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Finsterer J. Neuropathy, Ataxia, and Retinitis Pigmentosa Syndrome. J Clin Neuromuscul Dis 2023; 24:140-146. [PMID: 36809201 DOI: 10.1097/cnd.0000000000000422] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/23/2023]
Abstract
OBJECTIVES To provide an overview about the phenotype, genotype, treatment, and outcome of neuropathy, ataxia, and retinitis pigmentosa (NARP) syndrome. METHODS Systematic review by application of appropriate search terms. RESULTS NARP syndrome is a syndromic mitochondrial disorder due to pathogenic variants in MT-ATP6. The canonical phenotypic features of NARP syndrome include proximal muscle weakness, axonal neuropathy, cerebellar ataxia, and retinitis pigmentosa. Noncanonical phenotypic features in NARP include epilepsy, cerebral or cerebellar atrophy, optic atrophy, cognitive impairment, dementia, sleep apnea syndrome, hearing impairment, renal insufficiency, and diabetes. So far, 10 pathogenic variants in MT-ATP6 have been associated with NARP, NARP-like syndrome, or NARP/maternally inherited Leigh overlap syndrome. Most pathogenic MT-ATP6 variants are missense, but a few truncating pathogenic variants have been reported. The most common variant responsible for NARP is the transversion m.8993T>G. Only symptomatic treatment for NARP syndrome is available. In most of the cases, patients die prematurely. Patients with late-onset NARP survive longer. CONCLUSIONS NARP is a rare, syndromic, monogenic mitochondrial disorder due to pathogenic variants in MT-ATP6. The nervous system and the eyes are most commonly affected. Although only symptomatic treatment is available, the outcome is usually fair.
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Molecular Genetics Overview of Primary Mitochondrial Myopathies. J Clin Med 2022; 11:jcm11030632. [PMID: 35160083 PMCID: PMC8836969 DOI: 10.3390/jcm11030632] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2021] [Revised: 01/13/2022] [Accepted: 01/20/2022] [Indexed: 12/29/2022] Open
Abstract
Mitochondrial disorders are the most common inherited conditions, characterized by defects in oxidative phosphorylation and caused by mutations in nuclear or mitochondrial genes. Due to its high energy request, skeletal muscle is typically involved. According to the International Workshop of Experts in Mitochondrial Diseases held in Rome in 2016, the term Primary Mitochondrial Myopathy (PMM) should refer to those mitochondrial disorders affecting principally, but not exclusively, the skeletal muscle. The clinical presentation may include general isolated myopathy with muscle weakness, exercise intolerance, chronic ophthalmoplegia/ophthalmoparesis (cPEO) and eyelids ptosis, or multisystem conditions where there is a coexistence with extramuscular signs and symptoms. In recent years, new therapeutic targets have been identified leading to the launch of some promising clinical trials that have mainly focused on treating muscle symptoms and that require populations with defined genotype. Advantages in next-generation sequencing techniques have substantially improved diagnosis. So far, an increasing number of mutations have been identified as responsible for mitochondrial disorders. In this review, we focused on the principal molecular genetic alterations in PMM. Accordingly, we carried out a comprehensive review of the literature and briefly discussed the possible approaches which could guide the clinician to a genetic diagnosis.
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Palombo F, Peron C, Caporali L, Iannielli A, Maresca A, Di Meo I, Fiorini C, Segnali A, Sciacca FL, Rizzo A, Levi S, Suomalainen A, Prigione A, Broccoli V, Carelli V, Tiranti V. The relevance of mitochondrial DNA variants fluctuation during reprogramming and neuronal differentiation of human iPSCs. Stem Cell Reports 2021; 16:1953-1967. [PMID: 34329598 PMCID: PMC8365099 DOI: 10.1016/j.stemcr.2021.06.016] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2021] [Revised: 06/25/2021] [Accepted: 06/26/2021] [Indexed: 12/18/2022] Open
Abstract
The generation of inducible pluripotent stem cells (iPSCs) is a revolutionary technique allowing production of pluripotent patient-specific cell lines used for disease modeling, drug screening, and cell therapy. Integrity of nuclear DNA (nDNA) is mandatory to allow iPSCs utilization, while quality control of mitochondrial DNA (mtDNA) is rarely included in the iPSCs validation process. In this study, we performed mtDNA deep sequencing during the transition from parental fibroblasts to reprogrammed iPSC and to differentiated neuronal precursor cells (NPCs) obtained from controls and patients affected by mitochondrial disorders. At each step, mtDNA variants, including those potentially pathogenic, fluctuate between emerging and disappearing, and some having functional implications. We strongly recommend including mtDNA analysis as an unavoidable assay to obtain fully certified usable iPSCs and NPCs. mtDNA deep sequencing is mandatory in quality control of iPSCs mtDNA variants fluctuate at each step from fibroblasts/PBMC, to iPSCs and NPCs mtDNA variants greatly affect iPSC phenotype, reflecting their healthiness Results could be misinterpreted if mtDNA variants presence has not been assessed
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Affiliation(s)
- Flavia Palombo
- IRCCS Istituto delle Scienze Neurologiche di Bologna, Programma di Neurogenetica, Bologna 40139, Italy
| | - Camille Peron
- Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan 20133, Italy
| | - Leonardo Caporali
- IRCCS Istituto delle Scienze Neurologiche di Bologna, Programma di Neurogenetica, Bologna 40139, Italy
| | - Angelo Iannielli
- Division of Neuroscience, San Raffaele Scientific Institute, Milan 20132, Italy
| | - Alessandra Maresca
- IRCCS Istituto delle Scienze Neurologiche di Bologna, Programma di Neurogenetica, Bologna 40139, Italy
| | - Ivano Di Meo
- Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan 20133, Italy
| | - Claudio Fiorini
- IRCCS Istituto delle Scienze Neurologiche di Bologna, Programma di Neurogenetica, Bologna 40139, Italy; Department of Biomedical and NeuroMotor Sciences (DIBINEM), University of Bologna, Bologna 40123, Italy
| | - Alice Segnali
- Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan 20133, Italy
| | | | - Ambra Rizzo
- Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan 20133, Italy
| | - Sonia Levi
- Division of Neuroscience, San Raffaele Scientific Institute, Milan 20132, Italy; Vita-Salute San Raffaele University, Milan 20132, Italy
| | - Anu Suomalainen
- Stem Cell and Metabolism Research Program Unit, Faculty of Medicine, University of Helsinki, Helsinki 00014, Finland; Neuroscience Institute, HiLife, University of Helsinki, Helsinki 00014, Finland; HUSLab, Helsinki University Hospital, Helsinki 00014, Finland
| | - Alessandro Prigione
- Department of General Pediatrics, Neonatology and Pediatric Cardiology, Duesseldorf University Hospital, Medical Faculty, Heinrich Heine University, Duesseldorf 40225, Germany
| | - Vania Broccoli
- Division of Neuroscience, San Raffaele Scientific Institute, Milan 20132, Italy; National Research Council (CNR), Institute of Neuroscience, Milan 20132, Italy
| | - Valerio Carelli
- IRCCS Istituto delle Scienze Neurologiche di Bologna, Programma di Neurogenetica, Bologna 40139, Italy; Department of Biomedical and NeuroMotor Sciences (DIBINEM), University of Bologna, Bologna 40123, Italy
| | - Valeria Tiranti
- Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan 20133, Italy.
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4
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Al Khatib I, Shutt TE. Advances Towards Therapeutic Approaches for mtDNA Disease. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2019; 1158:217-246. [PMID: 31452143 DOI: 10.1007/978-981-13-8367-0_12] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Mitochondria maintain and express their own genome, referred to as mtDNA, which is required for proper mitochondrial function. While mutations in mtDNA can cause a heterogeneous array of disease phenotypes, there is currently no cure for this collection of diseases. Here, we will cover characteristics of the mitochondrial genome important for understanding the pathology associated with mtDNA mutations, and review recent approaches that are being developed to treat and prevent mtDNA disease. First, we will discuss mitochondrial replacement therapy (MRT), where mitochondria from a healthy donor replace maternal mitochondria harbouring mutant mtDNA. In addition to ethical concerns surrounding this procedure, MRT is only applicable in cases where the mother is known or suspected to carry mtDNA mutations. Thus, there remains a need for other strategies to treat patients with mtDNA disease. To this end, we will also discuss several alternative means to reduce the amount of mutant mtDNA present in cells. Such methods, referred to as heteroplasmy shifting, have proven successful in animal models. In particular, we will focus on the approach of targeting engineered endonucleases to specifically cleave mutant mtDNA. Together, these approaches offer hope to prevent the transmission of mtDNA disease and potentially reduce the impact of mtDNA mutations.
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Affiliation(s)
- Iman Al Khatib
- Deparments of Medical Genetics and Biochemistry & Molecular Biology, Cumming School of Medicine, Alberta Children's Hospital Research Institute, Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, Canada
| | - Timothy E Shutt
- Deparments of Medical Genetics and Biochemistry & Molecular Biology, Cumming School of Medicine, Alberta Children's Hospital Research Institute, Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, Canada.
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5
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Cardiovascular Manifestations of Mitochondrial Disease. BIOLOGY 2019; 8:biology8020034. [PMID: 31083569 PMCID: PMC6628328 DOI: 10.3390/biology8020034] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 02/27/2019] [Revised: 04/13/2019] [Accepted: 04/22/2019] [Indexed: 02/06/2023]
Abstract
Genetic mitochondrial cardiomyopathies are uncommon causes of heart failure that may not be seen by most physicians. However, the prevalence of mitochondrial DNA mutations and somatic mutations affecting mitochondrial function are more common than previously thought. In this review, the pathogenesis of genetic mitochondrial disorders causing cardiovascular disease is reviewed. Treatment options are presently limited to mostly symptomatic support, but preclinical research is starting to reveal novel approaches that may lead to better and more targeted therapies in the future. With better understanding and clinician education, we hope to improve clinician recognition and diagnosis of these rare disorders in order to improve ongoing care of patients with these diseases and advance research towards discovering new therapeutic strategies to help treat these diseases.
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6
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Mayorga L, Cueto JA, Correa AP, Guillamondegui MJ, Loos MA, Araoz VH, Laurito SR, Roqué M. Maternally inherited Leigh syndrome detected by Multiplex ligation-dependent probe amplification. Mitochondrial DNA B Resour 2019. [DOI: 10.1080/23802359.2018.1553510] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022] Open
Affiliation(s)
- Lía Mayorga
- Instituto de Histología y Embriología de Mendoza (IHEM), Universidad Nacional de Cuyo, CONICET, Mendoza, Argentina
| | - Juan A. Cueto
- Instituto de Histología y Embriología de Mendoza (IHEM), Universidad Nacional de Cuyo, CONICET, Mendoza, Argentina
| | | | | | - Mariana A. Loos
- Hospital de Pediatría J.P. Garrahan, Buenos Aires, Argentina
| | | | - Sergio R. Laurito
- Instituto de Histología y Embriología de Mendoza (IHEM), Universidad Nacional de Cuyo, CONICET, Mendoza, Argentina
| | - María Roqué
- Instituto de Histología y Embriología de Mendoza (IHEM), Universidad Nacional de Cuyo, CONICET, Mendoza, Argentina
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Dautant A, Meier T, Hahn A, Tribouillard-Tanvier D, di Rago JP, Kucharczyk R. ATP Synthase Diseases of Mitochondrial Genetic Origin. Front Physiol 2018; 9:329. [PMID: 29670542 PMCID: PMC5893901 DOI: 10.3389/fphys.2018.00329] [Citation(s) in RCA: 71] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2018] [Accepted: 03/15/2018] [Indexed: 01/30/2023] Open
Abstract
Devastating human neuromuscular disorders have been associated to defects in the ATP synthase. This enzyme is found in the inner mitochondrial membrane and catalyzes the last step in oxidative phosphorylation, which provides aerobic eukaryotes with ATP. With the advent of structures of complete ATP synthases, and the availability of genetically approachable systems such as the yeast Saccharomyces cerevisiae, we can begin to understand these molecular machines and their associated defects at the molecular level. In this review, we describe what is known about the clinical syndromes induced by 58 different mutations found in the mitochondrial genes encoding membrane subunits 8 and a of ATP synthase, and evaluate their functional consequences with respect to recently described cryo-EM structures.
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Affiliation(s)
- Alain Dautant
- Institut de Biochimie et Génétique Cellulaires, Centre National de la Recherche Scientifique UMR 5095, Université de Bordeaux, Bordeaux, France
| | - Thomas Meier
- Department of Life Sciences, Imperial College London, London, United Kingdom
| | - Alexander Hahn
- Department of Structural Biology, Max-Planck-Institute of Biophysics, Frankfurt, Germany
| | - Déborah Tribouillard-Tanvier
- Institut de Biochimie et Génétique Cellulaires, Centre National de la Recherche Scientifique UMR 5095, Université de Bordeaux, Bordeaux, France
| | - Jean-Paul di Rago
- Institut de Biochimie et Génétique Cellulaires, Centre National de la Recherche Scientifique UMR 5095, Université de Bordeaux, Bordeaux, France
| | - Roza Kucharczyk
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Warsaw, Poland
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8
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Sheng XQ, Wang YC. Novel two-step derivation method for the synchronous analysis of inherited metabolic disorders using urine. Exp Ther Med 2017; 13:1961-1968. [PMID: 28565794 DOI: 10.3892/etm.2017.4167] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2015] [Accepted: 01/03/2017] [Indexed: 12/11/2022] Open
Abstract
The aim of the present study was to conduct preliminary clinical screening and monitoring using a novel two-step derivatization process of urine in five categories of inherited metabolic disease (IMD). Urine samples (100 µl, containing 2.5 mmol/l creatinine) were taken from patients with IMDs. The collected urine was then treated using a two-step derivatization method (with oximation and silylation at room temperature), where urea and protein were removed. In the first step of the derivatization, α-ketoacids and α-aldehyde acids were prepared by oximation using novel oximation reagents. The second-step of the derivatization was that residues were silylated for analysis. Urine samples were examined using gas chromatography/mass spectrometry (GC/MS) and a retention time-locking technique. The simultaneous analysis and identification of >400 metabolites in >130 types of IMD was possible from the GC/MS results, where the IMDs included phenylketonuria, ornithine transcarbamylase deficiency, neonatal intrahepatic cholestasis caused by citrin deficiency, β-ureidopropionase deficiency and mitochondrial metabolic disorders. This method was demonstrated to have good repeatability. Considering α-ketoglutarate (α-KG) as an example, the relative standard deviations (RSDs) of the α-KG retention time and peak area were 0.8 and 3.9%, respectively, the blank spiked recovery rate was between 89.6 and 99.8%, and the RSD was ≤7.5% (n=5). The method facilitates the analysis of thermally non-stable and semi-volatile metabolites in urine, and greatly expands the range of materials that can be synchronously screened by GC/MS. Furthermore, it provides a comprehensive, effective and reliable biochemical analysis platform for the pathological research of IMDs.
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Affiliation(s)
- Xiao-Qi Sheng
- Hunan Province Technical Institute of Clinical Preventive and Treatment for Children's Inherited Metabolic Disorders, Maternal and Child Health Hospital of Hunan Province, Changsha, Hunan 410008, P.R. China
| | - Yi-Chao Wang
- Hunan Province Technical Institute of Clinical Preventive and Treatment for Children's Inherited Metabolic Disorders, Maternal and Child Health Hospital of Hunan Province, Changsha, Hunan 410008, P.R. China
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9
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Infantile mitochondrial disorder associated with subclinical hypothyroidism is caused by a rare mitochondrial DNA 8691A>G mutation. Neuroreport 2015; 26:588-92. [DOI: 10.1097/wnr.0000000000000392] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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10
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HEJZLAROVÁ K, MRÁČEK T, VRBACKÝ M, KAPLANOVÁ V, KARBANOVÁ V, NŮSKOVÁ H, PECINA P, HOUŠTĚK J. Nuclear Genetic Defects of Mitochondrial ATP Synthase. Physiol Res 2014; 63:S57-71. [DOI: 10.33549/physiolres.932643] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Disorders of ATP synthase, the key enzyme of mitochondrial energy provision belong to the most severe metabolic diseases presenting as early-onset mitochondrial encephalo-cardiomyopathies. Up to now, mutations in four nuclear genes were associated with isolated deficiency of ATP synthase. Two of them, ATP5A1 and ATP5E encode enzyme’s structural subunits α and ε, respectively, while the other two ATPAF2 and TMEM70 encode specific ancillary factors that facilitate the biogenesis of ATP synthase. All these defects share a similar biochemical phenotype with pronounced decrease in the content of fully assembled and functional ATP synthase complex. However, substantial differences can be found in their frequency, molecular mechanism of pathogenesis, clinical manifestation as well as the course of the disease progression. While for TMEM70 the number of reported patients as well as spectrum of the mutations is steadily increasing, mutations in ATP5A1, ATP5E and ATPAF2 genes are very rare. Apparently, TMEM70 gene is highly prone to mutagenesis and this type of a rare mitochondrial disease has a rather frequent incidence. Here we present overview of individual reported cases of nuclear mutations in ATP synthase and discuss, how their analysis can improve our understanding of the enzyme biogenesis.
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Affiliation(s)
| | | | | | | | | | | | | | - J. HOUŠTĚK
- Department of Bioenergetics, Institute of Physiology Academy of Sciences of the Czech Republic, Prague, Czech Republic
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11
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Gurses C, Azakli H, Alptekin A, Cakiris A, Abaci N, Arikan M, Kursun O, Gokyigit A, Ustek D. Mitochondrial DNA profiling via genomic analysis in mesial temporal lobe epilepsy patients with hippocampal sclerosis. Gene 2014; 538:323-7. [PMID: 24440288 DOI: 10.1016/j.gene.2014.01.030] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2013] [Revised: 12/28/2013] [Accepted: 01/10/2014] [Indexed: 11/25/2022]
Abstract
INTRODUCTION Mitochondria have an essential role in neuronal excitability and neuronal survival. In addition to energy production, mitochondria also play a crucial role in the maintenance of intracellular calcium homeostasis, generation of reactive oxygen species and mechanisms of cell death. There is a relative paucity of data about the role of mitochondria in epilepsy. Mitochondrial genome analysis is rarely carried out in the investigation of some diseases. In mesial temporal lobe epilepsies (MTLE) cases, genome analysis has never been used previously. The aim of this study is to show mitochondrial dysfunctions using genome analysis in patients with MTLE-hippocampal sclerosis (HS). METHODS 44 patients with MTLE-HS and 86 matched healthy unrelated controls were included in this study. The patients were divided into four groups according to their clinical presentation as the following: Group 1 consists of patients with intractable epilepsy who refused operation; Group 2 of operated seizure free patients; Group 3 of operated patients with seizures; and Group 4 unoperated seizure free patients with or without antiepileptic drugs. Blood samples were used to isolate DNA. Parallel tagged sequencing was employed to allow pyrosequencing of 130 samples. Complete mtDNA is amplified in two overlapping fragments (11 and 9 kb). The PCR amplicons were pooled in equimolar ratios. Titanium kits were used to produce shotgun libraries according to the manufacturer's protocol. RESULTS The average coverage in total was 130 ± 30 and an average of 2365127 bases and 337 bp fragment length was received from all samples. The mean mtDNA heteroplasmy in patients was 26.35 ± 12.3 and in controls 25.03 ± 9.34. Three mutations had prominently high significance in patient samples. The most significantly associated variation was located in the MT-ATP-8 gene (8502 A>T, Asn46Ile) whereas the other two were in the MT-ND4 (11994 C>T, Thr412Ile) and MT-ND5 (13231 A>C, Lys299Gln) genes. CONCLUSIONS We have observed that three mutations were significantly related to the presence of epilepsy. These mutations were found at the 8502, 11994, and 13,231 bp of mtDNA, which resulted in amino acid changes at the MT-ATP-8, MT-ND4 and MT-ND5 genes. Finding mutations can lead us to knowing more about the pathophysiology of the MTLE disease.
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Affiliation(s)
- Candan Gurses
- Neurology, Istanbul Faculty of Medicine, Istanbul University, Istanbul, Turkey.
| | - Hulya Azakli
- Genetics, Institute for Experimental Medicine, Istanbul University, Istanbul, Turkey
| | - Ahmet Alptekin
- Computer Engineering, Istanbul University, Istanbul, Turkey
| | - Aris Cakiris
- Genetics, Institute for Experimental Medicine, Istanbul University, Istanbul, Turkey
| | - Neslihan Abaci
- Genetics, Institute for Experimental Medicine, Istanbul University, Istanbul, Turkey
| | - Muzaffer Arikan
- Genetics, Institute for Experimental Medicine, Istanbul University, Istanbul, Turkey
| | - Olcay Kursun
- Computer Engineering, Istanbul University, Istanbul, Turkey
| | - Aysen Gokyigit
- Neurology, Istanbul Faculty of Medicine, Istanbul University, Istanbul, Turkey
| | - Duran Ustek
- Genetics, Institute for Experimental Medicine, Istanbul University, Istanbul, Turkey.
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Wong LJC. Challenges of bringing next generation sequencing technologies to clinical molecular diagnostic laboratories. Neurotherapeutics 2013; 10:262-72. [PMID: 23269496 PMCID: PMC3625389 DOI: 10.1007/s13311-012-0170-5] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Molecular diagnosis of complex dual genome mitochondrial disorders is a challenge. It requires the identification of deleterious mutations in one of the ~1,500 nuclear genes and the mitochondrial genome. If the molecular defect is in the mitochondrial genome, quantification of degree of mutation load (heteroplasmy) in affected tissues is important. Due to the extreme clinical and genetic heterogeneity, conventional sequence analysis of the candidate genes one-by-one is impractical, if not impossible. The newly developed massively parallel next generation sequencing (NGS) technique, that allows simultaneous sequence analysis of multiple target genes, when appropriately validated with deep coverage and proper quality controls, can be used as an effective comprehensive diagnostic approach in CLIA certified clinical laboratories.
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Affiliation(s)
- Lee-Jun C Wong
- Department of Molecular and Human Genetics, Baylor College of Medicine, One Baylor Plaza, NAB 2015, Houston, TX 77030, USA.
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13
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Next generation molecular diagnosis of mitochondrial disorders. Mitochondrion 2013; 13:379-87. [PMID: 23473862 DOI: 10.1016/j.mito.2013.02.001] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2012] [Revised: 01/31/2013] [Accepted: 02/04/2013] [Indexed: 12/21/2022]
Abstract
Mitochondrial disorders are by far the most genetically heterogeneous group of diseases, involving two genomes, the 16.6k b mitochondrial genome and ~1500 genes encoded in the nuclear genome. For maternally inherited mitochondrial DNA disorders, a complete molecular diagnosis requires several different methods for the detection and quantification of mtDNA point mutations and large deletions. For mitochondrial disorders caused by autosomal recessive, dominant, and X-linked nuclear genes, the diagnosis has relied on clinical, biochemical, and molecular studies to point to a group of candidate genes followed by stepwise Sanger sequencing of the candidate genes one-by-one. The development of Next Generation Sequencing (NGS) has revolutionized the diagnostic approach. Using massively parallel sequencing (MPS) analysis of the entire mitochondrial genome, mtDNA point mutations and deletions can be detected and quantified in one single step. The NGS approach also allows simultaneous analyses of a group of genes or the whole exome, thus, the mutations in causative gene(s) can be identified in one-step. New approaches make genetic analyses much faster and more efficient. Huge amounts of sequencing data produced by the new technologies brought new challenges to bioinformatics, analytical pipelines, and interpretation of numerous novel variants. This article reviews the clinical utility of next generation sequencing for the molecular diagnoses of complex dual genome mitochondrial disorders.
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Duno M, Wibrand F, Baggesen K, Rosenberg T, Kjaer N, Frederiksen AL. A novel mitochondrial mutation m.8989G>C associated with neuropathy, ataxia, retinitis pigmentosa - the NARP syndrome. Gene 2012; 515:372-5. [PMID: 23266623 DOI: 10.1016/j.gene.2012.12.066] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2012] [Accepted: 12/03/2012] [Indexed: 01/23/2023]
Abstract
The archetypal NARP syndrome is almost exclusively associated with the m.8993T>C/G mutation in the sixth subunit of the mitochondrial ATP synthase, whereas other mutations in the MT-ATP6 gene primarily associate with Leigh syndrome or Leber's hereditary optic neuropathy (LHON). We report a novel mitochondrial point mutation, m.8989G>C, in a patient presenting with neuropathy, ataxia and retinitis pigmentosa constituting the classical NARP phenotype. This mutation alters the amino acid right next to canonical NARP mutation. We suggest that classic NARP syndrome relates to a defined dysfunction of p.MT-ATP6.
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Affiliation(s)
- Morten Duno
- Dept. of Clinical Genetics, University Hospital, Rigshospitalet, Copenhagen, Denmark.
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