, Pratas J, Mendes C, Zuzarte M, Rego AC, Girão H, Wong LJC, Taylor RW, Grazina M. Disclosing the functional changes of two genetic alterations in a patient with Chronic Progressive External Ophthalmoplegia: Report of the novel mtDNA m.7486G>A variant. Neuromuscul Disord 2018; 28:350-360. [PMID: 29398297 PMCID: PMC5952895 DOI: 10.1016/j.nmd.2017.11.006] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2017] [Revised: 11/14/2017] [Accepted: 11/15/2017] [Indexed: 01/06/2023]
Abstract
Chronic Progressive External Ophthalmoplegia (CPEO) is characterized by ptosis and ophthalmoplegia and is usually caused by mitochondrial DNA (mtDNA) deletions or mt-tRNA mutations. The aim of the present work was to clarify the genetic defect in a patient presenting with CPEO and elucidate the underlying pathogenic mechanism. This 62-year-old female first developed ptosis of the right eye at the age of 12 and subsequently the left eye at 45 years, and was found to have external ophthalmoplegia at the age of 55 years. Histopathological abnormalities were detected in the patient's muscle, including ragged-red fibres, a mosaic pattern of COX-deficient muscle fibres and combined deficiency of respiratory chain complexes I and IV. Genetic investigation revealed the "common deletion" in the patient's muscle and fibroblasts. Moreover, a novel, heteroplasmic mt-tRNASer(UCN) variant (m.7486G>A) in the anticodon loop was detected in muscle homogenate (50%), fibroblasts (11%) and blood (4%). Single-fibre analysis showed segregation with COX-deficient fibres for both genetic alterations. Assembly defects of mtDNA-encoded complexes were demonstrated in fibroblasts. Functional analyses showed significant bioenergetic dysfunction, reduction in respiration rate and ATP production and mitochondrial depolarization. Multilamellar bodies were detected by electron microscopy, suggesting disturbance in autophagy. In conclusion, we report a CPEO patient with two possible genetic origins, both segregating with biochemical and histochemical defect. The "common mtDNA deletion" is the most likely cause, yet the potential pathogenic effect of a novel mt-tRNASer(UCN) variant cannot be fully excluded.
Collapse
Affiliation(s)
- Mafalda Bacalhau
- FMUC - Faculty of Medicine, University of Coimbra, Coimbra, Portugal; CNC - Center for Neuroscience and Cell Biology, Laboratory of Biochemical Genetics, University of Coimbra, Coimbra, Portugal
| | - Marta Simões
- CNC - Center for Neuroscience and Cell Biology, Laboratory of Biochemical Genetics, University of Coimbra, Coimbra, Portugal
| | - Mariana C Rocha
- Wellcome Centre for Mitochondrial Research, Institute of Neuroscience, The Medical School, Newcastle University, Newcastle Upon Tyne, UK
| | - Steven A Hardy
- Wellcome Centre for Mitochondrial Research, Institute of Neuroscience, The Medical School, Newcastle University, Newcastle Upon Tyne, UK
| | - Amy E Vincent
- Wellcome Centre for Mitochondrial Research, Institute of Neuroscience, The Medical School, Newcastle University, Newcastle Upon Tyne, UK
| | - João Durães
- CHUC - Neurology Department of Coimbra University Hospitals, Coimbra, Portugal
| | - Maria C Macário
- CHUC - Neurology Department of Coimbra University Hospitals, Coimbra, Portugal
| | - Maria João Santos
- FMUC - Faculty of Medicine, University of Coimbra, Coimbra, Portugal; CNC - Center for Neuroscience and Cell Biology, Laboratory of Biochemical Genetics, University of Coimbra, Coimbra, Portugal
| | - Olinda Rebelo
- CHUC - Neurology Department of Coimbra University Hospitals, Coimbra, Portugal
| | - Carla Lopes
- CNC - Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal
| | - João Pratas
- CNC - Center for Neuroscience and Cell Biology, Laboratory of Biochemical Genetics, University of Coimbra, Coimbra, Portugal
| | - Cândida Mendes
- CNC - Center for Neuroscience and Cell Biology, Laboratory of Biochemical Genetics, University of Coimbra, Coimbra, Portugal
| | - Mónica Zuzarte
- IBILI - Institute for Biomedical Imaging and Life Sciences, University of Coimbra, Coimbra, Portugal
| | - A Cristina Rego
- FMUC - Faculty of Medicine, University of Coimbra, Coimbra, Portugal; CNC - Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal
| | - Henrique Girão
- FMUC - Faculty of Medicine, University of Coimbra, Coimbra, Portugal; IBILI - Institute for Biomedical Imaging and Life Sciences, University of Coimbra, Coimbra, Portugal
| | - Lee-Jun C Wong
- Mitochondrial Diagnostic Laboratory, Baylor College of Medicine, Houston, USA
| | - Robert W Taylor
- Wellcome Centre for Mitochondrial Research, Institute of Neuroscience, The Medical School, Newcastle University, Newcastle Upon Tyne, UK
| | - Manuela Grazina
- FMUC - Faculty of Medicine, University of Coimbra, Coimbra, Portugal; CNC - Center for Neuroscience and Cell Biology, Laboratory of Biochemical Genetics, University of Coimbra, Coimbra, Portugal.
| |
Collapse
|
40
|
Soldath P, Madsen KL, Buch AE, Duno M, Wibrand F, Vissing J. Pure exercise intolerance and ophthalmoplegia associated with the m.12,294G > A mutation in the MT-TL2 gene: a case report. BMC Musculoskelet Disord 2017; 18:419. [PMID: 29052516 PMCID: PMC5649050 DOI: 10.1186/s12891-017-1781-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/19/2016] [Accepted: 10/12/2017] [Indexed: 12/22/2022] Open
Abstract
Background Pure exercise intolerance associated with exclusive affection of skeletal muscle is a very rare phenotype of patients with mitochondrial myopathy. Moreover, the exercise intolerance in these rare patients is yet not well explored, as most of known cases have not been assessed by objective testing, but only by interview. We report a patient with a mitochondrial DNA (mtDNA) mutation that gives rise to an exclusive myopathy associated with exercise intolerance and ophthalmoplegia. We quantified the patient’s exercise intolerance through detailed exercise testing. Case presentation A 39-year-old man presented with exercise intolerance and chronic progressive external ophthalmoplegia. Sequencing of the entire mtDNA identified a m.12,294G > A mutation in the MT-TL2 gene. The mutation was heteroplasmic in skeletal muscle (75%) while undetectable in blood, urinary sediment, and buccal mucosa as well as in tissues from the patient’s mother. The mutation affected a highly conserved site in the anticodon stem of the mitochondrial transfer RNA Leucine (CUN) molecule and lead to a severe combined respiratory chain defect. Exercise physiological studies in the patient demonstrated a significantly reduced maximal oxygen uptake of 20.4 ml O2 × min−1 × kg−1 (about half of normal) as well as threefold elevated lactate/pyruvate ratios. Conclusion The findings of our study support that the m.12,294G > A mutation is pathogenic. Likely, the mutation arose sporadically in early embryogenesis after differentiation of the mesoderm into muscle progenitor cells, leading to a pure myopathic phenotype.
Collapse
Affiliation(s)
- Patrick Soldath
- Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark. .,Department of Neurology, Copenhagen Neuromuscular Center, Rigshospitalet, Copenhagen, Denmark.
| | - Karen Lindhardt Madsen
- Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.,Department of Neurology, Copenhagen Neuromuscular Center, Rigshospitalet, Copenhagen, Denmark
| | - Astrid Emilie Buch
- Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.,Department of Neurology, Copenhagen Neuromuscular Center, Rigshospitalet, Copenhagen, Denmark
| | - Morten Duno
- Department of Clinical Genetics, Rigshospitalet, Copenhagen, Denmark
| | - Flemming Wibrand
- Department of Clinical Genetics, Rigshospitalet, Copenhagen, Denmark
| | - John Vissing
- Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.,Department of Neurology, Copenhagen Neuromuscular Center, Rigshospitalet, Copenhagen, Denmark
| |
Collapse
|
41
|
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] [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.
Collapse
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
| |
Collapse
|
42
|
Non-coding RNAs and disease: the classical ncRNAs make a comeback. Biochem Soc Trans 2017; 44:1073-8. [PMID: 27528754 DOI: 10.1042/bst20160089] [Citation(s) in RCA: 57] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2016] [Indexed: 01/16/2023]
Abstract
Many human diseases have been attributed to mutation in the protein coding regions of the human genome. The protein coding portion of the human genome, however, is very small compared with the non-coding portion of the genome. As such, there are a disproportionate number of diseases attributed to the coding compared with the non-coding portion of the genome. It is now clear that the non-coding portion of the genome produces many functional non-coding RNAs and these RNAs are slowly being linked to human diseases. Here we discuss examples where mutation in classical non-coding RNAs have been attributed to human disease and identify the future potential for the non-coding portion of the genome in disease biology.
Collapse
|
43
|
Schuelke M, Øien NC, Oldfors A. Myopathology in the times of modern genetics. Neuropathol Appl Neurobiol 2017; 43:44-61. [DOI: 10.1111/nan.12374] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2016] [Revised: 12/03/2016] [Accepted: 12/23/2016] [Indexed: 12/14/2022]
Affiliation(s)
- M. Schuelke
- Department of Neuropediatrics and NeuroCure Clinical Research Center; Charité-Universitätsmedizin; Berlin Germany
| | - N. C. Øien
- Department of Neuropediatrics and NeuroCure Clinical Research Center; Charité-Universitätsmedizin; Berlin Germany
- Max-Delbrück-Center for Molecular Medicine; Berlin Germany
| | - A. Oldfors
- Department of Pathology and Genetics; Institute of Biomedicine; University of Gothenburg; Gothenburg Sweden
| |
Collapse
|
44
|
Connor TM, Hoer S, Mallett A, Gale DP, Gomez-Duran A, Posse V, Antrobus R, Moreno P, Sciacovelli M, Frezza C, Duff J, Sheerin NS, Sayer JA, Ashcroft M, Wiesener MS, Hudson G, Gustafsson CM, Chinnery PF, Maxwell PH. Mutations in mitochondrial DNA causing tubulointerstitial kidney disease. PLoS Genet 2017; 13:e1006620. [PMID: 28267784 PMCID: PMC5360345 DOI: 10.1371/journal.pgen.1006620] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2016] [Revised: 03/21/2017] [Accepted: 02/07/2017] [Indexed: 11/19/2022] Open
Abstract
Tubulointerstitial kidney disease is an important cause of progressive renal failure whose aetiology is incompletely understood. We analysed a large pedigree with maternally inherited tubulointerstitial kidney disease and identified a homoplasmic substitution in the control region of the mitochondrial genome (m.547A>T). While mutations in mtDNA coding sequence are a well recognised cause of disease affecting multiple organs, mutations in the control region have never been shown to cause disease. Strikingly, our patients did not have classical features of mitochondrial disease. Patient fibroblasts showed reduced levels of mitochondrial tRNAPhe, tRNALeu1 and reduced mitochondrial protein translation and respiration. Mitochondrial transfer demonstrated mitochondrial transmission of the defect and in vitro assays showed reduced activity of the heavy strand promoter. We also identified further kindreds with the same phenotype carrying a homoplasmic mutation in mitochondrial tRNAPhe (m.616T>C). Thus mutations in mitochondrial DNA can cause maternally inherited renal disease, likely mediated through reduced function of mitochondrial tRNAPhe.
Collapse
Affiliation(s)
| | - Simon Hoer
- Cambridge Institute for Medical Research, University of Cambridge, United Kingdom
| | - Andrew Mallett
- Kidney Health Service, Royal Brisbane and Women’s Hospital, School of Medicine, The University of Queensland, Australia
| | - Daniel P. Gale
- UCL Centre for Nephrology, Royal Free Hospital, London, United Kingdom
| | | | - Viktor Posse
- Institute of Biomedicine, University of Gothenburg, Sweden
| | - Robin Antrobus
- Cambridge Institute for Medical Research, University of Cambridge, United Kingdom
| | - Pablo Moreno
- Cambridge Institute for Medical Research, University of Cambridge, United Kingdom
| | | | | | - Jennifer Duff
- Institute of Genetic Medicine, International Centre for Life, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Neil S. Sheerin
- Institute of Cellular Medicine, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - John A. Sayer
- Institute of Genetic Medicine, International Centre for Life, Newcastle University, Newcastle upon Tyne, United Kingdom
| | | | - Michael S. Wiesener
- Department of Nephrology and Hypertension, Friedrich-Alexander University Erlangen-Nürnberg, Erlangen, Germany
| | - Gavin Hudson
- Institute of Genetic Medicine, International Centre for Life, Newcastle University, Newcastle upon Tyne, United Kingdom
| | | | | | - Patrick H. Maxwell
- School of Clinical Medicine, Cambridge University, Cambridge, United Kingdom
| |
Collapse
|
45
|
Diroma MA, Lubisco P, Attimonelli M. A comprehensive collection of annotations to interpret sequence variation in human mitochondrial transfer RNAs. BMC Bioinformatics 2016; 17:338. [PMID: 28185569 PMCID: PMC5123245 DOI: 10.1186/s12859-016-1193-4] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
BACKGROUND The abundance of biological data characterizing the genomics era is contributing to a comprehensive understanding of human mitochondrial genetics. Nevertheless, many aspects are still unclear, specifically about the variability of the 22 human mitochondrial transfer RNA (tRNA) genes and their involvement in diseases. The complex enrichment and isolation of tRNAs in vitro leads to an incomplete knowledge of their post-transcriptional modifications and three-dimensional folding, essential for correct tRNA functioning. An accurate annotation of mitochondrial tRNA variants would be definitely useful and appreciated by mitochondrial researchers and clinicians since the most of bioinformatics tools for variant annotation and prioritization available so far cannot shed light on the functional role of tRNA variations. RESULTS To this aim, we updated our MToolBox pipeline for mitochondrial DNA analysis of high throughput and Sanger sequencing data by integrating tRNA variant annotations in order to identify and characterize relevant variants not only in protein coding regions, but also in tRNA genes. The annotation step in the pipeline now provides detailed information for variants mapping onto the 22 mitochondrial tRNAs. For each mt-tRNA position along the entire genome, the relative tRNA numbering, tRNA type, cloverleaf secondary domains (loops and stems), mature nucleotide and interactions in the three-dimensional folding were reported. Moreover, pathogenicity predictions for tRNA and rRNA variants were retrieved from the literature and integrated within the annotations provided by MToolBox, both in the stand-alone version and web-based tool at the Mitochondrial Disease Sequence Data Resource (MSeqDR) website. All the information available in the annotation step of MToolBox were exploited to generate custom tracks which can be displayed in the GBrowse instance at MSeqDR website. CONCLUSIONS To the best of our knowledge, specific data regarding mitochondrial variants in tRNA genes were introduced for the first time in a tool for mitochondrial genome analysis, supporting the interpretation of genetic variants in specific genomic contexts.
Collapse
Affiliation(s)
- Maria Angela Diroma
- Department of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari, Bari, 70126, Italy
| | - Paolo Lubisco
- Department of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari, Bari, 70126, Italy
| | - Marcella Attimonelli
- Department of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari, Bari, 70126, Italy.
| |
Collapse
|
46
|
Sen A, Cox RT. Fly Models of Human Diseases: Drosophila as a Model for Understanding Human Mitochondrial Mutations and Disease. Curr Top Dev Biol 2016; 121:1-27. [PMID: 28057297 DOI: 10.1016/bs.ctdb.2016.07.001] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Mitochondrial diseases are a prevalent, heterogeneous class of diseases caused by defects in oxidative phosphorylation, whose severity depends upon particular genetic mutations. These diseases can be difficult to diagnose, and current therapeutics have limited efficacy, primarily treating only symptoms. Because mitochondria play a pivotal role in numerous cellular functions, especially ATP production, their diminished activity has dramatic physiological consequences. While this in and of itself makes treating mitochondrial disease complex, these organelles contain their own DNA, mtDNA, whose products are required for ATP production, in addition to the hundreds of nucleus-encoded proteins. Drosophila offers a tractable whole-animal model to understand the mechanisms underlying loss of mitochondrial function, the subsequent cellular and tissue damage that results, and how these organelles are inherited. Human and Drosophila mtDNAs encode the same set of products, and the homologous nucleus-encoded genes required for mitochondrial function are conserved. In addition, Drosophila contain sufficiently complex organ systems to effectively recapitulate many basic symptoms of mitochondrial diseases, yet are relatively easy and fast to genetically manipulate. There are several Drosophila models for specific mitochondrial diseases, which have been recently reviewed (Foriel, Willems, Smeitink, Schenck, & Beyrath, 2015). In this review, we highlight the conservation between human and Drosophila mtDNA, the present and future techniques for creating mtDNA mutations for further study, and how Drosophila has contributed to our current understanding of mitochondrial inheritance.
Collapse
Affiliation(s)
- A Sen
- Uniformed Services University, Bethesda, MD, United States
| | - R T Cox
- Uniformed Services University, Bethesda, MD, United States.
| |
Collapse
|
47
|
Sallevelt SCEH, de Die-Smulders CEM, Hendrickx ATM, Hellebrekers DMEI, de Coo IFM, Alston CL, Knowles C, Taylor RW, McFarland R, Smeets HJM. De novo mtDNA point mutations are common and have a low recurrence risk. J Med Genet 2016; 54:73-83. [PMID: 27450679 PMCID: PMC5502310 DOI: 10.1136/jmedgenet-2016-103876] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2016] [Revised: 06/02/2016] [Accepted: 06/09/2016] [Indexed: 12/25/2022]
Abstract
Background Severe, disease-causing germline mitochondrial (mt)DNA mutations are maternally inherited or arise de novo. Strategies to prevent transmission are generally available, but depend on recurrence risks, ranging from high/unpredictable for many familial mtDNA point mutations to very low for sporadic, large-scale single mtDNA deletions. Comprehensive data are lacking for de novo mtDNA point mutations, often leading to misconceptions and incorrect counselling regarding recurrence risk and reproductive options. We aim to study the relevance and recurrence risk of apparently de novo mtDNA point mutations. Methods Systematic study of prenatal diagnosis (PND) and recurrence of mtDNA point mutations in families with de novo cases, including new and published data. ‘De novo’ based on the absence of the mutation in multiple (postmitotic) maternal tissues is preferred, but mutations absent in maternal blood only were also included. Results In our series of 105 index patients (33 children and 72 adults) with (likely) pathogenic mtDNA point mutations, the de novo frequency was 24.6%, the majority being paediatric. PND was performed in subsequent pregnancies of mothers of four de novo cases. A fifth mother opted for preimplantation genetic diagnosis because of a coexisting Mendelian genetic disorder. The mtDNA mutation was absent in all four prenatal samples and all 11 oocytes/embryos tested. A literature survey revealed 137 de novo cases, but PND was only performed for 9 (including 1 unpublished) mothers. In one, recurrence occurred in two subsequent pregnancies, presumably due to germline mosaicism. Conclusions De novo mtDNA point mutations are a common cause of mtDNA disease. Recurrence risk is low. This is relevant for genetic counselling, particularly for reproductive options. PND can be offered for reassurance.
Collapse
Affiliation(s)
- Suzanne C E H Sallevelt
- Department of Clinical Genetics, Maastricht University Medical Centre (MUMC), Maastricht, The Netherlands
| | - Christine E M de Die-Smulders
- Department of Clinical Genetics, Maastricht University Medical Centre (MUMC), Maastricht, The Netherlands.,Research School for Developmental Biology (GROW), Maastricht University, Maastricht, The Netherlands
| | - Alexandra T M Hendrickx
- Department of Clinical Genetics, Maastricht University Medical Centre (MUMC), Maastricht, The Netherlands
| | - Debby M E I Hellebrekers
- Department of Clinical Genetics, Maastricht University Medical Centre (MUMC), Maastricht, The Netherlands
| | - Irenaeus F M de Coo
- Department of Neurology, Erasmus MC-Sophia Children's Hospital Rotterdam, Rotterdam, The Netherlands
| | - Charlotte L Alston
- Wellcome Trust Centre for Mitochondrial Research, Institute of Neuroscience, The Medical School, Newcastle University, Newcastle upon Tyne, UK
| | - Charlotte Knowles
- Wellcome Trust Centre for Mitochondrial Research, Institute of Neuroscience, The Medical School, Newcastle University, Newcastle upon Tyne, UK
| | - Robert W Taylor
- Wellcome Trust Centre for Mitochondrial Research, Institute of Neuroscience, The Medical School, Newcastle University, Newcastle upon Tyne, UK
| | - Robert McFarland
- Wellcome Trust Centre for Mitochondrial Research, Institute of Neuroscience, The Medical School, Newcastle University, Newcastle upon Tyne, UK
| | - Hubert J M Smeets
- Department of Clinical Genetics, Maastricht University Medical Centre (MUMC), Maastricht, The Netherlands.,Research School for Developmental Biology (GROW), Maastricht University, Maastricht, The Netherlands.,Research School for Cardiovascular Diseases in Maastricht, CARIM, Maastricht University, Maastricht, The Netherlands
| |
Collapse
|
48
|
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. NEUROLOGY-GENETICS 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] [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
| |
Collapse
|
49
|
Hatakeyama H, Goto YI. Concise Review: Heteroplasmic Mitochondrial DNA Mutations and Mitochondrial Diseases: Toward iPSC-Based Disease Modeling, Drug Discovery, and Regenerative Therapeutics. Stem Cells 2016; 34:801-8. [DOI: 10.1002/stem.2292] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2015] [Revised: 11/20/2015] [Accepted: 12/09/2015] [Indexed: 01/19/2023]
Affiliation(s)
- Hideyuki Hatakeyama
- Department of Mental Retardation and Birth Defect Research; National Institute of Neuroscience, National Center of Neurology and Psychiatry; Tokyo Japan
- AMED-CREST, Japan Agency for Medical Research and Development; Tokyo Japan
| | - Yu-ichi Goto
- Department of Mental Retardation and Birth Defect Research; National Institute of Neuroscience, National Center of Neurology and Psychiatry; Tokyo Japan
- Medical Genome Center, National Center of Neurology and Psychiatry; Tokyo Japan
- AMED-CREST, Japan Agency for Medical Research and Development; Tokyo Japan
| |
Collapse
|
50
|
A mutation in MT-TW causes a tRNA processing defect and reduced mitochondrial function in a family with Leigh syndrome. Mitochondrion 2015; 25:113-9. [PMID: 26524491 DOI: 10.1016/j.mito.2015.10.008] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2015] [Revised: 09/29/2015] [Accepted: 10/26/2015] [Indexed: 01/10/2023]
Abstract
Leigh syndrome (LS) is a progressive mitochondrial neurodegenerative disorder, whose symptoms most commonly include psychomotor delay with regression, lactic acidosis and a failure to thrive. Here we describe three siblings with LS, but with additional manifestations including hypertrophic cardiomyopathy, hepatosplenomegaly, cholestatic hepatitis, and seizures. All three affected siblings were found to be homoplasmic for an m. 5559A>G mutation in the T stem of the mitochondrial DNA-encoded MT-TW by next generation sequencing. The m.5559A>G mutation causes a reduction in the steady state levels of tRNA(Trp) and this decrease likely affects the stability of other mitochondrial RNAs in the patient fibroblasts. We observe accumulation of an unprocessed transcript containing tRNA(Trp), decreased de novo protein synthesis and consequently lowered steady state levels of mitochondrial DNA-encoded proteins that compromise mitochondrial respiration. Our results show that the m.5559A>G mutation at homoplasmic levels causes LS in association with severe multi-organ disease (LS-plus) as a consequence of dysfunctional mitochondrial RNA metabolism.
Collapse
|