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Yi H, Liu CX, Ye SX, Liu YL. Special electromyographic features in a child with paramyotonia congenita: A case report and review of literature. World J Clin Cases 2024; 12:587-595. [PMID: 38322461 PMCID: PMC10841953 DOI: 10.12998/wjcc.v12.i3.587] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/21/2023] [Revised: 12/04/2023] [Accepted: 01/04/2024] [Indexed: 01/18/2024] Open
Abstract
BACKGROUND Paramyotonia congenita (PMC) stands as a rare sodium channelopaty of skeletal muscle, initially identified by Eulenburg. The identification of PMC often relies on electromyography (EMG), a diagnostic technique. The child's needle EMG unveiled trains of myotonic discharges with notably giant amplitudes, alongside irregular wave trains of myotonic discharges. This distinctive observation had not surfaced in earlier studies. CASE SUMMARY We report the case of a 3-year-old female child with PMC, who exhibited laryngeal stridor, muffled speech, myotonia from birth. Cold, exposure to cool water, crying, and physical activity exacerbated the myotonia, which was relieved in warmth, yet never normalized. Percussion myotonia was observable in bilateral biceps. Myotonia symptoms remained unchanged after potassium-rich food consumption like bananas. Hyperkalemic periodic paralysis was excluded. Cranial magnetic resonance imaging yielded normal results. Blood potassium remained within normal range, while creatine kinase showed slight elevation. Exome-wide genetic testing pinpointed a heterozygous mutation on chromosome SCN4A: c.3917G>A (p.G1306E). After a six-month mexiletine regimen, symptoms alleviated. CONCLUSION In this case revealed the two types of myotonic discharges, and had not been documented in other studies. We underscore two distinctive features: Giant-amplitude potentials and irregular waves.
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Affiliation(s)
- Hui Yi
- Department of Neuroelectrophysiology, Qilu Children’s Hospital of Shandong University, Jinan 250000, Shandong Province, China
| | - Chen-Xiang Liu
- Department of Neuroelectrophysiology, University of Health and Rehabilitation Sciences (Qingdao Municipal Hospital), Qingdao 266000, Shandong Province, China
| | - Shu-Xin Ye
- Department of Neuroelectrophysiology, Qilu Children’s Hospital of Shandong University, Jinan 250000, Shandong Province, China
| | - Yu-Lin Liu
- Department of Neuroelectrophysiology, Qilu Children’s Hospital of Shandong University, Jinan 250000, Shandong Province, China
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2
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Vicino A, Brugnoni R, Maggi L. Diagnostics in skeletal muscle channelopathies. Expert Rev Mol Diagn 2023; 23:1175-1193. [PMID: 38009256 DOI: 10.1080/14737159.2023.2288258] [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: 08/23/2023] [Accepted: 11/22/2023] [Indexed: 11/28/2023]
Abstract
INTRODUCTION Skeletal muscle channelopathies (SMCs) are a heterogenous group of disorders, caused by mutations in skeletal ion channels leading to abnormal muscle excitability, resulting in either delayed muscle relaxation (myotonia) which characterizes non-dystrophic myotonias (NDMs), or membrane transient inactivation, causing episodic weakness, typical of periodic paralyses (PPs). AREAS COVERED SMCs include myotonia congenita, paramyotonia congenita, and sodium-channel myotonia among NDMs, and hyper-normokalemic, hypokalemic, or late-onset periodic paralyses among PPs. When suspecting an SMC, a structured diagnostic approach is required. Detailed personal and family history and clinical examination are essential, while neurophysiological tests should confirm myotonia and rule out alternative diagnosis. Moreover, specific electrodiagnostic studies are important to further define the phenotype of de novo cases and drive molecular analyses together with clinical data. Definite diagnosis is achieved through genetic testing, either with Sanger sequencing or multigene next-generation sequencing panel. In still unsolved patients, more advanced techniques, as exome-variant sequencing or whole-genome sequencing, may be considered in expert centers. EXPERT OPINION The diagnostic approach to SMC is still mainly based on clinical data; moreover, definite diagnosis is sometimes complicated by the difficulty to establish a proper genotype-phenotype correlation. Lastly, further studies are needed to allow the genetic characterization of unsolved patients.
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Affiliation(s)
- Alex Vicino
- Neurology IV Unit, Neuroimmunology and Neuromuscular Diseases, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy
- Nerve-Muscle Unit, Neurology Service, Department of Clinical Neurosciences, Lausanne University Hospital and University of Lausanne, Lausanne, Switzerland
| | - Raffaella Brugnoni
- Neurology IV Unit, Neuroimmunology and Neuromuscular Diseases, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy
| | - Lorenzo Maggi
- Neurology IV Unit, Neuroimmunology and Neuromuscular Diseases, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy
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3
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Trivedi JR. Muscle Channelopathies. Continuum (Minneap Minn) 2022; 28:1778-1799. [PMID: 36537980 DOI: 10.1212/con.0000000000001183] [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: 12/24/2022]
Abstract
PURPOSE OF REVIEW This article describes the clinical features, diagnosis, pathophysiology, and management of nondystrophic myotonia and periodic paralysis. RECENT FINDINGS An increasing awareness exists about the genotype-phenotype overlap in skeletal muscle channelopathies, and thus genetic testing is needed to make a definitive diagnosis. Electrodiagnostic testing in channelopathies is highly specialized with significant overlap in various mutation subtypes. Randomized clinical trials have now been conducted in these disorders with expanded treatment options for patients with muscle channelopathies. SUMMARY Skeletal muscle channelopathies are rare heterogeneous conditions characterized by lifelong symptoms that require a comprehensive management plan that includes pharmacologic and nonpharmacologic interventions. The significant variability in biophysical features of various mutations, coupled with the difficulties of performing clinical trials in rare diseases, makes it challenging to design and implement treatment trials for muscle channelopathies.
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4
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Fullam TR, Chandrashekhar S, Farmakidis C, Jawdat O, Pasnoor M, Dimachkie MM, Statland JM. Non-dystrophic myotonia: 2-year clinical and patient reported outcomes. Muscle Nerve 2022; 66:148-158. [PMID: 35644941 PMCID: PMC9308727 DOI: 10.1002/mus.27649] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2021] [Revised: 05/24/2022] [Accepted: 05/25/2022] [Indexed: 11/06/2022]
Abstract
INTRODUCTION/AIMS Consistency of differences between non-dystrophic myotonias over time measured by standardized clinical/patient-reported outcomes is lacking. Evaluation of longitudinal data could establish clinically relevant endpoints for future research. METHODS Data from prospective observational study of 95 definite/clinically suspected non-dystrophic myotonia participants (six sites in the United States, United Kingdom, and Canada) between March 2006 and March 2009 were analyzed. Outcomes included: standardized symptom interview/exam, Short Form-36, Individualized Neuromuscular Quality of Life (INQoL), electrophysiological short/prolonged exercise tests, manual muscle testing, quantitative grip strength, modified get-up-and-go test. Patterns were assigned as described by Fournier et al. Comparisons were restricted to confirmed sodium channelopathies (SCN4A, baseline, year 1, year 2: n = 34, 19, 13), chloride channelopathies (CLCN1, n = 32, 26, 18), and myotonic dystrophy type 2 (DM2, n = 9, 6, 2). RESULTS Muscle stiffness was the most frequent symptom over time (54.7%-64.7%). Eyelid myotonia and paradoxical handgrip/eyelid myotonia were more frequent in SCN4A. Grip strength and combined manual muscle testing remained stable. Modified get-up-and-go showed less warm up in SCN4A but remained stable. Median post short exercise decrement was stable, except for SCN4A (baseline to year 2 decrement difference 16.6% [Q1, Q3: 9.5, 39.2]). Fournier patterns type 2 (CLCN1) and 1 (SCN4A) were most specific; 40.4% of participants had a change in pattern over time. INQoL showed higher impact for SCN4A and DM2 with scores stable over time. DISCUSSION Symptom frequency and clinical outcome assessments were stable with defined variability in myotonia measures supporting trial designs like cross over or combined n-of-1 as important for rare disorders.
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Affiliation(s)
- Timothy R Fullam
- Department of Neurology, University of Kansas Medical Center, Kansas City, Kansas, USA.,Department of Neurology, Brooke Army Medical Center, JBSA-Fort Sam, Houston, Texas, USA
| | - Swathy Chandrashekhar
- Department of Neurology, University of Kansas Medical Center, Kansas City, Kansas, USA
| | | | - Omar Jawdat
- Department of Neurology, University of Kansas Medical Center, Kansas City, Kansas, USA
| | - Mamatha Pasnoor
- Department of Neurology, University of Kansas Medical Center, Kansas City, Kansas, USA
| | - Mazen M Dimachkie
- Department of Neurology, University of Kansas Medical Center, Kansas City, Kansas, USA
| | - Jeffrey M Statland
- Department of Neurology, University of Kansas Medical Center, Kansas City, Kansas, USA
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5
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Treatment and Management of Disorders of Neuromuscular Hyperexcitability and Periodic Paralysis. Neuromuscul Disord 2022. [DOI: 10.1016/b978-0-323-71317-7.00018-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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6
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Asif M, Mocanu ID, Abdullah U, Höhne W, Altmüller J, Makhdoom EUH, Thiele H, Baig SM, Nürnberg P, Graul-Neumann L, Hussain MS. A novel missense variant of SCN4A co-segregates with congenital essential tremor in a consanguineous Kurdish family. Am J Med Genet A 2021; 188:1251-1258. [PMID: 34913263 DOI: 10.1002/ajmg.a.62610] [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: 09/14/2021] [Revised: 11/10/2021] [Accepted: 11/30/2021] [Indexed: 11/09/2022]
Abstract
Essential tremor (ET) is a neurological disorder characterized by bilateral and symmetric postural, isometric, and kinetic tremors of forelimbs produced during voluntary movements. To date, only a single SCN4A variant has been suggested to cause ET. In continuation of the previous report on the association between SCN4A and ET in a family from Spain, we validated the pathogenicity of a novel SCN4A variant and its involvement in ET in a second family affected by this disease. We recruited a Kurdish family with four affected members manifesting congenital tremor. Using whole-exome sequencing, we identified a novel missense variant in SCN4A, NM_000334.4:c.4679C>T; p.(Pro1560Leu), thus corroborating SCN4A's role in ET. The residue is highly conserved across vertebrates and the substitution is predicted to be pathogenic by various in silico tools. Western blotting and immunocytochemistry performed in cells derived from one of the patients showed reduced immunoreactivity of SCN4A as compared to control cells. The study provides supportive evidence for the role of SCN4A in the etiology of ET and expands the phenotypic spectrum of channelopathies to this neurological disorder.
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Affiliation(s)
- Maria Asif
- Cologne Center for Genomics (CCG), University of Cologne, Faculty of Medicine and University Hospital Cologne, Cologne, Germany.,Center for Biochemistry, Medical Faculty, University of Cologne, Cologne, Germany
| | - Ionut Dragos Mocanu
- Center for Biochemistry, Medical Faculty, University of Cologne, Cologne, Germany
| | - Uzma Abdullah
- University Institute of Biochemistry and Biotechnology (UIBB), PMAS-Arid Agriculture University, Rawalpindi, Pakistan
| | - Wolfgang Höhne
- Cologne Center for Genomics (CCG), University of Cologne, Faculty of Medicine and University Hospital Cologne, Cologne, Germany
| | - Janine Altmüller
- Cologne Center for Genomics (CCG), University of Cologne, Faculty of Medicine and University Hospital Cologne, Cologne, Germany.,Berlin Institute of Health at Charité-Universitätsmedizin Berlin, Core Facility Genomics, Berlin, Germany.,Max Delbrück Center for Molecular Medicine in the Helmholtz Association (MDC), Berlin, Germany
| | - Ehtisham Ul Haq Makhdoom
- Cologne Center for Genomics (CCG), University of Cologne, Faculty of Medicine and University Hospital Cologne, Cologne, Germany.,Center for Biochemistry, Medical Faculty, University of Cologne, Cologne, Germany.,Human Molecular Genetics Laboratory, Health Biotechnology Division, National Institute for Biotechnology and Genetic Engineering (NIBGE) College, PIEAS, Faisalabad, Pakistan.,Neurochemicalbiology and Genetics Laboratory (NGL), Department of Physiology, Faculty of Life Sciences, Government College University, Faisalabad, Pakistan
| | - Holger Thiele
- Cologne Center for Genomics (CCG), University of Cologne, Faculty of Medicine and University Hospital Cologne, Cologne, Germany
| | - Shahid Mahmood Baig
- Human Molecular Genetics Laboratory, Health Biotechnology Division, National Institute for Biotechnology and Genetic Engineering (NIBGE) College, PIEAS, Faisalabad, Pakistan.,Pakistan Science Foundation (PSF), Islamabad, Pakistan.,Department of Biological and Biomedical Sciences, Aga Khan University, Karachi, Pakistan
| | - Peter Nürnberg
- Cologne Center for Genomics (CCG), University of Cologne, Faculty of Medicine and University Hospital Cologne, Cologne, Germany.,Center for Molecular Medicine Cologne (CMMC), University of Cologne, Faculty of Medicine and University Hospital Cologne, Cologne, Germany
| | - Luitgard Graul-Neumann
- Charité-Universitätsmedizin Berlin, Institut für Medizinische Genetik und Humangenetik, Berlin, Germany
| | - Muhammad Sajid Hussain
- Cologne Center for Genomics (CCG), University of Cologne, Faculty of Medicine and University Hospital Cologne, Cologne, Germany.,Center for Biochemistry, Medical Faculty, University of Cologne, Cologne, Germany.,Center for Molecular Medicine Cologne (CMMC), University of Cologne, Faculty of Medicine and University Hospital Cologne, Cologne, Germany
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7
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Sampaio F, Soares S, Pereira S, Lemos JA, Mota Á. Sodium Channel Myotonia and a Novel Gly701Asp Mutation in the SCN4A Gene: From an Ophthalmological Symptom to a Familial Disease. Neuroophthalmology 2021; 45:41-44. [PMID: 33762787 DOI: 10.1080/01658107.2020.1779316] [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] [Indexed: 10/23/2022] Open
Abstract
A six-month-old female child came to an ophthalmology consultation because of a convergent strabismus, myotonia of the orbicularis muscles and difficulty walking in cold environments. Further investigation identified a family history of muscular myotonia in the father, grandmother and uncle. The father also presented with ocular myotonia. The child and family members underwent genetic testing, which was negative for CLCN1 mutations but was positive for a novel heterozygotic Gly701Asp mutation in the SCN4A gene, compatible with sodium channel myotonia. The non-dystrophic myotonias are caused by dysfunction of key skeletal muscle ion channels. Before the advent of DNA sequencing, non-dystrophic myotonias were differentiated based on clinical phenotypes. Sodium channel myotonia disorders are classically of dominant inheritance, in which eye closure myotonia is the most frequent manifestation. Over 40 different mutations have been reported in the SCN4A gene. The Gly701Asp mutation in exon 13 identified in this family has not been described before.
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Affiliation(s)
- Filipa Sampaio
- Ophthalmology Department, Hospital Pedro Hispano, Unidade Local De Saúde De Matosinhos, Matosinhos, Portugal
| | - Sérgia Soares
- Pediatric Department, Hospital Pedro Hispano, Unidade Local De Saúde De Matosinhos, Matosinhos, Portugal
| | - Sara Pereira
- Ophthalmology Department, Hospital Pedro Hispano, Unidade Local De Saúde De Matosinhos, Matosinhos, Portugal
| | - José Alberto Lemos
- Ophthalmology Department, Hospital Pedro Hispano, Unidade Local De Saúde De Matosinhos, Matosinhos, Portugal
| | - Ágata Mota
- Ophthalmology Department, Hospital Pedro Hispano, Unidade Local De Saúde De Matosinhos, Matosinhos, Portugal
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8
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Brugnoni R, Maggi L, Canioni E, Verde F, Gallone A, Ariatti A, Filosto M, Petrelli C, Logullo FO, Esposito M, Ruggiero L, Tonin P, Riguzzi P, Pegoraro E, Torri F, Ricci G, Siciliano G, Silani V, Merlini L, De Pasqua S, Liguori R, Pini A, Mariotti C, Moroni I, Imbrici P, Desaphy JF, Mantegazza R, Bernasconi P. Next-generation sequencing application to investigate skeletal muscle channelopathies in a large cohort of Italian patients. Neuromuscul Disord 2020; 31:336-347. [PMID: 33573884 DOI: 10.1016/j.nmd.2020.12.003] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2020] [Revised: 12/04/2020] [Accepted: 12/07/2020] [Indexed: 01/09/2023]
Abstract
Non-dystrophic myotonias and periodic paralyses are a heterogeneous group of disabling diseases classified as skeletal muscle channelopathies. Their genetic characterization is essential for prognostic and therapeutic purposes; however, several genes are involved. Sanger-based sequencing of a single gene is time-consuming, often expensive; thus, we designed a next-generation sequencing panel of 56 putative candidate genes for skeletal muscle channelopathies, codifying for proteins involved in excitability, excitation-contraction coupling, and metabolism of muscle fibres. We analyzed a large cohort of 109 Italian patients with a suspect of NDM or PP by next-generation sequencing. We identified 24 patients mutated in CLCN1 gene, 15 in SCN4A, 3 in both CLCN1 and SCN4A, 1 in ATP2A1, 1 in KCNA1 and 1 in CASQ1. Eight were novel mutations: p.G395Cfs*32, p.L843P, p.V829M, p.E258E and c.1471+4delTCAAGAC in CLCN1, p.K1302R in SCN4A, p.L208P in ATP2A1 and c.280-1G>C in CASQ1 genes. This study demonstrated the utility of targeted next generation sequencing approach in molecular diagnosis of skeletal muscle channelopathies and the importance of the collaboration between clinicians and molecular geneticists and additional methods for unclear variants to make a conclusive diagnosis.
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Affiliation(s)
- Raffaella Brugnoni
- Neurology IV Unit, Neuroimmunology and Neuromuscular Diseases, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy.
| | - Lorenzo Maggi
- Neurology IV Unit, Neuroimmunology and Neuromuscular Diseases, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy
| | - Eleonora Canioni
- Neurology IV Unit, Neuroimmunology and Neuromuscular Diseases, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy
| | - Federico Verde
- Department of Neurology-Stroke Unit and Laboratory of Neuroscience, IRCCS Istituto Auxologico Italiano, Milan, Italy; Department of Pathophysiology and Transplantation, "Dino Ferrari" Center, "Aldo Ravelli" Center for Neurotechnology and Experimental Brain Therapeutics, Università degli Studi di Milano, Milan, Italy
| | - Annamaria Gallone
- Neurology IV Unit, Neuroimmunology and Neuromuscular Diseases, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy
| | - Alessandra Ariatti
- Department of Neurosciences, Azienda Ospedaliero-Universitaria di Modena, Ospedale Civile di Baggiovara, Modena, Italy
| | - Massimiliano Filosto
- Center for Neuromuscular Diseases, Unit of Neurology, ASST Spedali Civili and University of Brescia, Brescia, Italy
| | | | | | - Marcello Esposito
- Department of Neurosciences, Reproductive, and Odontostomatological Sciences, University Federico II, Naples, Italy
| | - Lucia Ruggiero
- Department of Neurosciences, Reproductive, and Odontostomatological Sciences, University Federico II, Naples, Italy
| | - Paola Tonin
- Neurological Clinic, University of Verona, Verona, Italy
| | - Pietro Riguzzi
- Department of Neurosciences, University of Padova, Padova, Italy
| | - Elena Pegoraro
- Department of Neurosciences, University of Padova, Padova, Italy
| | - Francesca Torri
- Department of Clinical and Experimental Medicine, University of Pisa, Pisa, Italy
| | - Giulia Ricci
- Department of Clinical and Experimental Medicine, University of Pisa, Pisa, Italy
| | - Gabriele Siciliano
- Department of Clinical and Experimental Medicine, University of Pisa, Pisa, Italy
| | - Vincenzo Silani
- Department of Neurology-Stroke Unit and Laboratory of Neuroscience, IRCCS Istituto Auxologico Italiano, Milan, Italy; Department of Pathophysiology and Transplantation, "Dino Ferrari" Center, "Aldo Ravelli" Center for Neurotechnology and Experimental Brain Therapeutics, Università degli Studi di Milano, Milan, Italy
| | - Luciano Merlini
- DIBINEM-Department of Biomedical and Neuromotor Sciences, University of Bologna, Bologna, Italy
| | - Silvia De Pasqua
- Dipartimento di Scienze Biomediche e Neuromotorie, Università di Bologna, Bologna, Italy
| | - Rocco Liguori
- Dipartimento di Scienze Biomediche e Neuromotorie, Università di Bologna, Bologna, Italy
| | - Antonella Pini
- Neuromuscular Pediatric Unit, IRRCS Istituto delle Scienze Neurologiche di Bologna
| | - Caterina Mariotti
- Unit of Medical Genetics and Neurogenetics, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy
| | - Isabella Moroni
- Department of Pediatric Neuroscience, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy
| | - Paola Imbrici
- Department of Pharmacy-Drug Sciences, University of Bari "Aldo Moro", Bari, Italy
| | - Jean-Francois Desaphy
- Department of Biomedical Sciences and Human Oncology, School of Medicine, University of Bari "Aldo Moro", Bari, Italy
| | - Renato Mantegazza
- Neurology IV Unit, Neuroimmunology and Neuromuscular Diseases, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy
| | - Pia Bernasconi
- Neurology IV Unit, Neuroimmunology and Neuromuscular Diseases, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy
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9
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Brooks EK, Schweitzer D, Robinson HL. A case of paramyotonia congenita in pregnancy. Obstet Med 2020; 13:192-194. [PMID: 33343696 PMCID: PMC7726174 DOI: 10.1177/1753495x18816171] [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: 05/01/2018] [Accepted: 11/05/2018] [Indexed: 11/17/2022] Open
Abstract
Paramyotonia congenita is a rare autosomal dominant non-dystrophic myopathy caused by mutations in the SNC4A gene, which encodes for the voltage-gated sodium channel in skeletal muscle. Symptom onset is typically during early childhood and is characterised by myotonia followed by flaccid paralysis or weakness, usually exacerbated by repeated muscle contractions or cold temperatures. Pregnancy has been reported to increase symptoms of myotonia; however, there is limited information in the literature regarding the possible effects of paramyotonia congenita on pregnancy and labour. We present a successful case of a 20-year-old primigravida with confirmed paramyotonia congenita and review the literature regarding paramyotonia congenita during pregnancy.
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Affiliation(s)
- EK Brooks
- Department of Medicine, Ipswich Hospital, Ipswich, Queensland, Australia
| | - D Schweitzer
- Department of Neurology, Mater Hospital, Brisbane, Queensland, Australia
| | - HL Robinson
- Department of Medicine, Ipswich Hospital, Ipswich, Queensland, Australia
- Department of Obstetric Medicine, Royal Brisbane and Women’s Hospital, Brisbane, Queensland, Australia
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10
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Stunnenberg BC, LoRusso S, Arnold WD, Barohn RJ, Cannon SC, Fontaine B, Griggs RC, Hanna MG, Matthews E, Meola G, Sansone VA, Trivedi JR, van Engelen BG, Vicart S, Statland JM. Guidelines on clinical presentation and management of nondystrophic myotonias. Muscle Nerve 2020; 62:430-444. [PMID: 32270509 PMCID: PMC8117169 DOI: 10.1002/mus.26887] [Citation(s) in RCA: 44] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2020] [Revised: 04/01/2020] [Accepted: 04/04/2020] [Indexed: 12/26/2022]
Abstract
The nondystrophic myotonias are rare muscle hyperexcitability disorders caused by gain-of-function mutations in the SCN4A gene or loss-of-function mutations in the CLCN1 gene. Clinically, they are characterized by myotonia, defined as delayed muscle relaxation after voluntary contraction, which leads to symptoms of muscle stiffness, pain, fatigue, and weakness. Diagnosis is based on history and examination findings, the presence of electrical myotonia on electromyography, and genetic confirmation. In the absence of genetic confirmation, the diagnosis is supported by detailed electrophysiological testing, exclusion of other related disorders, and analysis of a variant of uncertain significance if present. Symptomatic treatment with a sodium channel blocker, such as mexiletine, is usually the first step in management, as well as educating patients about potential anesthetic complications.
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Affiliation(s)
- Bas C. Stunnenberg
- Department of Neurology, Radboud University Medical Center, Nijmegen, the Netherlands
| | - Samantha LoRusso
- Department of Neurology, Ohio State University Wexner Medical Center, Columbus, Ohio
| | - W. David Arnold
- Department of Neurology, Ohio State University Wexner Medical Center, Columbus, Ohio
| | - Richard J. Barohn
- Department of Neurology, University of Kansas Medical Center, Kansas City, Kansas
| | - Stephen C. Cannon
- Department of Physiology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, California
| | - Bertrand Fontaine
- Assistance Publique-Hôpitaix de Paris, Sorbonne Université, INSERM, Service of Neuro-Myology and UMR 974, Institute of Myology, University Hospital Pitié-Salpêtrière, Paris, France
| | - Robert C. Griggs
- Department of Neurology, University of Rochester, Rochester, New York
| | - Michael G. Hanna
- MRC Centre for Neuromuscular Diseases, Department of Neuromuscular diseases, UCL Queen Square Institute of Neurology, United Kingdom
| | - Emma Matthews
- MRC Centre for Neuromuscular Diseases, Department of Neuromuscular diseases, UCL Queen Square Institute of Neurology, United Kingdom
| | - Giovanni Meola
- Department of Neurorehabilitation Sciences, Casa Cura Policlinico, Milan, Italy
- Department of Biomedical Sciences for Health, University of Milan, Milan, Italy
| | - Valeria A. Sansone
- Department of Biomedical Sciences for Health, University of Milan, Milan, Italy
- Neurorehabilitation Unit, University of Milan, NEuroMuscular Omnicentre (NEMO), Fondazione Serena Onlus, Milan, Italy
| | - Jaya R. Trivedi
- Department of Neurology and Neurotherapeutics, UT Southwestern Medical Center, Dallas, Texas
| | | | - Savine Vicart
- Assistance Publique-Hôpitaix de Paris, Sorbonne Université, INSERM, Service of Neuro-Myology and UMR 974, Institute of Myology, University Hospital Pitié-Salpêtrière, Paris, France
| | - Jeffrey M. Statland
- Department of Neurology, University of Kansas Medical Center, Kansas City, Kansas
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11
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Maggi L, Brugnoni R, Canioni E, Tonin P, Saletti V, Sola P, Piccinelli SC, Colleoni L, Ferrigno P, Pini A, Masson R, Manganelli F, Lietti D, Vercelli L, Ricci G, Bruno C, Tasca G, Pizzuti A, Padovani A, Fusco C, Pegoraro E, Ruggiero L, Ravaglia S, Siciliano G, Morandi L, Dubbioso R, Mongini T, Filosto M, Tramacere I, Mantegazza R, Bernasconi P. Clinical and Molecular Spectrum of Myotonia and Periodic Paralyses Associated With Mutations in SCN4A in a Large Cohort of Italian Patients. Front Neurol 2020; 11:646. [PMID: 32849172 PMCID: PMC7403394 DOI: 10.3389/fneur.2020.00646] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2019] [Accepted: 05/29/2020] [Indexed: 11/25/2022] Open
Abstract
Background: Four main clinical phenotypes have been traditionally described in patients mutated in SCN4A, including sodium-channel myotonia (SCM), paramyotonia congenita (PMC), Hypokaliemic type II (HypoPP2), and Hyperkaliemic/Normokaliemic periodic paralysis (HyperPP/NormoPP); in addition, rare phenotypes associated with mutations in SCN4A are congenital myasthenic syndrome and congenital myopathy. However, only scarce data have been reported in literature on large patient cohorts including phenotypes characterized by myotonia and episodes of paralysis. Methods: We retrospectively investigated clinical and molecular features of 80 patients fulfilling the following criteria: (1) clinical and neurophysiological diagnosis of myotonia, or clinical diagnosis of PP, and (2) presence of a pathogenic SCN4A gene variant. Patients presenting at birth with episodic laryngospasm or congenital myopathy-like phenotype with later onset of myotonia were considered as neonatal SCN4A. Results: PMC was observed in 36 (45%) patients, SCM in 30 (37.5%), Hyper/NormoPP in 7 (8.7%), HypoPP2 in 3 (3.7%), and neonatal SCN4A in 4 (5%). The median age at onset was significantly earlier in PMC than in SCM (p < 0.01) and in Hyper/NormoPP than in HypoPP2 (p = 0.02). Cold-induced myotonia was more frequently observed in PMC (n = 34) than in SCM (n = 23) (p = 0.04). No significant difference was found in age at onset of episodes of paralysis among PMC and PP or in frequency of permanent weakness between PP (n = 4), SCM (n = 5), and PMC (n = 10). PP was more frequently associated with mutations in the S4 region of the NaV1.4 channel protein compared to SCM and PMC (p < 0.01); mutations causing PMC were concentrated in the C-terminal region of the protein, while SCM-associated mutations were detected in all the protein domains. Conclusions: Our data suggest that skeletal muscle channelopathies associated with mutations in SCN4A represent a continuum in the clinical spectrum.
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Affiliation(s)
- Lorenzo Maggi
- Neuroimmunology and Neuromuscular Diseases, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy
| | - Raffaella Brugnoni
- Neuroimmunology and Neuromuscular Diseases, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy
| | - Eleonora Canioni
- Neuroimmunology and Neuromuscular Diseases, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy
| | - Paola Tonin
- Section of Clinical Neurology, Department of Neurosciences, Biomedicine and Movement Sciences, University of Verona, Verona, Italy
| | - Veronica Saletti
- Developmental Neurology Unit, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy
| | - Patrizia Sola
- Clinica Neurologica, Azienda Ospedaliero Universitaria di Modena, Modena, Italy
| | - Stefano Cotti Piccinelli
- Unit of Neurology, Center for Neuromuscular Diseases, ASST Spedali Civili and University of Brescia, Brescia, Italy
| | - Lara Colleoni
- Neuroimmunology and Neuromuscular Diseases, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy
| | - Paola Ferrigno
- SC Neurologia e Stroke Unit, Azienda Ospedaliera Brotzu, Cagliari, Italy
| | - Antonella Pini
- Child Neurology and Psychiatry Unit, IRCCS Istituto delle Scienze Neurologiche di Bologna, Bologna, Italy
| | - Riccardo Masson
- Developmental Neurology Unit, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy
| | - Fiore Manganelli
- Department of Neurosciences, Reproductive Sciences and Odontostomatology, University of Naples "Federico II", Naples, Italy
| | | | - Liliana Vercelli
- Department of Neurosciences Rita Levi Montalcini, University of Turin, Turin, Italy
| | - Giulia Ricci
- Department of Clinical and Experimental Medicine, University of Pisa, Pisa, Italy
| | - Claudio Bruno
- Center of Translational and Experimental Myology, Istituto Giannina Gaslini, Genova, Italy
| | - Giorgio Tasca
- Unità Operativa Complessa di Neurologia, Dipartimento di Scienze Dell'Invecchiamento, Neurologiche, Ortopediche e della Testa-Collo, Fondazione Policlinico Universitario A. Gemelli IRCCS, Rome, Italy
| | - Antonio Pizzuti
- Fondazione IRCCS Casa Sollievo della Sofferenza, Laboratory of Medical Genetics, San Giovanni Rotondo, Italy.,Department of Experimental Medicine, Sapienza University of Rome, Rome, Italy
| | - Alessandro Padovani
- Unit of Neurology, Center for Neuromuscular Diseases, ASST Spedali Civili and University of Brescia, Brescia, Italy
| | - Carlo Fusco
- Dipartimento Materno-Infantile, S.C. Neuropsichiatria Infantile, Presidio Ospedaliero Provinciale Santa Maria Nuova, IRCCS di Reggio Emilia, Reggio Emilia, Italy
| | - Elena Pegoraro
- Department of Neurosciences, University of Padova, Padova, Italy
| | - Lucia Ruggiero
- Department of Neurosciences, Reproductive Sciences and Odontostomatology, University of Naples "Federico II", Naples, Italy
| | | | - Gabriele Siciliano
- Department of Clinical and Experimental Medicine, University of Pisa, Pisa, Italy
| | - Lucia Morandi
- Neuroimmunology and Neuromuscular Diseases, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy
| | - Raffaele Dubbioso
- Department of Neurosciences, Reproductive Sciences and Odontostomatology, University of Naples "Federico II", Naples, Italy
| | - Tiziana Mongini
- Department of Neurosciences Rita Levi Montalcini, University of Turin, Turin, Italy
| | - Massimiliano Filosto
- Unit of Neurology, Center for Neuromuscular Diseases, ASST Spedali Civili and University of Brescia, Brescia, Italy
| | - Irene Tramacere
- Research and Clinical Development Department, Scientific Directorate, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy
| | - Renato Mantegazza
- Neuroimmunology and Neuromuscular Diseases, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy
| | - Pia Bernasconi
- Neuroimmunology and Neuromuscular Diseases, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy
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Meyer AP, Roggenbuck J, LoRusso S, Kissel J, Smith RM, Kline D, Arnold WD. Genotype-Phenotype Correlations and Characterization of Medication Use in Inherited Myotonic Disorders. Front Neurol 2020; 11:593. [PMID: 32670189 PMCID: PMC7332828 DOI: 10.3389/fneur.2020.00593] [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: 12/05/2019] [Accepted: 05/22/2020] [Indexed: 11/13/2022] Open
Abstract
Introduction: Inherited myotonic disorders are genetically heterogeneous and associated with overlapping clinical features of muscle stiffness, weakness, and pain. Data on genotype-phenotype correlations are limited. In this study, clinical features and treatment patterns in genetically characterized myotonic disorders were compared. Methods: A retrospective chart review was completed in patients with genetic variants in CLCN1, SCN4A, DMPK, and CNBP to document clinical signs and symptoms, clinical testing, and antimyotonia medication use. Results: A total of 142 patients (27 CLCN1, 15 SCN4A, 89 DMPK, and 11 CNBP) were reviewed. The frequency of reported symptoms (stiffness, weakness, and pain) and electromyographic spontaneous activity were remarkably similar across genotypes. Most patients were not treated with antimyotonia agents, but those with non-dystrophic disorders were more likely to be on a treatment. Discussion: Among the features reviewed, we did not identify clinical or electrophysiological differences to distinguish CLCN1- and SCN4A-related myotonia. Weakness and pain were more prevalent in non-dystrophic disorders than previously identified. In addition, our results suggest that medical treatments in myotonic disorders may be under-utilized.
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Affiliation(s)
- Alayne P Meyer
- Division of Human Genetics, The Ohio State University, Columbus, OH, United States
| | - Jennifer Roggenbuck
- Division of Human Genetics, The Ohio State University, Columbus, OH, United States
| | - Samantha LoRusso
- Department of Neurology, The Ohio State University, Columbus, OH, United States
| | - John Kissel
- Department of Neurology, The Ohio State University, Columbus, OH, United States
| | - Rachel M Smith
- Department of Biomedical Informatics, Center for Biostatistics, The Ohio State University, Columbus, OH, United States
| | - David Kline
- Department of Biomedical Informatics, Center for Biostatistics, The Ohio State University, Columbus, OH, United States
| | - W David Arnold
- Department of Neurology, The Ohio State University, Columbus, OH, United States
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13
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Nakajima T, Kaneko Y, Dharmawan T, Kurabayashi M. Role of the voltage sensor module in Na v domain IV on fast inactivation in sodium channelopathies: The implication of closed-state inactivation. Channels (Austin) 2020; 13:331-343. [PMID: 31357904 PMCID: PMC6713248 DOI: 10.1080/19336950.2019.1649521] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
The segment 4 (S4) voltage sensor in voltage-gated sodium channels (Navs) have domain-specific functions, and the S4 segment in domain DIV (DIVS4) plays a key role in the activation and fast inactivation processes through the coupling of arginine residues in DIVS4 with residues of putative gating charge transfer center (pGCTC) in DIVS1-3. In addition, the first four arginine residues (R1-R4) in Nav DIVS4 have position-specific functions in the fast inactivation process, and mutations in these residues are associated with diverse phenotypes of Nav-related diseases (sodium channelopathies). R1 and R2 mutations commonly display a delayed fast inactivation, causing a gain-of-function, whereas R3 and R4 mutations commonly display a delayed recovery from inactivation and profound use-dependent current attenuation, causing a severe loss-of-function. In contrast, mutations of residues of pGCTC in Nav DIVS1-3 can also alter fast inactivation. Such alterations in fast inactivation may be caused by disrupted interactions of DIVS4 with DIVS1-3. Despite fast inactivation of Navs occurs from both the open-state (open-state inactivation; OSI) and closed state (closed-state inactivation; CSI), changes in CSI have received considerably less attention than those in OSI in the pathophysiology of sodium channelopathies. CSI can be altered by mutations of arginine residues in DIVS4 and residues of pGCTC in Navs, and altered CSI can be an underlying primary biophysical defect of sodium channelopathies. Therefore, CSI should receive focus in order to clarify the pathophysiology of sodium channelopathies.
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Affiliation(s)
- Tadashi Nakajima
- a Department of Cardiovascular Medicine, Gunma University Graduate School of Medicine , Maebashi , Gunma , Japan
| | - Yoshiaki Kaneko
- a Department of Cardiovascular Medicine, Gunma University Graduate School of Medicine , Maebashi , Gunma , Japan
| | - Tommy Dharmawan
- a Department of Cardiovascular Medicine, Gunma University Graduate School of Medicine , Maebashi , Gunma , Japan
| | - Masahiko Kurabayashi
- a Department of Cardiovascular Medicine, Gunma University Graduate School of Medicine , Maebashi , Gunma , Japan
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Raja Rayan DL, Hanna MG. Managing pregnancy and anaesthetics in patients with skeletal muscle channelopathies. Neuromuscul Disord 2020; 30:539-545. [PMID: 32622512 DOI: 10.1016/j.nmd.2020.05.007] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2020] [Revised: 04/14/2020] [Accepted: 05/22/2020] [Indexed: 11/15/2022]
Abstract
The skeletal muscle channelopathies are a group of rare diseases and include non-dystrophic myotonia and periodic paralysis. Given their rarity, little has been published on the management of anaesthesia and pregnancy in this cohort despite being important aspects of care. We have conducted a large study of over 70 patients who underwent anaesthesia and 87 pregnancies to investigate the problems encountered following anaesthesia or during pregnancy. This was performed via patient surveys sent out to genetically confirmed channelopathy patients seen at the National Hospital for Neurology and Neurosurgery. Most significantly in our cohort, patients frequently experienced a worsening or precipitation of symptoms during pregnancy (75%) or following anaesthetic (31%). None of our patients developed malignant hyperthermia, although there are confirmed reports of this in patients with periodic paralysis and mutations in RYR1. There was a significantly higher number of miscarriages compared to the normal population. There was no significant difference in antenatal or delivery complications compared to the general population. However, three neonates did have complications, all of whom were found to carry mutations in SCN4A. This study highlights the importance of counselling patients and clinicians for the possibility of worsening symptoms during pregnancy or anaesthesia and the careful management of neonates following delivery.
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Affiliation(s)
- Dipa L Raja Rayan
- MRC Centre for Neuromuscular Diseases, UCL Institute of Neurology, London, UK.
| | - Michael G Hanna
- MRC Centre for Neuromuscular Diseases, UCL Institute of Neurology, London, UK
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15
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Cibulcik F, Spalek P, Martinka I, Zidkova J, Grofik M, Sivak S, Kurca E. Paramyotonia congenita in a Slovak population: Genetic and pedigree analysis of 3 families. Biomed Pap Med Fac Univ Palacky Olomouc Czech Repub 2019; 163:362-365. [DOI: 10.5507/bp.2018.078] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2018] [Accepted: 12/09/2018] [Indexed: 11/23/2022] Open
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16
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Nanda S, Tandon V, Menon R, Sundaram S, Nair M. Clinico-Genotypic Correlation: Recurrent Attacks of Paralysis and Skeletal Muscle SCN4A Mutation (p.Ile693Thr). J Clin Neuromuscul Dis 2019; 21:42-46. [PMID: 31453854 DOI: 10.1097/cnd.0000000000000245] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Skeletal sodium channel mutations have been known to demonstrate a multitude of clinical manifestations of which one such commonly known entity is paramyotonia congenita. We describe the clinical features of proband in our case report and the various phenotypic manifestations described with the mentioned mutation from different centres. Our case serves to highlight the heterogeneity that exists in SCN4A mutations and the possible effect of other genetic/environmental factors in determining the final phenotype.
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Affiliation(s)
- Satyan Nanda
- Department of Neurology, Sree Chitra Tirunal Institute for Medical Sciences and Technology, Trivandrum, India
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17
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Palma Milla C, Prior De Castro C, Gómez-González C, Martínez-Montero P, I. Pascual Pascual S, Molano Mateos J. Myotonia congenita: mutation spectrum of CLCN1 in Spanish patients. J Genet 2019. [DOI: 10.1007/s12041-019-1115-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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18
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Pharmacogenetics of myotonic hNav1.4 sodium channel variants situated near the fast inactivation gate. Pharmacol Res 2019; 141:224-235. [DOI: 10.1016/j.phrs.2019.01.004] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/03/2018] [Revised: 01/02/2019] [Accepted: 01/02/2019] [Indexed: 12/13/2022]
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19
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Abstract
Skeletal muscle channelopathies are rare heterogeneous diseases with marked genotypic and phenotypic variability. These disorders cause lifetime disability and impact quality of life. Despite advances in understanding of the molecular pathology of these disorders, the diverse phenotypic manifestations remain a challenge in diagnosis, therapeutic, genetic counseling, and research planning. Electrodiagnostic testing is useful in directing the diagnosis, but has several limitations: patient discomfort, time consuming, and significant overlap of findings in muscle channelopathies. Although genetic testing is the gold standard in making a definitive diagnosis, a mutation might not be identified in many patients with a well-supported clinical diagnosis of periodic paralysis. In the recent past, there have been landmark clinical trials in non-dystrophic myotonia and periodic paralysis which are encouraging as they demonstrate the ability of robust clinical research consortia to conduct well-controlled trials of rare diseases.
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Affiliation(s)
- Lauren Phillips
- Department of Neurology and Neurotherapeutics, UT Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, Texas, 75390, USA
| | - Jaya R Trivedi
- Department of Neurology and Neurotherapeutics, UT Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, Texas, 75390, USA.
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20
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van Osch T, Stunnenberg BC, Sternberg D, Kerklaan BJ. Prolonged attacks of weakness with hypokalemia in SCN4A-related paramyotonia congenita. Muscle Nerve 2018; 58:E27-E28. [PMID: 30028520 DOI: 10.1002/mus.26190] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2018] [Revised: 06/01/2018] [Accepted: 06/05/2018] [Indexed: 11/07/2022]
Affiliation(s)
- Tim van Osch
- Departments of Neurology OLVG, OLVG West, Jan Tooropstraat 164, 1061 AE, Amsterdam and Zaans Medisch Centrum, Zaandam, the Netherlands
| | - Bas C Stunnenberg
- Radboud University Nijmegen Medical Center, Nijmegen, the Netherlands
| | - Damien Sternberg
- Assistance Publique Hôpitaux de Paris, Service de Biochimie, Hôpital Pitié-Salpêtrière, Paris, France
| | - Bertjan J Kerklaan
- Departments of Neurology OLVG, OLVG West, Jan Tooropstraat 164, 1061 AE, Amsterdam and Zaans Medisch Centrum, Zaandam, the Netherlands
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21
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Palma C, Prior C, Gómez-González C, Rodríguez-Antolin C, Martínez-Montero P, Pérez de Ayala L, Pascual SI, Molano Mateos J. A SCN4A mutation causing paramyotonia congenita. Neuromuscul Disord 2017; 27:1123-1125. [DOI: 10.1016/j.nmd.2017.09.008] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2017] [Revised: 07/24/2017] [Accepted: 09/18/2017] [Indexed: 11/29/2022]
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22
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Al-Ghamdi F, Darras BT, Ghosh PS. Spectrum of Nondystrophic Skeletal Muscle Channelopathies in Children. Pediatr Neurol 2017; 70:26-33. [PMID: 28325641 DOI: 10.1016/j.pediatrneurol.2017.02.006] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/10/2017] [Accepted: 02/10/2017] [Indexed: 01/21/2023]
Abstract
BACKGROUND The nondystrophic skeletal muscle channelopathies are a group of disorders caused by mutations of various voltage-gated ion channel genes, including nondystrophic myotonia and periodic paralysis. METHODS We identified patients with a diagnosis of muscle channelopathy from our neuromuscular database in a tertiary care pediatric center from 2005 to 2015. We then performed a retrospective review of their medical records for demographic characteristics, clinical features, investigations, treatment, and follow-up. RESULTS Thirty-three patients were identified. Seventeen had nondystrophic myotonia. Seven of them had chloride channelopathy (four Becker disease and three Thomsen disease). Warm-up phenomenon and muscle hypertrophy were common clinical manifestations in this subgroup. Ten patients had sodium channelopathy (four paramyotonia congenita and six other sodium channel myotonia). Stiffness of the facial muscles was an important presenting symptom, and eyelid myotonia was a common clinical finding in this subgroup. The majority of these patients had electrical myotonia. Mexiletine was effective in controlling the symptoms in patients who had received treatment. Sixteen children had periodic paralysis (four hyperkalemic periodic paralysis, eight hypokalemic periodic paralysis, and four Andersen-Tawil syndrome). Acetazolamide was commonly used to prevent paralytic attacks and was found to be effective. CONCLUSIONS Nondystrophic muscle channelopathies present with diverse clinical manifestations (myotonia, muscle hypertrophy, proximal weakness, swallowing difficulties, and periodic paralysis). Cardiac arrhythmias are potentially life threatening in Andersen-Tawil syndrome. Timely identification of these disorders is helpful for effective symptomatic management and genetic counseling.
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Affiliation(s)
- Fouad Al-Ghamdi
- Department of Neurology, Boston Children's Hospital, Boston, MA
| | - Basil T Darras
- Department of Neurology, Boston Children's Hospital, Boston, MA
| | - Partha S Ghosh
- Department of Neurology, Boston Children's Hospital, Boston, MA.
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23
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Abstract
The NaV1.4 sodium channel is highly expressed in skeletal muscle, where it carries almost all of the inward Na+ current that generates the action potential, but is not present at significant levels in other tissues. Consequently, mutations of SCN4A encoding NaV1.4 produce pure skeletal muscle phenotypes that now include six allelic disorders: sodium channel myotonia, paramyotonia congenita, hyperkalemic periodic paralysis, hypokalemic periodic paralysis, congenital myasthenia, and congenital myopathy with hypotonia. Mutation-specific alternations of NaV1.4 function explain the mechanistic basis for the diverse phenotypes and identify opportunities for strategic intervention to modify the burden of disease.
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Affiliation(s)
- Stephen C Cannon
- Department of Physiology, David Geffen School of Medicine at UCLA, Los Angeles, CA, 90095, USA.
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24
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Bednarz M, Stunnenberg BC, Kusters B, Kamsteeg EJ, Saris CG, Groome J, Winston V, Meola G, Jurkat-Rott K, Voermans NC. A novel Ile1455Thr variant in the skeletal muscle sodium channel alpha-subunit in a patient with a severe adult-onset proximal myopathy with electrical myotonia and a patient with mild paramyotonia phenotype. Neuromuscul Disord 2016; 27:175-182. [PMID: 28024841 DOI: 10.1016/j.nmd.2016.09.023] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2015] [Revised: 09/04/2016] [Accepted: 09/28/2016] [Indexed: 12/19/2022]
Abstract
In sodium channelopathies, a severe fixed myopathy caused by a dominant mutation is rare. We describe two unrelated patients with a novel variant, p.Ile1455Thr, with phenotypes of paramyotonia in one case and fixed proximal myopathy with latent myotonia in another. In-vitro whole cell patch-clamp studies show that the mutation slows inactivation and accelerates recovery, in line with other paramyotonia variants with destabilized fast inactivation as pathomechanism. Additionally, p.IleI1455 causes a loss-of-function by reduced membrane insertion, right-shift of activation, and slowed kinetics. Molecular dynamics simulations comparing wild type and mutant Nav1.4 showed that threonine substitution hindered D4S4 mobility in response to membrane depolarization, consistent with effects of the mutation on channel inactivation. The fixed myopathy is likely to be associated to gain-of-function leading to sodium accumulation, regional edema, T-tubular swelling and mitochondrial stress. A possible contribution of the loss-of-function features towards myotonia and myopathy is discussed.
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Affiliation(s)
- Marcin Bednarz
- Division of Neurophysiology, Ulm University, Ulm, Germany
| | - Bas C Stunnenberg
- Department of Neurology, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Benno Kusters
- Department of Pathology, Radboud University Medical Center, Nijmegen, The Netherlands; Department of Pathology, Maastricht University Medical Center, Maastricht, The Netherlands
| | - Erik-Jan Kamsteeg
- Department of Human Genetics, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Christiaan G Saris
- Department of Neurology, Radboud University Medical Center, Nijmegen, The Netherlands
| | - James Groome
- Department of Biological Sciences, Idaho State University, Pocatello, ID 83209, USA
| | - Vern Winston
- Department of Biological Sciences, Idaho State University, Pocatello, ID 83209, USA
| | - Giovanni Meola
- Department of Biomedical Sciences for Health, University of Milan, IRCCS Policlinico San Donato, Italy
| | | | - Nicol C Voermans
- Department of Neurology, Radboud University Medical Center, Nijmegen, The Netherlands.
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25
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Yang X, Jia H, An R, Xi J, Xu Y. Sequence CLCN1 and SCN4A in patients with Nondystrophic myotonias in Chinese populations: Genetic and pedigree analysis of 10 families and review of the literature. Channels (Austin) 2016; 11:55-65. [PMID: 27415035 DOI: 10.1080/19336950.2016.1212140] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Myotonia congenita (MC), paramyotonia congenita (PC) and sodium channel myotonias(SCM) were belonged to Non-dystrophic myotonias, in which muscle relaxation is delayed after voluntary or evoked contraction. These diseases can not be simply distinguished only based on symptoms and signs but also on genetics: more than 100 mutations in the CLCN1 gene have been associated with MC, while at least 20 mutations in the SCN4A gene have been associated with PC and SCM. Most of these genetics studies have been conducted outside China, only several MC, PC, and SCM families accepted gene scan were reported in China. Therefore we analyzed genetic mutations in CLCN1 and SCN4A in 10 Chinese families clinically diagnosed with Non-dystrophic myotonias. Our result revealed 12 potential disease-causing mutations(3 mutations were novel) that were present in the probands and affected family members. We also reviewed all available literature on mutations linked to these 3 disease in Chinese populations. Our results may help identify genetic determinants as well as clarify genotype-phenotype relationships.
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Affiliation(s)
- Xinglong Yang
- a Department of Neurology , West China Hospital, Sichuan University , Chengdu , Sichuan Province , P.R. China
| | - Hua Jia
- a Department of Neurology , West China Hospital, Sichuan University , Chengdu , Sichuan Province , P.R. China
| | - Ran An
- a Department of Neurology , West China Hospital, Sichuan University , Chengdu , Sichuan Province , P.R. China
| | - Jing Xi
- a Department of Neurology , West China Hospital, Sichuan University , Chengdu , Sichuan Province , P.R. China
| | - Yanming Xu
- a Department of Neurology , West China Hospital, Sichuan University , Chengdu , Sichuan Province , P.R. China
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26
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Abstract
Familial disorders of skeletal muscle excitability were initially described early in the last century and are now known to be caused by mutations of voltage-gated ion channels. The clinical manifestations are often striking, with an inability to relax after voluntary contraction (myotonia) or transient attacks of severe weakness (periodic paralysis). An essential feature of these disorders is fluctuation of symptoms that are strongly impacted by environmental triggers such as exercise, temperature, or serum K(+) levels. These phenomena have intrigued physiologists for decades, and in the past 25 years the molecular lesions underlying these disorders have been identified and mechanistic studies are providing insights for therapeutic strategies of disease modification. These familial disorders of muscle fiber excitability are "channelopathies" caused by mutations of a chloride channel (ClC-1), sodium channel (NaV1.4), calcium channel (CaV1.1), and several potassium channels (Kir2.1, Kir2.6, and Kir3.4). This review provides a synthesis of the mechanistic connections between functional defects of mutant ion channels, their impact on muscle excitability, how these changes cause clinical phenotypes, and approaches toward therapeutics.
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Affiliation(s)
- Stephen C Cannon
- Department of Physiology, David Geffen School of Medicine, UCLA, Los Angeles, CA, USA
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Spillane J, Kullmann DM, Hanna MG. Genetic neurological channelopathies: molecular genetics and clinical phenotypes. J Neurol Neurosurg Psychiatry 2016; 87:37-48. [PMID: 26558925 PMCID: PMC4717447 DOI: 10.1136/jnnp-2015-311233] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/11/2015] [Accepted: 09/13/2015] [Indexed: 01/08/2023]
Abstract
Evidence accumulated over recent years has shown that genetic neurological channelopathies can cause many different neurological diseases. Presentations relating to the brain, spinal cord, peripheral nerve or muscle mean that channelopathies can impact on almost any area of neurological practice. Typically, neurological channelopathies are inherited in an autosomal dominant fashion and cause paroxysmal disturbances of neurological function, although the impairment of function can become fixed with time. These disorders are individually rare, but an accurate diagnosis is important as it has genetic counselling and often treatment implications. Furthermore, the study of less common ion channel mutation-related diseases has increased our understanding of pathomechanisms that is relevant to common neurological diseases such as migraine and epilepsy. Here, we review the molecular genetic and clinical features of inherited neurological channelopathies.
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Affiliation(s)
- J Spillane
- Royal Free Hospital Foundation Trust London, London, UK MRC Centre for Neuromuscular Disease, UCL, London, UK
| | - D M Kullmann
- MRC Centre for Neuromuscular Disease, UCL, London, UK UCL, Institute of Neurology, London, UK
| | - M G Hanna
- MRC Centre for Neuromuscular Disease, UCL, London, UK UCL, Institute of Neurology, London, UK
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Bissay V, Van Malderen SCH, Keymolen K, Lissens W, Peeters U, Daneels D, Jansen AC, Pappaert G, Brugada P, De Keyser J, Van Dooren S. SCN4A variants and Brugada syndrome: phenotypic and genotypic overlap between cardiac and skeletal muscle sodium channelopathies. Eur J Hum Genet 2015; 24:400-7. [PMID: 26036855 DOI: 10.1038/ejhg.2015.125] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2014] [Revised: 04/03/2015] [Accepted: 05/06/2015] [Indexed: 12/19/2022] Open
Abstract
SCN5A mutations involving the α-subunit of the cardiac voltage-gated muscle sodium channel (NaV1.5) result in different cardiac channelopathies with an autosomal-dominant inheritance such as Brugada syndrome. On the other hand, mutations in SCN4A encoding the α-subunit of the skeletal voltage-gated sodium channel (NaV1.4) cause non-dystrophic myotonia and/or periodic paralysis. In this study, we investigated whether cardiac arrhythmias or channelopathies such as Brugada syndrome can be part of the clinical phenotype associated with SCN4A variants and whether patients with Brugada syndrome present with non-dystrophic myotonia or periodic paralysis and related gene mutations. We therefore screened seven families with different SCN4A variants and non-dystrophic myotonia phenotypes for Brugada syndrome and performed a neurological, neurophysiological and genetic work-up in 107 Brugada families. In the families with an SCN4A-associated non-dystrophic myotonia, three patients had a clinical diagnosis of Brugada syndrome, whereas we found a remarkably high prevalence of myotonic features involving different genes in the families with Brugada syndrome. One Brugada family carried an SCN4A variant that is predicted to probably affect function, one family suffered from a not genetically confirmed non-dystrophic myotonia, one family was diagnosed with myotonic dystrophy (DMPK gene) and one family had a Thomsen disease myotonia congenita (CLCN1 variant that affects function). Our findings and data suggest a possible involvement of SCN4A variants in the pathophysiological mechanism underlying the development of a spontaneous or drug-induced type 1 electrocardiographic pattern and the occurrence of malignant arrhythmias in some patients with Brugada syndrome.
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Affiliation(s)
- Véronique Bissay
- Department of Neurology, Center for Neurosciences, UZ Brussel, Vrije Universiteit Brussel (VUB), Brussels, Belgium
| | - Sophie C H Van Malderen
- Department of Cardiology, Heart Rhythm Management Center, UZ Brussel, Vrije Universiteit Brussel (VUB), Brussels, Belgium.,Department of Electrophysiology, Thorax Center, Erasmus MC, Rotterdam, The Netherlands
| | - Kathelijn Keymolen
- Center for Medical Genetics, Reproduction and Genetics; Genetics and Regenerative Medicine, UZ Brussel, Vrije Universiteit Brussel (VUB), Brussels, Belgium
| | - Willy Lissens
- Center for Medical Genetics, Reproduction and Genetics; Genetics and Regenerative Medicine, UZ Brussel, Vrije Universiteit Brussel (VUB), Brussels, Belgium
| | - Uschi Peeters
- Center for Medical Genetics, Reproduction and Genetics; Genetics and Regenerative Medicine, UZ Brussel, Vrije Universiteit Brussel (VUB), Brussels, Belgium
| | - Dorien Daneels
- Center for Medical Genetics, Reproduction and Genetics; Genetics and Regenerative Medicine, UZ Brussel, Vrije Universiteit Brussel (VUB), Brussels, Belgium
| | - Anna C Jansen
- Pediatric Neurology Unit, Department of Pediatrics, UZ Brussel, Vrije Universiteit Brussel (VUB), Brussels, Belgium
| | - Gudrun Pappaert
- Department of Cardiology, Heart Rhythm Management Center, UZ Brussel, Vrije Universiteit Brussel (VUB), Brussels, Belgium
| | - Pedro Brugada
- Department of Cardiology, Heart Rhythm Management Center, UZ Brussel, Vrije Universiteit Brussel (VUB), Brussels, Belgium
| | - Jacques De Keyser
- Department of Neurology, Center for Neurosciences, UZ Brussel, Vrije Universiteit Brussel (VUB), Brussels, Belgium.,Department of Neurology, University Medical Center Groningen, Groningen, The Netherlands
| | - Sonia Van Dooren
- Center for Medical Genetics, Reproduction and Genetics; Genetics and Regenerative Medicine, UZ Brussel, Vrije Universiteit Brussel (VUB), Brussels, Belgium
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Abstract
INTRODUCTION Skeletal muscle channelopathies are rare disorders of muscle membrane excitability. Their episodic nature may result in diagnostic difficulty and delays in diagnosis. Advances in diagnostic clinical electrophysiology combined with DNA-based diagnosis have improved diagnostic accuracy and efficiency. Ascribing pathogenic status to identified genetic variants in muscle channel genes may be complex and functional analysis, including molecular expression, may help with this. Accurate clinical and genetic diagnosis enables genetic counselling, advice regarding prognosis and aids treatment selection. AREAS COVERED An approach to accurate and efficient diagnosis is outlined. The importance of detailed clinical evaluation including careful history, examination and family history is emphasised. The role of specialised electrodiagnostics combined with DNA testing and molecular expression is considered. New potential biomarkers including muscle MRI using MRC Centre protocols are discussed. EXPERT OPINION A combined diagnostic approach using careful clinical assessment, specialised neurophysiology and DNA testing will now achieve a clear diagnosis in most patients with muscle channelopathies. An accurate diagnosis enables genetic counselling and provides information regarding prognosis and treatment selection. Genetic analysis often identifies new variants of uncertain significance. In this situation, functional expression studies as part of a diagnostic service will enable determination of pathogenic status of novel genetic variants.
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Affiliation(s)
- Jennifer Spillane
- UCL, Institute of Neurology, MRC Centre for Neuromuscular Diseases , Queen Square, London, WC1N3BG UK ,
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Caietta E, Milh M, Sternberg D, Lépine A, Boulay C, McGonigal A, Chabrol B. Diagnosis and outcome of SCN4A-related severe neonatal episodic laryngospasm (SNEL): 2 new cases. Pediatrics 2013; 132:e784-7. [PMID: 23958773 DOI: 10.1542/peds.2012-3065] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Mutations of SCN4A encoding the skeletal muscle sodium channel Nav 1.4 cause several types of disease, including sodium channel myotonias. The latter may be responsible for neonatal symptoms, including severe neonatal episodic laryngospasm (SNEL). Establishing the diagnosis of SCN4A-related SNEL early in the neonatal period is crucial because treatment is available that can reduce laryngospasm and improve vital and cerebral outcome. We report 2 new unrelated French patients who presented with SNEL. The first patient was initially diagnosed with laryngomalacia and underwent laryngeal surgery in the neonatal period before being diagnosed with myotonia at 14 months of age. The episodes of laryngospasm disappeared spontaneously, although occasional circumstances such as cold exposure could trigger laryngeal reactions; in addition, he developed myotonia corresponding to an adult myotonia permanens phenotype. This patient is now 24 years old and leading a normal life. The second patient was initially diagnosed with gastroesophageal reflux, then SNEL; his condition improved with carbamazepine treatment, and he is now 6 months old. The diagnostic sequence in both patients was the same: first, severe episodic apneic attacks necessitating hospitalization occurring in the first week of life; second, observation of muscle hypertrophy and peripheral hypertonia with a clear myotonic pattern on electromyogram (at 14 and 3 months of age, respectively); third, genetic testing revealing de novo SCN4A G1306E mutation. Both patients have had good therapeutic response to sodium channel blockers (carbamazepine or mexiletine).
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Affiliation(s)
- Emilie Caietta
- Service de Neuropédiatrie, Hôpital Timone Enfants, Marseille, France.
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Trivedi JR, Bundy B, Statland J, Salajegheh M, Rayan DR, Venance SL, Wang Y, Fialho D, Matthews E, Cleland J, Gorham N, Herbelin L, Cannon S, Amato A, Griggs RC, Hanna MG, Barohn RJ. Non-dystrophic myotonia: prospective study of objective and patient reported outcomes. ACTA ACUST UNITED AC 2013; 136:2189-200. [PMID: 23771340 DOI: 10.1093/brain/awt133] [Citation(s) in RCA: 69] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Non-dystrophic myotonias are rare diseases caused by mutations in skeletal muscle chloride and sodium ion channels with considerable phenotypic overlap between diseases. Few prospective studies have evaluated the sensitivity of symptoms and signs of myotonia in a large cohort of patients. We performed a prospective observational study of 95 participants with definite or clinically suspected non-dystrophic myotonia recruited from six sites in the USA, UK and Canada between March 2006 and March 2009. We used the common infrastructure and data elements provided by the NIH-funded Rare Disease Clinical Research Network. Outcomes included a standardized symptom interview and physical exam; the Short Form-36 and the Individualized Neuromuscular Quality of Life instruments; electrophysiological short and prolonged exercise tests; manual muscle testing; and a modified get-up-and-go test. Thirty-two participants had chloride channel mutations, 34 had sodium channel mutations, nine had myotonic dystrophy type 2, one had myotonic dystrophy type 1, and 17 had no identified mutation. Phenotype comparisons were restricted to those with sodium channel mutations, chloride channel mutations, and myotonic dystrophy type 2. Muscle stiffness was the most prominent symptom overall, seen in 66.7% to 100% of participants. In comparison with chloride channel mutations, participants with sodium mutations had an earlier age of onset of stiffness (5 years versus 10 years), frequent eye closure myotonia (73.5% versus 25%), more impairment on the Individualized Neuromuscular Quality of Life summary score (20.0 versus 9.44), and paradoxical eye closure myotonia (50% versus 0%). Handgrip myotonia was seen in three-quarters of participants, with warm up of myotonia in 75% chloride channel mutations, but also 35.3% of sodium channel mutations. The short exercise test showed ≥10% decrement in the compound muscle action potential amplitude in 59.3% of chloride channel participants compared with 27.6% of sodium channel participants, which increased post-cooling to 57.6% in sodium channel mutations. In evaluation of patients with clinical and electrical myotonia, despite considerable phenotypic overlap, the presence of eye closure myotonia, paradoxical myotonia, and an increase in short exercise test sensitivity post-cooling suggest sodium channel mutations. Outcomes designed to measure stiffness or the electrophysiological correlates of stiffness may prove useful for future clinical trials, regardless of underlying mutation, and include patient-reported stiffness, bedside manoeuvres to evaluate myotonia, muscle specific quality of life instruments and short exercise testing.
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Affiliation(s)
- Jaya R Trivedi
- Department of Neurology and Neurotherapeutics, UT Southwestern Medical Centre, Dallas, TX 75390, USA.
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Heatwole CR, Statland JM, Logigian EL. The diagnosis and treatment of myotonic disorders. Muscle Nerve 2013; 47:632-48. [PMID: 23536309 DOI: 10.1002/mus.23683] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/14/2012] [Indexed: 12/12/2022]
Abstract
Myotonia is a defining clinical symptom and sign common to a relatively small group of muscle diseases, including the myotonic dystrophies and the nondystrophic myotonic disorders. Myotonia can be observed on clinical examination, as can its electrical correlate, myotonic discharges, on electrodiagnostic testing. Research interest in the myotonic disorders continues to expand rapidly, which justifies a review of the scientific bases, clinical manifestations, and numerous therapeutic approaches associated with these disorders. We review the pathomechanisms of myotonia, the clinical features of the dystrophic and nondystrophic myotonic disorders, and the diagnostic approach and treatment options for patients with symptomatic myotonia.
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Affiliation(s)
- Chad R Heatwole
- Department of Neurology, Box 673, University of Rochester Medical Center, 601 Elmwood Avenue, Rochester, New York, New York 14642, USA.
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Nurputra DK, Nakagawa T, Takeshima Y, Harahap ISK, Morikawa S, Sakaeda T, Lai PS, Matsuo M, Takaoka Y, Nishio H. Paramyotonia congenita: from clinical diagnosis to in silico protein modeling analysis. Pediatr Int 2012; 54:602-12. [PMID: 22507243 DOI: 10.1111/j.1442-200x.2012.03646.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
BACKGROUND Paramyotonia congenita (PMC) is an autosomal dominant disorder characterized by cold- or exercise-induced myotonia. PMC is caused by a mutation in SCN4A which encodes the α-subunit of the skeletal muscle sodium channel. METHODS The patient was an 11-year-old Japanese girl who was diagnosed as having PMC. To confirm the diagnosis, an orbital ice-pack test and blinking tests were performed. Next, to identify the mutation, genetic analysis of SCN4A was performed. Finally, to evaluate the mutation effect on the protein structure, in silico protein modeling analysis was performed. RESULTS Cold- and exercise-induced myotonia was reproduced in the patient with non-invasive bedside tests: ice-pack and blinking tests. In the genetic analysis, a missense mutation, c.4343G>A in SCN4A, was identified, which may result in an arginine to histidine substitution at 1448 in the protein sequence (p.Arg1448His). According to the protein modeling analysis, the mutation neutralized the positive electrostatic charge at 1448 in the DIV/S4 segment and disrupted the beginning of the helical structure in the DIV/S3-S4 linker of the SCN4A protein. CONCLUSIONS Diagnostic physical interventions in the patient confirmed the phenotype presentation consistent with PMC, and the in silico protein modeling analysis of p.Arg1448His predicted structural changes which can affect function of the protein. All the data confirmed the diagnosis of PMC in the patient and added to existing literature emphasizing the important role of arginine residue at 1448.
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Affiliation(s)
- Dian K Nurputra
- Department of Community Medicine and Social Health Care, Kobe University Graduate School of Medicine, 7-5-1 Kusunoki-Cho, Chuo-Ku, Kobe 650-0017, Japan
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Savio-Galimberti E, Gollob MH, Darbar D. Voltage-gated sodium channels: biophysics, pharmacology, and related channelopathies. Front Pharmacol 2012; 3:124. [PMID: 22798951 PMCID: PMC3394224 DOI: 10.3389/fphar.2012.00124] [Citation(s) in RCA: 76] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2011] [Accepted: 06/11/2012] [Indexed: 12/19/2022] Open
Abstract
Voltage-gated sodium channels (VGSC) are multi-molecular protein complexes expressed in both excitable and non-excitable cells. They are primarily formed by a pore-forming multi-spanning integral membrane glycoprotein (α-subunit) that can be associated with one or more regulatory β-subunits. The latter are single-span integral membrane proteins that modulate the sodium current (INa) and can also function as cell adhesion molecules. In vitro some of the cell-adhesive functions of the β-subunits may play important physiological roles independently of the α-subunits. Other endogenous regulatory proteins named “channel partners” or “channel interacting proteins” (ChiPs) like caveolin-3 and calmodulin/calmodulin kinase II (CaMKII) can also interact and modulate the expression and/or function of VGSC. In addition to their physiological roles in cell excitability and cell adhesion, VGSC are the site of action of toxins (like tetrodotoxin and saxitoxin), and pharmacologic agents (like antiarrhythmic drugs, local anesthetics, antiepileptic drugs, and newly developed analgesics). Mutations in genes that encode α- and/or β-subunits as well as the ChiPs can affect the structure and biophysical properties of VGSC, leading to the development of diseases termed sodium “channelopathies”. This review will outline the structure, function, and biophysical properties of VGSC as well as their pharmacology and associated channelopathies and highlight some of the recent advances in this field.
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Affiliation(s)
- Eleonora Savio-Galimberti
- Division of Cardiovascular Medicine, Department of Medicine, Vanderbilt University Nashville, TN, USA
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Jurkat-Rott K, Groome J, Lehmann-Horn F. Pathophysiological role of omega pore current in channelopathies. Front Pharmacol 2012; 3:112. [PMID: 22701429 PMCID: PMC3372090 DOI: 10.3389/fphar.2012.00112] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2012] [Accepted: 05/23/2012] [Indexed: 12/12/2022] Open
Abstract
In voltage-gated cation channels, a recurrent pattern for mutations is the neutralization of positively charged residues in the voltage-sensing S4 transmembrane segments. These mutations cause dominant ion channelopathies affecting many tissues such as brain, heart, and skeletal muscle. Recent studies suggest that the pathogenesis of associated phenotypes is not limited to alterations in the gating of the ion-conducting alpha pore. Instead, aberrant so-called omega currents, facilitated by the movement of mutated S4 segments, also appear to contribute to symptoms. Surprisingly, these omega currents conduct cations with varying ion selectivity and are activated in either a hyperpolarized or depolarized voltage range. This review gives an overview of voltage sensor channelopathies in general and focuses on pathogenesis of skeletal muscle S4 disorders for which current knowledge is most advanced.
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Mazón MJ, Barros F, De la Peña P, Quesada JF, Escudero A, Cobo AM, Pascual-Pascual SI, Gutiérrez-Rivas E, Guillén E, Arpa J, Eraso P, Portillo F, Molano J. Screening for mutations in Spanish families with myotonia. Functional analysis of novel mutations in CLCN1 gene. Neuromuscul Disord 2012; 22:231-43. [DOI: 10.1016/j.nmd.2011.10.013] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2011] [Revised: 10/09/2011] [Accepted: 10/13/2011] [Indexed: 11/28/2022]
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Simkin D, Bendahhou S. Skeletal muscle na channel disorders. Front Pharmacol 2011; 2:63. [PMID: 22016737 PMCID: PMC3192954 DOI: 10.3389/fphar.2011.00063] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2011] [Accepted: 09/28/2011] [Indexed: 11/13/2022] Open
Abstract
Five inherited human disorders affecting skeletal muscle contraction have been traced to mutations in the gene encoding the voltage-gated sodium channel Nav1.4. The main symptoms of these disorders are myotonia or periodic paralysis caused by changes in skeletal muscle fiber excitability. Symptoms of these disorders vary from mild or latent disease to incapacitating or even death in severe cases. As new human sodium channel mutations corresponding to disease states become discovered, the importance of understanding the role of the sodium channel in skeletal muscle function and disease state grows.
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Affiliation(s)
- Dina Simkin
- UMR 6097, CNRS, TIANP, University of Nice Sophia-Antipolis Nice, France
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Burge J, Hanna MG. Muscle Channelopathies. Neuromuscul Disord 2011. [DOI: 10.1002/9781119973331.ch13] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Statland JM, Wang Y, Richesson R, Bundy B, Herbelin L, Gomes J, Trivedi J, Venance S, Amato A, Hanna M, Griggs R, Barohn RJ. An interactive voice response diary for patients with non-dystrophic myotonia. Muscle Nerve 2011; 44:30-5. [PMID: 21674518 DOI: 10.1002/mus.22007] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
INTRODUCTION Non-dystrophic myotonia (NDM) is caused by mutations in muscle chloride and sodium channels. Currently, there is no standardized instrument for documenting symptom frequency and severity in NDM. METHODS Subjects used an automated, interactive, telephone-based voice response diary (IVR) to record frequency and severity of stiffness, weakness, pain, and tiredness once a week for 8 weeks, after their baseline visits. RESULTS We describe the IVR and report data on 76 subjects for a total of 385 person-weeks. Overall there were 5.1 calls per subject. Forty-eight subjects called in 5 or more times, and 14 called in 8 times. Stiffness was both the most frequent and severe symptom. Warm-up and handgrip myotonia were associated with higher severity scores for stiffness. CONCLUSIONS IVR is a convenient technology to allow patient reporting of repeated and real-time symptom frequency and severity, and it is presently being used in a trial of mexiletine in NDM.
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Affiliation(s)
- Jeffrey M Statland
- Department of Neurology, University of Rochester Medical Center, Rochester, New York, USA
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Bissay V, Keymolen K, Lissens W, Laureys G, Schmedding E, De Keyser J. Late onset painful cold-aggravated myotonia: Three families with SCN4A L1436P mutation. Neuromuscul Disord 2011; 21:590-3. [DOI: 10.1016/j.nmd.2011.05.006] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2011] [Revised: 03/31/2011] [Accepted: 05/10/2011] [Indexed: 10/18/2022]
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Matthews E, Miller JAL, MacLeod MR, Ironside J, Ambler G, Labrum R, Sud R, Holton JL, Hanna MG. Sodium and chloride channelopathies with myositis: coincidence or connection? Muscle Nerve 2011; 44:283-8. [PMID: 21698652 DOI: 10.1002/mus.22120] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/25/2010] [Indexed: 11/10/2022]
Abstract
INTRODUCTION A proximal myopathy develops in some patients with muscle channelopathies, but the causative molecular mechanisms are unknown. METHODS We reviewed retrospectively all clinical and muscle biopsy findings of 3 patients with channelopathy and additional myositis. Direct DNA sequencing was performed. RESULTS Pathogenic mutations were identified in each case. Biopsies demonstrated inflammatory infiltrates. CONCLUSIONS Clinicians should consider muscle biopsy in channelopathy patients with severe myalgia and/or subacute weakness and accompanying elevated creatine kinase. Chance association of myositis and channelopathy is statistically unlikely. An alternative hypothesis suggests that inflammatory insults could contribute to myopathy in some patients.
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Affiliation(s)
- Emma Matthews
- Medical Research Council Centre for Neuromuscular Disease, UCL, Institute of Neurology, Queen Square, London WC1N 3BG, UK
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Skeletal muscle channelopathies: new insights into the periodic paralyses and nondystrophic myotonias. Curr Opin Neurol 2009; 22:524-31. [PMID: 19571750 DOI: 10.1097/wco.0b013e32832efa8f] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
PURPOSE OF REVIEW To summarize advances in our understanding of the clinical phenotypes, genetics, and molecular pathophysiology of the periodic paralyses, the nondystrophic myotonias, and other muscle channelopathies. RECENT FINDINGS The number of pathogenic mutations causing periodic paralysis, nondystrophic myotonias, and ryanodinopathies continues to grow with the advent of exon hierarchy analysis strategies for genetic screening and better understanding and recognition of disease phenotypes. Recent studies have expanded and clarified the role of gating pore current in channelopathy pathogenesis. It has been shown that the gating pore current can account for the molecular and phenotypic diseases observed in the muscle sodium channelopathies, and, given that homologous residues are affected in mutations of calcium channels, it is possible that pore leak represents a pathomechanism applicable to many channel diseases. Improvements in treatment of the muscle channelopathies are on the horizon. A randomized controlled trial has been initiated for the study of mexiletine in nondystrophic myotonias. The class IC antiarrhythmia drug flecainide has been shown to depress ventricular ectopy and improve exercise capacity in patients with Andersen-Tawil syndrome. SUMMARY Recent studies have expanded our understanding of gating pore current as a disease-causing mechanism in the muscle channelopathies and have allowed new correlations to be drawn between disease genotype and phenotype.
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Matthews E, Fialho D, Tan SV, Venance SL, Cannon SC, Sternberg D, Fontaine B, Amato AA, Barohn RJ, Griggs RC, Hanna MG. The non-dystrophic myotonias: molecular pathogenesis, diagnosis and treatment. ACTA ACUST UNITED AC 2009; 133:9-22. [PMID: 19917643 DOI: 10.1093/brain/awp294] [Citation(s) in RCA: 140] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
The non-dystrophic myotonias are an important group of skeletal muscle channelopathies electrophysiologically characterized by altered membrane excitability. Many distinct clinical phenotypes are now recognized and range in severity from severe neonatal myotonia with respiratory compromise through to milder late-onset myotonic muscle stiffness. Specific genetic mutations in the major skeletal muscle voltage gated chloride channel gene and in the voltage gated sodium channel gene are causative in most patients. Recent work has allowed more precise correlations between the genotype and the electrophysiological and clinical phenotype. The majority of patients with myotonia have either a primary or secondary loss of membrane chloride conductance predicted to result in reduction of the resting membrane potential. Causative mutations in the sodium channel gene result in an abnormal gain of sodium channel function that may show marked temperature dependence. Despite significant advances in the clinical, genetic and molecular pathophysiological understanding of these disorders, which we review here, there are important unresolved issues we address: (i) recent work suggests that specialized clinical neurophysiology can identify channel specific patterns and aid genetic diagnosis in many cases however, it is not yet clear if such techniques can be refined to predict the causative gene in all cases or even predict the precise genotype; (ii) although clinical experience indicates these patients can have significant progressive morbidity, the detailed natural history and determinants of morbidity have not been specifically studied in a prospective fashion; (iii) some patients develop myopathy, but its frequency, severity and possible response to treatment remains undetermined, furthermore, the pathophysiogical link between ion channel dysfunction and muscle degeneration is unknown; (iv) there is currently insufficient clinical trial evidence to recommend a standard treatment. Limited data suggest that sodium channel blocking agents have some efficacy. However, establishing the effectiveness of a therapy requires completion of multi-centre randomized controlled trials employing accurate outcome measures including reliable quantitation of myotonia. More specific pharmacological approaches are required and could include those which might preferentially reduce persistent muscle sodium currents or enhance the conductance of mutant chloride channels. Alternative strategies may be directed at preventing premature mutant channel degradation or correcting the mis-targeting of the mutant channels.
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Affiliation(s)
- E Matthews
- MRC Centre for Neuromuscular Diseases, UCL, Institute of Neurology, Queen Square, London, WC1N 3BG, England
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Rajakulendran S, Tan SV, Matthews E, Tomlinson SE, Labrum R, Sud R, Kullmann DM, Schorge S, Hanna MG. A patient with episodic ataxia and paramyotonia congenita due to mutations in KCNA1 and SCN4A. Neurology 2009; 73:993-5. [PMID: 19770477 DOI: 10.1212/wnl.0b013e3181b87959] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Affiliation(s)
- S Rajakulendran
- Medical Research Council Centre for Neuromuscular Disease, Queen Square, London, WC1N 3BG, UK
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Matthews E, Guet A, Mayer M, Vicart S, Pemble S, Sternberg D, Fontaine B, Hanna MG. Neonatal hypotonia can be a sodium channelopathy: recognition of a new phenotype. Neurology 2008; 71:1740-2. [PMID: 19015492 DOI: 10.1212/01.wnl.0000335269.21550.0e] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Affiliation(s)
- E Matthews
- MRC Centre for Neuromuscular Disease, Institute of Neurology, UCL, Queen Square, London, UK
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