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Iyer KA, Barnakov V, Samsó M. Three-dimensional perspective on ryanodine receptor mutations causing skeletal and cardiac muscle-related diseases. Curr Opin Pharmacol 2023; 68:102327. [PMID: 36516687 PMCID: PMC9908851 DOI: 10.1016/j.coph.2022.102327] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2022] [Revised: 10/18/2022] [Accepted: 11/12/2022] [Indexed: 12/14/2022]
Abstract
Mutations in RyR alter the cell's Ca2+ homeostasis and can cause serious health problems for which few effective therapies are available. Until recently, there was little structural context for the hundreds of mutations linked to muscular disorders reported for this large channel. Growing knowledge of the three-dimensional structure of RyR starts to illustrate the fine control of Ca2+ release. Current efforts directed towards understanding how disease mutations impinge in such processes will be crucial for future design of novel therapies. In this review article we discuss the up-to-date information about mutations according to their role in the 3D structure, and classified them to provide context from a structural perspective.
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Affiliation(s)
- Kavita A Iyer
- Department of Physiology and Biophysics, School of Medicine, Virginia Commonwealth University, Richmond, VA, USA
| | - Vadim Barnakov
- Department of Physiology and Biophysics, School of Medicine, Virginia Commonwealth University, Richmond, VA, USA
| | - Montserrat Samsó
- Department of Physiology and Biophysics, School of Medicine, Virginia Commonwealth University, Richmond, VA, 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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Watanabe T, Miyoshi H, Noda Y, Narasaki S, Morio A, Toyota Y, Kimura H, Mukaida K, Yasuda T, Tsutsumi YM. Effects of Remimazolam and Propofol on Ca 2+ Regulation by Ryanodine Receptor 1 with Malignant Hyperthermia Mutation. BIOMED RESEARCH INTERNATIONAL 2021; 2021:8845129. [PMID: 33490280 PMCID: PMC7801102 DOI: 10.1155/2021/8845129] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/27/2020] [Revised: 11/21/2020] [Accepted: 12/21/2020] [Indexed: 12/14/2022]
Abstract
BACKGROUND We investigated the potential safety of remimazolam and propofol in malignant hyperthermia- (HM-) susceptible patients using ryanodine receptor 1- (RYR1-) expressing human embryonic kidney- (HEK-) 293 cells. METHODS We compared the enhanced responsiveness of HEK-293 cells expressing wild-type RYR1 with that of mutant RYR1 to caffeine following perfusion with remimazolam or propofol. Furthermore, we investigated whether RYR1 enhanced the responsiveness of cells to remimazolam or propofol and compared the median effective concentration (EC50; i.e., the concentration required to reach half-maximal activation) using an unpaired two-tailed t-test while a P < 0.05 was considered significant. RESULTS Remimazolam and propofol did not promote the caffeine-induced increase in intracellular Ca2+ levels in HEK-293 cells expressing mutant RYR1 even with exposure to approximately 100-fold the clinically used concentration. In wild-type RYR1, EC50 values of remimazolam following refusion vs. nonperfusion were 2.86 mM vs. 2.75 mM (P = 0.76) while for propofol perfusion vs. nonperfusion, they were 2.76 mM vs. 2.75 mM, respectively (P = 0.83). In mutant RYR1, EC50 values of remimazolam refusion vs. nonperfusion were 1.58 mM vs. 1.71 mM, respectively (P = 0.63) while for propofol perfusion vs. nonperfusion, they were 1.65 mM vs. 1.71 mM, respectively (P = 0.73). Remimazolam and propofol increased intracellular Ca2+ levels in a concentration-dependent manner, but the effect was not enhanced by RYR1. EC50 values of remimazolam with non-RYR1 vs. wild-type RYR1 were 1.00 mM vs. 0.92 mM, respectively (P = 0.91) while those of propofol were 1.09 mM vs. 1.05 mM, respectively (P = 0.84). CONCLUSIONS The increase in intracellular Ca2+ concentration caused by remimazolam or propofol was not considered an RYR1-mediated reaction. We conclude that remimazolam and propofol can be safely used as an anesthetic in MH-susceptible patients with RYR1-mutation without causing MH and may be safely substituted for an MH-triggering anesthetic when RYR1-mediated MH occurs.
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Affiliation(s)
- Tomoyuki Watanabe
- Department of Anesthesiology and Critical Care, Hiroshima University, Hiroshima 734-8551, Japan
| | - Hirotsugu Miyoshi
- Department of Anesthesiology and Critical Care, Hiroshima University, Hiroshima 734-8551, Japan
| | - Yuko Noda
- Department of Anesthesiology and Critical Care, Hiroshima University, Hiroshima 734-8551, Japan
| | - Soshi Narasaki
- Department of Anesthesiology and Critical Care, Hiroshima University, Hiroshima 734-8551, Japan
| | - Atsushi Morio
- Department of Anesthesiology and Critical Care, Hiroshima University, Hiroshima 734-8551, Japan
| | - Yukari Toyota
- Department of Anesthesiology and Critical Care, Hiroshima University, Hiroshima 734-8551, Japan
| | - Hiroshi Kimura
- Department of Anesthesiology and Critical Care, Hiroshima University, Hiroshima 734-8551, Japan
| | - Keiko Mukaida
- Department of Anesthesiology, Hiroshima Prefectural Rehabilitation Center, Higashihiroshima 739-0036, Japan
| | - Toshimichi Yasuda
- Department of Anesthesiology and Critical Care, Hiroshima University, Hiroshima 734-8551, Japan
| | - Yasuo M. Tsutsumi
- Department of Anesthesiology and Critical Care, Hiroshima University, Hiroshima 734-8551, Japan
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T lymphocytes from malignant hyperthermia-susceptible mice display aberrations in intracellular calcium signaling and mitochondrial function. Cell Calcium 2020; 93:102325. [PMID: 33310301 DOI: 10.1016/j.ceca.2020.102325] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2020] [Revised: 11/22/2020] [Accepted: 11/23/2020] [Indexed: 01/05/2023]
Abstract
Gain-of-function RyR1-p.R163C mutation in ryanodine receptors type 1 (RyR1) deregulates Ca2+ signaling and mitochondrial function in skeletal muscle and causes malignant hyperthermia in humans and mice under triggering conditions. We investigated whether T lymphocytes from heterozygous RyR1-p.R163C knock-in mutant mice (HET T cells) display measurable aberrations in resting cytosolic Ca2+ concentration ([Ca2+]i), Ca2+ release from the store, store-operated Ca2+ entry (SOCE), and mitochondrial inner membrane potential (ΔΨm) compared with T lymphocytes from wild-type mice (WT T cells). We explored whether these variables can be used to distinguish between T cells with normal and altered RyR1 genotype. HET and WT T cells were isolated from spleen and lymph nodes and activated in vitro using phytohemagglutinin P. [Ca2+]i and ΔΨm dynamics were examined using Fura 2 and tetramethylrhodamine methyl ester fluorescent dyes, respectively. Activated HET T cells displayed elevated resting [Ca2+]i, diminished responses to Ca2+ mobilization with thapsigargin, and decreased rate of [Ca2+]i elevation in response to SOCE compared with WT T cells. Pretreatment of HET T cells with ryanodine or dantrolene sodium reduced disparities in the resting [Ca2+]i and ability of thapsigargin to mobilize Ca2+ between HET and WT T cells. While SOCE elicited dissipation of the ΔΨm in WT T cells, it produced ΔΨm hyperpolarization in HET T cells. When used as the classification variable, the amplitude of thapsigargin-induced Ca2+ transient showed the best promise in predicting the presence of RyR1-p.R163C mutation. Other significant variables identified by machine learning analysis were the ratio of resting cytosolic Ca2+ level to the amplitude of thapsigargin-induced Ca2+ transient and an integral of changes in ΔΨm in response to SOCE. Our study demonstrated that gain-of-function mutation in RyR1 significantly affects Ca2+ signaling and mitochondrial fiction in T lymphocytes, which suggests that this mutation may cause altered immune responses in its carrier. Our data link the RyR1-p.R163C mutation, which causes inherited skeletal muscle diseases, to deregulation of Ca2+ signaling and mitochondrial function in immune T cells and establish proof-of-principle for in vitro T cell-based diagnostic assay for hereditary RyR1 hyperfunction.
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Lawal TA, Wires ES, Terry NL, Dowling JJ, Todd JJ. Preclinical model systems of ryanodine receptor 1-related myopathies and malignant hyperthermia: a comprehensive scoping review of works published 1990-2019. Orphanet J Rare Dis 2020; 15:113. [PMID: 32381029 PMCID: PMC7204063 DOI: 10.1186/s13023-020-01384-x] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2019] [Accepted: 04/14/2020] [Indexed: 02/07/2023] Open
Abstract
BACKGROUND Pathogenic variations in the gene encoding the skeletal muscle ryanodine receptor (RyR1) are associated with malignant hyperthermia (MH) susceptibility, a life-threatening hypermetabolic condition and RYR1-related myopathies (RYR1-RM), a spectrum of rare neuromuscular disorders. In RYR1-RM, intracellular calcium dysregulation, post-translational modifications, and decreased protein expression lead to a heterogenous clinical presentation including proximal muscle weakness, contractures, scoliosis, respiratory insufficiency, and ophthalmoplegia. Preclinical model systems of RYR1-RM and MH have been developed to better understand underlying pathomechanisms and test potential therapeutics. METHODS We conducted a comprehensive scoping review of scientific literature pertaining to RYR1-RM and MH preclinical model systems in accordance with the PRISMA Scoping Reviews Checklist and the framework proposed by Arksey and O'Malley. Two major electronic databases (PubMed and EMBASE) were searched without language restriction for articles and abstracts published between January 1, 1990 and July 3, 2019. RESULTS Our search yielded 5049 publications from which 262 were included in this review. A majority of variants tested in RYR1 preclinical models were localized to established MH/central core disease (MH/CCD) hot spots. A total of 250 unique RYR1 variations were reported in human/rodent/porcine models with 95% being missense substitutions. The most frequently reported RYR1 variant was R614C/R615C (human/porcine total n = 39), followed by Y523S/Y524S (rabbit/mouse total n = 30), I4898T/I4897T/I4895T (human/rabbit/mouse total n = 20), and R163C/R165C (human/mouse total n = 18). The dyspedic mouse was utilized by 47% of publications in the rodent category and its RyR1-null (1B5) myotubes were transfected in 23% of publications in the cellular model category. In studies of transfected HEK-293 cells, 57% of RYR1 variations affected the RyR1 channel and activation core domain. A total of 15 RYR1 mutant mouse strains were identified of which ten were heterozygous, three were compound heterozygous, and a further two were knockout. Porcine, avian, zebrafish, C. elegans, canine, equine, and drosophila model systems were also reported. CONCLUSIONS Over the past 30 years, there were 262 publications on MH and RYR1-RM preclinical model systems featuring more than 200 unique RYR1 variations tested in a broad range of species. Findings from these studies have set the foundation for therapeutic development for MH and RYR1-RM.
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Affiliation(s)
- Tokunbor A Lawal
- National Institute of Nursing Research, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Emily S Wires
- National Institute on Drug Abuse, National Institutes of Health, Baltimore, MD, USA
| | - Nancy L Terry
- National Institutes of Health Library, National Institutes of Health, Bethesda, MD, USA
| | - James J Dowling
- Program for Genetics and Genome Biology, Hospital for Sick Children, Toronto, Ontario, Canada
| | - Joshua J Todd
- National Institute of Nursing Research, National Institutes of Health, Bethesda, MD, 20892, USA.
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RYR1 Sequence Variants in Myopathies: Expression and Functional Studies in Two Families. BIOMED RESEARCH INTERNATIONAL 2019; 2019:7638946. [PMID: 31165076 PMCID: PMC6500691 DOI: 10.1155/2019/7638946] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/14/2018] [Accepted: 03/19/2019] [Indexed: 12/26/2022]
Abstract
The skeletal muscle ryanodine receptor (RyR1), i.e., the Ca2+ channel of the sarco/endoplasmic reticulum (S/ER), and the voltage-dependent calcium channel Cav1.1 are the principal channels involved in excitation-contraction coupling in skeletal muscle. RYR1 gene variants are linked to distinct skeletal muscle disorders, including malignant hyperthermia susceptibility and central core disease (CCD), mainly with autosomal dominant inheritance, and autosomal recessive myopathies with a broad phenotypic and histopathological spectrum. The age at onset of RYR1-related myopathies varies from infancy to adulthood. We report the identification of four RYR1 variants in two Italian families: one with myopathy and variants c.4003C>T (p.R1335C) and c.7035C>A (p.S2345R), and another with CCD and variants c.9293G>T (p.S3098I) and c.14771_14772insTAGACAGGGTGTTGCTCTGTTGCCCTTCTT (p.F4924_V4925insRQGVALLPFF). We demonstrate that, in patient-specific lymphoblastoid cells, the c.4003C>T (p.R1335C) variant is not expressed and the in-frame 30-nucleotide insertion variant is expressed at a low level. Moreover, Ca2+ release in response to the RyR1 agonist 4-chloro-m-cresol and to thapsigargin showed that the c.7035C>A (p.S2345R) variant causes depletion of S/ER Ca2+ stores and that the compound heterozygosity for variant c.9293G>T (p.S3098I) and the 30-nucleotide insertion increases RyR1-dependent Ca2+ release without affecting ER Ca2+ stores. In conclusion, we detected and functionally characterized disease-causing variants of the RyR1 channel in patient-specific lymphoblastoid cells. This paper is dedicated to the memory and contribution of Luigi Del Vecchio.
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Todd JJ, Sagar V, Lawal TA, Allen C, Razaqyar MS, Shelton MS, Chrismer IC, Zhang X, Cosgrove MM, Kuo A, Vasavada R, Jain MS, Waite M, Rajapakse D, Witherspoon JW, Wistow G, Meilleur KG. Correlation of phenotype with genotype and protein structure in RYR1-related disorders. J Neurol 2018; 265:2506-2524. [PMID: 30155738 PMCID: PMC6182665 DOI: 10.1007/s00415-018-9033-2] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2018] [Revised: 08/17/2018] [Accepted: 08/18/2018] [Indexed: 01/01/2023]
Abstract
Variants in the skeletal muscle ryanodine receptor 1 gene (RYR1) result in a spectrum of RYR1-related disorders. Presentation during infancy is typical and ranges from delayed motor milestones and proximal muscle weakness to severe respiratory impairment and ophthalmoplegia. We aimed to elucidate correlations between genotype, protein structure and clinical phenotype in this rare disease population. Genetic and clinical data from 47 affected individuals were analyzed and variants mapped to the cryo-EM RyR1 structure. Comparisons of clinical severity, motor and respiratory function and symptomatology were made according to the mode of inheritance and affected RyR1 structural domain(s). Overall, 49 RYR1 variants were identified in 47 cases (dominant/de novo, n = 35; recessive, n = 12). Three variants were previously unreported. In recessive cases, facial weakness, neonatal hypotonia, ophthalmoplegia/paresis, ptosis, and scapular winging were more frequently observed than in dominant/de novo cases (all, p < 0.05). Both dominant/de novo and recessive cases exhibited core myopathy histopathology. Clinically severe cases were typically recessive or had variants localized to the RyR1 cytosolic shell domain. Motor deficits were most apparent in the MFM-32 standing and transfers dimension, [median (IQR) 85.4 (18.8)% of maximum score] and recessive cases exhibited significantly greater overall motor function impairment compared to dominant/de novo cases [79.7 (18.8)% vs. 87.5 (17.7)% of maximum score, p = 0.03]. Variant mapping revealed patterns of clinical severity across RyR1 domains, including a structural plane of interest within the RyR1 cytosolic shell, in which 84% of variants affected the bridging solenoid. We have corroborated genotype-phenotype correlations and identified RyR1 regions that may be especially sensitive to structural modification.
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Affiliation(s)
- Joshua J Todd
- Neuromuscular Symptoms Unit, Tissue Injury Branch, National Institute of Nursing Research, National Institutes of Health, 10 Center Drive, Room 2A07, Bethesda, MD, 20892, USA.
| | - Vatsala Sagar
- Section on Molecular Structure and Functional Genomics, National Eye Institute, National Institutes of Health, Bethesda, MD, USA
| | - Tokunbor A Lawal
- Neuromuscular Symptoms Unit, Tissue Injury Branch, National Institute of Nursing Research, National Institutes of Health, 10 Center Drive, Room 2A07, Bethesda, MD, 20892, USA
| | - Carolyn Allen
- Neuromuscular Symptoms Unit, Tissue Injury Branch, National Institute of Nursing Research, National Institutes of Health, 10 Center Drive, Room 2A07, Bethesda, MD, 20892, USA
| | - Muslima S Razaqyar
- Neuromuscular Symptoms Unit, Tissue Injury Branch, National Institute of Nursing Research, National Institutes of Health, 10 Center Drive, Room 2A07, Bethesda, MD, 20892, USA
| | - Monique S Shelton
- Neuromuscular Symptoms Unit, Tissue Injury Branch, National Institute of Nursing Research, National Institutes of Health, 10 Center Drive, Room 2A07, Bethesda, MD, 20892, USA
| | - Irene C Chrismer
- Neuromuscular Symptoms Unit, Tissue Injury Branch, National Institute of Nursing Research, National Institutes of Health, 10 Center Drive, Room 2A07, Bethesda, MD, 20892, USA
| | - Xuemin Zhang
- Neuromuscular Symptoms Unit, Tissue Injury Branch, National Institute of Nursing Research, National Institutes of Health, 10 Center Drive, Room 2A07, Bethesda, MD, 20892, USA
| | - Mary M Cosgrove
- Neuromuscular Symptoms Unit, Tissue Injury Branch, National Institute of Nursing Research, National Institutes of Health, 10 Center Drive, Room 2A07, Bethesda, MD, 20892, USA
| | - Anna Kuo
- Neuromuscular Symptoms Unit, Tissue Injury Branch, National Institute of Nursing Research, National Institutes of Health, 10 Center Drive, Room 2A07, Bethesda, MD, 20892, USA
| | - Ruhi Vasavada
- Mark O. Hatfield Clinical Research Center, Rehabilitation Medicine Department, National Institutes of Health, Bethesda, MD, USA
| | - Minal S Jain
- Mark O. Hatfield Clinical Research Center, Rehabilitation Medicine Department, National Institutes of Health, Bethesda, MD, USA
| | - Melissa Waite
- Mark O. Hatfield Clinical Research Center, Rehabilitation Medicine Department, National Institutes of Health, Bethesda, MD, USA
| | - Dinusha Rajapakse
- Section on Molecular Structure and Functional Genomics, National Eye Institute, National Institutes of Health, Bethesda, MD, USA
| | - Jessica W Witherspoon
- Neuromuscular Symptoms Unit, Tissue Injury Branch, National Institute of Nursing Research, National Institutes of Health, 10 Center Drive, Room 2A07, Bethesda, MD, 20892, USA
| | - Graeme Wistow
- Section on Molecular Structure and Functional Genomics, National Eye Institute, National Institutes of Health, Bethesda, MD, USA
| | - Katherine G Meilleur
- Neuromuscular Symptoms Unit, Tissue Injury Branch, National Institute of Nursing Research, National Institutes of Health, 10 Center Drive, Room 2A07, Bethesda, MD, 20892, USA
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Ravenscroft G, Davis MR, Lamont P, Forrest A, Laing NG. New era in genetics of early-onset muscle disease: Breakthroughs and challenges. Semin Cell Dev Biol 2016; 64:160-170. [PMID: 27519468 DOI: 10.1016/j.semcdb.2016.08.002] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2016] [Revised: 08/07/2016] [Accepted: 08/08/2016] [Indexed: 10/21/2022]
Abstract
Early-onset muscle disease includes three major entities that present generally at or before birth: congenital myopathies, congenital muscular dystrophies and congenital myasthenic syndromes. Almost exclusively there is weakness and hypotonia, although cases manifesting hypertonia are increasingly being recognised. These diseases display a wide phenotypic and genetic heterogeneity, with the uptake of next generation sequencing resulting in an unparalleled extension of the phenotype-genotype correlations and "diagnosis by sequencing" due to unbiased sequencing. Perhaps now more than ever, detailed clinical evaluations are necessary to guide the genetic diagnosis; with arrival at a molecular diagnosis frequently occurring following dialogue between the molecular geneticist, the referring clinician and the pathologist. There is an ever-increasing blurring of the boundaries between the congenital myopathies, dystrophies and myasthenic syndromes. In addition, many novel disease genes have been described and new insights have been gained into skeletal muscle development and function. Despite the advances made, a significant percentage of patients remain without a molecular diagnosis, suggesting that there are many more human disease genes and mechanisms to identify. It is now technically- and clinically-feasible to perform next generation sequencing for severe diseases on a population-wide scale, such that preconception-carrier screening can occur. Newborn screening for selected early-onset muscle diseases is also technically and ethically-achievable, with benefits to the patient and family from early management of these diseases and should also be implemented. The need for world-wide Reference Centres to meticulously curate polymorphisms and mutations within a particular gene is becoming increasingly apparent, particularly for interpretation of variants in the large genes which cause early-onset myopathies: NEB, RYR1 and TTN. Functional validation of candidate disease variants is crucial for accurate interpretation of next generation sequencing and appropriate genetic counseling. Many published "pathogenic" variants are too frequent in control populations and are thus likely rare polymorphisms. Mechanisms need to be put in place to systematically update the classification of variants such that accurate interpretation of variants occurs. In this review, we highlight the recent advances made and the challenges ahead for the molecular diagnosis of early-onset muscle diseases.
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Affiliation(s)
- Gianina Ravenscroft
- Harry Perkins Institute of Medical Research and the Centre for Medical Research, University of Western Australia, Nedlands, Australia
| | - Mark R Davis
- Department of Diagnostic Genomics, Pathwest, QEII Medical Centre, Nedlands, Australia
| | - Phillipa Lamont
- Harry Perkins Institute of Medical Research and the Centre for Medical Research, University of Western Australia, Nedlands, Australia; Neurogenetic unit, Dept of Neurology, Royal Perth Hospital and The Perth Children's Hospital, Western Australia, Australia
| | - Alistair Forrest
- Harry Perkins Institute of Medical Research and the Centre for Medical Research, University of Western Australia, Nedlands, Australia
| | - Nigel G Laing
- Harry Perkins Institute of Medical Research and the Centre for Medical Research, University of Western Australia, Nedlands, Australia; Department of Diagnostic Genomics, Pathwest, QEII Medical Centre, Nedlands, Australia.
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