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Harikrishna GV, Padmanabha H, Polavarapu K, Anjanappa RM, Preethish-Kumar V, Nandeesh BN, Vengalil S, Nashi S, Baskar D, Thomas A, Bardhan M, Arunachal G, Menon D, Sanka SB, Manjunath N, Nalini A. Phenotype-Genotype Correlation of a Cohort of Patients with Congenital Myopathy: A Single Centre Experience from India. J Neuromuscul Dis 2024; 11:935-957. [PMID: 38968056 PMCID: PMC11380309 DOI: 10.3233/jnd-230021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/07/2024]
Abstract
Background Congenital myopathies (CMs) are a diverse group of inherited muscle disorders with broad genotypic and phenotypic heterogeneity. While the literature on CM is available from European countries, comprehensive data from the Indian subcontinent is lacking. Objectives This study aims to describe the clinical and histopathological characteristics of a cohort of genetically confirmed CMs from India and attempts to do phenotype-genotype correlation. Methods A retrospective chart review of genetically confirmed CMs was evaluated between January 2016 and December 2020 at the neuromuscular clinic. The clinical, genetic, and follow-up data were recorded in a pre-structured proforma as per the medical records, and the data was analyzed. Results A total of 31(M: F = 14 : 17) unrelated patients were included. The median age at onset and duration of illness are 2.0(IQR:1-8) years and 6.0(IQR:3-10) years respectively. Clinical features observed were proximodistal weakness (54.8%), facial weakness (64.5%), and myopathic facies (54.8%), followed by ptosis (33.3%), and ophthalmoplegia (19.4%). Muscle histopathology was available in 38.7% of patients, and centronuclear myopathy was the most common histopathology finding. The pathogenic genetic variants were identified in RYR1 (29.0%), DNM2 (19.4%), SELENON (12.9%), KBTBD13 (9.7%), NEB (6.5%), and MYPN (6.5%) genes. Novel mutations were observed in 30.3% of the cohort. Follow-up details were available in 77.4% of children, and the median duration of follow-up and age at last follow-up was 4.5 (Range 0.5-11) years and 13 (Range 3-35) years, respectively. The majority were ambulant with minimal assistance at the last follow-up. Mortality was noted in 8.3% due to respiratory failure in Centronuclear myopathy 1 and congenital myopathy 3 with rigid spines (SELENON). Conclusion This study highlights the various phenotypes and patterns of genetic mutations in a cohort of pediatric patients with congenital myopathy from India. Centronuclear myopathy was the most common histological classification and the mutations in RYR1 followed by DNM2 gene were the common pathogenic variants identified. The majority were independent in their activities of daily living during the last follow-up, highlighting the fact that the disease has slow progression irrespective of the genotype.
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Affiliation(s)
| | - Hansashree Padmanabha
- Department of Neurology, National Institute of Mental Health and Neuro Sciences (NIMHANS), Bengaluru, Karnataka, India
| | - Kiran Polavarapu
- Department of Medicine, Children's Hospital of Eastern Ontario Research Institute, University of Ottawa and Division of Neurology, The Ottawa Hospital, Ottawa, Canada
| | | | | | | | - Seena Vengalil
- Department of Neurology, National Institute of Mental Health and Neuro Sciences (NIMHANS), Bengaluru, Karnataka, India
| | - Saraswati Nashi
- Department of Neurology, National Institute of Mental Health and Neuro Sciences (NIMHANS), Bengaluru, Karnataka, India
| | - Dipti Baskar
- Department of Neurology, National Institute of Mental Health and Neuro Sciences (NIMHANS), Bengaluru, Karnataka, India
| | - Aneesha Thomas
- Department of Neurology, National Institute of Mental Health and Neuro Sciences (NIMHANS), Bengaluru, Karnataka, India
| | - Mainak Bardhan
- Department of Neurology, National Institute of Mental Health and Neuro Sciences (NIMHANS), Bengaluru, Karnataka, India
| | - Gautham Arunachal
- Department of Human Genetics, National Institute of Mental Health and Neuro Sciences (NIMHANS), Bengaluru, Karnataka, India
| | - Deepak Menon
- Department of Neurology, National Institute of Mental Health and Neuro Sciences (NIMHANS), Bengaluru, Karnataka, India
| | - Sai Bhargava Sanka
- Department of Neurology, National Institute of Mental Health and Neuro Sciences (NIMHANS), Bengaluru, Karnataka, India
| | - Nisha Manjunath
- Department of Neurology, National Institute of Mental Health and Neuro Sciences (NIMHANS), Bengaluru, Karnataka, India
| | - Atchayaram Nalini
- Department of Neurology, National Institute of Mental Health and Neuro Sciences (NIMHANS), Bengaluru, Karnataka, India
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Granger A, Beecher G, Liewluck T, Nicolau S, Flanigan KM, Laughlin RS, Milone M. Inherited myopathy plus: Double-trouble from rare neuromuscular disorders. Neuromuscul Disord 2023; 33:153-160. [PMID: 36628841 DOI: 10.1016/j.nmd.2022.12.009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2022] [Revised: 11/21/2022] [Accepted: 12/14/2022] [Indexed: 12/23/2022]
Abstract
A rare disorder in the USA is one that affects <200,000 people, making inherited myopathies rare diseases. Increasing access to genetic testing has been instrumental for the diagnosis of inherited myopathies. Genetic findings, however, require clinical correlation due to variable phenotype, polygenic etiology of certain inherited disorders, and possible co-existing independent neuromuscular disorders. We searched the Mayo Clinic Rochester medical record (2004-2020) to identify adult patients carrying pathogenic variants or likely pathogenic variants in genes causative of myopathies and having a coexisting independent neuromuscular disorder classified as rare at https://rarediseases.info.nih.gov/. One additional patient was identified at Nationwide Children's hospital. Clinical and laboratory findings were reviewed. We identified 14 patients from 13 families fulfilling search criteria. Seven patients had a "double-trouble" inherited myopathy; two had an inherited myopathy with coexistent idiopathic myositis; three had an inherited myopathy with coexisting rare neuromuscular disorder of neurogenic type; a female DMD carrier had co-existing distal spinal muscular atrophy, which was featuring the clinical phenotype; and a patient with a MYH7 pathogenic variant had Sandhoff disease causing motor neuron disease. These cases highlight the relevance of correlating genetic findings, even when diagnostic, with clinical features, to allow precise diagnosis, optimal care, and accurate prognosis.
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Affiliation(s)
- Andre Granger
- Department of Neurology, Mayo Clinic, Rochester, MN, USA
| | | | | | - Stefan Nicolau
- Center for Gene Therapy, Nationwide Children's Hospital, Columbus, OH, USA
| | - Kevin M Flanigan
- Center for Gene Therapy, Nationwide Children's Hospital, Columbus, OH, USA
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Fusto A, Cassandrini D, Fiorillo C, Codemo V, Astrea G, D’Amico A, Maggi L, Magri F, Pane M, Tasca G, Sabbatini D, Bello L, Battini R, Bernasconi P, Fattori F, Bertini ES, Comi G, Messina S, Mongini T, Moroni I, Panicucci C, Berardinelli A, Donati A, Nigro V, Pini A, Giannotta M, Dosi C, Ricci E, Mercuri E, Minervini G, Tosatto S, Santorelli F, Bruno C, Pegoraro E. Expanding the clinical-pathological and genetic spectrum of RYR1-related congenital myopathies with cores and minicores: an Italian population study. Acta Neuropathol Commun 2022; 10:54. [PMID: 35428369 PMCID: PMC9013059 DOI: 10.1186/s40478-022-01357-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2022] [Accepted: 03/25/2022] [Indexed: 11/10/2022] Open
Abstract
Mutations in the RYR1 gene, encoding ryanodine receptor 1 (RyR1), are a well-known cause of Central Core Disease (CCD) and Multi-minicore Disease (MmD). We screened a cohort of 153 patients carrying an histopathological diagnosis of core myopathy (cores and minicores) for RYR1 mutation. At least one RYR1 mutation was identified in 69 of them and these patients were further studied. Clinical and histopathological features were collected. Clinical phenotype was highly heterogeneous ranging from asymptomatic or paucisymptomatic hyperCKemia to severe muscle weakness and skeletal deformity with loss of ambulation. Sixty-eight RYR1 mutations, generally missense, were identified, of which 16 were novel. The combined analysis of the clinical presentation, disease progression and the structural bioinformatic analyses of RYR1 allowed to associate some phenotypes to mutations in specific domains. In addition, this study highlighted the structural bioinformatics potential in the prediction of the pathogenicity of RYR1 mutations. Further improvement in the comprehension of genotype-phenotype relationship of core myopathies can be expected in the next future: the actual lack of the human RyR1 crystal structure paired with the presence of large intrinsically disordered regions in RyR1, and the frequent presence of more than one RYR1 mutation in core myopathy patients, require designing novel investigation strategies to completely address RyR1 mutation effect.
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Mauri E, Piga D, Govoni A, Brusa R, Pagliarani S, Ripolone M, Dilena R, Cinnante C, Sciacco M, Cassandrini D, Nigro V, Bresolin N, Corti S, Comi GP, Magri F. Early Findings in Neonatal Cases of RYR1-Related Congenital Myopathies. Front Neurol 2021; 12:664618. [PMID: 34262519 PMCID: PMC8273285 DOI: 10.3389/fneur.2021.664618] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2021] [Accepted: 04/21/2021] [Indexed: 12/03/2022] Open
Abstract
Ryanodine receptor type 1-related congenital myopathies are the most represented subgroup among congenital myopathies (CMs), typically presenting a central core or multiminicore muscle histopathology and high clinical heterogeneity. We evaluated a cohort of patients affected with Ryanodine receptor type 1-related congenital myopathy (RYR1-RCM), focusing on four patients who showed a severe congenital phenotype and underwent a comprehensive characterization at few months of life. To date there are few reports on precocious instrumental assessment. In two out of the four patients, a muscle biopsy was performed in the first days of life (day 5 and 37, respectively) and electron microscopy was carried out in two patients detecting typical features of congenital myopathy. Two patients underwent brain MRI in the first months of life (15 days and 2 months, respectively), one also a fetal brain MRI. In three children electromyography was performed in the first week of life and neurogenic signs were excluded. Muscle MRI obtained within the first years of life showed a typical pattern of RYR1-CM. The diagnosis was confirmed through genetic analysis in three out of four cases using Next Generation Sequencing (NGS) panels. The development of a correct and rapid diagnosis is a priority and may lead to prompt medical management and helps optimize inclusion in future clinical trials.
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Affiliation(s)
- Eleonora Mauri
- Neurology Unit, Foundation IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy
| | - Daniela Piga
- Neurology Unit, Foundation IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy
| | - Alessandra Govoni
- Neurology Unit, Foundation IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy
| | - Roberta Brusa
- Neurology Unit, Foundation IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy
| | - Serena Pagliarani
- Neuroscience Section, Dino Ferrari Centre, Department of Pathophysiology and Transplantation (DEPT), University of Milan, Milan, Italy
| | - Michela Ripolone
- Neuromuscular and Rare Diseases Unit, Istituto di Ricerca e Cura a Carattere Scientifico Foundation Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy
| | - Robertino Dilena
- Neuropathophysiology Unit, Istituto di Ricerca e Cura a Carattere Scientifico Foundation Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy
| | - Claudia Cinnante
- Neuroradiology Unit, Istituto di Ricerca e Cura a Carattere Scientifico Foundation Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy
| | - Monica Sciacco
- Neuromuscular and Rare Diseases Unit, Istituto di Ricerca e Cura a Carattere Scientifico Foundation Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy
| | - Denise Cassandrini
- Molecular Medicine, Istituto di Ricerca e Cura a Carattere Scientifico Fondazione Stella Maris, Pisa, Italy
| | - Vincenzo Nigro
- "Luigi Vanvitelli" University and Telethon Institute of Genetics and Medicine (TIGEM), Naples, Italy
| | - Nereo Bresolin
- Neurology Unit, Foundation IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy.,Neuroscience Section, Dino Ferrari Centre, Department of Pathophysiology and Transplantation (DEPT), University of Milan, Milan, Italy
| | - Stefania Corti
- Neurology Unit, Foundation IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy.,Neuroscience Section, Dino Ferrari Centre, Department of Pathophysiology and Transplantation (DEPT), University of Milan, Milan, Italy
| | - Giacomo P Comi
- Neuroscience Section, Dino Ferrari Centre, Department of Pathophysiology and Transplantation (DEPT), University of Milan, Milan, Italy.,Neuromuscular and Rare Diseases Unit, Istituto di Ricerca e Cura a Carattere Scientifico Foundation Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy
| | - Francesca Magri
- Neurology Unit, Foundation IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy
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Lawal TA, Todd JJ, Witherspoon JW, Bönnemann CG, Dowling JJ, Hamilton SL, Meilleur KG, Dirksen RT. Ryanodine receptor 1-related disorders: an historical perspective and proposal for a unified nomenclature. Skelet Muscle 2020; 10:32. [PMID: 33190635 PMCID: PMC7667763 DOI: 10.1186/s13395-020-00243-4] [Citation(s) in RCA: 41] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2020] [Accepted: 08/18/2020] [Indexed: 12/14/2022] Open
Abstract
The RYR1 gene, which encodes the sarcoplasmic reticulum calcium release channel or type 1 ryanodine receptor (RyR1) of skeletal muscle, was sequenced in 1988 and RYR1 variations that impair calcium homeostasis and increase susceptibility to malignant hyperthermia were first identified in 1991. Since then, RYR1-related myopathies (RYR1-RM) have been described as rare, histopathologically and clinically heterogeneous, and slowly progressive neuromuscular disorders. RYR1 variants can lead to dysfunctional RyR1-mediated calcium release, malignant hyperthermia susceptibility, elevated oxidative stress, deleterious post-translational modifications, and decreased RyR1 expression. RYR1-RM-affected individuals can present with delayed motor milestones, contractures, scoliosis, ophthalmoplegia, and respiratory insufficiency. Historically, RYR1-RM-affected individuals were diagnosed based on morphologic features observed in muscle biopsies including central cores, cores and rods, central nuclei, fiber type disproportion, and multi-minicores. However, these histopathologic features are not always specific to RYR1-RM and often change over time. As additional phenotypes were associated with RYR1 variations (including King-Denborough syndrome, exercise-induced rhabdomyolysis, lethal multiple pterygium syndrome, adult-onset distal myopathy, atypical periodic paralysis with or without myalgia, mild calf-predominant myopathy, and dusty core disease) the overlap among diagnostic categories is ever increasing. With the continuing emergence of new clinical subtypes along the RYR1 disease spectrum and reports of adult-onset phenotypes, nuanced nomenclatures have been reported (RYR1- [related, related congenital, congenital] myopathies). In this narrative review, we provide historical highlights of RYR1 research, accounts of the main diagnostic disease subtypes and propose RYR1-related disorders (RYR1-RD) as a unified nomenclature to describe this complex and evolving disease spectrum.
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Affiliation(s)
- Tokunbor A Lawal
- Tissue Injury Branch, National Institute of Nursing Research, National Institutes of Health, Bethesda, MD, USA.
| | - Joshua J Todd
- Tissue Injury Branch, National Institute of Nursing Research, National Institutes of Health, Bethesda, MD, USA
| | - Jessica W Witherspoon
- Tissue Injury Branch, National Institute of Nursing Research, National Institutes of Health, Bethesda, MD, USA
| | - Carsten G Bönnemann
- Neurogenetics Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, USA
| | - James J Dowling
- Departments of Paediatrics and Molecular Genetics, Hospital for Sick Children and University of Toronto, Toronto, Canada
| | - Susan L Hamilton
- Molecular Physiology & Biophysics, Baylor College of Medicine, Houston, TX, USA
| | - Katherine G Meilleur
- Tissue Injury Branch, National Institute of Nursing Research, National Institutes of Health, Bethesda, MD, USA
| | - Robert T Dirksen
- Department of Pharmacology and Physiology, University of Rochester Medical Center, Rochester, NY, USA
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A Rare Case of Severe Congenital RYR1-Associated Myopathy. Case Rep Genet 2018; 2018:6184185. [PMID: 30155320 PMCID: PMC6092990 DOI: 10.1155/2018/6184185] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2018] [Revised: 06/28/2018] [Accepted: 07/19/2018] [Indexed: 01/27/2023] Open
Abstract
Congenital myopathies are a group of rare inherited diseases, defined by hypotonia and muscle weakness. We report clinical and genetic characteristics of a male preterm newborn, whose phenotype was characterized by severe hypotonia and hyporeactivity, serious respiratory distress syndrome that required mechanical ventilation, clubfoot, and other dysmorphic features. The diagnostic procedure was completed with the complete exome sequencing of the proband and of his parents and his sister, which showed new mutations in the ryanodine receptor gene (RYR1), which maps to chromosome 19q13.2 and encodes the skeletal muscle isoform of a calcium-release channel in the sarcoplasmic reticulum (RyR1). This report confirms that early diagnosis and accurate study of genomic disorders are very important, enabling proper genetic counselling of the reproductive risk, as well as disease prognosis and patient management.
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Samões R, Oliveira J, Taipa R, Coelho T, Cardoso M, Gonçalves A, Santos R, Melo Pires M, Santos M. RYR1-Related Myopathies: Clinical, Histopathologic and Genetic Heterogeneity Among 17 Patients from a Portuguese Tertiary Centre. J Neuromuscul Dis 2018; 4:67-76. [PMID: 28269792 DOI: 10.3233/jnd-160199] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
BACKGROUND Pathogenic variants in ryanodine receptor type 1 (RYR1) gene are an important cause of congenital myopathy. The clinical, histopathologic and genetic spectrum is wide. OBJECTIVE Review a group of the patients diagnosed with ryanodinopathy in a tertiary centre from North Portugal, as an attempt to define some phenotypical patterns that may help guiding future diagnosis. METHODS Patients were identified from the database of the reference centre for Neuromuscular Disorders in North Portugal. Their data (clinical, histological and genetic) was retrospectively accessed. RESULTS Seventeen RYR1-related patients (including 4 familial cases) were identified. They were divided in groups according to three distinctive clinical characteristics: extraocular muscle (EOM) weakness (N = 6), disproportionate axial muscle weakness (N = 2) and joint laxity (N = 5). The fourth phenotype includes patients with mild tetraparesis and no distinctive clinical features (N = 4). Four different histopathological patterns were found: centronuclear (N = 5), central core (N = 4), type 1 fibres predominance (N = 4) and congenital fibre type disproportion (N = 1) myopathies. Each index case, except two patients, had a different RYR1 variant. Four new genetic variants were identified. All centronuclear myopathies were associated with autosomal recessive inheritance and EOM weakness. All central core myopathies were caused by pathogenic variants in hotspot 3 with autosomal dominant inheritance. Three genetic variants were reported to be associated to malignant hyperthermia susceptibility. CONCLUSIONS Distinctive clinical features were recognized as diagnostically relevant: extraocular muscle weakness (and centronuclear pattern on muscle biopsy), severe axial weakness disproportionate to the ambulatory state and mild tetraparesis associated with (proximal) joint laxity. There was a striking genetic heterogeneity, including four new RYR1 variants.
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Affiliation(s)
- Raquel Samões
- Department of Neurology, Centro Hospitalar do Porto, Porto, Portugal
| | - Jorge Oliveira
- Unidade de Genética Molecular, Centro de Genética Médica, Centro Hospitalar do Porto, Porto, Portugal.,Unidade Multidisciplinar de Investigação Biomédica (UMIB), Instituto de Ciências Biomédicas Abel Salazar (ICBAS), Universidade do Porto, Porto, Portugal
| | - Ricardo Taipa
- Neuropathology Unit, Centro Hospitalar do Porto, Porto, Portugal
| | - Teresa Coelho
- Department of Neurophysiology and Neuromuscular Disorders Outpatient Clinic, Centro Hospitalar do Porto, Porto, Portugal
| | - Márcio Cardoso
- Department of Neurophysiology and Neuromuscular Disorders Outpatient Clinic, Centro Hospitalar do Porto, Porto, Portugal
| | - Ana Gonçalves
- Unidade de Genética Molecular, Centro de Genética Médica, Centro Hospitalar do Porto, Porto, Portugal.,Unidade Multidisciplinar de Investigação Biomédica (UMIB), Instituto de Ciências Biomédicas Abel Salazar (ICBAS), Universidade do Porto, Porto, Portugal
| | - Rosário Santos
- Unidade de Genética Molecular, Centro de Genética Médica, Centro Hospitalar do Porto, Porto, Portugal.,Unidade Multidisciplinar de Investigação Biomédica (UMIB), Instituto de Ciências Biomédicas Abel Salazar (ICBAS), Universidade do Porto, Porto, Portugal.,UCIBIO/REQUIMTE, Departamento de Ciências Biológicas, Laboratório de Bioquímica, Faculdade de Farmácia, Universidade do Porto, Porto, Portugal
| | | | - Manuela Santos
- Neuromuscular Disorders Outpatient Clinic and Department of Neuropaediatrics, Centro Hospitalar do Porto, Porto, Portugal
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Nishikawa A, Mitsuhashi S, Miyata N, Nishino I. Targeted massively parallel sequencing and histological assessment of skeletal muscles for the molecular diagnosis of inherited muscle disorders. J Med Genet 2016; 54:104-110. [DOI: 10.1136/jmedgenet-2016-104073] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2016] [Revised: 07/28/2016] [Accepted: 08/08/2016] [Indexed: 01/04/2023]
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New massive parallel sequencing approach improves the genetic characterization of congenital myopathies. J Hum Genet 2016; 61:497-505. [PMID: 26841830 DOI: 10.1038/jhg.2016.2] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2015] [Revised: 11/28/2015] [Accepted: 01/05/2016] [Indexed: 01/08/2023]
Abstract
Congenital myopathies (CMs) are a heterogeneous group of muscle diseases characterized by hypotonia, delayed motor skills and muscle weakness with onset during the first years of life. The diagnostic workup of CM is highly dependent on the interpretation of the muscle histology, where typical pathognomonic findings are suggestive of a CM but are not necessarily gene specific. Over 20 loci have been linked to these myopathies, including three exceptionally large genes (TTN, NEB and RYR1), which are a challenge for molecular diagnosis. We developed a new approach using massive parallel sequencing (MPS) technology to simultaneously analyze 20 genes linked to CMs. Assay design was based on the Ion AmpliSeq strategy and sequencing runs were performed on an Ion PGM system. A total of 12 patients were analyzed in this study. Among the 2534 variants detected, 14 pathogenic mutations were successfully identified in the DNM2, NEB, RYR1, SEPN1 and TTN genes. Most of these had not been documented and/or fully characterized, hereby contributing to expand the CM mutational spectrum. The utility of this approach was demonstrated by the identification of mutations in 70% of the patients included in this study, which is relevant for CMs especially considering its wide phenotypic and genetic heterogeneity.
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Compound RYR1 heterozygosity resulting in a complex phenotype of malignant hyperthermia susceptibility and a core myopathy. Neuromuscul Disord 2015; 25:567-76. [DOI: 10.1016/j.nmd.2015.04.007] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2014] [Revised: 03/31/2015] [Accepted: 04/15/2015] [Indexed: 11/19/2022]
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