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Zhao B, Zhu Z, Zhao J, Yang M, Zhang Y, Li H, Pan S, Qi X, Yu Y. Clinical Reasoning: A 17-Year-Old Girl With Progressive Cognitive Impairment. Neurology 2023; 101:e1466-e1472. [PMID: 37491326 PMCID: PMC10573138 DOI: 10.1212/wnl.0000000000207597] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2022] [Accepted: 05/15/2023] [Indexed: 07/27/2023] Open
Abstract
A 17-year-old girl presented with a long history of cognitive impairment, personality and behavioral changes, dysarthria, and paroxysmal lower-extremity weakness. She was initially suspected of having mitochondrial encephalomyopathy with lactic acidosis and stroke-like episodes because of stroke-like symptoms, such as episodic lower-extremity weakness, as well as abnormal brain MRI findings of generalized cerebral atrophy, extensive high-intensity lesions in the cortex and subcortical white matter on fluid-attenuated inversion recovery images, decreased N-acetyl aspartate/creatine ratio, and a lactate peak in the focal area on spectrum images. However, there were no relatives with similar presentations in the family of the patient. The whole mitochondrial genome and whole-exome sequencing did not suggest pathogenic mutations, and no abnormalities were found in the blood or CSF lactate levels. In this case, we detail the clinical manifestations, diagnostic workup, and imaging findings. This case highlights the importance of assessing cognitive function and the relevant differential diagnoses in an adolescent with cognitive impairment.
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Affiliation(s)
- Bo Zhao
- From the Department of Neurology (B.Z., Y.Z., X.Q., Y.Y.), The First Medical Center, Chinese PLA General Hospital, Beijing; The Second School of Clinical Medicine (B.Z., M.Y., S.P.), Southern Medical University, Guangzhou; Department of Hyperbaric Oxygen (B.Z., H.L., S.P.), and Department of Emergency (Z.Z.), Sixth Medical Center of Chinese PLA General Hospital; and Department of Neurology (J.Z.), The 305th Hospital of the People's Liberation Army, Beijing, China
| | - Zonghong Zhu
- From the Department of Neurology (B.Z., Y.Z., X.Q., Y.Y.), The First Medical Center, Chinese PLA General Hospital, Beijing; The Second School of Clinical Medicine (B.Z., M.Y., S.P.), Southern Medical University, Guangzhou; Department of Hyperbaric Oxygen (B.Z., H.L., S.P.), and Department of Emergency (Z.Z.), Sixth Medical Center of Chinese PLA General Hospital; and Department of Neurology (J.Z.), The 305th Hospital of the People's Liberation Army, Beijing, China
| | - Jinjing Zhao
- From the Department of Neurology (B.Z., Y.Z., X.Q., Y.Y.), The First Medical Center, Chinese PLA General Hospital, Beijing; The Second School of Clinical Medicine (B.Z., M.Y., S.P.), Southern Medical University, Guangzhou; Department of Hyperbaric Oxygen (B.Z., H.L., S.P.), and Department of Emergency (Z.Z.), Sixth Medical Center of Chinese PLA General Hospital; and Department of Neurology (J.Z.), The 305th Hospital of the People's Liberation Army, Beijing, China
| | - Miao Yang
- From the Department of Neurology (B.Z., Y.Z., X.Q., Y.Y.), The First Medical Center, Chinese PLA General Hospital, Beijing; The Second School of Clinical Medicine (B.Z., M.Y., S.P.), Southern Medical University, Guangzhou; Department of Hyperbaric Oxygen (B.Z., H.L., S.P.), and Department of Emergency (Z.Z.), Sixth Medical Center of Chinese PLA General Hospital; and Department of Neurology (J.Z.), The 305th Hospital of the People's Liberation Army, Beijing, China
| | - Yimo Zhang
- From the Department of Neurology (B.Z., Y.Z., X.Q., Y.Y.), The First Medical Center, Chinese PLA General Hospital, Beijing; The Second School of Clinical Medicine (B.Z., M.Y., S.P.), Southern Medical University, Guangzhou; Department of Hyperbaric Oxygen (B.Z., H.L., S.P.), and Department of Emergency (Z.Z.), Sixth Medical Center of Chinese PLA General Hospital; and Department of Neurology (J.Z.), The 305th Hospital of the People's Liberation Army, Beijing, China
| | - Hang Li
- From the Department of Neurology (B.Z., Y.Z., X.Q., Y.Y.), The First Medical Center, Chinese PLA General Hospital, Beijing; The Second School of Clinical Medicine (B.Z., M.Y., S.P.), Southern Medical University, Guangzhou; Department of Hyperbaric Oxygen (B.Z., H.L., S.P.), and Department of Emergency (Z.Z.), Sixth Medical Center of Chinese PLA General Hospital; and Department of Neurology (J.Z.), The 305th Hospital of the People's Liberation Army, Beijing, China
| | - Shuyi Pan
- From the Department of Neurology (B.Z., Y.Z., X.Q., Y.Y.), The First Medical Center, Chinese PLA General Hospital, Beijing; The Second School of Clinical Medicine (B.Z., M.Y., S.P.), Southern Medical University, Guangzhou; Department of Hyperbaric Oxygen (B.Z., H.L., S.P.), and Department of Emergency (Z.Z.), Sixth Medical Center of Chinese PLA General Hospital; and Department of Neurology (J.Z.), The 305th Hospital of the People's Liberation Army, Beijing, China
| | - Xiaokun Qi
- From the Department of Neurology (B.Z., Y.Z., X.Q., Y.Y.), The First Medical Center, Chinese PLA General Hospital, Beijing; The Second School of Clinical Medicine (B.Z., M.Y., S.P.), Southern Medical University, Guangzhou; Department of Hyperbaric Oxygen (B.Z., H.L., S.P.), and Department of Emergency (Z.Z.), Sixth Medical Center of Chinese PLA General Hospital; and Department of Neurology (J.Z.), The 305th Hospital of the People's Liberation Army, Beijing, China
| | - Yingxin Yu
- From the Department of Neurology (B.Z., Y.Z., X.Q., Y.Y.), The First Medical Center, Chinese PLA General Hospital, Beijing; The Second School of Clinical Medicine (B.Z., M.Y., S.P.), Southern Medical University, Guangzhou; Department of Hyperbaric Oxygen (B.Z., H.L., S.P.), and Department of Emergency (Z.Z.), Sixth Medical Center of Chinese PLA General Hospital; and Department of Neurology (J.Z.), The 305th Hospital of the People's Liberation Army, Beijing, China.
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2
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Wang A, Zhao J, Zhao Y, Yan Y. Late-onset MELAS syndrome in a 46-year-old man with initial symptom of chest tightness: a case report. Eur Heart J Case Rep 2023; 7:ytad441. [PMID: 37767231 PMCID: PMC10519872 DOI: 10.1093/ehjcr/ytad441] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2023] [Revised: 08/14/2023] [Accepted: 08/30/2023] [Indexed: 09/29/2023]
Abstract
Background Mitochondrial Encephalomyopathy, Lactic Acidosis, and Stroke-like episodes (MELAS) syndrome is a rare mitochondrial disorder caused by mutations in mitochondrial DNA, resulting in impaired energy production and affecting multiple organs. We present a suspected MELAS syndrome case with the initial symptom of chest tightness. Case summary A 46-year-old man sought medical attention due to progressively worsening chest tightness during physical activity. He had been receiving treatment for type 2 diabetes for 15 years. One year ago, he presented with symptoms of hearing impairment. Transthoracic echocardiography revealed increased thickness of the left ventricular wall. Serum protein electrophoresis showed no evidence of light-chain amyloidosis, and the 99mTc-3,3-diphosphono-1,2-propanodicarboxylic acid scan showed no definite uptake in the heart muscle. The patient's head magnetic resonance imaging (MRI) indicated lacunar infarcts. The lactate threshold test was positive. The biopsy of the skeletal muscle showed broken red fibre infiltration on modified Gomori trichrome staining, and electron microscopy revealed signs of mitochondrial cardiomyopathy, including mild mitochondrial swelling, lipid accumulation, and myofibril damage. A whole-exome genetic test was used to detect the m.3243A>G mutation in the MT-TL1 gene. Based on these findings, MELAS syndrome was the most probable diagnosis. Discussion The patient presented with chest tightness in adulthood, without any accompanying psychoneurological symptoms. However, the patient presented with other symptoms, including diabetes mellitus, hearing loss, abnormal lactate levels, ischaemic lesions on head MRI, and left ventricular hypertrophy. By identifying a mutation in the MT-TL1 gene and conducting a muscle biopsy, the diagnosis of MELAS syndrome was definitively confirmed.
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Affiliation(s)
- Ai Wang
- Department of Cardiology, Zhongshan Hospital, Fudan University, 180 Fenglin Road, Shanghai 200032, China
| | - Ji Zhao
- Department of Cardiology, Zhongshan Hospital, Fudan University, 180 Fenglin Road, Shanghai 200032, China
| | - Yun Zhao
- Department of Cardiovascular Surgery, Shanghai Geriatric Medical Center, 2560 Chunshen Road, Shanghai 201104, China
| | - Yan Yan
- Department of Cardiology, Zhongshan Hospital, Fudan University, 180 Fenglin Road, Shanghai 200032, China
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3
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Bernardino Gomes TM, Ng YS, Pickett SJ, Turnbull DM, Vincent AE. Mitochondrial DNA disorders: From pathogenic variants to preventing transmission. Hum Mol Genet 2021; 30:R245-R253. [PMID: 34169319 PMCID: PMC8490015 DOI: 10.1093/hmg/ddab156] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2021] [Revised: 05/28/2021] [Accepted: 06/01/2021] [Indexed: 11/27/2022] Open
Abstract
Mitochondrial DNA (mtDNA) disorders are recognized as one of the most common causes of inherited metabolic disorders. The mitochondrial genome occurs in multiple copies resulting in both homoplasmic and heteroplasmic pathogenic mtDNA variants. A biochemical defect arises when the pathogenic variant level reaches a threshold, which differs between variants. Moreover, variants can segregate, clonally expand, or be lost from cellular populations resulting in a dynamic and tissue-specific mosaic pattern of oxidative deficiency. MtDNA is maternally inherited but transmission patterns of heteroplasmic pathogenic variants are complex. During oogenesis, a mitochondrial bottleneck results in offspring with widely differing variant levels to their mother, whilst highly deleterious variants, such as deletions, are not transmitted. Complemented by a complex interplay between mitochondrial and nuclear genomes, these peculiar genetics produce marked phenotypic variation, posing challenges to the diagnosis and clinical management of patients. Novel therapeutic compounds and several genetic therapies are currently under investigation, but proven disease-modifying therapies remain elusive. Women who carry pathogenic mtDNA variants require bespoke genetic counselling to determine their reproductive options. Recent advances in in vitro fertilization techniques, have greatly improved reproductive choices, but are not without their challenges. Since the first pathogenic mtDNA variants were identified over 30 years ago, there has been remarkable progress in our understanding of these diseases. However, many questions remain unanswered and future studies are required to investigate the mechanisms of disease progression and to identify new disease-specific therapeutic targets.
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Affiliation(s)
- Tiago M Bernardino Gomes
- Wellcome Centre for Mitochondrial Research, Translational and Clinical Research Institute, Newcastle University, Newcastle upon Tyne, NE2 4HH, UK.,NHS Highly Specialised Service for Rare Mitochondrial Disorders, Newcastle upon Tyne Hospitals NHS Foundation Trust, Newcastle upon Tyne, NE2 4HH, UK
| | - Yi Shiau Ng
- Wellcome Centre for Mitochondrial Research, Translational and Clinical Research Institute, Newcastle University, Newcastle upon Tyne, NE2 4HH, UK.,NHS Highly Specialised Service for Rare Mitochondrial Disorders, Newcastle upon Tyne Hospitals NHS Foundation Trust, Newcastle upon Tyne, NE2 4HH, UK
| | - Sarah J Pickett
- Wellcome Centre for Mitochondrial Research, Translational and Clinical Research Institute, Newcastle University, Newcastle upon Tyne, NE2 4HH, UK
| | - Doug M Turnbull
- Wellcome Centre for Mitochondrial Research, Translational and Clinical Research Institute, Newcastle University, Newcastle upon Tyne, NE2 4HH, UK
| | - Amy E Vincent
- Wellcome Centre for Mitochondrial Research, Translational and Clinical Research Institute, Newcastle University, Newcastle upon Tyne, NE2 4HH, UK
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Richter U, McFarland R, Taylor RW, Pickett SJ. The molecular pathology of pathogenic mitochondrial tRNA variants. FEBS Lett 2021; 595:1003-1024. [PMID: 33513266 PMCID: PMC8600956 DOI: 10.1002/1873-3468.14049] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2020] [Revised: 01/14/2021] [Accepted: 01/18/2021] [Indexed: 12/16/2022]
Abstract
Mitochondrial diseases are clinically and genetically heterogeneous disorders, caused by pathogenic variants in either the nuclear or mitochondrial genome. This heterogeneity is particularly striking for disease caused by variants in mitochondrial DNA-encoded tRNA (mt-tRNA) genes, posing challenges for both the treatment of patients and understanding the molecular pathology. In this review, we consider disease caused by the two most common pathogenic mt-tRNA variants: m.3243A>G (within MT-TL1, encoding mt-tRNALeu(UUR) ) and m.8344A>G (within MT-TK, encoding mt-tRNALys ), which together account for the vast majority of all mt-tRNA-related disease. We compare and contrast the clinical disease they are associated with, as well as their molecular pathologies, and consider what is known about the likely molecular mechanisms of disease. Finally, we discuss the role of mitochondrial-nuclear crosstalk in the manifestation of mt-tRNA-associated disease and how research in this area not only has the potential to uncover molecular mechanisms responsible for the vast clinical heterogeneity associated with these variants but also pave the way to develop treatment options for these devastating diseases.
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Affiliation(s)
- Uwe Richter
- Wellcome Centre for Mitochondrial ResearchThe Medical SchoolNewcastle UniversityUK
- Molecular and Integrative Biosciences Research ProgrammeFaculty of Biological and Environmental SciencesUniversity of HelsinkiFinland
- Newcastle University Biosciences InstituteNewcastle UniversityUK
| | - Robert McFarland
- Wellcome Centre for Mitochondrial ResearchThe Medical SchoolNewcastle UniversityUK
- Newcastle University Translational and Clinical Research InstituteNewcastle UniversityUK
| | - Robert W. Taylor
- Wellcome Centre for Mitochondrial ResearchThe Medical SchoolNewcastle UniversityUK
- Newcastle University Translational and Clinical Research InstituteNewcastle UniversityUK
| | - Sarah J. Pickett
- Wellcome Centre for Mitochondrial ResearchThe Medical SchoolNewcastle UniversityUK
- Newcastle University Translational and Clinical Research InstituteNewcastle UniversityUK
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5
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Jiang P, Ling Y, Zhu T, Luo X, Tao Y, Meng F, Cheng W, Ji Y. Mitochondrial tRNA mutations in Chinese Children with Tic Disorders. Biosci Rep 2020; 40:BSR20201856. [PMID: 33289513 PMCID: PMC7755120 DOI: 10.1042/bsr20201856] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2020] [Revised: 11/09/2020] [Accepted: 11/18/2020] [Indexed: 12/17/2022] Open
Abstract
AIMS To conduct the clinical, genetic and molecular characterization of 494 Han Chinese subjects with Tic disorders (TD). METHODS In this study, we performed the mutational analysis of 22 mitochondrial tRNA genes in a large cohort of 494 Han Chinese subjects with TD via Sanger sequencing. These variants were then assessed for their pathogenic potential via phylogenetic, functional, and structural analyses. RESULTS A total of 73 tRNA gene variants (49 known and 24 novel) on 22 tRNA genes were identified. Among these, 18 tRNA variants that were absent or present in <1% of 485 Chinese control patient samples were localized to highly conserved nucleotides, or changed the modified nucleotides, and had the potential structural to alter tRNA structure and function. These variants were thus considered to be TD-associated mutations. In total, 25 subjects carried one of these 18 putative TD-associated tRNA variants with the total prevalence of 4.96%. LIMITATIONS The phenotypic variability and incomplete penetrance of tic disorders in pedigrees carrying these tRNA mutations suggested the involvement of modifier factors, such as nuclear encoded genes associated mitochondrion, mitochondrial haplotypes, epigenetic and environmental factors. CONCLUSION Our data provide the evidence that mitochondrial tRNA mutations are the important causes of tic disorders among Chinese population. These findings also advance current understanding regarding the clinical relevance of tRNA mutations, and will guide future studies aimed at elucidating the pathophysiology of maternal tic disorders.
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Affiliation(s)
- Peifang Jiang
- Department of Neurology, The Children’s Hospital, Zhejiang University School of Medicine, National Clinical Research Center For Child Health, Hangzhou, China
| | - Yinjie Ling
- Department of Neurology, The Children’s Hospital, Zhejiang University School of Medicine, National Clinical Research Center For Child Health, Hangzhou, China
- Department of Pediatrics, First People’s Hospital of Huzhou, Huzhou, China
| | - Tao Zhu
- Department of Critical Care Medicine, Sir Run Run Shaw Hospital, School of Medicine, Zhejiang University, Hangzhou, China
| | - Xiaoying Luo
- Department of Neurology, The Children’s Hospital, Zhejiang University School of Medicine, National Clinical Research Center For Child Health, Hangzhou, China
| | - Yilin Tao
- Department of Neurology, The Children’s Hospital, Zhejiang University School of Medicine, National Clinical Research Center For Child Health, Hangzhou, China
| | - Feilong Meng
- Division of Medical Genetics and Genomics, The Children’s Hospital, Zhejiang University School of Medicine, National Clinical Research Center for Child Health, Zhejiang, China
- Institute of Genetics, Zhejiang University, Hangzhou, Zhejiang, China
| | - Weixin Cheng
- Institute of Genetics, Zhejiang University, Hangzhou, Zhejiang, China
| | - Yanchun Ji
- Division of Medical Genetics and Genomics, The Children’s Hospital, Zhejiang University School of Medicine, National Clinical Research Center for Child Health, Zhejiang, China
- Institute of Genetics, Zhejiang University, Hangzhou, Zhejiang, China
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6
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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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7
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van Tienen F, Zelissen R, Timmer E, van Gisbergen M, Lindsey P, Quattrocelli M, Sampaolesi M, Mulder-den Hartog E, de Coo I, Smeets H. Healthy, mtDNA-mutation free mesoangioblasts from mtDNA patients qualify for autologous therapy. Stem Cell Res Ther 2019; 10:405. [PMID: 31864395 PMCID: PMC6925445 DOI: 10.1186/s13287-019-1510-8] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2019] [Revised: 11/13/2019] [Accepted: 11/26/2019] [Indexed: 12/12/2022] Open
Abstract
BACKGROUND Myopathy and exercise intolerance are prominent clinical features in carriers of a point-mutation or large-scale deletion in the mitochondrial DNA (mtDNA). In the majority of patients, the mtDNA mutation is heteroplasmic with varying mutation loads between tissues of an individual. Exercise-induced muscle regeneration has been shown to be beneficial in some mtDNA mutation carriers, but is often not feasible for this patient group. In this study, we performed in vitro analysis of mesoangioblasts from mtDNA mutation carriers to assess their potential to be used as source for autologous myogenic cell therapy. METHODS We assessed the heteroplasmy level of patient-derived mesoangioblasts, isolated from skeletal muscle of multiple carriers of different mtDNA point-mutations (n = 25). Mesoangioblast cultures with < 10% mtDNA mutation were further analyzed with respect to immunophenotype, proliferation capacity, in vitro myogenic differentiation potential, mitochondrial function, and mtDNA quantity. RESULTS This study demonstrated that mesoangioblasts in half of the patients contained no or a very low mutation load (< 10%), despite a much higher mutation load in their skeletal muscle. Moreover, none of the large-scale mtDNA deletion carriers displayed the deletion in mesoangioblasts, despite high percentages in skeletal muscle. The mesoangioblasts with no or a very low mutation load (< 10%) displayed normal mitochondrial function, proliferative capacity, and myogenic differentiation capacity. CONCLUSIONS Our data demonstrates that in half of the mtDNA mutation carriers, their mesoangioblasts are (nearly) mutation free and can potentially be used as source for autologous cell therapy for generation of new muscle fibers without mtDNA mutation and normal mitochondrial function.
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Affiliation(s)
- Florence van Tienen
- Department of Clinical Genetics, Maastricht University Medical Centre+, Maastricht, The Netherlands.,School for Developmental Biology and Oncology (GROW), Maastricht University Medical Centre+, P.O. box 616, 6200MD, Maastricht, The Netherlands.,School for Mental Health and Neurosciences (MHeNS), Maastricht University Medical Centre+, Maastricht, The Netherlands.,Department of Genetics and Cell Biology, Division Clinical Genomics, Maastricht University Medical Centre+, Maastricht, The Netherlands
| | - Ruby Zelissen
- School for Developmental Biology and Oncology (GROW), Maastricht University Medical Centre+, P.O. box 616, 6200MD, Maastricht, The Netherlands.,Department of Genetics and Cell Biology, Division Clinical Genomics, Maastricht University Medical Centre+, Maastricht, The Netherlands
| | - Erika Timmer
- School for Developmental Biology and Oncology (GROW), Maastricht University Medical Centre+, P.O. box 616, 6200MD, Maastricht, The Netherlands.,Department of Genetics and Cell Biology, Division Clinical Genomics, Maastricht University Medical Centre+, Maastricht, The Netherlands
| | - Marike van Gisbergen
- School for Developmental Biology and Oncology (GROW), Maastricht University Medical Centre+, P.O. box 616, 6200MD, Maastricht, The Netherlands.,Department of Radiation Oncology (MaastRO Lab), Maastricht University Medical Centre+, Maastricht, The Netherlands
| | - Patrick Lindsey
- Department of Genetics and Cell Biology, Division Clinical Genomics, Maastricht University Medical Centre+, Maastricht, The Netherlands
| | - Mattia Quattrocelli
- Translational Cardiomyology, Department of Development and Regeneration, KU Leuven, Leuven, Belgium.,Center for Genetic Medicine, Northwestern University, Chicago, USA
| | - Maurilio Sampaolesi
- Translational Cardiomyology, Department of Development and Regeneration, KU Leuven, Leuven, Belgium.,Human Anatomy Unit, Department of Public Health, Experimental and Forensic Medicine, University of Pavia, Pavia, Italy
| | - Elvira Mulder-den Hartog
- Department of Pediatric Surgery, Erasmus Medical Center, Rotterdam, The Netherlands.,Neuromuscular and Mitochondrial research center (NeMo), Rotterdam/Maastricht, The Netherlands
| | - Irenaeus de Coo
- School for Mental Health and Neurosciences (MHeNS), Maastricht University Medical Centre+, Maastricht, The Netherlands.,Department of Genetics and Cell Biology, Division Clinical Genomics, Maastricht University Medical Centre+, Maastricht, The Netherlands.,Neuromuscular and Mitochondrial research center (NeMo), Rotterdam/Maastricht, The Netherlands
| | - Hubert Smeets
- School for Developmental Biology and Oncology (GROW), Maastricht University Medical Centre+, P.O. box 616, 6200MD, Maastricht, The Netherlands. .,School for Mental Health and Neurosciences (MHeNS), Maastricht University Medical Centre+, Maastricht, The Netherlands. .,Department of Genetics and Cell Biology, Division Clinical Genomics, Maastricht University Medical Centre+, Maastricht, The Netherlands.
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8
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Boggan RM, Lim A, Taylor RW, McFarland R, Pickett SJ. Resolving complexity in mitochondrial disease: Towards precision medicine. Mol Genet Metab 2019; 128:19-29. [PMID: 31648942 DOI: 10.1016/j.ymgme.2019.09.003] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/16/2019] [Revised: 09/12/2019] [Accepted: 09/12/2019] [Indexed: 12/12/2022]
Abstract
Mitochondrial diseases, caused by mutations in either the nuclear or mitochondrial genomes (mtDNA), are the most common form of inherited neurometabolic disorders. They are remarkably heterogeneous, both in their clinical presentation and genetic etiology, presenting challenges for diagnosis, clinical management and elucidation of molecular mechanism. The multifaceted nature of these diseases, compounded by the unique characteristics of mitochondrial genetics, cement their space in the field of complex disease. In this review we examine the m.3243A>G variant, one of the most prevalent mitochondrial DNA mutations, using it as an exemplar to demonstrate the challenges presented by these complex disorders. Disease caused by m.3243A>G is one of the most phenotypically diverse of all mitochondrial diseases; we outline known causes of this heterogeneity including mtDNA heteroplasmy, mtDNA copy number and nuclear genetic factors. We consider the impact that this has in the clinic, discussing the personalized management of common manifestations attributed to this pathogenic mtDNA variant, including hearing impairment, diabetes mellitus, myopathy, cardiac disease, stroke-like episodes and gastrointestinal disturbances. Future research into this complex disorder must account for this heterogeneity, benefitting from the use of large patient cohorts to build upon current clinical expertise. Through multi-disciplinary collaboration, the complexities of this mitochondrial disease can be addressed with the variety of diagnostic, prognostic, and treatment approaches that are moulded to best fit the needs of each individual patient.
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Affiliation(s)
- Róisín M Boggan
- Wellcome Centre for Mitochondrial Research, Institute of Neuroscience, The Medical School, Newcastle University, Newcastle upon Tyne NE2 4HH, UK
| | - Albert Lim
- Wellcome Centre for Mitochondrial Research, Institute of Neuroscience, The Medical School, Newcastle University, Newcastle upon Tyne NE2 4HH, UK
| | - Robert W Taylor
- Wellcome Centre for Mitochondrial Research, Institute of Neuroscience, The Medical School, Newcastle University, Newcastle upon Tyne NE2 4HH, UK
| | - Robert McFarland
- Wellcome Centre for Mitochondrial Research, Institute of Neuroscience, The Medical School, Newcastle University, Newcastle upon Tyne NE2 4HH, UK.
| | - Sarah J Pickett
- Wellcome Centre for Mitochondrial Research, Institute of Neuroscience, The Medical School, Newcastle University, Newcastle upon Tyne NE2 4HH, UK
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9
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Veitia RA. How the most common mitochondrial DNA mutation (m.3243A>G) vanishes from leukocytes: a mathematical model. Hum Mol Genet 2019; 27:1565-1571. [PMID: 29474538 DOI: 10.1093/hmg/ddy063] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2017] [Accepted: 02/15/2018] [Indexed: 01/24/2023] Open
Abstract
Mitochondrial diseases may be caused by alterations of the mitochondrial genome. The pathogenic variant m.3243A>G is one of the most frequent causes of mitochondrial disease and the most common mitochondrial DNA mutation. Patients with a variant in mitochondrial DNA can have a mixture of mutated and wild-type genomes (heteroplasmy). In the case of the pathogenic variant m.3243A>G, the degree of heteroplasmy (H) correlates to some extent with the severity of the disease. Several longitudinal studies, where H is measured at two different time-points, have shown an annual decline in leukocyte H values. Thus far, only an exponential decay of H with time has been noted but a mechanistic model is lacking. Here, I describe a deterministic mathematical model that accounts for the decline of H in leukocytes based on selective mechanisms acting at the stem cell level. The 'inverted-sigmoid' model provides estimates of at-birth H levels closer to those observed in post-mitotic tissues, such as skeletal muscle, than the estimates provided by an exponential decay. The new model never leads to predictions of H > 100% and provides a stronger correlation between at-birth H values in leukocytes and the scores of the Newcastle Mitochondrial Disease Scale for Adults, which can be of practical utility. This model could be extended to other mitochondrial DNA disease-causing variants.
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Affiliation(s)
- Reiner A Veitia
- Institut Jacques Monod, Université Paris Diderot, Paris, France
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Tarnopolsky MA, Sundaram ANE, Provias J, Brady L, Sadikovic B. CPEO - Like mitochondrial myopathy associated with m.8340G>A mutation. Mitochondrion 2018; 46:69-72. [PMID: 29501485 DOI: 10.1016/j.mito.2018.02.008] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2017] [Revised: 02/22/2018] [Accepted: 02/23/2018] [Indexed: 11/19/2022]
Abstract
Two patients with an m.8340G>A mitochondrial DNA variant have been reported with one patient showing ptosis, ophthalmoparesis and myopathy at 53% heteroplasmy and another with pigmentary retinopathy, cataracts and sensory neural deafness and slightly higher heteroplasmy (65%). Here we report that higher muscle mutant heteroplasmy (93%) for m.8340G>A is associated with ptosis, ophthalmoparesis and mitochondrial myopathy, thus confirming the initial phenotypic association and showing that heteroplasmy per se does not explain the phenotypic spectrum of disease associated with the m.8340G>A mutation.
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Affiliation(s)
- Mark A Tarnopolsky
- Department of Pediatrics, McMaster University, Hamilton, Ontario, Canada.
| | - Arun N E Sundaram
- Department of Ophthalmology and Vision Sciences, Sunnybrook Health Sciences Center, University of Toronto, Toronto, Ontario, Canada
| | - John Provias
- Department of Pathology and Molecular Medicine, McMaster University, Hamilton, Ontario, Canada
| | - Lauren Brady
- Department of Pediatrics, McMaster University, Hamilton, Ontario, Canada
| | - Bekim Sadikovic
- Molecular Genetics Laboratory, Molecular Diagnostics Division, London Health Sciences Centre, Children's Health Research Institute, London, Ontario, Canada
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Sofou K, de Coo IFM, Ostergaard E, Isohanni P, Naess K, De Meirleir L, Tzoulis C, Uusimaa J, Lönnqvist T, Bindoff LA, Tulinius M, Darin N. Phenotype-genotype correlations in Leigh syndrome: new insights from a multicentre study of 96 patients. J Med Genet 2017; 55:21-27. [PMID: 29101127 DOI: 10.1136/jmedgenet-2017-104891] [Citation(s) in RCA: 46] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2017] [Revised: 09/21/2017] [Accepted: 10/04/2017] [Indexed: 01/24/2023]
Abstract
BACKGROUND Leigh syndrome is a phenotypically and genetically heterogeneous mitochondrial disorder. While some genetic defects are associated with well-described phenotypes, phenotype-genotype correlations in Leigh syndrome are not fully explored. OBJECTIVE We aimed to identify phenotype-genotype correlations in Leigh syndrome in a large cohort of systematically evaluated patients. METHODS We studied 96 patients with genetically confirmed Leigh syndrome diagnosed and followed in eight European centres specialising in mitochondrial diseases. RESULTS We found that ataxia, ophthalmoplegia and cardiomyopathy were more prevalent among patients with mitochondrial DNA defects. Patients with mutations in MT-ND and NDUF genes with complex I deficiency shared common phenotypic features, such as early development of central nervous system disease, followed by high occurrence of cardiac and ocular manifestations. The cerebral cortex was affected in patients with NDUF mutations significantly more often than the rest of the cohort. Patients with the m.8993T>G mutation in MT-ATP6 gene had more severe clinical and radiological manifestations and poorer disease outcome compared with patients with the m.8993T>C mutation. CONCLUSION Our study provides new insights into phenotype-genotype correlations in Leigh syndrome and particularly in patients with complex I deficiency and with defects in the mitochondrial ATP synthase.
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Affiliation(s)
- Kalliopi Sofou
- Department of Pediatrics, The Queen Silvia Children's Hospital, University of Gothenburg, Gothenburg, Sweden
| | - Irenaeus F M de Coo
- Department of Neurology, The Erasmus University Medical Center, Rotterdam, Netherlands
| | - Elsebet Ostergaard
- Department of Clinical Genetics, Copenhagen University Hospital Rigshospitalet, Copenhagen, Denmark
| | - Pirjo Isohanni
- Department of Paediatric Neurology, Children's Hospital, University of Helsinki, Helsinki University Hospital, Helsinki, Finland.,Research Programs Unit, Molecular Neurology, Biomedicum, University of Helsinki, Helsinki, Finland
| | - Karin Naess
- Centre for Inherited Metabolic Diseases, Karolinska University Hospital, Stockholm, Sweden
| | - Linda De Meirleir
- Department of Paediatric Neurology, University Hospital Vrije Universiteit Brussel (VUB), Brussels, Belgium
| | - Charalampos Tzoulis
- Department of Neurology, Haukeland University Hospital, Bergen, Norway.,Department of Clinical Medicine, University of Bergen, Bergen, Norway
| | - Johanna Uusimaa
- Department of Paediatrics, Institute of Clinical Medicine, University of Oulu, Oulu, Finland.,Medical Research Center, Oulu University Hospital, Oulu, Finland
| | - Tuula Lönnqvist
- Department of Paediatric Neurology, Children's Hospital, University of Helsinki, Helsinki University Hospital, Helsinki, Finland
| | - Laurence Albert Bindoff
- Department of Neurology, Haukeland University Hospital, Bergen, Norway.,Department of Clinical Medicine, University of Bergen, Bergen, Norway
| | - Már Tulinius
- Department of Pediatrics, The Queen Silvia Children's Hospital, University of Gothenburg, Gothenburg, Sweden
| | - Niklas Darin
- Department of Pediatrics, The Queen Silvia Children's Hospital, University of Gothenburg, Gothenburg, Sweden
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Nascimento A, Ortez C, Jou C, O'Callaghan M, Ramos F, Garcia-Cazorla À. Neuromuscular Manifestations in Mitochondrial Diseases in Children. Semin Pediatr Neurol 2016; 23:290-305. [PMID: 28284391 DOI: 10.1016/j.spen.2016.11.004] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Mitochondrial diseases exhibit significant clinical and genetic heterogeneity. Mitochondria are highly dynamic organelles that are the major contributor of adenosine triphosphate, through oxidative phosphorylation. These disorders may be developed at any age, with isolated or multiple system involvement, and in any pattern of inheritance. Defects in the mitochondrial respiratory chain impair energy production and almost invariably involve skeletal muscle and peripheral nerves, causing exercise intolerance, cramps, recurrent myoglobinuria, or fixed weakness, which often affects extraocular muscles and results in droopy eyelids (ptosis), progressive external ophthalmoplegia, peripheral ataxia, and peripheral polyneuropathy. This review describes the main neuromuscular symptomatology through different syndromes reported in the literature and from our experience. We want to highlight the importance of searching for the "clue clinical signs" associated with inheritance pattern as key elements to guide the complex diagnosis process and genetic studies in mitochondrial diseases.
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Affiliation(s)
- Andrés Nascimento
- Department of Neurology, Neuromuscular Units, Hospital Sant Joan de Déu, Instituto de Salud Carlos III, Barcelona, Spain; Center for Biomedical Research on Rare Diseases (CIBERER), Institute of Pediatric Research Sant Joan de Déu, Madrid, Spain.
| | - Carlos Ortez
- Department of Neurology, Neuromuscular Units, Hospital Sant Joan de Déu, Instituto de Salud Carlos III, Barcelona, Spain
| | - Cristina Jou
- Department of Neurology, Neuromuscular Units, Hospital Sant Joan de Déu, Instituto de Salud Carlos III, Barcelona, Spain; Center for Biomedical Research on Rare Diseases (CIBERER), Institute of Pediatric Research Sant Joan de Déu, Madrid, Spain
| | - Mar O'Callaghan
- Center for Biomedical Research on Rare Diseases (CIBERER), Institute of Pediatric Research Sant Joan de Déu, Madrid, Spain; Department of Neurology, Neurometabolic Units, Hospital Sant Joan de Déu, Instituto de Salud Carlos III, Barcelona, Spain
| | - Federico Ramos
- Center for Biomedical Research on Rare Diseases (CIBERER), Institute of Pediatric Research Sant Joan de Déu, Madrid, Spain; Department of Neurology, Neurometabolic Units, Hospital Sant Joan de Déu, Instituto de Salud Carlos III, Barcelona, Spain
| | - Àngels Garcia-Cazorla
- Center for Biomedical Research on Rare Diseases (CIBERER), Institute of Pediatric Research Sant Joan de Déu, Madrid, Spain; Department of Neurology, Neurometabolic Units, Hospital Sant Joan de Déu, Instituto de Salud Carlos III, Barcelona, Spain
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Rubegni A, Cardaioli E, Chini E, Da Pozzo P, Battisti C, Malandrini A, Federico A. A case of 3243A>G mutation in mtDNA presenting as apparently idiopathic hyperCKemia. J Neurol Sci 2014; 338:232-4. [DOI: 10.1016/j.jns.2014.01.010] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2013] [Revised: 12/14/2013] [Accepted: 01/06/2014] [Indexed: 10/25/2022]
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Mancuso M, Orsucci D, Angelini C, Bertini E, Carelli V, Comi GP, Donati A, Minetti C, Moggio M, Mongini T, Servidei S, Tonin P, Toscano A, Uziel G, Bruno C, Ienco EC, Filosto M, Lamperti C, Catteruccia M, Moroni I, Musumeci O, Pegoraro E, Ronchi D, Santorelli FM, Sauchelli D, Scarpelli M, Sciacco M, Valentino ML, Vercelli L, Zeviani M, Siciliano G. The m.3243A>G mitochondrial DNA mutation and related phenotypes. A matter of gender? J Neurol 2014; 261:504-10. [PMID: 24375076 DOI: 10.1007/s00415-013-7225-3] [Citation(s) in RCA: 92] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2013] [Revised: 12/16/2013] [Accepted: 12/17/2013] [Indexed: 11/25/2022]
Abstract
The m.3243A>G "MELAS" (mitochondrial encephalopathy with lactic acidosis and stroke-like episodes) mutation is one of the most common point mutations of the mitochondrial DNA, but its phenotypic variability is incompletely understood. The aim of this study was to revise the phenotypic spectrum associated with the mitochondrial m.3243A>G mutation in 126 Italian carriers of the mutation, by a retrospective, database-based study ("Nation-wide Italian Collaborative Network of Mitochondrial Diseases"). Our results confirmed the high clinical heterogeneity of the m.3243A>G mutation. Hearing loss and diabetes were the most frequent clinical features, followed by stroke-like episodes. "MIDD" (maternally-inherited diabetes and deafness) and "PEO" (progressive external ophthalmoplegia) are nosographic terms without any real prognostic value, because these patients may be even more prone to the development of multisystem complications such as stroke-like episodes and heart involvement. The "MELAS" acronym is convincing and useful to denote patients with histological, biochemical and/or molecular evidence of mitochondrial disease who experience stroke-like episodes. Of note, we observed for the first time that male gender could represent a risk factor for the development of stroke-like episodes in Italian m.3243A>G carriers. Gender effect is not a new concept in mitochondrial medicine, but it has never been observed in MELAS. A better elucidation of the complex network linking mitochondrial dysfunction, apoptosis, estrogen effects and stroke-like episodes may hold therapeutic promises.
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Martikainen MH, Kytövuori L, Majamaa K. Juvenile parkinsonism, hypogonadism and Leigh-like MRI changes in a patient with m.4296G>A mutation in mitochondrial DNA. Mitochondrion 2013; 13:83-6. [PMID: 23395828 DOI: 10.1016/j.mito.2013.01.012] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2012] [Revised: 09/18/2012] [Accepted: 01/31/2013] [Indexed: 10/27/2022]
Abstract
Leigh syndrome is a mitochondrial disease with considerable clinical and genetic variation. We present a 16-year-old boy with Leigh-like syndrome and broad developmental retardation, parkinsonism and hypogonadism. Sequencing of the entire mitochondrial DNA from blood revealed the m.4296G>A mutation in the MT-TI gene. The mutation was heteroplasmic with a 95% proportion of the mutant genome, while the proportion was 58% in the blood of the patient's clinically healthy mother. Our results suggest that m.4296G>A is pathogenic in humans, and that the phenotype related to this change includes Leigh-like syndrome in adolescence with parkinsonism and hypogonadism, in addition to the previously reported early infantile Leigh syndrome.
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Affiliation(s)
- Mika H Martikainen
- University of Turku and Turku University Hospital, Division of Clinical Neurosciences, Turku, Finland
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McKelvie P, Satchi K, McNab AA, Kennedy P. Orbicularis oculi: morphological changes mimicking mitochondrial cytopathy in a series of control normal muscles. Clin Exp Ophthalmol 2011; 40:497-502. [DOI: 10.1111/j.1442-9071.2011.02727.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
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Roels F, Verloo P, Eyskens F, François B, Seneca S, De Paepe B, Martin JJ, Meersschaut V, Praet M, Scalais E, Espeel M, Smet J, Van Goethem G, Van Coster R. Mitochondrial mosaics in the liver of 3 infants with mtDNA defects. BMC Clin Pathol 2009; 9:4. [PMID: 19500334 PMCID: PMC2706255 DOI: 10.1186/1472-6890-9-4] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2008] [Accepted: 06/05/2009] [Indexed: 01/01/2023] Open
Abstract
Background In muscle cytochrome oxidase (COX) negative fibers (mitochondrial mosaics) have often been visualized. Methods COX activity staining of liver for light and electron microscopy, muscle stains, blue native gel electrophoresis and activity assays of respiratory chain proteins, their immunolocalisation, mitochondrial and nuclear DNA analysis. Results Three unrelated infants showed a mitochondrial mosaic in the liver after staining for COX activity, i.e. hepatocytes with strongly reactive mitochondria were found adjacent to cells with many negative, or barely reactive, mitochondria. Deficiency was most severe in the patient diagnosed with Pearson syndrome. Ragged-red fibers were absent in muscle biopsies of all patients. Enzyme biochemistry was not diagnostic in muscle, fibroblasts and lymphocytes. Blue native gel electrophoresis of liver tissue, but not of muscle, demonstrated a decreased activity of complex IV; in both muscle and liver subcomplexes of complex V were seen. Immunocytochemistry of complex IV confirmed the mosaic pattern in two livers, but not in fibroblasts. MRI of the brain revealed severe white matter cavitation in the Pearson case, but only slight cortical atrophy in the Alpers-Huttenlocher patient, and a normal image in the 3rd. MtDNA in leucocytes showed a common deletion in 50% of the mtDNA molecules of the Pearson patient. In the patient diagnosed with Alpers-Huttenlocher syndrome, mtDNA was depleted for 60% in muscle. In the 3rd patient muscular and hepatic mtDNA was depleted for more than 70%. Mutations in the nuclear encoded gene of POLG were subsequently found in both the 2nd and 3rd patients. Conclusion Histoenzymatic COX staining of a liver biopsy is fast and yields crucial data about the pathogenesis; it indicates whether mtDNA should be assayed. Each time a mitochondrial disorder is suspected and muscle data are non-diagnostic, a liver biopsy should be recommended. Mosaics are probably more frequent than observed until now. A novel pathogenic mutation in POLG is reported. Tentative explanations for the mitochondrial mosaics are, in one patient, unequal partition of mutated mitochondria during mitoses, and in two others, an interaction between products of several genes required for mtDNA maintenance.
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Affiliation(s)
- Frank Roels
- Department of Pathology, Ghent University Hospital, block A, De Pintelaan 185, 9000 Gent, Belgium.
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Lindroos MM, Majamaa K, Tura A, Mari A, Kalliokoski KK, Taittonen MT, Iozzo P, Nuutila P. m.3243A>G mutation in mitochondrial DNA leads to decreased insulin sensitivity in skeletal muscle and to progressive beta-cell dysfunction. Diabetes 2009; 58:543-9. [PMID: 19073775 PMCID: PMC2646052 DOI: 10.2337/db08-0981] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
OBJECTIVE To study insulin sensitivity and perfusion in skeletal muscle together with the beta-cell function in subjects with the m.3243A>G mutation in mitochondrial DNA, the most common cause of mitochondrial diabetes. RESEARCH DESIGN AND METHODS We measured skeletal muscle glucose uptake and perfusion using positron emission tomography and 2-[18F]fluoro-2-deoxyglucose and [15O]H2O during euglycemic hyperinsulinemia in 15 patients with m.3243A>G. These patients included five subjects with no diabetes as defined by the oral glucose tolerance test (OGTT) (group 1), three with GHb <6.1% and newly found diabetes by OGTT (group 2), and seven with a previously diagnosed diabetes (group 3). Control subjects consisted of 13 healthy individuals who were similar to the carriers of m.3243A>G with respect to age and physical activity. Beta-cell function was assessed using the OGTT and subsequent mathematical modeling. RESULTS Skeletal muscle glucose uptake was significantly lower in groups 1, 2, and 3 than in the control subjects. The glucose sensitivity of beta-cells in group 1 patients was similar to that of the control subjects, whereas in group 2 and 3 patients, the glucose sensitivity was significantly lower. The insulin secretion parameters correlated strongly with the proportion of m.3243A>G mutation in muscle. CONCLUSIONS Our findings show that subjects with m.3243A>G are insulin resistant in skeletal muscle even when beta-cell function is not markedly impaired or glucose control compromised. We suggest that both the skeletal muscle insulin sensitivity and the beta-cell function are affected before the onset of the mitochondrial diabetes caused by the m.3243A>G mutation.
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Affiliation(s)
- Markus M Lindroos
- Turku PET Centre, University of Turku and Turku University Hospital, Turku, Finland.
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Wortmann SB, Rodenburg RJ, Backx AP, Schmitt E, Smeitink JAM, Morava E. Early cardiac involvement in children carrying the A3243G mtDNA mutation. Acta Paediatr 2007; 96:450-1. [PMID: 17407476 DOI: 10.1111/j.1651-2227.2006.00158.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
UNLABELLED The phenotypic spectrum of the mitochondrial A3243G DKA mutation is highly variable, particularly when occuring in childhood. In contrast to the classical presentation in adulthood (MELAS syndrome; mitochondria! myopathy, encephalopathy, lactic acidosis and stroke-like episodes) children show a different pattern of symptoms, often without the typical encephalopathy or psychomotor regression. We present six children carrying the A3243G mtDNA mutation with a heteroplasmy above 50 % in muscle tissue. The age of diagnosis ranged from 2 weeks up to 14.5 years. The clinical presentation was rather non-specific including muscle weakness, developmental delay and epilepsy. In this small pediatric group we detected presymptomatic cardiac involvement in five out of six children already at an early stage of disease. The cardiac pathology included cardiomyopathy and biventricular hypertrophy with rhythm disturbances (for example long QT-syndrome). The observed cardiac changes do not always increase the risk of cardiac deterioration; however, two of our patients died early on. CONCLUSION We hypothesize that the A3243G mutation might be underdiagnosed, as patients could suffer from an unexplained cardiac death before the diagnosis is made. We advise performing regular repeated ECGs and echocardiography in all children carrying a A3243G mtDNA mutation independently from the presence of cardiac symptoms.
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Affiliation(s)
- S B Wortmann
- Department of Pediatrics, Radboud University Nijmegen Medical Centre, Nijmegen Centre for Mitochondrial Disorders, Nijmegen, The Netherlands
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Annunen-Rasila J, Kärppä M, Finnilä S, Ylä-Outinen H, Veijola J, Tuominen H, Peltonen J, Majamaa K. Cytoskeletal structure in cells harboring two mutations: R133C in NOTCH3 and 5650G>A in mitochondrial DNA. Mitochondrion 2007; 7:96-100. [PMID: 17276737 DOI: 10.1016/j.mito.2006.11.004] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2006] [Accepted: 09/21/2006] [Indexed: 11/20/2022]
Abstract
We have previously described a patient with cerebral autosomal-dominant arteriopathy with subcortical infarcts and leucoencephalopathy (CADASIL) caused by R133C mutation in NOTCH3 and with a concomitant myopathy caused by a G to A point mutation at base pair 5650 (5650G>A) in the gene encoding tRNA(Ala) in mitochondrial DNA (mtDNA). In the present study, we have examined the morphology of the cytoskeletal components in fibroblasts and myoblasts of this patient. Immunolabeling revealed that tubulin network was sparse and formed asters in these cells, whereas no changes were found in actin and vimentin networks in comparison to the control cell lines. Furthermore, mitochondria were less abundant and the branches of the mitochondrial network were reduced in number. Muscle histochemical analysis showed ragged red fibres (RRFs) and cytochrome c oxidase (COX)-negative fibres. The mean proportion of mtDNA with 5650G>A was lower in histologically normal muscle fibres than in the COX-negative fibres and in the RRFs. These findings suggest that 5650G>A is a pathogenic mtDNA mutation. However, the changes in tubulin network and mitochondrial distribution in patient fibroblasts and myoblasts cannot solely be explained by this mutation.
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Abstract
PURPOSE OF REVIEW Our understanding of mitochondrial diseases (defined restrictively as defects of the mitochondrial respiratory chain) is expanding rapidly. In this review, I will give the latest information on disorders affecting predominantly or exclusively skeletal muscle. RECENT FINDINGS The most recently described mitochondrial myopathies are due to defects in nuclear DNA, including coenzyme Q10 deficiency and mutations in genes controlling mitochondrial DNA abundance and structure, such as POLG, TK2, and MPV17. Barth syndrome, an X-linked recessive mitochondrial myopathy/cardiopathy, is associated with decreased amount and altered structure of cardiolipin, the main phospholipid of the inner mitochondrial membrane, but a secondary impairment of respiratory chain function is plausible. The role of mutations in protein-coding genes of mitochondrial DNA in causing isolated myopathies has been confirmed. Mutations in tRNA genes of mitochondrial DNA can also cause predominantly myopathic syndromes and--contrary to conventional wisdom--these mutations can be homoplasmic. SUMMARY Defects in the mitochondrial respiratory chain impair energy production and almost invariably involve skeletal muscle, causing exercise intolerance, cramps, recurrent myoglobinuria, or fixed weakness, which often affects extraocular muscles and results in droopy eyelids (ptosis) and progressive external ophthalmoplegia.
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Affiliation(s)
- Salvatore DiMauro
- Department of Neurology, Columbia University Medical Center, New York, NY 10032, USA.
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Bibliography. Current world literature. Raynaud phenomenon, scleroderma, overlap syndromes and other fibrosing syndromes. Curr Opin Rheumatol 2006; 18:654-6. [PMID: 17053515 DOI: 10.1097/bor.0b013e328010f1cd] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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