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Cannon SJ, Hall T, Hawkes G, Colclough K, Boggan RM, Wright CF, Pickett SJ, Hattersley AT, Weedon MN, Patel KA. Penetrance and expressivity of mitochondrial variants in a large clinically unselected population. Hum Mol Genet 2024; 33:465-474. [PMID: 37988592 PMCID: PMC10877468 DOI: 10.1093/hmg/ddad194] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2023] [Revised: 10/30/2023] [Accepted: 11/10/2023] [Indexed: 11/23/2023] Open
Abstract
Whole genome sequencing (WGS) from large clinically unselected cohorts provides a unique opportunity to assess the penetrance and expressivity of rare and/or known pathogenic mitochondrial variants in population. Using WGS from 179 862 clinically unselected individuals from the UK Biobank, we performed extensive single and rare variant aggregation association analyses of 15 881 mtDNA variants and 73 known pathogenic variants with 15 mitochondrial disease-relevant phenotypes. We identified 12 homoplasmic and one heteroplasmic variant (m.3243A>G) with genome-wide significant associations in our clinically unselected cohort. Heteroplasmic m.3243A>G (MAF = 0.0002, a known pathogenic variant) was associated with diabetes, deafness and heart failure and 12 homoplasmic variants increased aspartate aminotransferase levels including three low-frequency variants (MAF ~0.002 and beta~0.3 SD). Most pathogenic mitochondrial disease variants (n = 66/74) were rare in the population (<1:9000). Aggregated or single variant analysis of pathogenic variants showed low penetrance in unselected settings for the relevant phenotypes, except m.3243A>G. Multi-system disease risk and penetrance of diabetes, deafness and heart failure greatly increased with m.3243A>G level ≥ 10%. The odds ratio of these traits increased from 5.61, 12.3 and 10.1 to 25.1, 55.0 and 39.5, respectively. Diabetes risk with m.3243A>G was further influenced by type 2 diabetes genetic risk. Our study of mitochondrial variation in a large-unselected population identified novel associations and demonstrated that pathogenic mitochondrial variants have lower penetrance in clinically unselected settings. m.3243A>G was an exception at higher heteroplasmy showing a significant impact on health making it a good candidate for incidental reporting.
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Affiliation(s)
- Stuart J Cannon
- Department of Clinical and Biomedical Sciences, University of Exeter, 79 Heavitree Road, Exeter, EX2 4TH, United Kingdom
| | - Timothy Hall
- Department of Clinical and Biomedical Sciences, University of Exeter, 79 Heavitree Road, Exeter, EX2 4TH, United Kingdom
| | - Gareth Hawkes
- Department of Clinical and Biomedical Sciences, University of Exeter, 79 Heavitree Road, Exeter, EX2 4TH, United Kingdom
| | - Kevin Colclough
- Exeter Genomics Laboratory, RILD Building, Royal Devon University Healthcare NHS Foundation Trust, Barrack Road, Exeter, EX2 5DW, United Kingdom
| | - Roisin M Boggan
- Wellcome Centre for Mitochondrial Research, Translational and Clinical Research Institute, Newcastle University, Framlington Place, Newcastle upon Tyne, NE2 4HH, United Kingdom
| | - Caroline F Wright
- Department of Clinical and Biomedical Sciences, University of Exeter, 79 Heavitree Road, Exeter, EX2 4TH, United Kingdom
| | - Sarah J Pickett
- Wellcome Centre for Mitochondrial Research, Translational and Clinical Research Institute, Newcastle University, Framlington Place, Newcastle upon Tyne, NE2 4HH, United Kingdom
| | - Andrew T Hattersley
- Department of Clinical and Biomedical Sciences, University of Exeter, 79 Heavitree Road, Exeter, EX2 4TH, United Kingdom
| | - Michael N Weedon
- Department of Clinical and Biomedical Sciences, University of Exeter, 79 Heavitree Road, Exeter, EX2 4TH, United Kingdom
| | - Kashyap A Patel
- Department of Clinical and Biomedical Sciences, University of Exeter, 79 Heavitree Road, Exeter, EX2 4TH, United Kingdom
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Franklin IG, Milne P, Childs J, Boggan RM, Barrow I, Lawless C, Gorman GS, Ng YS, Collin M, Russell OM, Pickett SJ. T cell differentiation drives the negative selection of pathogenic mitochondrial DNA variants. Life Sci Alliance 2023; 6:e202302271. [PMID: 37652671 PMCID: PMC10471888 DOI: 10.26508/lsa.202302271] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2023] [Revised: 08/08/2023] [Accepted: 08/09/2023] [Indexed: 09/02/2023] Open
Abstract
Pathogenic mitochondrial DNA (mtDNA) single-nucleotide variants are a common cause of adult mitochondrial disease. Levels of some variants decrease with age in blood. Given differing division rates, longevity, and energetic requirements within haematopoietic lineages, we hypothesised that cell-type-specific metabolic requirements drive this decline. We coupled cell-sorting with mtDNA sequencing to investigate mtDNA variant levels within progenitor, myeloid, and lymphoid lineages from 26 individuals harbouring one of two pathogenic mtDNA variants (m.3243A>G and m.8344A>G). For both variants, cells of the T cell lineage show an enhanced decline. High-throughput single-cell analysis revealed that decline is driven by increasing proportions of cells that have cleared the variant, following a hierarchy that follows the current orthodoxy of T cell differentiation and maturation. Furthermore, patients with pathogenic mtDNA variants have a lower proportion of T cells than controls, indicating a key role for mitochondrial function in T cell homeostasis. This work identifies the ability of T cell subtypes to selectively purify their mitochondrial genomes, and identifies pathogenic mtDNA variants as a new means to track blood cell differentiation status.
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Affiliation(s)
- Imogen G Franklin
- https://ror.org/01kj2bm70 Wellcome Centre for Mitochondrial Research, Translational and Clinical Research Institute, Newcastle University, Newcastle upon Tyne, England
| | - Paul Milne
- https://ror.org/01kj2bm70 Haematopoiesis and Immunogenomics Laboratory, Translational and Clinical Research Institute, Newcastle University, Newcastle upon Tyne, England
| | - Jordan Childs
- https://ror.org/01kj2bm70 Wellcome Centre for Mitochondrial Research, Translational and Clinical Research Institute, Newcastle University, Newcastle upon Tyne, England
| | - Róisín M Boggan
- https://ror.org/01kj2bm70 Wellcome Centre for Mitochondrial Research, Translational and Clinical Research Institute, Newcastle University, Newcastle upon Tyne, England
| | - Isabel Barrow
- https://ror.org/01kj2bm70 Wellcome Centre for Mitochondrial Research, Translational and Clinical Research Institute, Newcastle University, Newcastle upon Tyne, England
- NHS Highly Specialised Service for Rare Mitochondrial Disorders, Newcastle upon Tyne NHS Foundation Trust, Newcastle upon Tyne, England
- https://ror.org/01kj2bm70 NIHR Newcastle Biomedical Research Centre, Newcastle upon Tyne Hospitals NHS Foundation Trust and Newcastle University, Newcastle upon Tyne, England
| | - Conor Lawless
- https://ror.org/01kj2bm70 Wellcome Centre for Mitochondrial Research, Translational and Clinical Research Institute, Newcastle University, Newcastle upon Tyne, England
| | - Gráinne S Gorman
- https://ror.org/01kj2bm70 Wellcome Centre for Mitochondrial Research, Translational and Clinical Research Institute, Newcastle University, Newcastle upon Tyne, England
- NHS Highly Specialised Service for Rare Mitochondrial Disorders, Newcastle upon Tyne NHS Foundation Trust, Newcastle upon Tyne, England
- https://ror.org/01kj2bm70 NIHR Newcastle Biomedical Research Centre, Newcastle upon Tyne Hospitals NHS Foundation Trust and Newcastle University, Newcastle upon Tyne, England
| | - Yi Shiau Ng
- https://ror.org/01kj2bm70 Wellcome Centre for Mitochondrial Research, Translational and Clinical Research Institute, Newcastle University, Newcastle upon Tyne, England
- NHS Highly Specialised Service for Rare Mitochondrial Disorders, Newcastle upon Tyne NHS Foundation Trust, Newcastle upon Tyne, England
| | - Matthew Collin
- https://ror.org/01kj2bm70 Haematopoiesis and Immunogenomics Laboratory, Translational and Clinical Research Institute, Newcastle University, Newcastle upon Tyne, England
| | - Oliver M Russell
- https://ror.org/01kj2bm70 Wellcome Centre for Mitochondrial Research, Translational and Clinical Research Institute, Newcastle University, Newcastle upon Tyne, England
- https://ror.org/01kj2bm70 NIHR Newcastle Biomedical Research Centre, Newcastle upon Tyne Hospitals NHS Foundation Trust and Newcastle University, Newcastle upon Tyne, England
| | - Sarah J Pickett
- https://ror.org/01kj2bm70 Wellcome Centre for Mitochondrial Research, Translational and Clinical Research Institute, Newcastle University, Newcastle upon Tyne, England
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3
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Cosma J, Russo A, Schino S, Belli M, Mango R, Chiricolo G, Martuscelli E, Mariano EG. Acute myocardial infarction in a patient with MELAS syndrome: a possible link? Minerva Cardiol Angiol 2023; 71:374-380. [PMID: 35767235 DOI: 10.23736/s2724-5683.22.06021-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/20/2023]
Abstract
The mitochondrial encephalomyopathy, lactic acidosis, and stroke (MELAS) syndrome is a mitochondrial disorder, commonly caused by m.3243A>G mutation in the MT-TL1 gene. It encodes for the mitochondrial leucine transfer RNA (tRNA Leu [UUR]), implicated in the translation of proteins involved in the assembly and function of mitochondrial complexes in the electron transport chain. The m.3243A>G mutation determines complex I (CI) deficiency, ultimately leading to NADH accumulation, higher rates of glycolysis in order to compensate for the reduced ATP production and increase in lactates, the end-product of glycolysis. Disruption of the oxidative phosphorylation function with an inability to produce sufficient energy results in multi-organ dysfunction, with high energy demanding cells, such as myocytes and neurons, being the most affected ones. Therefore, MELAS syndrome is characterized by a heterogeneous clinical spectrum. Here we report on a case of a 55-year-old man affected by MELA syndrome with no cardiovascular risk factors. He was admitted to our department because of a non ST-segment elevation myocardial infarction (NSTEMI). A coronary angioplasty of the posterior descending artery and of the left anterior descending artery was realized. Transthoracic echocardiography showed inferior and anterior left ventricular wall hypokinesis together with a moderate left ventricle hypertrophy. Cardiac involvement is reported in about a third of the patients and left ventricular hypertrophy (LVH) is the most common phenotype, with possible dilated cardiomyopathy in end-stage disease; brady- arrhythmias and tachy-arrhythmias are also frequently reported as well as Wolff- Parkinson-White (WPW) syndrome. Organ impairment and clinical manifestations depend on the heteroplasmy level of mutant DNA in cells that can differ among individuals, explaining why some patients present a more severe disease. A clear relationship between MELAS syndrome and atherosclerosis has never been established, however recently advocated. In vitro studies in MELAS patients have shown that higher mitochondrial ROS levels and increased expression of oxidative stress-related genes, as a consequence of complex I deficiency and disrupted electron transport, allow circulating LDL to be promptly oxidized into ox-LDL, contributing to endothelial dysfunction and atherosclerosis plaque formation. In light of the recent evidence suggesting a possible link between mitochondrial disorders and atherosclerosis, we speculate that MELAS syndrome may have played a role in the pathogenesis of coronary artery disease in our patient. Further investigations are needed to confirm a pathogenetic link.
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Affiliation(s)
- Joseph Cosma
- Department of Cardiology, Tor Vergata University of Rome, Rome, Italy -
- Department of Cardiology, Saint Martin Private Hospital Center, Caen, France -
| | - Alessandro Russo
- Department of Cardiology, Tor Vergata University of Rome, Rome, Italy
| | - Sofia Schino
- Department of Cardiology, Tor Vergata University of Rome, Rome, Italy
| | - Martina Belli
- Department of Cardiology, Tor Vergata University of Rome, Rome, Italy
| | - Ruggiero Mango
- Department of Cardiology, Tor Vergata University of Rome, Rome, Italy
| | - Gaetano Chiricolo
- Department of Cardiology, Tor Vergata University of Rome, Rome, Italy
| | | | - Enrica G Mariano
- Department of Cardiology, Tor Vergata University of Rome, Rome, Italy
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Ng YS, Gorman GS. Stroke-like episodes in adult mitochondrial disease. HANDBOOK OF CLINICAL NEUROLOGY 2023; 194:65-78. [PMID: 36813321 DOI: 10.1016/b978-0-12-821751-1.00005-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/22/2023]
Abstract
Stroke-like episode is a paroxysmal neurological manifestation which affects a specific group of patients with mitochondrial disease. Focal-onset seizures, encephalopathy, and visual disturbances are prominent findings associated with stroke-like episodes, with a predilection for the posterior cerebral cortex. The most common cause of stroke-like episodes is the m.3243A>G variant in MT-TL1 gene followed by recessive POLG variants. This chapter aims to review the definition of stroke-like episode and delineate the clinical phenomenology, neuroimaging and EEG findings typically seen in patients. In addition, several lines of evidence supporting neuronal hyper-excitability as the key mechanism of stroke-like episodes are discussed. The management of stroke-like episodes should focus on aggressive seizure management and treatment for concomitant complications such as intestinal pseudo-obstruction. There is no robust evidence to prove the efficacy of l-arginine for both acute and prophylactic settings. Progressive brain atrophy and dementia are the sequalae of recurrent stroke-like episode, and the underlying genotype in part predicts prognosis.
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Affiliation(s)
- Yi Shiau Ng
- Wellcome Centre for Mitochondrial Research, Translational and Clinical Research Institute, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Gráinne S Gorman
- Wellcome Centre for Mitochondrial Research, Translational and Clinical Research Institute, Newcastle University, Newcastle upon Tyne, United Kingdom.
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Dawod PGA, Jancic J, Marjanovic A, Brankovic M, Jankovic M, Samardzic J, Gamil Anwar Dawod A, Novakovic I, Abdel Motaleb FI, Radlovic V, Kostic VS, Nikolic D. Mutational Analysis and mtDNA Haplogroup Characterization in Three Serbian Cases of Mitochondrial Encephalomyopathies and Literature Review. Diagnostics (Basel) 2021; 11:1969. [PMID: 34829316 PMCID: PMC8620769 DOI: 10.3390/diagnostics11111969] [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: 09/05/2021] [Revised: 10/19/2021] [Accepted: 10/21/2021] [Indexed: 12/15/2022] Open
Abstract
Mitochondrial encephalomyopathies (MEMP) are heterogeneous multisystem disorders frequently associated with mitochondrial DNA (mtDNA) mutations. Clinical presentation varies considerably in age of onset, course, and severity up to death in early childhood. In this study, we performed molecular genetic analysis for mtDNA pathogenic mutation detection in Serbian children, preliminary diagnosed clinically, biochemically and by brain imaging for mitochondrial encephalomyopathies disorders. Sanger sequencing analysis in three Serbian probands revealed two known pathogenic mutations. Two probands had a heteroplasmic point mutation m.3243A>G in the MT-TL1 gene, which confirmed mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episode syndrome (MELAS), while a single case clinically manifested for Leigh syndrome had an almost homoplasmic (close to 100%) m.8993T>G mutation in the MT-ATP6 gene. After full mtDNA MITOMASTER analysis and PhyloTree build 17, we report MELAS' association with haplogroups U and H (U2e and H15 subclades); likewise, the mtDNA-associated Leigh syndrome proband shows a preference for haplogroup H (H34 subclade). Based on clinical-genetic correlation, we suggest that haplogroup H may contribute to the mitochondrial encephalomyopathies' phenotypic variability of the patients in our study. We conclude that genetic studies for the distinctive mitochondrial encephalomyopathies should be well-considered for realizing clinical severity and possible outcomes.
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Affiliation(s)
- Phepy G. A. Dawod
- Faculty of Medicine, University of Belgrade, 11000 Belgrade, Serbia; (P.G.A.D.); (J.J.); (A.M.); (M.B.); (I.N.); (V.R.); (V.S.K.)
- Department of Medical Biochemistry and Molecular Biology, Faculty of Medicine, Ain Shams University, Cairo 11591, Egypt;
| | - Jasna Jancic
- Faculty of Medicine, University of Belgrade, 11000 Belgrade, Serbia; (P.G.A.D.); (J.J.); (A.M.); (M.B.); (I.N.); (V.R.); (V.S.K.)
- Clinic of Neurology and Psychiatry of Children and Youth, 11000 Belgrade, Serbia
| | - Ana Marjanovic
- Faculty of Medicine, University of Belgrade, 11000 Belgrade, Serbia; (P.G.A.D.); (J.J.); (A.M.); (M.B.); (I.N.); (V.R.); (V.S.K.)
| | - Marija Brankovic
- Faculty of Medicine, University of Belgrade, 11000 Belgrade, Serbia; (P.G.A.D.); (J.J.); (A.M.); (M.B.); (I.N.); (V.R.); (V.S.K.)
| | - Milena Jankovic
- Neurology Clinic, Clinical Center of Serbia, 11000 Belgrade, Serbia;
| | - Janko Samardzic
- Institute of Pharmacology, Clinical Pharmacology and Toxicology, Faculty of Medicine, University of Belgrade, 11000 Belgrade, Serbia;
| | - Ayman Gamil Anwar Dawod
- Internal Medicine, Hepatogastroenterology and Endoscopy Department, Faculty of Medicine, Ain Shams University, Cairo 11591, Egypt;
| | - Ivana Novakovic
- Faculty of Medicine, University of Belgrade, 11000 Belgrade, Serbia; (P.G.A.D.); (J.J.); (A.M.); (M.B.); (I.N.); (V.R.); (V.S.K.)
| | - Fayda I. Abdel Motaleb
- Department of Medical Biochemistry and Molecular Biology, Faculty of Medicine, Ain Shams University, Cairo 11591, Egypt;
| | - Vladimir Radlovic
- Faculty of Medicine, University of Belgrade, 11000 Belgrade, Serbia; (P.G.A.D.); (J.J.); (A.M.); (M.B.); (I.N.); (V.R.); (V.S.K.)
- Pediatric Surgery Department, University Children’s Hospital, 11000 Belgrade, Serbia
| | - Vladimir S. Kostic
- Faculty of Medicine, University of Belgrade, 11000 Belgrade, Serbia; (P.G.A.D.); (J.J.); (A.M.); (M.B.); (I.N.); (V.R.); (V.S.K.)
- Neurology Clinic, Clinical Center of Serbia, 11000 Belgrade, Serbia;
| | - Dejan Nikolic
- Faculty of Medicine, University of Belgrade, 11000 Belgrade, Serbia; (P.G.A.D.); (J.J.); (A.M.); (M.B.); (I.N.); (V.R.); (V.S.K.)
- Physical Medicine and Rehabilitation Department, University Children’s Hospital, Tirsova 10, 11000 Belgrade, Serbia
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Montano V, Gruosso F, Simoncini C, Siciliano G, Mancuso M. Clinical features of mtDNA-related syndromes in adulthood. Arch Biochem Biophys 2020; 697:108689. [PMID: 33227288 DOI: 10.1016/j.abb.2020.108689] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2020] [Revised: 11/06/2020] [Accepted: 11/15/2020] [Indexed: 01/26/2023]
Abstract
Mitochondrial diseases are the most common inheritable metabolic diseases, due to defects in oxidative phosphorylation. They are caused by mutations of nuclear or mitochondrial DNA in genes involved in mitochondrial function. The peculiarity of "mitochondrial DNA genetics rules" in part explains the marked phenotypic variability, the complexity of genotype-phenotype correlations and the challenge of genetic counseling. The new massive genetic sequencing technologies have changed the diagnostic approach, enhancing mitochondrial DNA-related syndromes diagnosis and often avoiding the need of a tissue biopsy. Here we present the most common phenotypes associated with a mitochondrial DNA mutation with the recent advances in diagnosis and in therapeutic perspectives.
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Affiliation(s)
- V Montano
- Department of Clinical and Experimental Medicine, Neurological Clinic, University of Pisa, Italy
| | - F Gruosso
- Department of Clinical and Experimental Medicine, Neurological Clinic, University of Pisa, Italy
| | - C Simoncini
- Department of Clinical and Experimental Medicine, Neurological Clinic, University of Pisa, Italy
| | - G Siciliano
- Department of Clinical and Experimental Medicine, Neurological Clinic, University of Pisa, Italy
| | - M Mancuso
- Department of Clinical and Experimental Medicine, Neurological Clinic, University of Pisa, Italy.
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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.
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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
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Establishment of variant free-iPSC (UOMi003-A) line from patient with mitochondrial encephalopathy, lactic acidosis, and stroke-like episodes. Stem Cell Res 2020; 48:101935. [PMID: 32777772 DOI: 10.1016/j.scr.2020.101935] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/03/2020] [Revised: 07/22/2020] [Accepted: 07/28/2020] [Indexed: 11/21/2022] Open
Abstract
Heteroplasmy in patients affected with Mitochondrial Encephalopathy, Lactic Acidosis, and Stroke-like episodes (MELAS) offers a chance to harvest specific cells which might have a very low or no mutation load of the mitochondrial DNA. Here we demonstrate establishment of induced pluripotent stem cells (iPSC) cell lines (with normal mitochondrial DNA copies), from unaffected tissues of a male patient with MELAS harbouring m.3243A > G mutations. This platform allowed us to compare specific pathway differences between the cells of the affected tissues of the patients and their isogenic counterparts derived from iPSCs, which do not harbour the mutations.
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Ago T, Ueki K, Wakisaka Y, Nakamura K, Kitazono T. Response to Letter regarding case report, “Mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes due to m.3243A > G mutation in a 76-year-old woman”. J Neurol Sci 2020; 414:116925. [DOI: 10.1016/j.jns.2020.116925] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2020] [Accepted: 05/13/2020] [Indexed: 10/24/2022]
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Tabebi M, Safi W, Felhi R, Alila Fersi O, Keskes L, Abid M, Mnif M, Fakhfakh F. The first concurrent detection of mitochondrial DNA m.3243A>G mutation, deletion, and depletion in a family with mitochondrial diabetes. Mol Genet Genomic Med 2020; 8:e1292. [PMID: 32394641 PMCID: PMC7336730 DOI: 10.1002/mgg3.1292] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2020] [Revised: 04/09/2020] [Accepted: 04/13/2020] [Indexed: 12/13/2022] Open
Abstract
BACKGROUND Mitochondrial diabetes (MD) is a rare monogenic form of diabetes and divided into type l and type 2. It is characterized by a strong familial clustering of diabetes with the presence of maternal transmission in conjunction with bilateral hearing impairment in most of the carriers. The most common form of MD is associated with the m.3243A>G mutation in the mitochondrial MT-TL1, but there are also association with a range of other point mutations, deletion, and depletion in mtDNA. METHODS The mitochondrial genome anomalies were investigated in a family with clinical features of MD, which includes a proband presenting severe MD conditions including cardiomyopathy, retinopathy, and psychomotor retardation. RESULTS By investigating the patient's blood leukocytes and skeletal muscle, we identified the m.3243A>G mutation in heteroplasmic state. This mutation was absent in the rest of the family members. In addition, our analysis revealed in the proband a large mtDNA heteroplasmic deletion (~1 kb) and a reduction in mtDNA copy number. CONCLUSION Our study points out, for the first time, a severe phenotypic expression of the m.3243A>G point mutation in association with mtDNA deletion and depletion in MD.
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Affiliation(s)
- Mouna Tabebi
- Molecular and Functional Genetics Laboratory, Faculty of Science of Sfax, University of Sfax, Sfax, Tunisia.,Human Molecular Genetics Laboratory, Faculty of Medicine of Sfax, University of Sfax, Sfax, Tunisia
| | - Wajdi Safi
- Department of Endocrinology Diabetology, CHU Hedi Chaker, Sfax, Tunisia
| | - Rahma Felhi
- Molecular and Functional Genetics Laboratory, Faculty of Science of Sfax, University of Sfax, Sfax, Tunisia
| | - Olfa Alila Fersi
- Molecular and Functional Genetics Laboratory, Faculty of Science of Sfax, University of Sfax, Sfax, Tunisia
| | - Leila Keskes
- Human Molecular Genetics Laboratory, Faculty of Medicine of Sfax, University of Sfax, Sfax, Tunisia
| | - Mohamed Abid
- Department of Endocrinology Diabetology, CHU Hedi Chaker, Sfax, Tunisia
| | - Mouna Mnif
- Department of Endocrinology Diabetology, CHU Hedi Chaker, Sfax, Tunisia
| | - Faiza Fakhfakh
- Molecular and Functional Genetics Laboratory, Faculty of Science of Sfax, University of Sfax, Sfax, Tunisia
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Ueki K, Wakisaka Y, Nakamura K, Shono Y, Wada S, Yoshikawa Y, Matsukuma Y, Uchiumi T, Kang D, Kitazono T, Ago T. Mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes due to m.3243A > G mutation in a 76-year-old woman. J Neurol Sci 2020; 412:116791. [PMID: 32224343 DOI: 10.1016/j.jns.2020.116791] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2020] [Revised: 03/03/2020] [Accepted: 03/18/2020] [Indexed: 10/24/2022]
Affiliation(s)
- Kana Ueki
- Department of Medicine and Clinical Science, Graduate School of Medical Sciences, Kyushu University, Fukuoka 812-8582, Japan
| | - Yoshinobu Wakisaka
- Department of Medicine and Clinical Science, Graduate School of Medical Sciences, Kyushu University, Fukuoka 812-8582, Japan
| | - Kuniyuki Nakamura
- Department of Medicine and Clinical Science, Graduate School of Medical Sciences, Kyushu University, Fukuoka 812-8582, Japan
| | - Yuji Shono
- Department of Medicine and Clinical Science, Graduate School of Medical Sciences, Kyushu University, Fukuoka 812-8582, Japan; Emergency and Critical Care Center, Kyushu University Hospital, Fukuoka 812-8582, Japan
| | - Shinichi Wada
- Department of Medicine and Clinical Science, Graduate School of Medical Sciences, Kyushu University, Fukuoka 812-8582, Japan
| | - Yoji Yoshikawa
- Department of Medicine and Clinical Science, Graduate School of Medical Sciences, Kyushu University, Fukuoka 812-8582, Japan
| | - Yuta Matsukuma
- Department of Medicine and Clinical Science, Graduate School of Medical Sciences, Kyushu University, Fukuoka 812-8582, Japan
| | - Takeshi Uchiumi
- Department of Biological Sciences and Technology, Graduate School of Medical Sciences, Kyushu University, Fukuoka 812-8582, Japan; Department of Clinical Chemistry and Laboratory Medicine, Graduate School of Medical Sciences, Kyushu University, Fukuoka 812-8582, Japan
| | - Dongchong Kang
- Department of Clinical Chemistry and Laboratory Medicine, Graduate School of Medical Sciences, Kyushu University, Fukuoka 812-8582, Japan
| | - Takanari Kitazono
- Department of Medicine and Clinical Science, Graduate School of Medical Sciences, Kyushu University, Fukuoka 812-8582, Japan
| | - Tetsuro Ago
- Department of Medicine and Clinical Science, Graduate School of Medical Sciences, Kyushu University, Fukuoka 812-8582, Japan.
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12
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Steele H, Gomez‐Duran A, Pyle A, Hopton S, Newman J, Stefanetti RJ, Charman SJ, Parikh JD, He L, Viscomi C, Jakovljevic DG, Hollingsworth KG, Robinson AJ, Taylor RW, Bottolo L, Horvath R, Chinnery PF. Metabolic effects of bezafibrate in mitochondrial disease. EMBO Mol Med 2020; 12:e11589. [PMID: 32107855 PMCID: PMC7059007 DOI: 10.15252/emmm.201911589] [Citation(s) in RCA: 46] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2019] [Revised: 01/29/2020] [Accepted: 01/29/2020] [Indexed: 12/16/2022] Open
Abstract
Mitochondrial disorders affect 1/5,000 and have no cure. Inducing mitochondrial biogenesis with bezafibrate improves mitochondrial function in animal models, but there are no comparable human studies. We performed an open-label observational experimental medicine study of six patients with mitochondrial myopathy caused by the m.3243A>G MTTL1 mutation. Our primary aim was to determine the effects of bezafibrate on mitochondrial metabolism, whilst providing preliminary evidence of safety and efficacy using biomarkers. The participants received 600-1,200 mg bezafibrate daily for 12 weeks. There were no clinically significant adverse events, and liver function was not affected. We detected a reduction in the number of complex IV-immunodeficient muscle fibres and improved cardiac function. However, this was accompanied by an increase in serum biomarkers of mitochondrial disease, including fibroblast growth factor 21 (FGF-21), growth and differentiation factor 15 (GDF-15), plus dysregulation of fatty acid and amino acid metabolism. Thus, although potentially beneficial in short term, inducing mitochondrial biogenesis with bezafibrate altered the metabolomic signature of mitochondrial disease, raising concerns about long-term sequelae.
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Affiliation(s)
- Hannah Steele
- Institute of Genetic MedicineNewcastle UniversityNewcastle upon TyneUK
| | - Aurora Gomez‐Duran
- Department of Clinical NeurosciencesUniversity of Cambridge, Cambridge Biomedical CampusCambridgeUK
- MRC Mitochondrial Biology UnitUniversity of CambridgeCambridgeUK
| | - Angela Pyle
- Institute of Genetic MedicineNewcastle UniversityNewcastle upon TyneUK
- Wellcome Centre for Mitochondrial ResearchNewcastle UniversityNewcastle upon TyneUK
| | - Sila Hopton
- Wellcome Centre for Mitochondrial ResearchNewcastle UniversityNewcastle upon TyneUK
- NHS Highly Specialised Service for Rare Mitochondrial Disorders of Adults and ChildrenNewcastle upon Tyne Hospitals NHS Foundation TrustNewcastle upon TyneUK
| | - Jane Newman
- Wellcome Centre for Mitochondrial ResearchNewcastle UniversityNewcastle upon TyneUK
- Institute of NeuroscienceNewcastle UniversityNewcastle upon TyneUK
| | | | - Sarah J Charman
- Institute of Cellular MedicineNewcastle UniversityNewcastle upon TyneUK
| | - Jehill D Parikh
- Institute of Cellular MedicineNewcastle UniversityNewcastle upon TyneUK
| | - Langping He
- Wellcome Centre for Mitochondrial ResearchNewcastle UniversityNewcastle upon TyneUK
- NHS Highly Specialised Service for Rare Mitochondrial Disorders of Adults and ChildrenNewcastle upon Tyne Hospitals NHS Foundation TrustNewcastle upon TyneUK
| | - Carlo Viscomi
- MRC Mitochondrial Biology UnitUniversity of CambridgeCambridgeUK
| | | | | | - Alan J Robinson
- MRC Mitochondrial Biology UnitUniversity of CambridgeCambridgeUK
| | - Robert W Taylor
- Wellcome Centre for Mitochondrial ResearchNewcastle UniversityNewcastle upon TyneUK
- NHS Highly Specialised Service for Rare Mitochondrial Disorders of Adults and ChildrenNewcastle upon Tyne Hospitals NHS Foundation TrustNewcastle upon TyneUK
- Institute of NeuroscienceNewcastle UniversityNewcastle upon TyneUK
| | - Leonardo Bottolo
- Department of Medical GeneticsUniversity of CambridgeCambridgeUK
- The Alan Turing InstituteLondonUK
- MRC Biostatistics UnitUniversity of CambridgeCambridgeUK
| | - Rita Horvath
- Department of Clinical NeurosciencesUniversity of Cambridge, Cambridge Biomedical CampusCambridgeUK
| | - Patrick F Chinnery
- Department of Clinical NeurosciencesUniversity of Cambridge, Cambridge Biomedical CampusCambridgeUK
- MRC Mitochondrial Biology UnitUniversity of CambridgeCambridgeUK
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13
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Grady JP, Pickett SJ, Ng YS, Alston CL, Blakely EL, Hardy SA, Feeney CL, Bright AA, Schaefer AM, Gorman GS, McNally RJ, Taylor RW, Turnbull DM, McFarland R. mtDNA heteroplasmy level and copy number indicate disease burden in m.3243A>G mitochondrial disease. EMBO Mol Med 2019; 10:emmm.201708262. [PMID: 29735722 PMCID: PMC5991564 DOI: 10.15252/emmm.201708262] [Citation(s) in RCA: 177] [Impact Index Per Article: 35.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Mitochondrial disease associated with the pathogenic m.3243A>G variant is a common, clinically heterogeneous, neurogenetic disorder. Using multiple linear regression and linear mixed modelling, we evaluated which commonly assayed tissue (blood N = 231, urine N = 235, skeletal muscle N = 77) represents the m.3243A>G mutation load and mitochondrial DNA (mtDNA) copy number most strongly associated with disease burden and progression. m.3243A>G levels are correlated in blood, muscle and urine (R2 = 0.61–0.73). Blood heteroplasmy declines by ~2.3%/year; we have extended previously published methodology to adjust for age. In urine, males have higher mtDNA copy number and ~20% higher m.3243A>G mutation load; we present formulas to adjust for this. Blood is the most highly correlated mutation measure for disease burden and progression in m.3243A>G‐harbouring individuals; increasing age and heteroplasmy contribute (R2 = 0.27, P < 0.001). In muscle, heteroplasmy, age and mtDNA copy number explain a higher proportion of variability in disease burden (R2 = 0.40, P < 0.001), although activity level and disease severity are likely to affect copy number. Whilst our data indicate that age‐corrected blood m.3243A>G heteroplasmy is the most convenient and reliable measure for routine clinical assessment, additional factors such as mtDNA copy number may also influence disease severity.
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Affiliation(s)
- John P Grady
- Wellcome Centre for Mitochondrial Research, Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, UK
| | - Sarah J Pickett
- Wellcome Centre for Mitochondrial Research, Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, UK
| | - Yi Shiau Ng
- Wellcome Centre for Mitochondrial Research, Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, UK
| | - Charlotte L Alston
- Wellcome Centre for Mitochondrial Research, Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, UK.,NHS Highly Specialised Mitochondrial Diagnostic Laboratory, Newcastle upon Tyne Hospitals NHS Foundation Trust, Newcastle upon Tyne, UK
| | - Emma L Blakely
- Wellcome Centre for Mitochondrial Research, Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, UK.,NHS Highly Specialised Mitochondrial Diagnostic Laboratory, Newcastle upon Tyne Hospitals NHS Foundation Trust, Newcastle upon Tyne, UK
| | - Steven A Hardy
- Wellcome Centre for Mitochondrial Research, Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, UK.,NHS Highly Specialised Mitochondrial Diagnostic Laboratory, Newcastle upon Tyne Hospitals NHS Foundation Trust, Newcastle upon Tyne, UK
| | - Catherine L Feeney
- Wellcome Centre for Mitochondrial Research, Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, UK
| | - Alexandra A Bright
- Wellcome Centre for Mitochondrial Research, Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, UK
| | - Andrew M Schaefer
- Wellcome Centre for Mitochondrial Research, Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, UK
| | - Gráinne S Gorman
- Wellcome Centre for Mitochondrial Research, Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, UK
| | - Richard Jq McNally
- Institute of Health and Society, Newcastle University, Newcastle upon Tyne, UK
| | - Robert W Taylor
- Wellcome Centre for Mitochondrial Research, Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, UK.,NHS Highly Specialised Mitochondrial Diagnostic Laboratory, Newcastle upon Tyne Hospitals NHS Foundation Trust, Newcastle upon Tyne, UK
| | - Doug M Turnbull
- Wellcome Centre for Mitochondrial Research, Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, UK
| | - Robert McFarland
- Wellcome Centre for Mitochondrial Research, Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, UK
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14
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Cruz ACP, Ferrasa A, Muotri AR, Herai RH. Frequency and association of mitochondrial genetic variants with neurological disorders. Mitochondrion 2018; 46:345-360. [PMID: 30218715 DOI: 10.1016/j.mito.2018.09.005] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2018] [Revised: 08/24/2018] [Accepted: 09/11/2018] [Indexed: 12/17/2022]
Abstract
Mitochondria are small cytosolic organelles and the main source of energy production for the cells, especially in the brain. This organelle has its own genome, the mitochondrial DNA (mtDNA), and genetic variants in this molecule can alter the normal energy metabolism in the brain, contributing to the development of a wide assortment of Neurological Disorders (ND), including neurodevelopmental syndromes, neurodegenerative diseases and neuropsychiatric disorders. These ND are comprised by a heterogeneous group of syndromes and diseases that encompass different cognitive phenotypes and behavioral disorders, such as autism, Asperger's syndrome, pervasive developmental disorder, attention deficit hyperactivity disorder, Huntington disease, Leigh Syndrome and bipolar disorder. In this work we carried out a Systematic Literature Review (SLR) to identify and describe the mitochondrial genetic variants associated with the occurrence of ND. Most of genetic variants found in mtDNA were associated with Single Nucleotide Polimorphisms (SNPs), ~79%, with ~15% corresponding to deletions, ~3% to Copy Number Variations (CNVs), ~2% to insertions and another 1% included mtDNA replication problems and genetic rearrangements. We also found that most of the variants were associated with coding regions of mitochondrial proteins but were also found in regulatory transcripts (tRNA and rRNA) and in the D-Loop replication region of the mtDNA. After analysis of mtDNA deletions and CNV, none of them occur in the D-Loop region. This SLR shows that all transcribed mtDNA molecules have mutations correlated with ND. Finally, we describe that all mtDNA variants found were associated with deterioration of cognitive (dementia) and intellectual functions, learning disabilities, developmental delays, and personality and behavior problems.
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Affiliation(s)
- Ana Carolina P Cruz
- Experimental Multiuser Laboratory (LEM), Graduate Program in Health Sciences (PPGCS), School of Medicine (PPGCS), Pontifícia Universidade Católica do Paraná (PUCPR), Curitiba, Paraná 80215-901, Brazil
| | - Adriano Ferrasa
- Experimental Multiuser Laboratory (LEM), Graduate Program in Health Sciences (PPGCS), School of Medicine (PPGCS), Pontifícia Universidade Católica do Paraná (PUCPR), Curitiba, Paraná 80215-901, Brazil; Department of Informatics (DEINFO), Universidade Estadual de Ponta Grossa (UEPG), Ponta Grossa, Paraná 84030-900, Brazil
| | - Alysson R Muotri
- University of California San Diego, School of Medicine, Department of Pediatrics/Rady Children's Hospital San Diego, Department of Cellular & Molecular Medicine, Stem Cell Program, La Jolla, CA 92037-0695, USA
| | - Roberto H Herai
- Experimental Multiuser Laboratory (LEM), Graduate Program in Health Sciences (PPGCS), School of Medicine (PPGCS), Pontifícia Universidade Católica do Paraná (PUCPR), Curitiba, Paraná 80215-901, Brazil; Lico Kaesemodel Institute (ILK), Curitiba, Paraná 80240-000, Brazil.
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15
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The heart in m.3243A>G carriers. Herz 2018; 45:356-361. [DOI: 10.1007/s00059-018-4739-6] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2018] [Revised: 06/23/2018] [Accepted: 07/24/2018] [Indexed: 11/25/2022]
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16
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Poulton J, Finsterer J, Yu-Wai-Man P. Genetic Counselling for Maternally Inherited Mitochondrial Disorders. Mol Diagn Ther 2018; 21:419-429. [PMID: 28536827 DOI: 10.1007/s40291-017-0279-7] [Citation(s) in RCA: 76] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The aim of this review was to provide an evidence-based approach to frequently asked questions relating to the risk of transmitting a maternally inherited mitochondrial disorder (MID). We do not address disorders linked with disturbed mitochondrial DNA (mtDNA) maintenance, causing mtDNA depletion or multiple mtDNA deletions, as these are autosomally inherited. The review addresses questions regarding prognosis, recurrence risks and the strategies available to prevent disease transmission. The clinical and genetic complexity of maternally inherited MIDs represent a major challenge for patients, their relatives and health professionals. Since many of the genetic and pathophysiological aspects of MIDs remain unknown, counselling of affected patients and at-risk family members remains difficult. MtDNA mutations are maternally transmitted or, more rarely, they are sporadic, occurring de novo (~25%). Females carrying homoplasmic mtDNA mutations will transmit the mutant species to all of their offspring, who may or may not exhibit a similar phenotype depending on modifying, secondary factors. Females carrying heteroplasmic mtDNA mutations will transmit a variable amount of mutant mtDNA to their offspring, which can result in considerable phenotypic heterogeneity among siblings. The majority of mtDNA rearrangements, such as single large-scale deletions, are sporadic, but there is a small risk of recurrence (~4%) among the offspring of affected women. The range and suitability of reproductive choices for prospective mothers is a complex area of mitochondrial medicine that needs to be managed by experienced healthcare professionals as part of a multidisciplinary team. Genetic counselling is facilitated by the identification of the underlying causative genetic defect. To provide more precise genetic counselling, further research is needed to clarify the secondary factors that account for the variable penetrance and the often marked differential expressivity of pathogenic mtDNA mutations both within and between families.
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Affiliation(s)
- Joanna Poulton
- Nuffield Department of Obstetrics and Gynaecology, University of Oxford, Oxford, UK
| | - Josef Finsterer
- Krankenanstalt Rudolfstiftung, Postfach 20, 1180, Vienna, Austria.
| | - Patrick Yu-Wai-Man
- Wellcome Trust Centre for Mitochondrial Research, Institute of Genetic Medicine, Newcastle University, Newcastle upon Tyne, UK.,Newcastle Eye Centre, Royal Victoria Infirmary, Newcastle upon Tyne, UK.,NIHR Biomedical Research Centre, Moorfields Eye Hospital and UCL Institute of Ophthalmology, London, UK.,Department of Clinical Neurosciences, School of Clinical Medicine, University of Cambridge, Cambridge, UK
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17
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Pickett SJ, Grady JP, Ng YS, Gorman GS, Schaefer AM, Wilson IJ, Cordell HJ, Turnbull DM, Taylor RW, McFarland R. Phenotypic heterogeneity in m.3243A>G mitochondrial disease: The role of nuclear factors. Ann Clin Transl Neurol 2018; 5:333-345. [PMID: 29560378 PMCID: PMC5846390 DOI: 10.1002/acn3.532] [Citation(s) in RCA: 91] [Impact Index Per Article: 15.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2017] [Accepted: 12/21/2017] [Indexed: 01/23/2023] Open
Abstract
Objective The pathogenic mitochondrial DNA m.3243A>G mutation is associated with a wide range of clinical features, making disease prognosis extremely difficult to predict. We aimed to understand the cause of this heterogeneity. Methods We examined the phenotypic profile of 238 adult m.3243A>G carriers (patients and asymptomatic carriers) from the UK MRC Mitochondrial Disease Patient Cohort using the Newcastle Mitochondrial Disease Adult Scale. We modeled the role of risk factors for the development of specific phenotypes using proportional odds logistic regression. As mitochondria are under the dual control of their own and the nuclear genome, we examined the role of additive nuclear genetic factors in the development of these phenotypes within 46 pedigrees from the cohort. Results Seizures and stroke‐like episodes affect 25% and 17% of patients, respectively; more common features include hearing impairment, gastrointestinal disturbance, psychiatric involvement, and ataxia. Age, age‐adjusted blood heteroplasmy levels, and sex are poor predictors of phenotypic severity. Hearing impairment, diabetes, and encephalopathy show the strongest associations, but pseudo‐R2 values are low (0.14–0.17). We found a high heritability estimate for psychiatric involvement (h2=0.76, P = 0.0003) and moderate estimates for cognition (h2=0.46, P = 0.0021), ataxia (h2 = 0.45, P = 0.0011), migraine (h2 = 0.41, P = 0.0138), and hearing impairment (h2 = 0.40, P = 0.0050). Interpretation Our results provide good evidence for the presence of nuclear genetic factors influencing clinical outcomes in m.3234A>G‐related disease, paving the way for future work identifying these through large‐scale genetic linkage and association studies, increasing our understanding of the pathogenicity of m.3243A>G and providing improved estimates of prognosis.
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Affiliation(s)
- Sarah J Pickett
- Wellcome Centre for Mitochondrial Research Institute of Neuroscience Newcastle University Newcastle upon Tyne UK
| | - John P Grady
- Wellcome Centre for Mitochondrial Research Institute of Neuroscience Newcastle University Newcastle upon Tyne UK.,Present address: Kinghorn Centre for Clinical Genomics Garvan Institute Sydney NSW Australia
| | - Yi Shiau Ng
- 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
| | - Andrew M Schaefer
- Wellcome Centre for Mitochondrial Research Institute of Neuroscience Newcastle University Newcastle upon Tyne UK
| | - Ian J Wilson
- Institute of Genetic Medicine Newcastle University Newcastle upon Tyne UK
| | - Heather J Cordell
- Institute of Genetic Medicine Newcastle University Newcastle upon Tyne 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 McFarland
- Wellcome Centre for Mitochondrial Research Institute of Neuroscience Newcastle University Newcastle upon Tyne UK
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18
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Hearing impairment in m.3243A>G carriers requires comprehensive work- and follow-up. Clin Neurol Neurosurg 2016; 150:199-200. [PMID: 27605023 DOI: 10.1016/j.clineuro.2016.08.031] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2016] [Accepted: 08/27/2016] [Indexed: 11/20/2022]
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