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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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Holt IJ, Speijer D, Kirkwood TBL. The road to rack and ruin: selecting deleterious mitochondrial DNA variants. Philos Trans R Soc Lond B Biol Sci 2015; 369:20130451. [PMID: 24864317 DOI: 10.1098/rstb.2013.0451] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Mitochondria constitute the major energy-producing compartment of the eukaryotic cell. These organelles contain many molecules of DNA that contribute only a handful of proteins required for energy production. Mutations in the DNA of mitochondria were identified as a cause of human disease a quarter of a century ago, and they have subsequently been implicated in ageing. The process whereby deleterious variants come to dominate a cell, tissue or human is the subject of debate. It is likely to involve multiple, often competing, factors, as selection pressures on mitochondrial DNA can be both indirect and intermittent, and are subjected to rapid change. Here, we assess the different models and the prospects for preventing the accumulation of deleterious mitochondrial DNA variants with time.
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Affiliation(s)
- Ian J Holt
- MRC National Institute for Medical Research, Mill Hill, London NW7 1AA, UK
| | - Dave Speijer
- Department of Medical Biochemistry, Academic Medical Centre, University of Amsterdam, 1105 AZ Amsterdam, The Netherlands
| | - Thomas B L Kirkwood
- Institute for Ageing and Health, Newcastle University, Campus for Ageing and Vitality, Newcastle upon Tyne NE4 5PL, UK
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Chapman TP, Hadley G, Fratter C, Cullen SN, Bax BE, Bain MD, Sapsford RA, Poulton J, Travis SP. Unexplained gastrointestinal symptoms: think mitochondrial disease. Dig Liver Dis 2014; 46:1-8. [PMID: 23768727 DOI: 10.1016/j.dld.2013.04.008] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/24/2012] [Revised: 04/06/2013] [Accepted: 04/14/2013] [Indexed: 02/08/2023]
Abstract
Defects in mitochondrial function are increasingly recognised as central to the pathogenesis of many diseases, both inherited and acquired. Many of these mitochondrial defects arise from abnormalities in mitochondrial DNA and can result in multisystem disease, with gastrointestinal involvement common. Moreover, mitochondrial disease may present with a range of non-specific symptoms, and thus can be easily misdiagnosed, or even considered to be non-organic. We describe the clinical, histopathological and genetic findings of six patients from three families with gastrointestinal manifestations of mitochondrial disease. In two of the patients, anorexia nervosa was considered as an initial diagnosis. These cases illustrate the challenges of both diagnosing and managing mitochondrial disease and highlight two important but poorly understood aspects, the clinical and the genetic. The pathophysiology of gastrointestinal involvement in mitochondrial disease is discussed and emerging treatments are described. Finally, we provide a checklist of investigations for the gastroenterologist when mitochondrial disease is suspected.
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Affiliation(s)
- Thomas P Chapman
- Translational Gastroenterology Unit, John Radcliffe Hospital, Oxford, UK
| | - Gina Hadley
- Translational Gastroenterology Unit, John Radcliffe Hospital, Oxford, UK
| | - Carl Fratter
- Oxford Medical Genetics Laboratories, Churchill Hospital, Oxford, UK
| | - Sue N Cullen
- Buckinghamshire Hospitals NHS Trust, Department of Gastroenterology, Level 6, Queen Alexandra Road, High Wycombe, UK
| | - Bridget E Bax
- Division of Clinical Sciences, St. George's University of London, London, UK
| | - Murray D Bain
- Division of Clinical Sciences, St. George's University of London, London, UK
| | | | - Joanna Poulton
- Nuffield Dept Obstetrics and Gynaecology, University of Oxford, The Women's Centre, Oxford, UK
| | - Simon P Travis
- Translational Gastroenterology Unit, John Radcliffe Hospital, Oxford, UK.
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Minimizing the damage: repair pathways keep mitochondrial DNA intact. Nat Rev Mol Cell Biol 2012; 13:659-71. [PMID: 22992591 DOI: 10.1038/nrm3439] [Citation(s) in RCA: 280] [Impact Index Per Article: 23.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Mitochondrial DNA (mtDNA) faces the universal challenges of genome maintenance: the accurate replication, transmission and preservation of its integrity throughout the life of the organism. Although mtDNA was originally thought to lack DNA repair activity, four decades of research on mitochondria have revealed multiple mtDNA repair pathways, including base excision repair, single-strand break repair, mismatch repair and possibly homologous recombination. These mtDNA repair pathways are mediated by enzymes that are similar in activity to those operating in the nucleus, and in all cases identified so far in mammals, they are encoded by nuclear genes.
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Spinazzola A. Mitochondrial DNA mutations and depletion in pediatric medicine. Semin Fetal Neonatal Med 2011; 16:190-6. [PMID: 21652274 DOI: 10.1016/j.siny.2011.04.011] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Mitochondrial disorders are a group of diseases traditionally ascribed to defects of the respiratory chain, which is the only metabolic pathway in the cell that is under the control of the two separate genetic systems, the mitochondrial genome (mtDNA) and the nuclear genome (nDNA). Therefore the genetic classification of the primary mitochondrial diseases distinguishes disorders due to mutations in mtDNA, which are sporadic or maternal inherited, from disorders due to mutations in nDNA, which are governed by the stricter rules of mendelian genetics. Pathological alterations of mtDNA fall into two main categories: primary mutations of mitochondrial DNA (point mutations and rearrangements) and mtDNA perturbation, due to mutations in nuclear genes whose products are involved in mtDNA maintenance or replication. This article will focus on the primary mitochondrial DNA mutations and mtDNA depletion syndromes related to neonatal-infant human pathology.
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Affiliation(s)
- A Spinazzola
- MRC, Mitochondrial Biology Unit, Wellcome Trust, MRC Building, Hills Road, Cambridge CB2 0XY, UK.
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Abstract
Recent reports of strong selection of mitochondrial DNA (mtDNA) during transmission in animal models of mtDNA disease, and of nuclear transfer in both animal models and humans, have important scientific implications. These are directly applicable to the genetic management of mtDNA disease. The risk that a mitochondrial disorder will be transmitted is difficult to estimate due to heteroplasmy—the existence of normal and mutant mtDNA in the same individual, tissue, or cell. In addition, the mtDNA bottleneck during oogenesis frequently results in dramatic and unpredictable inter-generational fluctuations in the proportions of mutant and wild-type mtDNA. Pre-implantation genetic diagnosis (PGD) for mtDNA disease enables embryos produced by in vitro fertilization (IVF) to be screened for mtDNA mutations. Embryos determined to be at low risk (i.e., those having low mutant mtDNA load) can be preferentially transferred to the uterus with the aim of initiating unaffected pregnancies. New evidence that some types of deleterious mtDNA mutations are eliminated within a few generations suggests that women undergoing PGD have a reasonable chance of generating embryos with a lower mutant load than their own. While nuclear transfer may become an alternative approach in future, there might be more difficulties, ethical as well as technical. This Review outlines the implications of recent advances for genetic management of these potentially devastating disorders.
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Zhou RR, Wang B, Wang J, Schatten H, Zhang YZ. Is the mitochondrial cloud the selection machinery for preferentially transmitting wild-type mtDNA between generations? Rewinding Müller's ratchet efficiently. Curr Genet 2010; 56:101-7. [PMID: 20179933 DOI: 10.1007/s00294-010-0291-5] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2009] [Revised: 12/30/2009] [Accepted: 01/24/2010] [Indexed: 11/30/2022]
Abstract
In animal mitochondrial DNA inheritance, it remains largely unclear where the mitochondrial genetic bottleneck localizes and how it works in rewinding Müller's ratchet. In a variety of different animals germ plasm mRNAs typically aggregate along with numerous mitochondria to form the mitochondrial cloud (MC) during oogenesis. The MC has been found to serve as messenger transport organizer for germ plasm mRNAs. Germ plasm RNAs in MC will specifically distribute to the primordial germ cells of the future embryo. It has been proposed that the MC might be the site where selected mitochondria accumulate for specific transmission to grandchildren but this idea received relatively little attention and the criterion by which mitochondria are selected remains unknown. Our recent results in zebrafish provided further evidence for selective mitochondria accumulation in the MC by showing that mitochondria with high-inner membrane potential tend to be recruited preferentially into the MC, and these mitochondria are transported along with germ plasm to the cortex of the vegetal pole. By analyzing the composition, behavior and functions of the MC, and in reviewing related literature, we found strong support for the proposition that the MC corresponds to the position and function of the mitochondrial genetic bottleneck.
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Affiliation(s)
- Rong Rong Zhou
- Department of Life Sciences, Liaocheng University, Liaocheng 252059, Shandong, China
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Schiff M, Loublier S, Coulibaly A, Bénit P, Ogier de Baulny H, Rustin P. Mitochondria and diabetes mellitus: untangling a conflictive relationship? J Inherit Metab Dis 2009; 32:684-698. [PMID: 19821144 DOI: 10.1007/s10545-009-1263-0] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/15/2009] [Revised: 08/19/2009] [Accepted: 08/25/2009] [Indexed: 01/19/2023]
Abstract
Diabetes mellitus is occasionally observed in patients with skeletal muscle respiratory chain deficiency, suggesting that skeletal muscle mitochondrial dysfunction might play a pathogenic role in type 2 diabetes (T2D). In support of this hypothesis, decreased muscle mitochondrial activity has been reported in T2D patients and in mouse models of diabetes. However, recent work by several groups suggests that decreased muscle mitochondrial function may be a consequence rather than a cause of diabetes, since decreased mitochondrial function in mice affords protection from diabetes and obesity. We review the data on this controversial but important issue of potential links between mitochondrial dysfunction and diabetes.
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Affiliation(s)
- M Schiff
- Hôpital Robert Debré, Paris, France
- Université Paris 7, Faculté de médecine Denis Diderot, IFR02, Paris, France
- Centre de référence Maladies Métaboliques, Hôpital Robert Debré, APHP, Paris, France
| | - S Loublier
- Hôpital Robert Debré, Paris, France
- Université Paris 7, Faculté de médecine Denis Diderot, IFR02, Paris, France
| | - A Coulibaly
- Hôpital Robert Debré, Paris, France
- Université Paris 7, Faculté de médecine Denis Diderot, IFR02, Paris, France
| | - P Bénit
- Hôpital Robert Debré, Paris, France
- Université Paris 7, Faculté de médecine Denis Diderot, IFR02, Paris, France
| | - H Ogier de Baulny
- Centre de référence Maladies Métaboliques, Hôpital Robert Debré, APHP, Paris, France
| | - P Rustin
- Hôpital Robert Debré, Paris, France.
- Université Paris 7, Faculté de médecine Denis Diderot, IFR02, Paris, France.
- INSERM U676, Bâtiment Ecran, Hôpital Robert Debré, 48, boulevard Sérurier, 75019, Paris, France.
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Sadun AA, Carelli V. The role of mitochondria in health, ageing, and diseases affecting vision. Br J Ophthalmol 2006; 90:809-10. [PMID: 16782943 PMCID: PMC1857143 DOI: 10.1136/bjo.2006.091884] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
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Abu-Amero KK, Bosley TM. Increased relative mitochondrial DNA content in leucocytes of patients with NAION. Br J Ophthalmol 2006; 90:823-5. [PMID: 16540486 PMCID: PMC1857173 DOI: 10.1136/bjo.2006.090332] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
AIM To investigate possible changes in relative mitochondrial DNA (mtDNA) content in patients with non-arteritic anterior ischaemic optic neuropathy (NAION). METHODS 19 patients with NAION were compared to 32 controls matched for age, sex distribution, and ethnicity. DNA was extracted from leucocytes and competitive multiplex polymerase chain reaction was carried out with two primer pairs (one pair for mtDNA ND1 gene and the other pair for beta actin nuclear gene) in the presence of a fluorescent dye. RESULTS The mean relative mtDNA content in controls (0.93 (SD 0.11); 95% CI 0.89 to 0.97) was significantly less than in NAION patients (2.40 (1.05); 95% CI 1.90 to 2.91; p < 0.001). Relative mtDNA content was negatively correlated with Snellen visual acuity (Spearman's rho; r = -0.37; p = 0.022). CONCLUSION Increased relative mtDNA content in NAION patients may imply a response to oxidative stress, possibly in part because of mitochondrial respiratory chain defects. Significantly more non-synonymous mtDNA nucleotide changes, significantly increased relative mtDNA content, and a significant association between relative mtDNA content and visual acuity all imply that mitochondrial abnormalities may be a risk factor for NAION.
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Affiliation(s)
- K K Abu-Amero
- Mitochondrial Research Laboratory, Department of Genetics, King Faisal Specialist Hospital and Research Centre, Riyadh, Kingdom of Saudi Arabia.
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Jacobs LJAM, de Wert G, Geraedts JPM, de Coo IFM, Smeets HJM. The transmission of OXPHOS disease and methods to prevent this. Hum Reprod Update 2005; 12:119-36. [PMID: 16199488 DOI: 10.1093/humupd/dmi042] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
Diseases owing to defects of oxidative phosphorylation (OXPHOS) affect approximately 1 in 8,000 individuals. Clinical manifestations can be extremely variable and range from single-affected tissues to multisystemic syndromes. In general, tissues with a high energy demand, like brain, heart and muscle, are affected. The OXPHOS system is under dual genetic control, and mutations in both nuclear and mitochondrial genes can cause OXPHOS diseases. The expression and segregation of mitochondrial DNA (mtDNA) mutations is different from nuclear gene defects. The mtDNA mutations can be either homoplasmic or heteroplasmic and in the latter case disease becomes manifest when the mutation exceeds a tissue-specific threshold. This mutation load can vary between tissues and often an exact correlation between mutation load and phenotypic expression is lacking. The transmission of mtDNA mutations is exclusively maternal, but the mutation load between embryos can vary tremendously because of a segregational bottleneck. Diseases by nuclear gene mutations show a normal Mendelian inheritance pattern and often have a more constant clinical manifestation. Given the prevalence and severity of OXPHOS disorders and the lack of adequate therapy, existing and new methods for the prevention of transmission of OXPHOS disorders, like prenatal diagnosis (PND), preimplantation genetic diagnosis (PGD), cytoplasmic transfer (CT) and nuclear transfer (NT), are technically and ethically evaluated.
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Affiliation(s)
- L J A M Jacobs
- Department of Genetics and Cell Biology, University of Maastricht, 6200 MD Maastricht, The Netherlands
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Chinnery PF, DiMauro S, Shanske S, Schon EA, Zeviani M, Mariotti C, Carrara F, Lombes A, Laforet P, Ogier H, Jaksch M, Lochmüller H, Horvath R, Deschauer M, Thorburn DR, Bindoff LA, Poulton J, Taylor RW, Matthews JNS, Turnbull DM. Risk of developing a mitochondrial DNA deletion disorder. Lancet 2004; 364:592-6. [PMID: 15313359 DOI: 10.1016/s0140-6736(04)16851-7] [Citation(s) in RCA: 156] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
BACKGROUND Pathogenic mitochondrial DNA (mtDNA) mutations are found in at least one in 8000 individuals. No effective treatment for mtDNA disorders is available, making disease prevention important. Many patients with mtDNA disease harbour a single pathogenic mtDNA deletion, but the risk factors for new cases and disease recurrence are not known. METHODS We did a multicentre study of 226 families in which a single mtDNA deletion had been identified in the proband, including patients with chronic progressive external ophthalmoplegia, Kearns Sayre syndrome, or Pearson's syndrome. We studied the relation between maternal age and the risk of unaffected mothers having an affected child, and determined the recurrence risks among the siblings and offspring of affected individuals. FINDINGS We noted no relation between maternal age and the risk of unaffected mothers having children with an mtDNA deletion disorder. None of the 251 siblings of the index cases developed clinical features of mtDNA disease. Risk of recurrence among the offspring of affected women was 4.11% (95% CI 0.86-11.54, or one in 117 to one in nine births). Only one of the mothers who had an affected child had a duplication of mtDNA in skeletal muscle. INTERPRETATION Unlike nuclear chromosomal rearrangements, incidence of mtDNA deletion disorders does not increase with maternal age, and unaffected mothers are unlikely to have more than one affected child. Affected women were previously thought to have a negligible chance of having clinically affected offspring, but the actual risk is, on average, about one in 24 births.
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Jacobs LJAM, Jongbloed RJE, Wijburg FA, de Klerk JBC, Geraedts JPM, Nijland JG, Scholte HR, de Coo IFM, Smeets HJM. Pearson syndrome and the role of deletion dimers and duplications in the mtDNA. J Inherit Metab Dis 2004; 27:47-55. [PMID: 14970745 DOI: 10.1023/b:boli.0000016601.49372.18] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Pearson syndrome is an often fatal multisystem disease associated with mitochondrial DNA rearrangements. Here we report a patient with a novel mtDNA deletion of 3.4 kb ranging from nucleotides 6097 to 9541 in combination with deletion dimers. The mutation percentage in different tissues (blood, muscle and liver) varied between 64% and 95%. After a remission period of about a year, the patient suddenly died at the age of 3 years owing to a severe lactic acidosis. A second patient with a previously reported deletion of 8 kb and a milder phenotype was found to have mitochondrial duplications and died at the age of 10 years. From these data and data from previous reports, we hypothesize that duplications might be beneficial in the clinical course of the disease and in life expectancy.
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Affiliation(s)
- L J A M Jacobs
- Department of Genetics and Cell Biology, University of Maastricht, Research Institute Growth and Development (GROW), Maastricht
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Spiropoulos J, Chinnery PF, Turnbull DM. Pathogenic mitochondrial DNA mutations and human reproduction. HUM FERTIL 2002; 2:133-137. [PMID: 11844341 DOI: 10.1080/1464727992000198511] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Affiliation(s)
- John Spiropoulos
- Department of Reproductive Medicine, University of Newcastle upon Tyne, Newcastle upon Tyne NE2 4HH, UK
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Munnich A, Rustin P. Clinical spectrum and diagnosis of mitochondrial disorders. AMERICAN JOURNAL OF MEDICAL GENETICS 2002; 106:4-17. [PMID: 11579420 DOI: 10.1002/ajmg.1391] [Citation(s) in RCA: 182] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Respiratory chain deficiencies have long been regarded as neuromuscular diseases mostly originating from mutations in the mitochondrial DNA. Actually, oxidative phosphorylation, i.e., adenosine triphosphate (ATP) synthesis-coupled electron transfer from substrate to oxygen through the respiratory chain, does not only occur in the neuromuscular system. For this reason, a respiratory chain deficiency can theoretically give rise to any symptom, in any organ or tissue, at any age and with any mode of inheritance, owing to the dual genetic origin of respiratory chain enzymes (nuclear DNA and mitochondrial DNA). In recent years, it has become increasingly clear that genetic defects of oxidative phosphorylation account for a large variety of clinical symptoms in both childhood and adulthood. Diagnosis of a respiratory chain deficiency is difficult initially when only one symptom is present, and easier when additional, seemingly unrelated, symptoms are observed. The clinical heterogeneity is echoed by the genetic heterogeneity illustrated by the increasing number of nuclear genes that have been shown to be involved in these diseases. In the absence of clear-cut genotype-phenotype correlations and in front of the large number of possibly involved genes, biochemical analyses are still the cornerstone of the diagnosis of this condition.
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Affiliation(s)
- A Munnich
- Service de Génétique Médicale and Unité de Recherches sur les Handicaps Génétiques de l'Enfant INSERM U-393, Hôpital des Enfants-Malades, 149, rue de Sèvres, 75743 Paris Cedex 15, France
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Parra D, González A, Mugueta C, Martínez A, Monreal I. Laboratory approach to mitochondrial diseases. J Physiol Biochem 2001; 57:267-84. [PMID: 11800289 DOI: 10.1007/bf03179820] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
Dysfunction in mitochondrial processes has been related to several pathologies. In these disorders, the cell suffers oxidative imbalance that is mostly due to defects in pyruvate metabolism, mitochondrial fatty acids oxidation, the citric acid cycle or electron transport by the mitochondrial respiratory chain. These metabolic alterations produce mitochondrial diseases that have been related to inherited syndromes, such as MERRF or MELAS. The main affected organs are brain, skeletal muscle, kidney, heart and liver, because of the high energetic demand and the oxidative metabolism. Moreover, the relationship between mitochondrial dysfunction and neurodegenerative processes, such as Parkinson disease or Alzheimer disease, as well as ageing, has been shown. Because mitochondrias are the target of several xenobiotics, such as aspirin, AZT or alcohol consumption, mitochondrial impairment has also been proposed as a mechanism of toxicity. Most laboratory tests that are available in the diagnosis of mitochondrial illness are assayed in tissue biopsies and are usually difficult to interpret. Recently, it has been shown that non-invasive techniques, such as nuclear magnetic resonance or the 2-keto[1-(13)C]isocaproic acid breath test, may be useful to assess mitochondrial function. This article attempts to show the laboratory approach to mitochondrial diseases, reviewing new techniques that could be of great value in the research of mitochondrial function, such as the 2-keto[1-(13)C]isocaproic breath test.
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Affiliation(s)
- D Parra
- Department of Clinical Biochemistry, Clínica Universitaria de Navarra, Pamplona, Spain
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17
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Kirches E, Michael M, Warich-Kirches M, Schneider T, Weis S, Krause G, Mawrin C, Dietzmann K. Heterogeneous tissue distribution of a mitochondrial DNA polymorphism in heteroplasmic subjects without mitochondrial disorders. J Med Genet 2001; 38:312-7. [PMID: 11333867 PMCID: PMC1734867 DOI: 10.1136/jmg.38.5.312] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
CONTEXT Several maternally inherited point mutations of the mitochondrial genome cause mitochondrial disorders, but the correlation between genotype and phenotype remains obscure in many cases. The same mutation may cause various diseases, probably because of a different tissue distribution. OBJECTIVE To assess the role of random somatic segregation in generating interperson differences by analysis of an apparently neutral polymorphism. DESIGN Screening of 81 brain samples from subjects without mitochondrial disorders and selection of five necropsy cases showing a high level of heteroplasmy for the polymorphism. MAIN OUTCOME MEASURES A proportion of various distinct genotypes in the mtDNA pool of the tissues, identified by fluorescent PCR products, representing a short polycytosine tract of variable length in the mitochondrial displacement loop. RESULTS Differences were found between organs or groups of organs within subjects, pointing towards somatic segregation of mtDNA. In addition, marked differences of this organ distribution occurred between subjects, which cannot be explained by tissue specific selection. CONCLUSIONS The observed interperson differences can be explained by somatic segregation, which occurs randomly at various developmental stages. Besides tissue specific selection, this process might participate in the distribution of pathogenic mtDNA mutations.
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Affiliation(s)
- E Kirches
- Institute of Neuropathology, Otto-von-Guericke- University, Leipziger Strasse 44, 39120 Magdeburg, Germany.
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Abstract
Over the past 11 years, a considerable body of evidence has accumulated implicating defects in the mitochondrial energy-generating pathway, oxidative phosphorylation, in a wide variety of degenerative diseases including myopathy and cardiomyopathy. Most classes of pathogenic mitochondrial DNA mutations affect the heart, in association with a variety of other clinical manifestations that can include skeletal muscle, the central nervous system (including eye), the endocrine system, and the renal system. To better understand the pathophysiologic basis of mitochondrial diseases and their role in myopathy and cardiomyopathy, several mouse models of mitochondrial disease have been prepared. Mitochondrial DNA mutations from cultured cells have been introduced into mice; nuclear DNA genes involved in mitochondrial energy production and reactive oxygen species detoxification have been genetically inactivated, which resulted in mice with hypertrophic and dilated cardiomyopathy, respectively. Physiologic characterization of these mice has confirmed the importance of decreased mitochondrial energy production, increased mitochondrial reactive oxygen species production, and the mitochondrial initiation of apoptosis in mitochondrial disease. With these insights, new therapeutic approaches for neuromuscular and cardiac disease have been suggested.
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Affiliation(s)
- D C Wallace
- Center for Molecular Medicine, Emory University School of Medicine, Atlanta, GA 30322, USA
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Armstrong MR, Blok VC, Phillips MS. A multipartite mitochondrial genome in the potato cyst nematode Globodera pallida. Genetics 2000; 154:181-92. [PMID: 10628979 PMCID: PMC1460896 DOI: 10.1093/genetics/154.1.181] [Citation(s) in RCA: 77] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The mitochondrial genome (mtDNA) of the plant parasitic nematode Globodera pallida exists as a population of small, circular DNAs that, taken individually, are of insufficient length to encode the typical metazoan mitochondrial gene complement. As far as we are aware, this unusual structural organization is unique among higher metazoans, although interesting comparisons can be made with the multipartite mitochondrial genome organizations of plants and fungi. The variation in frequency between populations displayed by some components of the mtDNA is likely to have major implications for the way in which mtDNA can be used in population and evolutionary genetic studies of G. pallida.
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Affiliation(s)
- M R Armstrong
- Department of Nematology, Scottish Crop Research Institute, Dundee, Scotland DD2 5DA.
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Melov S, Schneider JA, Coskun PE, Bennett DA, Wallace DC. Mitochondrial DNA rearrangements in aging human brain and in situ PCR of mtDNA. Neurobiol Aging 1999; 20:565-71. [PMID: 10638530 DOI: 10.1016/s0197-4580(99)00092-5] [Citation(s) in RCA: 77] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Deletions of the mitochondrial DNA (mtDNA) have been shown to accumulate with age in a variety of species regardless of mean or maximal life span. This implies that such mutations are either a molecular biomarker of senescence or that they are more causally linked to senescence itself. One assay that can be used to detect these mtDNA mutations is the long-extension polymerase chain reaction assay. This assay amplifies approximately 16 kb of the mtDNA in mammalian mitochondria and preferentially amplifies mtDNAs that are either deleted or duplicated. We have applied this assay to the aging human brain and found a heterogeneous array of rearranged mtDNAs. In addition, we have developed in situ polymerase chain reaction to detect mtDNA within individual cells of both the mouse and the human brain as a first step in identifying and enumerating cells containing mutant mtDNAs in situ.
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Affiliation(s)
- S Melov
- Center For Molecular Medicine, Emory University, Atlanta, GA 30322, USA.
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21
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Marchington DR, Macaulay V, Hartshorne GM, Barlow D, Poulton J. Evidence from human oocytes for a genetic bottleneck in an mtDNA disease. Am J Hum Genet 1998; 63:769-75. [PMID: 9718339 PMCID: PMC1377397 DOI: 10.1086/302009] [Citation(s) in RCA: 100] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Abstract
We have examined oocytes from a patient with Kearn-Sayre syndrome caused by mtDNA rearrangements. In mtDNA diseases, mutant and wild-type mtDNA frequently coexist in affected individuals (the condition of heteroplasmy). The proportion of mutant mtDNA transmitted from mother to offspring is variable because of a genetic bottleneck, and the "dose" of mutant mtDNA received influences the severity of the phenotype. The feasibility of prenatal diagnosis is critically dependent on the nature and timing of this bottleneck. Significant levels of rearranged mtDNA were detectable in the majority of the patient's oocytes, by use of multiplex PCR, with wide variation, in the levels of mutant and wild-type molecules, between individual oocytes. We also used length variation in a homopolymeric C tract, which is often heteroplasmic in normal controls, to identify founder subpopulations of mtDNAs in this patient's oocytes. We present direct evidence that the number of segregating units (n) is three to five orders of magnitude less than the number of mitochondria in the human female oocyte. In some cases, the best estimate of n may correspond to a single mitochondrion, if it is assumed that intergenerational transmission of mtDNA can be treated as a single sampling event. The bottleneck appears to contribute a major component of the variable transmission from mother to oocyte, in this patient and in a control. That this bottleneck had occurred by the time that oocytes were mature advances the prospects for prenatal diagnosis of mtDNA diseases.
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Affiliation(s)
- D R Marchington
- Department of Paediatrics, University of Oxford, United Kingdom
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22
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Hao H, Manfredi G, Moraes CT. Functional and structural features of a tandem duplication of the human mtDNA promoter region. Am J Hum Genet 1997; 60:1363-72. [PMID: 9199557 PMCID: PMC1716123 DOI: 10.1086/515474] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
An approximately 260-bp tandem duplication of the human mtDNA regulatory region has been identified in patients with mitochondrial disorders and in a specific Caucasian haplogroup. The functional significance of this mtDNA duplication was difficult to assess, because it was present at very low levels in human tissues. We have isolated several transmitochondrial cybrid lines harboring this mutation, one of which (clone CA17.1) was essentially homoplasmic for the duplication. Oxidative-phosphorylation function was not impaired in clone CA17.1, suggesting that this mtDNA alteration is not pathogenic. mtDNA copy number and steady-state levels of heavy- and light-strand transcripts were unaltered in clone CA 17.1. The steady-state levels of RNAs made from the two promoters (either from the heavy-strand or from the light-strand) were also similar, indicating that oppositely oriented promoters did not interfere with each other.
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Affiliation(s)
- H Hao
- Department of Neurology, University of Miami, FL, USA
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23
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Melov S, Hinerfeld D, Esposito L, Wallace DC. Multi-organ characterization of mitochondrial genomic rearrangements in ad libitum and caloric restricted mice show striking somatic mitochondrial DNA rearrangements with age. Nucleic Acids Res 1997; 25:974-82. [PMID: 9023106 PMCID: PMC146531 DOI: 10.1093/nar/25.5.974] [Citation(s) in RCA: 85] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Mitochondrial DNA (mtDNA) rearrangements have been shown to accumulate with age in the post-mitotic tissues of a variety of animals and have been hypothesized to result in the age-related decline of mitochondrial bioenergetics leading to tissue and organ failure. Caloric restriction in rodents has been shown to extend life span supporting an association between bioenergetics and senescence. In the present study, we use full length mtDNA amplification by long-extension polymerase chain reaction (LX-PCR) to demonstrate that mice accumulate a wide variety of mtDNA rearrangements with age in post mitotic tissues. Similarly, using an alternative PCR strategy, we have found that 2-4 kb minicircles containing the origin of heavy-strand replication accumulate with age in heart but not brain. Analysis of mtDNA structure and conformation by Southern blots of unrestricted DNA resolved by field inversion gel electrophoresis have revealed that the brain mtDNAs of young animals contain the traditional linear, nicked, and supercoiled mtDNAs while old animals accumulate substantial levels of a slower migrating species we designate age-specific mtDNAs. In old caloric restricted animals, a wide variety of rearranged mtDNAs can be detected by LX-PCR in post mitotic tissues, but Southern blots of unrestricted DNA reveals a marked reduction in the levels of the age- specific mtDNA species. These observations confirm that mtDNA mutations accumulate with age in mice and suggest that caloric restriction impedes this progress.
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Affiliation(s)
- S Melov
- Center for Genetics and Molecular Medicine, 1462 Clifton Rd., Emory University, Atlanta, GA 30322, USA
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24
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Handran SD, Werth JL, DeVivo DC, Rothman SM. Mitochondrial morphology and intracellular calcium homeostasis in cytochrome oxidase-deficient human fibroblasts. Neurobiol Dis 1997; 3:287-98. [PMID: 9173926 DOI: 10.1006/nbdi.1996.0125] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Mitochondrial encephalomyopathies arise from mutations in the mitochondrial or nuclear genome and result in defective energy metabolism. Investigation of cellular pathophysiology in these disorders has been limited to nonneuronal explant cultures such as fibroblasts and myoblasts. While investigating mitochondrial structure and function in fibroblasts obtained from control and cytochrome oxidase-deficient (COX) patients, we observed possible abnormalities by vital dye confocal microscopy. Most notable were swelling, reticulation (e.g., intricate fusion of mitochondria), and proliferation of mitochondria. However, a detailed quantitative comparison of mitochondrial morphology in age-, sex-, and passage-matched cultures revealed no significant differences between control and cytochrome oxidase-deficient fibroblasts, nor any differences with passage. In addition, COX fibroblasts exhibited no obvious impairment of intracellular calcium handling, measured by fura-2. These results indicate that cytochrome oxidase deficiency, at the level in these cultures, does not produce structural or ionic concentration alterations in fibroblasts. Future investigation of the pathophysiology of this respiratory chain disorder may require excitable tissue.
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Affiliation(s)
- S D Handran
- Center for the Study of Nervous System Injury and Department of Neurology, Washington University School of Medicine, St. Louis, Missouri, 63110, USA
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25
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Abstract
Mitochondria have their own DNA which is maternally inherited. Mitochondrial DNA (mtDNA) diseases are extremely variable because of the genetics of mtDNA and the unique pathogenesis of these disorders. This makes predicting the prognosis and the transmission of mtDNA disorders difficult. While mtDNA polymorphisms at a single base position are common, the overwhelming majority of the mitochondrial genomes within a single human individual are usually identical. When there is a point mutation difference between a mother and her offspring, there may be a complete switching of mtDNA type within a single generation. It is generally assumed that there is a genetic bottleneck whereby a single or small number of founder mtDNA(s) populate the organism, but it is not known at which stages the restriction/amplification of mtDNA subtype(s) occur, and this uncertainty impedes antenatal diagnosis for mtDNA disorders. Autosomally inherited disorders of mitochondrial function may be caused by mutations in genes for the components of the respiratory chain and for the machinery of mitochondrial biogenesis, which are nuclear-encoded. Accurate diagnosis of these disorders is important as prenatal diagnosis is available in a minority of cases.
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Affiliation(s)
- J Poulton
- Department of Paediatrics, John Radcliffe Hospital, Headington, Oxford, U.K
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26
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Gudikote JP, Van Tuyle GC. Rearrangements in the shorter arc of rat mitochondrial DNA involving the region of the heavy and light strand promoters. Mutat Res 1996; 356:275-86. [PMID: 8841497 DOI: 10.1016/0027-5107(96)00073-5] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Brain mtDNA from rats ranging in age from 1 day to 33 months were analyzed for large-scale rearrangements using nested PCR. The region of the mtDNA targeted by the primers was the shorter are between the two origins of replication and encompassed the heavy (H) and light (L) strand promoters (HSP) and (LSP). Rearrangements lacking 4 to 5 kb of genomic sequence were found in animals of all ages. Twenty-two different rearrangements were sequenced; two of these were found replicated in several different animals. All the rearrangements identified lacked an HSP and six lacked an LSP as well. The end points of each rearrangement had short direct repeats of 9 bp or less, but repeats of 4 bp or less were the most common. The mode of involvement of the direct repeats in the rearrangement mechanism varied since in some cases a sequence precisely equivalent to one member of the paired repeats was found at the junction; whereas in other cases, more or less than one complete member was found. Sixteen of the 22 rearrangements terminated on one side within a 22-bp locus, or hot spot, located at a potential stem-loop structure midway between the HSP and LSP. The other ends of these rearrangements were at different sites. In addition, a secondary hot spot was found near the junction between the tRNA(Ala) and tRNA(Asn) genes, which lie in a cluster of five tRNA genes that surround the stem-loop structure of the L-strand origin of replication. The data suggest a link between secondary structure and short direct repeats and the rearrangement mechanism(s). The results of this study, in conjunction with out previous study of the longer arc of rat mtDNA (Van Tuyle, G.C., J.P. Gudikote, V.H. Hurt, B.B. Miller and C.A. Moore (1996) Multiple, Large deletions in rat mitochondrial DNA: Evidence for a major hot spot, Mutation Res., 349, 95-107), indicate that nearly the entire mitochondrial genome is subject to rearrangement mutations that are detectable in brain tissue throughout an animal's life span.
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MESH Headings
- Age Factors
- Animals
- Base Sequence
- Brain/cytology
- Cloning, Molecular
- DNA, Mitochondrial/genetics
- DNA, Mitochondrial/ultrastructure
- Electrophoresis, Agar Gel
- Gene Rearrangement
- Molecular Sequence Data
- Polymerase Chain Reaction
- Promoter Regions, Genetic
- RNA, Transfer, Ala/genetics
- RNA, Transfer, Asn/genetics
- Rats
- Rats, Inbred F344
- Rats, Sprague-Dawley
- Repetitive Sequences, Nucleic Acid
- Transcription, Genetic
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Affiliation(s)
- J P Gudikote
- Department of Biochemistry and Molecular Biophysics, Virginia Commonwealth University, Richmond 23298-0614, USA
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27
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Ohno K, Yamamoto M, Engel AG, Harper CM, Roberts LR, Tan GH, Fatourechi V. MELAS- and Kearns-Sayre-type co-mutation [corrected] with myopathy and autoimmune polyendocrinopathy. Ann Neurol 1996; 39:761-6. [PMID: 8651648 DOI: 10.1002/ana.410390612] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
A 35-year-old woman with features of Kearns-Sayre syndrome consisting of progressive ptosis, ophthalmoparesis, mitochondrial myopathy, and pigmentary retinopathy also had autoimmune polyglandular syndrome type 11 (Addison's disease, autoimmune insulin-dependent diabetes mellitus, Hashimoto's thyroiditis, and primary ovarian failure). There was no history of similarly affected relatives. Analysis of muscle mitochondrial DNA (mtDNA) revealed a 2,532-bp deletion of the type seen in Kearns-Sayre syndrome as well as a heteroplasmic A3243G mutation in the tRNA-Leu(UUR) gene of the type seen in mitochondrial myopathy, encephalopathy, lactic acidosis, and strokelike episodes (MELAS). The patient's blood and her mother's blood harbored the A3243G mutation but not the deletion, and the maternal grandmother's blood had neither mutation. In muscle, the species of mtDNA harboring the deletion was exclusively associated with the species harboring the A3243G mutation, suggesting that the point mutation predisposed to the large-scale deletion. The mtDNA species with both mutations accounted for 88% of total muscle mtDNA. Other and as yet unrecognized point mutations in mtDNA might also be associated with, and possible causally related to, large-scale mtDNA deletions.
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Affiliation(s)
- K Ohno
- Department of Neurology and Muscle Research Laboratory, Mayo Clinic, Rochester, MN 55905, USA
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28
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Stoicheff H, Vital C. Mitochondrial DNA and disease. N Engl J Med 1996; 334:270; author reply 271. [PMID: 8532013 DOI: 10.1056/nejm199601253340415] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
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29
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Abramowicz MJ, Cochaux P, Cohen LH, Vamos E. Pernicious anaemia and hypoparathyroidism in a patient with Kearns-Sayre syndrome with mitochondrial DNA duplication. J Inherit Metab Dis 1996; 19:109-11. [PMID: 8739941 DOI: 10.1007/bf01799405] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Affiliation(s)
- M J Abramowicz
- Department of Genetics, Brussels University Clinics, Erasme Hospital, Belgium
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