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Sukri A, Noorizhab MNF, Teh LK, Salleh MZ. Insight of the mitochondrial genomes of the Orang Asli and Malays: The heterogeneity and the disease-associated variants. Mitochondrion 2021; 62:74-84. [PMID: 34748985 DOI: 10.1016/j.mito.2021.10.010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2021] [Revised: 10/27/2021] [Accepted: 10/28/2021] [Indexed: 11/27/2022]
Abstract
Orang Asli are the oldest inhabitants in Peninsular Malaysia that forms as a national minority while the Malays are the majority. The study aimed to screen the mitochondrial genomes of the Orang Asli and the Malays to discover the disease-associated variants. A total of 99 Orang Asli from six tribes (Bateq, Cheq Wong, Orang Kanaq, Kensiu, Lanoh, and Semai) were recruited. Mitochondrial genome sequencing was conducted using a next-generation sequencing platform. Furthermore, we retrieved mitochondrial DNA sequences from the Malays for comparison. The clinical significance, pathogenicity prediction and frequency of variants were determined using online tools. Variants associated with mitochondrial diseases were detected in the 2 populations. A high frequency of variants associated with mitochondrial diseases, breast cancer, prostate cancer, and cervical cancer were detected in the Orang Asli and modern Malays. As medicine evolves to adopt prediction and prevention of diseases, this study highlights the need for intervention to adopt genomics medicine to strategise better healthcare management as a way forward for Precision Health.
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Affiliation(s)
- Asif Sukri
- Integrative Pharmacogenomics Institute, Universiti Teknologi MARA Cawangan Selangor, Puncak Alam Campus, 42300 Puncak Alam, Selangor, Malaysia
| | - Mohd Nur Fakhruzzaman Noorizhab
- Integrative Pharmacogenomics Institute, Universiti Teknologi MARA Cawangan Selangor, Puncak Alam Campus, 42300 Puncak Alam, Selangor, Malaysia; Faculty of Pharmacy, Universiti Teknologi MARA Cawangan Selangor, Puncak Alam Campus, 42300 Puncak Alam, Selangor, Malaysia
| | - Lay Kek Teh
- Integrative Pharmacogenomics Institute, Universiti Teknologi MARA Cawangan Selangor, Puncak Alam Campus, 42300 Puncak Alam, Selangor, Malaysia; Faculty of Pharmacy, Universiti Teknologi MARA Cawangan Selangor, Puncak Alam Campus, 42300 Puncak Alam, Selangor, Malaysia
| | - Mohd Zaki Salleh
- Integrative Pharmacogenomics Institute, Universiti Teknologi MARA Cawangan Selangor, Puncak Alam Campus, 42300 Puncak Alam, Selangor, Malaysia.
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Hu C, Li X, Zhao L, Shi Y, Zhou S, Wang Y. Clinical Profile and Outcome of Pediatric Mitochondrial Myopathy in China. Front Neurol 2020; 11:1000. [PMID: 33013660 PMCID: PMC7506116 DOI: 10.3389/fneur.2020.01000] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2020] [Accepted: 07/30/2020] [Indexed: 12/16/2022] Open
Abstract
Introduction: Mitochondrial myopathy in children has notable clinical and genetic heterogeneity, but detailed data is lacking. Patients and Methods: In this study, we retrospectively reviewed the clinical presentation, laboratory investigation, genetic and histopathological characteristics, and follow-ups of 21 pediatric mitochondrial myopathy cases from China. Results: Twenty-four patients suspected with mitochondrial myopathy were enrolled initially and 21 were genetically identified. Fourteen patients were found to harbor mitochondrial DNA point mutations (14/21, 66.7%), including m.3243A>G (9/15, 60%), m.3303C>T (2/15, 13.3%), m.3302A>G (1/15, 6.7%), m.3250T>C (1/15, 6.7%), m.3251A>G (1/15, 6.7%), of whom 12 patients presented with progressive proximal mitochondrial myopathy (12/14, 85.7%). Three patients revealed large-scale deletion in blood or muscle tissue (3/21, 14.3%), presenting with Kearns-Sayer syndrome (1/3, 33.3%) or chronic progressive external ophthalmoplegia (2/3, 66.7%). Four patients were found to harbor pathogenic nuclear gene variants (4/21, 19.0%), including five variants in TK2 gene and two variants in SURF1 gene. During the follow-ups up to 7 years, 10 patients developed cardiomyopathy (10/21, 47.6%), 13 patients occurred at least once hypercapnic respiratory failure (13/21, 61.9%), six experienced recurrent respiratory failure and intubation (6/21, 28.6%), eight patients failed to survive (8/21, 38.1%). With nocturnal non-invasive ventilation of BiPAP, three patients recovered from respiratory failure, and led a relative stable and functional life (3/21, 14.3%). Conclusion: Mitochondrial myopathy in children has great clinical, pathological, and genetical heterogeneity. Progressive proximal myopathy is most prevalent. Mitochondrial DNA point mutations are most common. And respiratory failure is a critical risk factor of poor prognosis.
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Affiliation(s)
- Chaoping Hu
- Neurology Department, Children's Hospital of Fudan University, Shanghai, China
| | - Xihua Li
- Neurology Department, Children's Hospital of Fudan University, Shanghai, China
| | - Lei Zhao
- Neurology Department, Children's Hospital of Fudan University, Shanghai, China
| | - Yiyun Shi
- Neurology Department, Children's Hospital of Fudan University, Shanghai, China
| | - Shuizhen Zhou
- Neurology Department, Children's Hospital of Fudan University, Shanghai, China
| | - Yi Wang
- Neurology Department, Children's Hospital of Fudan University, Shanghai, China
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Yuan H, Yang H, Peng L, Peng Y, Chen Z, Wan L, Wang C, Shi Y, Zhang VW, Tang B, Qiu R, Jiang H. Profiling of mitochondrial genomes in SCA3/MJD patients from mainland China. Gene 2020; 738:144487. [PMID: 32087274 DOI: 10.1016/j.gene.2020.144487] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2019] [Revised: 02/15/2020] [Accepted: 02/19/2020] [Indexed: 02/08/2023]
Abstract
Spinocerebellar ataxia type 3, also known as Machado-Joseph disease (SCA3/MJD), is the most common type of autosomal dominant cerebellar ataxias. Few studies focused on the changes of the whole mitochondrial genomes of SCA3/MJD patients and its relationship with the pathogenesis of SCA3/MJD. We adapted one-step long-range PCR to amplify the entire mitochondrial DNA (mtDNA) followed by next-generation sequencing technology to investigate the information of whole mitochondrial genomes in 38 SCA3/MJD patients and 31 healthy controls from mainland China. Compared to the healthy control group, the mitochondrial variations in SCA3/MJD patients were more concentrated in the tRNA-transcribed genes which were further found to be potentially associated with the pathogenesis of SCA3/MJD by SKAT-O analysis. However, owning variations in tRNA-transcribed genes could not affect the age of onset (AO) of SCA3/MJD patients. We also noticed that the variant loads greater than 90% took up more in SCA3/MJD patients than in controls. Moreover, from our preliminary study, compared to the patients whose ages of onset were elder than 20, the mitochondrial genomes showed no difference in those AO less than 20. This is the first study to demonstrate the feasibility of using the next-generation sequencing technology for mtDNA variant analysis of SCA3/MJD patients from mainland China. And this research enriches the genetic information of SCA3/MJD and provides a direction for further investigations about the mitochondrial genomes in SCA3/MJD.
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Affiliation(s)
- Hongyu Yuan
- Department of Neurology, Xiangya Hospital, Central South University, Changsha, Hunan, China
| | - Huihua Yang
- Department of Neurology, Xiangya Hospital, Central South University, Changsha, Hunan, China
| | - Linliu Peng
- Department of Neurology, Xiangya Hospital, Central South University, Changsha, Hunan, China
| | - Yun Peng
- Department of Neurology, Xiangya Hospital, Central South University, Changsha, Hunan, China
| | - Zhao Chen
- Department of Neurology, Xiangya Hospital, Central South University, Changsha, Hunan, China
| | - Linlin Wan
- Department of Neurology, Xiangya Hospital, Central South University, Changsha, Hunan, China
| | - Chunrong Wang
- Department of Neurology, Xiangya Hospital, Central South University, Changsha, Hunan, China
| | - Yuting Shi
- Department of Neurology, Xiangya Hospital, Central South University, Changsha, Hunan, China
| | - Victor Wei Zhang
- AmCare Genomics Laboratory, Guangzhou, China; Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
| | - Beisha Tang
- Department of Neurology, Xiangya Hospital, Central South University, Changsha, Hunan, China; National Clinical Research Center for Geriatric Diseases, Central South University, Changsha, Hunan, China; Key Laboratory of Hunan Province in Neurodegenerative Disorders, Central South University, Changsha, Hunan, China; Laboratory of Medical Genetics, Central South University, Changsha, Hunan, China
| | - Rong Qiu
- School of Computer Science and Engineering, Central South University, Changsha, China.
| | - Hong Jiang
- Department of Neurology, Xiangya Hospital, Central South University, Changsha, Hunan, China; National Clinical Research Center for Geriatric Diseases, Central South University, Changsha, Hunan, China; Key Laboratory of Hunan Province in Neurodegenerative Disorders, Central South University, Changsha, Hunan, China; Laboratory of Medical Genetics, Central South University, Changsha, Hunan, China; Xinjiang Medical University, Urumchi, Xinjiang, China.
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Liu G, Shen X, Sun Y, Lv Q, Li Y, Du A. Heteroplasmy and phenotype spectrum of the mitochondrial tRNA Leu (UUR) gene m.3243A>G mutation in seven Han Chinese families. J Neurol Sci 2020; 408:116562. [PMID: 31722256 DOI: 10.1016/j.jns.2019.116562] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2019] [Revised: 11/03/2019] [Accepted: 11/04/2019] [Indexed: 01/06/2023]
Abstract
The m.3243A > G mutation in the mitochondrial tRNALeu (UUR) gene is associated with a variety of phenotypic heterogeneity. The clinical spectrum and phenotypic-genotypic correlations in the Chinese patients are poorly understood. In the present study, we reported the clinical and genetic characterization, as well as haplogroups of seven Han Chinese families carrying the m.3243A > G mutation. Of the 39 matrilineal individuals, five suffered from mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes (MELAS), two had life-threatening mitochondrial myopathy (LTMM), and one patient had neuropathy, ataxia, and retinitis pigmentosa (NARP)-like syndrome. The LTMM and NARP like syndromes enriched the phenotypic profile of the m.3243A > G mutation. The heteroplasmy of the m.3243A > G mutation ranged from 16% to 59% in MELAS, 29% to 79% in LTMM, and 57% in a NARP-like syndrome patient. The levels ranged from 0% to 14% in patients that manifested with pure diabetes and pure hearing loss, and 0% to 5% in 13 normal family members. However, we particularly noticed heteroplasmy in four asymptomatic individuals in one LTMM family carried the heteroplasmy mutation ranged from 22% to 78%, implying that there were other modifying factors in this family. The modulation of the phenotype of mtDNA mutations requires further investigation.
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Affiliation(s)
- Gailing Liu
- Department of Neurology, Tongren Hospital, Shanghai Jiaotong University School of Medicine, Shanghai 200336, China
| | - Xiya Shen
- Department of Neurology, Tongren Hospital, Shanghai Jiaotong University School of Medicine, Shanghai 200336, China
| | - Yongan Sun
- Department of Neurology, Perking University First Hospital, Beijing 100034, China
| | - Qing Lv
- Department of Neurology, Tongren Hospital, Shanghai Jiaotong University School of Medicine, Shanghai 200336, China
| | - Yuanyuan Li
- Department of Neurology, Tongren Hospital, Shanghai Jiaotong University School of Medicine, Shanghai 200336, China
| | - Ailian Du
- Department of Neurology, Tongren Hospital, Shanghai Jiaotong University School of Medicine, Shanghai 200336, China; Department of Neurology, Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou 310009, China.
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Zhou Y, Yi J, Liu L, Wang X, Dong L, Du A. Acute mitochondrial myopathy with respiratory insufficiency and motor axonal polyneuropathy. Int J Neurosci 2017; 128:231-236. [PMID: 28969510 DOI: 10.1080/00207454.2017.1387113] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
BACKGROUND Mitochondrial myopathies (MMs) are mainly presented with chronic muscle weakness and accompanied with other syndromes. MM with acute respiratory insufficiency is rare. AIMS To reveal the clinical, pathological and molecular characteristics of a life-threatening MM. METHODS Muscle biopsy and enzyme staining were performed in skeletal muscles. Mitochondrial DNA (mtDNA) sequencing was analyzed and heteroplasmy were quantified by pyrosequencing. RESULTS All three patients had tachycardia, acute lactic acidosis, dyspnea and sudden severe muscle weakness. Two patients had calf edema and abdominal pain, and one had a heart attack. Electromyography in two patients showed dramatically decreased axonal amplitudes of motor nerves. Muscle biopsies showed ragged red fibers and dramatic mitochondrial abnormality. A mtDNA m.3243A>G mutation was identified in Patient 1 (mutation load: 29% in blood and 73% in muscle) and Patient 3 (79% in blood and 89% in muscle). A mtDNA m.8344A>G mutation was found in Patient 2 (mutation load 80.4% in blood). CONCLUSION MM characterized by lactic acidosis, respiratory failure and acute motor axonal neuropathy is life threatening.
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Affiliation(s)
- Ying Zhou
- a Department of Cardiology , Second Affiliated Hospital, Zhejiang University School of Medicine , Hangzhou , China
| | - Jianhua Yi
- b Department of Emergency Medicine , Second Affiliated Hospital, Zhejiang University School of Medicine , Hangzhou , China
| | - Li Liu
- c Mitochondrial Disease Research Center, Institute of Genetics , College of Life Science, Zhejiang University , Hangzhou , China
| | - Xiaoping Wang
- d Department of Neurology , Tongren Hospital, Shanghai Jiaotong University School of Medicine , Shanghai , China
| | - Liang Dong
- a Department of Cardiology , Second Affiliated Hospital, Zhejiang University School of Medicine , Hangzhou , China
| | - Ailian Du
- d Department of Neurology , Tongren Hospital, Shanghai Jiaotong University School of Medicine , Shanghai , China
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Ogawa E, Shimura M, Fushimi T, Tajika M, Ichimoto K, Matsunaga A, Tsuruoka T, Ishige M, Fuchigami T, Yamazaki T, Mori M, Kohda M, Kishita Y, Okazaki Y, Takahashi S, Ohtake A, Murayama K. Clinical validity of biochemical and molecular analysis in diagnosing Leigh syndrome: a study of 106 Japanese patients. J Inherit Metab Dis 2017; 40:685-693. [PMID: 28429146 PMCID: PMC5579154 DOI: 10.1007/s10545-017-0042-6] [Citation(s) in RCA: 70] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/06/2016] [Revised: 03/01/2017] [Accepted: 03/24/2017] [Indexed: 01/30/2023]
Abstract
Leigh syndrome (LS) is a progressive neurodegenerative disorder of infancy and early childhood. It is clinically diagnosed by typical manifestations and characteristic computed tomography (CT) or magnetic resonance imaging (MRI) studies. Unravelling mitochondrial respiratory chain (MRC) dysfunction behind LS is essential for deeper understanding of the disease, which may lead to the development of new therapies and cure. The aim of this study was to evaluate the clinical validity of various diagnostic tools in confirming MRC disorder in LS and Leigh-like syndrome (LL). The results of enzyme assays, molecular analysis, and cellular oxygen consumption rate (OCR) measurements were examined. Of 106 patients, 41 were biochemically and genetically verified, and 34 had reduced MRC activity but no causative mutations. Seven patients with normal MRC complex activities had mutations in the MT-ATP6 gene. Five further patients with normal activity in MRC were identified with causative mutations. Conversely, 12 out of 60 enzyme assays performed for genetically verified patients returned normal results. No biochemical or genetic background was confirmed for 19 patients. OCR was reduced in ten out of 19 patients with negative enzyme assay results. Inconsistent enzyme assay results between fibroblast and skeletal muscle biopsy samples were observed in 33% of 37 simultaneously analyzed cases. These data suggest that highest diagnostic rate is reached using a combined enzymatic and genetic approach, analyzing more than one type of biological materials where suitable. Microscale oxygraphy detected MRC impairment in 50% cases with no defect in MRC complex activities.
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Affiliation(s)
- Erika Ogawa
- Department of Metabolism, Chiba Children's Hospital, 579-1 Heta-cho, Midori-ku, Chiba, 266-0007, Japan
- Department of Pediatrics and Child Health, Nihon University School of Medicine, 30-1 Ohyaguchikami-cho, Itabashi-ku, Tokyo, 173-8610, Japan
| | - Masaru Shimura
- Department of Metabolism, Chiba Children's Hospital, 579-1 Heta-cho, Midori-ku, Chiba, 266-0007, Japan
| | - Takuya Fushimi
- Department of Metabolism, Chiba Children's Hospital, 579-1 Heta-cho, Midori-ku, Chiba, 266-0007, Japan
| | - Makiko Tajika
- Department of Metabolism, Chiba Children's Hospital, 579-1 Heta-cho, Midori-ku, Chiba, 266-0007, Japan
| | - Keiko Ichimoto
- Department of Metabolism, Chiba Children's Hospital, 579-1 Heta-cho, Midori-ku, Chiba, 266-0007, Japan
| | - Ayako Matsunaga
- Department of Metabolism, Chiba Children's Hospital, 579-1 Heta-cho, Midori-ku, Chiba, 266-0007, Japan
| | - Tomoko Tsuruoka
- Department of Metabolism, Chiba Children's Hospital, 579-1 Heta-cho, Midori-ku, Chiba, 266-0007, Japan
| | - Mika Ishige
- Department of Pediatrics and Child Health, Nihon University School of Medicine, 30-1 Ohyaguchikami-cho, Itabashi-ku, Tokyo, 173-8610, Japan
| | - Tatsuo Fuchigami
- Department of Pediatrics and Child Health, Nihon University School of Medicine, 30-1 Ohyaguchikami-cho, Itabashi-ku, Tokyo, 173-8610, Japan
| | - Taro Yamazaki
- Department of Pediatrics, Saitama Medical University, 38 Morohongo, Moroyama, Saitama, 350-0495, Japan
| | - Masato Mori
- Department of Pediatrics, Matsudo City Hospital, Matsudo, 4005 Kamihongo, Matsudo, Chiba, 271-8511, Japan
| | - Masakazu Kohda
- Division of Translational Research, Research Center for Genomic Medicine, Saitama Medical University, 1397-1 Yamane, Hidaka, Saitama, 350-1241, Japan
| | - Yoshihito Kishita
- Division of Functional Genomics and Systems Medicine, Research Center for Genomic Medicine, Saitama Medical University, 1397-1 Yamane, Hidaka, Saitama, 350-1241, Japan
| | - Yasushi Okazaki
- Division of Translational Research, Research Center for Genomic Medicine, Saitama Medical University, 1397-1 Yamane, Hidaka, Saitama, 350-1241, Japan
- Division of Functional Genomics and Systems Medicine, Research Center for Genomic Medicine, Saitama Medical University, 1397-1 Yamane, Hidaka, Saitama, 350-1241, Japan
| | - Shori Takahashi
- Department of Pediatrics and Child Health, Nihon University School of Medicine, 30-1 Ohyaguchikami-cho, Itabashi-ku, Tokyo, 173-8610, Japan
| | - Akira Ohtake
- Department of Pediatrics, Saitama Medical University, 38 Morohongo, Moroyama, Saitama, 350-0495, Japan.
| | - Kei Murayama
- Department of Metabolism, Chiba Children's Hospital, 579-1 Heta-cho, Midori-ku, Chiba, 266-0007, Japan.
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Lacomis D. Electrophysiology of neuromuscular disorders in critical illness. Muscle Nerve 2013; 47:452-63. [PMID: 23386582 DOI: 10.1002/mus.23615] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/31/2012] [Indexed: 01/03/2023]
Abstract
INTRODUCTION Neuromuscular disorders, predominantly critical illness myopathy (CIM) and critical illness polyneuropathy (CIP) occur in approximately one-third of patients in intensive care units. The aim of this study was to review the important role of electrophysiology in this setting. RESULTS In CIM, sarcolemmal inexcitability causes low amplitude compound muscle action potentials (CMAPs) that may have prolonged durations. Needle electrode examination usually reveals early recruitment of short duration motor unit potentials, often with fibrillation potentials. In CIP, the findings are usually those of a generalized axonal sensorimotor polyneuropathy. Direct muscle stimulation aids in differentiating CIP and CIM and in identifying mixed disorders along with other electrodiagnostic and histopathologic studies. Identifying evolving reductions in fibular CMAP amplitudes in intensive care unit (ICU) patients predicts development of neuromuscular weakness. CONCLUSIONS Knowledge of the various neuromuscular disorders in critically ill patients, their risk factors, and associated electrodiagnostic findings can lead to development of a rational approach to diagnosis of the cause of neuromuscular weakness in ICU patients.
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Affiliation(s)
- David Lacomis
- Department of Neurology, University of Pittsburgh School of Medicine, 200 Lothrop Street, F878, Pittsburgh, Pennsylvania 15213, USA.
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Uusimaa J, Jungbluth H, Fratter C, Crisponi G, Feng L, Zeviani M, Hughes I, Treacy EP, Birks J, Brown GK, Sewry CA, McDermott M, Muntoni F, Poulton J. Reversible infantile respiratory chain deficiency is a unique, genetically heterogenous mitochondrial disease. J Med Genet 2011; 48:660-668. [PMID: 21931168 PMCID: PMC4562368 DOI: 10.1136/jmg.2011.089995] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
OBJECTIVES Homoplasmic maternally inherited, m.14674T>C or m. 14674T>G mt-tRNA(Glu) mutations have recently been identified in reversible infantile cytochrome c oxidase deficiency (or 'benign COX deficiency'). This study sought other genetic defects that may give rise to similar presentations. PATIENTS Eight patients from seven families with clinicopathological features of infantile reversible cytochrome c oxidase deficiency were investigated. METHODS The study reviewed the diagnostic features and performed molecular genetic analyses of mitochondrial DNA and nuclear encoded candidate genes. RESULTS Patients presented with subacute onset of profound hypotonia, feeding difficulties and lactic acidosis within the first months of life. Although recovery was remarkable, a mild myopathy persisted into adulthood. Histopathological findings in muscle included increased lipid and/or glycogen content, ragged-red and COX negative fibres. Biochemical studies suggested more generalised abnormalities than pure COX deficiency. Clinical improvement was reflected by normalisation of lactic acidosis and histopathological abnormalities. The m.14674T>C mt-tRNA(Glu) mutation was identified in four families, but none had the m. 14674T>G mutation. Furthermore, in two families pathogenic mutations were also found in the nuclear TRMU gene which has not previously been associated with this phenotype. In one family, the genetic aetiology still remains unknown. CONCLUSIONS Benign COX deficiency is better described as 'reversible infantile respiratory chain deficiency'. It is genetically heterogeneous, and patients not carrying the m.14674T>C or T>G mt-tRNA(Glu) mutations may have mutations in the TRMU gene. Diagnosing this disorder at the molecular level is a significant advance for paediatric neurologists and intensive care paediatricians, enabling them to select children with an excellent prognosis for continuing respiratory support from those with severe mitochondrial presentation in infancy.
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Affiliation(s)
- J Uusimaa
- Nuffield Department of Obstetrics and Gynaecology, University of Oxford, The Women's Centre, John Radcliffe Hospital, Oxford, UK
| | - H Jungbluth
- Department of Clinical Neuroscience, King's College Hospital, London, UK
- Department of Paediatric Neurology - Neuromuscular Service, Evelina Children's Hospital, St Thomas' Hospital, London, UK
| | - C Fratter
- Oxford Medical Genetics Lab, Churchill Hospital, Oxford, UK
| | - G Crisponi
- Servizio di Puericultura, Universita' di Cagliari, Italy
| | - L Feng
- Dubowitz Neuromuscular Centre, UCL Institute of Child Health, London, UK
| | - M Zeviani
- Unit of Molecular Neurogenetics, "C. Besta" Neurological Institute - IRCCS Foundation, Milan, Italy
| | - I Hughes
- Department of Paediatric Neurology, Manchester Children's Hospital, Manchester, UK
| | - E P Treacy
- National Centre for Inherited Metabolic Disease, Children's University Hospital, Dublin Republic of Ireland
| | - J Birks
- Centre for Statistics in Medicine, University of Oxford, UK
| | - G K Brown
- Department of Biochemistry, University of Oxford, UK
| | - C A Sewry
- Dubowitz Neuromuscular Centre, UCL Institute of Child Health, London, UK
| | - M McDermott
- Our Lady's Hospital for Sick Children, Dublin, Ireland
| | - F Muntoni
- Dubowitz Neuromuscular Centre, UCL Institute of Child Health, London, UK
| | - J Poulton
- Nuffield Department of Obstetrics and Gynaecology, University of Oxford, The Women's Centre, John Radcliffe Hospital, Oxford, UK
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Abstract
Neuromuscular disorders that are diagnosed in the intensive care unit (ICU) usually cause substantial limb weakness and contribute to ventilatory dysfunction. Although some lead to ICU admission, ICU-acquired disorders, mainly critical illness myopathy (CIM) and critical illness polyneuropathy (CIP), are more frequent and are associated with considerable morbidity. Approximately 25% to 45% of patients admitted to the ICU develop CIM, CIP, or both. Their clinical features often overlap; therefore, nerve conduction studies and electromyography are particularly helpful diagnostically, and more sophisticated electrodiagnostic studies and histopathologic evaluation are required in some circumstances. A number of prospective studies have identified risk factors for CIP and CIM, but their limitations often include the inability to separate CIM from CIP. Animal models reveal evidence of a channelopathy in both CIM and CIP, and human studies also identified axonal degeneration in CIP and myosin loss in CIM. Outcomes are variable. They tend to be better with CIM, and some patients have longstanding disabilities. Future studies of well-characterized patients with CIP and CIM should refine our understanding of risk factors, outcomes, and pathogenic mechanisms, leading to better interventions.
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Affiliation(s)
- David Lacomis
- Department of Neurology and Pathology (Neuropathology), University of Pittsburgh School of Medicine, PA, USA.
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10
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A novel mitochondrial tRNAGlu (MTTE) gene mutation causing chronic progressive external ophthalmoplegia at low levels of heteroplasmy in muscle. J Neurol Sci 2011; 298:140-4. [PMID: 20810132 DOI: 10.1016/j.jns.2010.08.014] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2010] [Revised: 07/30/2010] [Accepted: 08/06/2010] [Indexed: 11/20/2022]
Abstract
Mitochondrial respiratory chain defects are associated with diverse clinical phenotypes in both adults and children, and may be caused by mutations in either nuclear or mitochondrial DNA (mtDNA). We report the molecular genetic investigations of a patient with chronic progressive external ophthalmoplegia (CPEO) and myopathy where muscle biopsies taken 11 years apart revealed a progressive increase in the proportion of cytochrome c oxidase (COX)-deficient fibres. Mitochondrial genetic analysis of the early biopsy had seemingly excluded both mtDNA rearrangements and mtDNA point mutations. Sequencing mtDNA from individual COX-deficient muscle fibres in the second biopsy, however, identified an unreported m.14723T>C substitution within the mitochondrial tRNAGlu (MTTE) gene, which fulfilled all canonical criteria for pathogenicity. The m.14723T>C mutation was absent from several tissues, including muscle, from maternal relatives suggesting a de novo event, whilst quantitative analysis of the first muscle biopsy confirmed a very low level of the mutation (7% mutated mtDNA), highlighting a potential problem whereby pathogenic mtDNA mutations may remain undetected using established screening methodologies.
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11
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Sacconi S, Baillif-Gostoli S, Desnuelle C. [Retinal involvement and genetic myopathy]. Rev Neurol (Paris) 2010; 166:998-1009. [PMID: 21071050 DOI: 10.1016/j.neurol.2010.09.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2010] [Revised: 05/25/2010] [Accepted: 09/22/2010] [Indexed: 01/06/2023]
Abstract
INTRODUCTION In genetic diseases, association between retinal and muscular involvement is uncommon, quite specific and frequently allows the diagnosis. In this context, three types of retinal involvement have been described: retinitis pigmentosa (RP), pattern retinal dystrophy (PRD) and exudative retinitis resembling Coats disease (CD). STATE OF THE ART The association between RP, PRD and muscle weakness is highly evocative of a mitochondrial disorder. Extra ocular muscles may be affected, but limb girdle or distal weakness can also be present in association or not with symptoms and signs of multisystemic involvement. In a large number of patients suffering from facioscapulohumeral muscular dystrophy (FSHD), retinal vessels telangectasia can be found at the fundoscopic examination. This finding, which corresponds to a developmental abnormality of peripheral retinal blood vessels, is not progressive and remains clinically asymptomatic. Nevertheless, a few patients with FSHD can develop an exsudative retinopathy resembling Coats disease with the risk of the major complication, recurrent retinal detachments. PERSPECTIVES AND CONCLUSIONS Considering the diagnostic interest and the deleterious consequences that may follow retinal involvement, close collaboration between the neurologist and ophthalmologist is needed in order to establish the diagnosis, detect complications early, and set up appropriate therapies.
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Affiliation(s)
- S Sacconi
- Centre de référence des maladies neuromusculaires et SLA, hôpital Archet 1, CHU de Nice, 151, route de Saint-Antoine-de-Ginestière, 06202 Nice, France.
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12
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Abstract
BACKGROUND Control of ventilation depends on a brainstem neuronal network that controls activity of the motor neurons innervating the respiratory muscles. This network includes the pontine respiratory group and the dorsal and ventral respiratory groups in the medulla. Neurologic disorders affecting these areas or the respiratory motor unit may lead to abnormal breathing. REVIEW SUMMARY The brainstem respiratory network contains neurons critical for respiratory rhythmogenesis; this network receives inputs from peripheral and central chemoreceptors sensitive to levels of carbon dioxide (PaCO2) and oxygen (PaO2) and from forebrain structures that control respiration as part of integrated behaviors such as speech or exercise. Manifestations associated with disorders of this network include sleep apnea and dysrhythmic breathing frequently associated with disturbances of cardiovagal and sympathetic vasomotor control. Common disorders associated with impaired cardiorespiratory control include brainstem stroke or compression, syringobulbia, Chiari malformation, high cervical spinal cord injuries, and multiple system atrophy. By far, neuromuscular disorders are the more common neurologic conditions leading to respiratory failure. CONCLUSIONS Respiratory dysfunction constitute an early and relatively major manifestation of several neurologic disorders and may be due to an abnormal breathing pattern generation due to involvement of the cardiorespiratory network or more frequently to respiratory muscle weakness.
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13
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Scaglia F, Wong LJC. Human mitochondrial transfer RNAs: role of pathogenic mutation in disease. Muscle Nerve 2008; 37:150-71. [PMID: 17999409 DOI: 10.1002/mus.20917] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
The human mitochondrial genome encodes 13 proteins. All are subunits of the respiratory chain complexes involved in energy metabolism. These proteins are translated by a set of 22 mitochondrial transfer RNAs (tRNAs) that are required for codon reading. Human mitochondrial tRNA genes are hotspots for pathogenic mutations and have attracted interest over the last two decades with the rapid discovery of point mutations associated with a vast array of neuromuscular disorders and diverse clinical phenotypes. In this review, we use a scoring system to determine the pathogenicity of the mutations and summarize the current knowledge of structure-function relationships of these mutant tRNAs. We also provide readers with an overview of a large variety of mechanisms by which mutations may affect the mitochondrial translation machinery and cause disease.
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Affiliation(s)
- Fernando Scaglia
- Department of Molecular and Human Genetics, Baylor College of Medicine, One Baylor Plaza, Houston, Texas 77030, USA
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14
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Pancrudo J, Shanske S, Bonilla E, Daras M, Akman HO, Krishna S, Malkin E, DiMauro S. Mitochondrial encephalomyopathy due to a novel mutation in the tRNAGlu of mitochondrial DNA. J Child Neurol 2007; 22:858-62. [PMID: 17715279 DOI: 10.1177/0883073807304199] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
A 14-year-old boy had exercise intolerance, weakness, ataxia, and lactic acidosis. Because his muscle biopsy showed a mosaic pattern of fibers staining intensely with the succinate dehydrogenase reaction but not at all with the cytochrome c oxidase reaction, we sequenced his mitochondrial DNA and found a novel mutation (C14680A) in the gene for tRNAGlu. The mutation was present in accessible tissues from the asymptomatic mother but not from a brother with Asperger syndrome. These data expand the clinical heterogeneity of mutations in this mitochondrial gene.
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Affiliation(s)
- Jacklyn Pancrudo
- H. Houston Merritt Clinical Research Center for Muscular Dystrophy and Related Diseases, Department of Neurology, 4-420 College of Physicians and Surgeons, Columbia University Medical Center, 630 W. 168th Street, New York, NY 10032, USA
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15
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Pereira C, Nogueira C, Barbot C, Tessa A, Soares C, Fattori F, Guimarães A, Santorelli FM, Vilarinho L. Identification of a new mtDNA mutation (14724G>A) associated with mitochondrial leukoencephalopathy. Biochem Biophys Res Commun 2007; 354:937-41. [PMID: 17266923 DOI: 10.1016/j.bbrc.2007.01.068] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2007] [Accepted: 01/15/2007] [Indexed: 10/23/2022]
Abstract
We report a novel 14724G>A mutation in the mitochondrial tRNA glutamic acid gene in a 4-year-old boy with myopathy and leukoencephalopathy. A muscle biopsy showed cytochrome c oxidase-negative ragged-red fibers and biochemical analysis of the respiratory chain enzymes in muscle homogenate revealed partial complex I and complex IV deficiencies. The mutation, which affects the dihydrouridine arm at a conserved site, was nearly homoplasmic in muscle and heteroplasmic in blood DNA of the proband, but it was absent in peripheral leukocytes from the asymptomatic mother, sister, and two maternal aunts, suggesting that it arose de novo. This report proposes to look for variants in the mitochondrial genome when dealing with otherwise undetermined leukodystrophies of childhood.
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Affiliation(s)
- Cristina Pereira
- Instituto de Genética Médica Jacinto de Magalhães, Praça Pedro Nunes, 88, 4099-028 Porto, Portugal
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16
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Shahrizaila N, Kinnear WJM, Wills AJ. Respiratory involvement in inherited primary muscle conditions. J Neurol Neurosurg Psychiatry 2006; 77:1108-15. [PMID: 16980655 PMCID: PMC2077539 DOI: 10.1136/jnnp.2005.078881] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Patients with inherited muscle disorders can develop respiratory muscle weakness leading to ventilatory failure. Predicting the extent of respiratory involvement in the different types of inherited muscle disorders is important, as it allows clinicians to impart prognostic information and offers an opportunity for early interventional management strategies. The approach to respiratory assessment in patients with muscle disorders, the current knowledge of respiratory impairment in different muscle disorders and advice on the management of respiratory complications are summarised.
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Affiliation(s)
- N Shahrizaila
- Department of Neurology, Queen's Medical Centre, Nottingham NG7 2UH, UK
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17
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Anitori R, Manning K, Quan F, Weleber RG, Buist NRM, Shoubridge EA, Kennaway NG. Contrasting phenotypes in three patients with novel mutations in mitochondrial tRNA genes. Mol Genet Metab 2005; 84:176-88. [PMID: 15670724 DOI: 10.1016/j.ymgme.2004.10.003] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/29/2004] [Revised: 10/01/2004] [Accepted: 10/02/2004] [Indexed: 11/22/2022]
Abstract
We studied three patients, each harboring a novel mutation at a highly conserved position in a different mitochondrial tRNA gene. The mutation in patient 1 (T5543C) was associated with isolated mitochondrial myopathy, and occurred in the anticodon loop of tRNA(Trp). In patient 2, with mitochondrial myopathy and marked retinopathy, the mutation (G14710A) resulted in an anticodon swap (Glu to Lys) in tRNA(Glu). Patient 3, who manifested mitochondrial encephalomyopathy and moderate retinal dysfunction, harbored a mutation (C3287A) in the TpsiC loop of tRNA(Leu(UUR)). The mutations were heteroplasmic in muscle in all cases, and sporadic in two cases. PCR-RFLP analysis in all patients showed much higher amounts of mutated mtDNA in affected tissue (muscle) than unaffected tissue (blood), and significantly higher levels of mutated mtDNA in cytochrome c oxidase (COX)-negative muscle fibers than in COX-positive fibers, confirming the pathogenicity of these mutations. The mutation was also detected in single hair roots from all three patients, indicating that each mutation must have arisen early in embryonic development or in maternal germ cells. This suggests that individual hair root analyses may reflect a wider tissue distribution of mutated mtDNA than is clinically apparent, and might be useful in predicting prognosis and, perhaps, the risk of transmitting the mutation to offspring. Our data suggest a correlation between clinical phenotype and distribution of mutated mtDNA in muscle versus hair roots. Furthermore, the high threshold for phenotypic expression in single muscle fibers (92-96%) suggests that therapies may only need to increase the percentage of wild-type mtDNA by a small amount to be beneficial.
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Affiliation(s)
- Roberto Anitori
- Department of Molecular and Medical Genetics, Oregon Health & Science University, Portland, OR 97239, USA
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