1
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Cannon SC. Periodic paralysis. HANDBOOK OF CLINICAL NEUROLOGY 2024; 203:39-58. [PMID: 39174253 DOI: 10.1016/b978-0-323-90820-7.00002-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/24/2024]
Abstract
Periodic paralysis is a rare, dominantly inherited disorder of skeletal muscle in which episodic attacks of weakness are caused by a transient impairment of fiber excitability. Attacks of weakness are often elicited by characteristic environmental triggers, which were the basis for clinically delineating subtypes of periodic paralysis and are an important distinction for optimal disease management. All forms of familial periodic paralysis are caused by mutations of ion channels, often selectively expressed in skeletal muscle, that destabilize the resting potential. The missense mutations usually alter channel function through gain-of-function changes rather than producing a complete loss-of-function null. The knowledge of which channel gene harbors a variant, whether that variant is expected to (or known to) alter function, and how altered function impairs fiber excitability aides in the interpretation of patient signs and symptoms, the interpretation of gene test results, and how to optimize therapeutic intervention for symptom management and improve quality of life.
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Affiliation(s)
- Stephen C Cannon
- Departments of Physiology and of Neurology, David Geffen School of Medicine at UCLA, Los Angeles, CA, United States.
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2
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Zhang Q, Li M, Yang G, Liu X, Yu Z, Peng S. Protocatechuic acid, ferulic acid and relevant defense enzymes correlate closely with walnut resistance to Xanthomonas arboricola pv. juglandis. BMC PLANT BIOLOGY 2022; 22:598. [PMID: 36539704 PMCID: PMC9764544 DOI: 10.1186/s12870-022-03997-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/01/2022] [Accepted: 12/12/2022] [Indexed: 06/17/2023]
Abstract
BACKGROUND Juglans regia L. is an important nut tree that has a wide range of distribution in temperate regions of the world. In some walnut orchards, walnut blight can become a problematic disease that affects the growth of walnut trees. To explore the correlation between biochemical response and walnut resistance, we inoculated four walnut cultivars with Xanthomonas arboricola pv. juglandis (Xaj). The walnut cultivars were, namely, 'Xiangling', 'Xiluo 2', 'Yuanfeng' and 'Xifu 2'. Total phenol content (TPC) and total flavonoid content (TFC) were measured, whereby nine major phenolic compounds and several relevant enzymes were identified. RESULTS The results showed that the most resistant and susceptible walnut varieties were 'Xiluo 2' and 'Xifu 2' respectively. The reaction of walnut to Xaj was characterized by the early accumulation of phenolic compounds in the infected site. After inoculation with Xaj, we found that the resistant variety 'Xiluo 2' show the significant differences with other varieties at different time points through the determination of related antioxidant enzymes such as catalase (CAT) and peroxidase (POD). Meanwhile, the phenylalanine ammonia lyase (PAL) of 'Xiluo 2' increased significantly at 8 day post infection (dpi) and made differences from the control samples, while other varieties changed little. And the polyphenol oxidase (PPO) was significantly higher than in the control at 16 dpi, maintaining the highest and the lowest activity in 'Xiluo 2' and 'Xifu 2' respectively. It was also found that the content of protocatechuic acid in all cultivars increased significantly at 4 dpi, and 'Xiluo 2' was significantly higher than that of the control. In the early stage of the disease, ferulic acid content increased significantly in 'Xiluo 2'. CONCLUSION Our findings confirmed that the metabolism of phenolic compounds and related defense enzymes are of great significance in the response of walnut to Xaj.
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Affiliation(s)
- Qian Zhang
- Laboratory of Walnut Research Center, College of Forestry, Northwest A & F University, Shaanxi, 712100, Yangling, China
| | - Meixuan Li
- Laboratory of Walnut Research Center, College of Forestry, Northwest A & F University, Shaanxi, 712100, Yangling, China
| | - Guiyan Yang
- Laboratory of Walnut Research Center, College of Forestry, Northwest A & F University, Shaanxi, 712100, Yangling, China
| | - Xiaoqiang Liu
- Department of Foreign Languages, Northwest A & F University, Shaanxi, 712100, Yangling, China
| | - Zhongdong Yu
- Laboratory of Walnut Research Center, College of Forestry, Northwest A & F University, Shaanxi, 712100, Yangling, China
| | - Shaobing Peng
- Laboratory of Walnut Research Center, College of Forestry, Northwest A & F University, Shaanxi, 712100, Yangling, China.
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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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Nicole S, Lory P. New Challenges Resulting From the Loss of Function of Na v1.4 in Neuromuscular Diseases. Front Pharmacol 2021; 12:751095. [PMID: 34671263 PMCID: PMC8521073 DOI: 10.3389/fphar.2021.751095] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2021] [Accepted: 09/16/2021] [Indexed: 11/13/2022] Open
Abstract
The voltage-gated sodium channel Nav1.4 is a major actor in the excitability of skeletal myofibers, driving the muscle force in response to nerve stimulation. Supporting further this key role, mutations in SCN4A, the gene encoding the pore-forming α subunit of Nav1.4, are responsible for a clinical spectrum of human diseases ranging from muscle stiffness (sodium channel myotonia, SCM) to muscle weakness. For years, only dominantly-inherited diseases resulting from Nav1.4 gain of function (GoF) were known, i.e., non-dystrophic myotonia (delayed muscle relaxation due to myofiber hyperexcitability), paramyotonia congenita and hyperkalemic or hypokalemic periodic paralyses (episodic flaccid muscle weakness due to transient myofiber hypoexcitability). These last 5 years, SCN4A mutations inducing Nav1.4 loss of function (LoF) were identified as the cause of dominantly and recessively-inherited disorders with muscle weakness: periodic paralyses with hypokalemic attacks, congenital myasthenic syndromes and congenital myopathies. We propose to name this clinical spectrum sodium channel weakness (SCW) as the mirror of SCM. Nav1.4 LoF as a cause of permanent muscle weakness was quite unexpected as the Na+ current density in the sarcolemma is large, securing the ability to generate and propagate muscle action potentials. The properties of SCN4A LoF mutations are well documented at the channel level in cellular electrophysiological studies However, much less is known about the functional consequences of Nav1.4 LoF in skeletal myofibers with no available pertinent cell or animal models. Regarding the therapeutic issues for Nav1.4 channelopathies, former efforts were aimed at developing subtype-selective Nav channel antagonists to block myofiber hyperexcitability. Non-selective, Nav channel blockers are clinically efficient in SCM and paramyotonia congenita, whereas patient education and carbonic anhydrase inhibitors are helpful to prevent attacks in periodic paralyses. Developing therapeutic tools able to counteract Nav1.4 LoF in skeletal muscles is then a new challenge in the field of Nav channelopathies. Here, we review the current knowledge regarding Nav1.4 LoF and discuss the possible therapeutic strategies to be developed in order to improve muscle force in SCW.
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Affiliation(s)
- Sophie Nicole
- Institut de Génomique Fonctionnelle (IGF), Université de Montpellier, CNRS, INSERM, Montpellier, France.,LabEx 'Ion Channel Science and Therapeutics (ICST), Montpellier, France
| | - Philippe Lory
- Institut de Génomique Fonctionnelle (IGF), Université de Montpellier, CNRS, INSERM, Montpellier, France.,LabEx 'Ion Channel Science and Therapeutics (ICST), Montpellier, France
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5
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Maggi L, Bonanno S, Altamura C, Desaphy JF. Ion Channel Gene Mutations Causing Skeletal Muscle Disorders: Pathomechanisms and Opportunities for Therapy. Cells 2021; 10:cells10061521. [PMID: 34208776 PMCID: PMC8234207 DOI: 10.3390/cells10061521] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2021] [Revised: 06/03/2021] [Accepted: 06/10/2021] [Indexed: 02/06/2023] Open
Abstract
Skeletal muscle ion channelopathies (SMICs) are a large heterogeneous group of rare genetic disorders caused by mutations in genes encoding ion channel subunits in the skeletal muscle mainly characterized by myotonia or periodic paralysis, potentially resulting in long-term disabilities. However, with the development of new molecular technologies, new genes and new phenotypes, including progressive myopathies, have been recently discovered, markedly increasing the complexity in the field. In this regard, new advances in SMICs show a less conventional role of ion channels in muscle cell division, proliferation, differentiation, and survival. Hence, SMICs represent an expanding and exciting field. Here, we review current knowledge of SMICs, with a description of their clinical phenotypes, cellular and molecular pathomechanisms, and available treatments.
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Affiliation(s)
- Lorenzo Maggi
- Neuroimmunology and Neuromuscular Disorders Unit, Fondazione IRCCS Istituto Neurologico Carlo Besta, 20133 Milan, Italy;
- Correspondence:
| | - Silvia Bonanno
- Neuroimmunology and Neuromuscular Disorders Unit, Fondazione IRCCS Istituto Neurologico Carlo Besta, 20133 Milan, Italy;
| | - Concetta Altamura
- Department of Biomedical Sciences and Human Oncology, School of Medicine, University of Bari Aldo Moro, 70124 Bari, Italy; (C.A.); (J.-F.D.)
| | - Jean-François Desaphy
- Department of Biomedical Sciences and Human Oncology, School of Medicine, University of Bari Aldo Moro, 70124 Bari, Italy; (C.A.); (J.-F.D.)
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6
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Mantegazza M, Cestèle S, Catterall WA. Sodium channelopathies of skeletal muscle and brain. Physiol Rev 2021; 101:1633-1689. [PMID: 33769100 DOI: 10.1152/physrev.00025.2020] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Voltage-gated sodium channels initiate action potentials in nerve, skeletal muscle, and other electrically excitable cells. Mutations in them cause a wide range of diseases. These channelopathy mutations affect every aspect of sodium channel function, including voltage sensing, voltage-dependent activation, ion conductance, fast and slow inactivation, and both biosynthesis and assembly. Mutations that cause different forms of periodic paralysis in skeletal muscle were discovered first and have provided a template for understanding structure, function, and pathophysiology at the molecular level. More recent work has revealed multiple sodium channelopathies in the brain. Here we review the well-characterized genetics and pathophysiology of the periodic paralyses of skeletal muscle and then use this information as a foundation for advancing our understanding of mutations in the structurally homologous α-subunits of brain sodium channels that cause epilepsy, migraine, autism, and related comorbidities. We include studies based on molecular and structural biology, cell biology and physiology, pharmacology, and mouse genetics. Our review reveals unexpected connections among these different types of sodium channelopathies.
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Affiliation(s)
- Massimo Mantegazza
- Université Cote d'Azur, Valbonne-Sophia Antipolis, France.,CNRS UMR7275, Institut de Pharmacologie Moléculaire et Cellulaire, Valbonne-Sophia Antipolis, France.,INSERM, Valbonne-Sophia Antipolis, France
| | - Sandrine Cestèle
- Université Cote d'Azur, Valbonne-Sophia Antipolis, France.,CNRS UMR7275, Institut de Pharmacologie Moléculaire et Cellulaire, Valbonne-Sophia Antipolis, France
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7
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Desaphy JF, Altamura C, Vicart S, Fontaine B. Targeted Therapies for Skeletal Muscle Ion Channelopathies: Systematic Review and Steps Towards Precision Medicine. J Neuromuscul Dis 2021; 8:357-381. [PMID: 33325393 PMCID: PMC8203248 DOI: 10.3233/jnd-200582] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
BACKGROUND Skeletal muscle ion channelopathies include non-dystrophic myotonias (NDM), periodic paralyses (PP), congenital myasthenic syndrome, and recently identified congenital myopathies. The treatment of these diseases is mainly symptomatic, aimed at reducing muscle excitability in NDM or modifying triggers of attacks in PP. OBJECTIVE This systematic review collected the evidences regarding effects of pharmacological treatment on muscle ion channelopathies, focusing on the possible link between treatments and genetic background. METHODS We searched databases for randomized clinical trials (RCT) and other human studies reporting pharmacological treatments. Preclinical studies were considered to gain further information regarding mutation-dependent drug effects. All steps were performed by two independent investigators, while two others critically reviewed the entire process. RESULTS For NMD, RCT showed therapeutic benefits of mexiletine and lamotrigine, while other human studies suggest some efficacy of various sodium channel blockers and of the carbonic anhydrase inhibitor (CAI) acetazolamide. Preclinical studies suggest that mutations may alter sensitivity of the channel to sodium channel blockers in vitro, which has been translated to humans in some cases. For hyperkalemic and hypokalemic PP, RCT showed efficacy of the CAI dichlorphenamide in preventing paralysis. However, hypokalemic PP patients carrying sodium channel mutations may have fewer benefits from CAI compared to those carrying calcium channel mutations. Few data are available for treatment of congenital myopathies. CONCLUSIONS These studies provided limited information about the response to treatments of individual mutations or groups of mutations. A major effort is needed to perform human studies for designing a mutation-driven precision medicine in muscle ion channelopathies.
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Affiliation(s)
- Jean-François Desaphy
- Department of Biomedical Sciences and Human Oncology, School of Medicine, University of Bari Aldo Moro, Bari, Italy
| | - Concetta Altamura
- Department of Biomedical Sciences and Human Oncology, School of Medicine, University of Bari Aldo Moro, Bari, Italy
| | - Savine Vicart
- Sorbonne Université, INSERM, Assistance Publique Hôpitaux de Paris, Centre de Recherche en Myologie-UMR 974, Reference center in neuro-muscular channelopathies, Institute of Myology, Hôpital Universitaire Pitié-Salpêtrière, Paris, France
| | - Bertrand Fontaine
- Sorbonne Université, INSERM, Assistance Publique Hôpitaux de Paris, Centre de Recherche en Myologie-UMR 974, Reference center in neuro-muscular channelopathies, Institute of Myology, Hôpital Universitaire Pitié-Salpêtrière, Paris, France
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8
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Abstract
Skeletal muscle channelopathies are rare genetic neuromuscular conditions that include the nondystrophic myotonias and periodic paralyses. They cause disabling muscle symptoms and can limit educational potential, work opportunities, socialization, and quality of life. Effective therapy is available, making it essential to recognize and treat this group of disorders. Here, the authors highlight important aspects regarding diagnosis and management using illustrative case reports.
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Affiliation(s)
- Vinojini Vivekanandam
- Department of Neuromuscular Diseases, Queen Square Centre for Neuromuscular Diseases, UCL Queen Square Institute of Neurology and National Hospital for Neurology and Neurosurgery, London WC1N 3BG, UK
| | - Pinki Munot
- Dubowitz Neuromuscular Centre, Great Ormond Street Hospital for Children, London, UK
| | - Michael G Hanna
- Department of Neuromuscular Diseases, Queen Square Centre for Neuromuscular Diseases, UCL Queen Square Institute of Neurology and National Hospital for Neurology and Neurosurgery, London WC1N 3BG, UK
| | - Emma Matthews
- Department of Neuromuscular Diseases, Queen Square Centre for Neuromuscular Diseases, UCL Queen Square Institute of Neurology and National Hospital for Neurology and Neurosurgery, London WC1N 3BG, UK.
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9
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Vivekanandam V, Männikkö R, Matthews E, Hanna MG. Improving genetic diagnostics of skeletal muscle channelopathies. Expert Rev Mol Diagn 2020; 20:725-736. [PMID: 32657178 DOI: 10.1080/14737159.2020.1782195] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
INTRODUCTION Skeletal muscle channelopathies are rare inherited conditions that cause significant morbidity and impact on quality of life. Some subsets have a mortality risk. Improved genetic methodology and understanding of phenotypes have improved diagnostic accuracy and yield. AREAS COVERED We discuss diagnostic advances since the advent of next-generation sequencing and the role of whole exome and genome sequencing. Advances in genotype-phenotype-functional correlations have improved understanding of inheritance and phenotypes. We outline new phenotypes, particularly in the pediatric setting and consider co-existing mutations that may act as genetic modifiers. We also discuss four newly identified genes associated with skeletal muscle channelopathies. EXPERT OPINION Next-generation sequencing using gene panels has improved diagnostic rates, identified new mutations, and discovered patients with co-existing pathogenic mutations ('double trouble'). This field has previously focussed on single genes, but we are now beginning to understand interactions between co-existing mutations, genetic modifiers, and their role in pathomechanisms. New genetic observations in pediatric presentations of channelopathies broadens our understanding of the conditions. Genetic and mechanistic advances have increased the potential to develop treatments.
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Affiliation(s)
- Vinojini Vivekanandam
- Queen Square Centre for Neuromuscular Diseases and Department of Neuromuscular Diseases, Queen Square Institute of Neurology, UCL and National Hospital for Neurology and Neurosurgery , London, UK
| | - Roope Männikkö
- Queen Square Centre for Neuromuscular Diseases and Department of Neuromuscular Diseases, Queen Square Institute of Neurology, UCL and National Hospital for Neurology and Neurosurgery , London, UK
| | - Emma Matthews
- Queen Square Centre for Neuromuscular Diseases and Department of Neuromuscular Diseases, Queen Square Institute of Neurology, UCL and National Hospital for Neurology and Neurosurgery , London, UK
| | - Michael G Hanna
- Queen Square Centre for Neuromuscular Diseases and Department of Neuromuscular Diseases, Queen Square Institute of Neurology, UCL and National Hospital for Neurology and Neurosurgery , London, UK
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10
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Zukić S, Sinanović O, Alečković-Halilović M, Hodžić R, Kovačević L, Hodžić S. Hyperkalemic periodic paralysis aggravated by voltage - gate sodium channel blocker antiepileptic drug? Med Hypotheses 2020; 139:109683. [PMID: 32248037 DOI: 10.1016/j.mehy.2020.109683] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2020] [Revised: 03/08/2020] [Accepted: 03/18/2020] [Indexed: 11/15/2022]
Abstract
Hyperkalemic periodic paralysis (hyperkalemic PP) is a rare muscle disease that has onset in infancy or early childhood and is manifested by transient episodes of paralysis. In this case we presented a young male adult with attacks of weakness, after commencement of the antiepileptic drug - Carbamazepine. We hypothesize that Carbamazepine, as voltage-gate sodium channel blocker, aggravated the symptoms of hyperkalemic PP, as sodium channelopathies, in this young-male-patient, trough influence on membrane depolarization.
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Affiliation(s)
- S Zukić
- Department of Neurology, University Clinical Centre Tuzla, Bosnia and Herzegovina.
| | - O Sinanović
- Medical Faculty, University of Tuzla, Bosnia and Herzegovina.
| | - M Alečković-Halilović
- Department of Nephrology, Dialysis and Renal Transplantation, Clinic for Internal Diseases, University Clinical Centre Tuzla, Bosnia and Herzegovina
| | - R Hodžić
- Department of Neurology, University Clinical Centre Tuzla, Bosnia and Herzegovina
| | - L Kovačević
- Department of Neurology, University Clinical Centre Tuzla, Bosnia and Herzegovina
| | - S Hodžić
- Clinic for Internal Diseases, University Clinical Centre Tuzla, Bosnia and Herzegovina
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11
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Matthews E, Balestrini S, Sisodiya SM, Hanna MG. Muscle and brain sodium channelopathies: genetic causes, clinical phenotypes, and management approaches. THE LANCET CHILD & ADOLESCENT HEALTH 2020; 4:536-547. [PMID: 32142633 DOI: 10.1016/s2352-4642(19)30425-0] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/18/2019] [Revised: 10/29/2019] [Accepted: 12/12/2019] [Indexed: 01/26/2023]
Abstract
Voltage-gated sodium channels are essential for excitability of skeletal muscle fibres and neurons. An increasing number of disabling or fatal paediatric neurological disorders linked to mutations of voltage-gated sodium channel genes are recognised. Muscle phenotypes include episodic paralysis, myotonia, neonatal hypotonia, respiratory compromise, laryngospasm or stridor, congenital myasthenia, and myopathy. Evidence suggests a possible link between sodium channel dysfunction and sudden infant death. Increasingly recognised phenotypes of brain sodium channelopathies include several epilepsy disorders and complex encephalopathies. Together, these early-onset muscle and brain phenotypes have a substantial morbidity and a considerable mortality. Important advances in understanding the pathophysiological mechanisms underlying these channelopathies have helped to identify effective targeted therapies. The availability of effective treatments underlines the importance of increasing clinical awareness and the need to achieve a precise genetic diagnosis. In this Review, we describe the expanded range of phenotypes of muscle and brain sodium channelopathies and the underlying knowledge regarding mechanisms of sodium channel dysfunction. We also outline a diagnostic approach and review the available treatment options.
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Affiliation(s)
- Emma Matthews
- Department of Neuromuscular Diseases, Medical Research Council Centre for Neuromuscular Diseases, University College London Queen Square Institute of Neurology, London, UK; National Hospital for Neurology and Neurosurgery, University College London Hospitals National Health Service Foundation Trust, London, UK.
| | - Simona Balestrini
- Department of Clinical and Experimental Epilepsy, University College London Queen Square Institute of Neurology, London, UK; Chalfont Centre for Epilepsy, Buckinghamshire, UK; National Hospital for Neurology and Neurosurgery, University College London Hospitals National Health Service Foundation Trust, London, UK
| | - Sanjay M Sisodiya
- Department of Clinical and Experimental Epilepsy, University College London Queen Square Institute of Neurology, London, UK; Chalfont Centre for Epilepsy, Buckinghamshire, UK; National Hospital for Neurology and Neurosurgery, University College London Hospitals National Health Service Foundation Trust, London, UK
| | - Michael G Hanna
- Department of Neuromuscular Diseases, Medical Research Council Centre for Neuromuscular Diseases, University College London Queen Square Institute of Neurology, London, UK; National Hospital for Neurology and Neurosurgery, University College London Hospitals National Health Service Foundation Trust, London, UK
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12
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Sansone VA. Episodic Muscle Disorders. Continuum (Minneap Minn) 2019; 25:1696-1711. [PMID: 31794467 DOI: 10.1212/con.0000000000000802] [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: 11/15/2022]
Abstract
PURPOSE OF REVIEW This article reviews the episodic muscle disorders, including benign cramp-fasciculation syndrome, the periodic paralyses, and the nondystrophic myotonias. The core diagnostic criteria for a diagnosis of primary periodic paralysis, including clues to distinguish between the hypokalemic and hyperkalemic forms, and the distinctive elements that characterize Andersen-Tawil syndrome are discussed. Management of patients with these disorders is also discussed. RECENT FINDINGS Childhood presentations of periodic paralysis have recently been described, including atypical findings. Carbonic anhydrase inhibitors, such as dichlorphenamide, have recently been approved by the US Food and Drug Administration (FDA) for the treatment of both hypokalemic and hyperkalemic forms of periodic paralysis. Muscle MRI may be a useful outcome measure in pharmacologic trials in periodic paralysis. Genetic research continues to identify additional gene mutations responsible for periodic paralysis. SUMMARY This article will help neurologists diagnose and manage episodic muscle disorders and, in particular, the periodic paralyses and the nondystrophic myotonias.
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13
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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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14
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Abstract
Voltage-gated sodium (Na+) channels are expressed in virtually all electrically excitable tissues and are essential for muscle contraction and the conduction of impulses within the peripheral and central nervous systems. Genetic disorders that disrupt the function of these channels produce an array of Na+ channelopathies resulting in neuronal impairment, chronic pain, neuromuscular pathologies, and cardiac arrhythmias. Because of their importance to the conduction of electrical signals, Na+ channels are the target of a wide variety of local anesthetic, antiarrhythmic, anticonvulsant, and antidepressant drugs. The voltage-gated family of Na+ channels is composed of α-subunits that encode for the voltage sensor domains and the Na+-selective permeation pore. In vivo, Na+ channel α-subunits are associated with one or more accessory β-subunits (β1-β4) that regulate gating properties, trafficking, and cell-surface expression of the channels. The permeation pore of Na+ channels is divided in two parts: the outer mouth of the pore is the site of the ion selectivity filter, while the inner cytoplasmic pore serves as the channel activation gate. The cytoplasmic lining of the permeation pore is formed by the S6 segments that include highly conserved aromatic amino acids important for drug binding. These residues are believed to undergo voltage-dependent conformational changes that alter drug binding as the channels cycle through the closed, open, and inactivated states. The purpose of this chapter is to broadly review the mechanisms of Na+ channel gating and the models used to describe drug binding and Na+ channel inhibition.
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Affiliation(s)
- M E O'Leary
- Cooper Medical School of Rowan University, Camden, NJ, USA
| | - M Chahine
- CERVO Brain Research Center, Institut universitaire en santé mentale de Québec, Quebec City, QC, Canada.
- Department of Medicine, Université Laval, Quebec City, QC, Canada.
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15
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Marakhonov AV, Varenikov GG, Skoblov MY. Sodium Channelopathies: From Molecular Physiology towards Medical Genetics. RUSS J GENET+ 2018. [DOI: 10.1134/s102279541801009x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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16
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Matthews E, Silwal A, Sud R, Hanna MG, Manzur AY, Muntoni F, Munot P. Skeletal Muscle Channelopathies: Rare Disorders with Common Pediatric Symptoms. J Pediatr 2017; 188:181-185.e6. [PMID: 28662944 DOI: 10.1016/j.jpeds.2017.05.081] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/12/2017] [Revised: 03/31/2017] [Accepted: 05/31/2017] [Indexed: 10/19/2022]
Abstract
OBJECTIVE To ascertain the presenting symptoms of children with skeletal muscle channelopathies to promote early diagnosis and treatment. STUDY DESIGN Retrospective case review of 38 children with a skeletal muscle channelopathy attending the specialist pediatric neuromuscular service at Great Ormond Street Hospital over a 15-year period. RESULTS Gait disorder and leg cramps are a frequent presentation of myotonic disorders (19 of 29). Strabismus or extraocular myotonia (9 of 19) and respiratory and/or bulbar symptoms (11 of 19) are common among those with sodium channelopathy. Neonatal hypotonia was observed in periodic paralysis. Scoliosis and/or contractures were demonstrated in 6 of 38 children. School attendance or ability to engage fully in all activities was often limited (25 of 38). CONCLUSIONS Children with skeletal muscle channelopathies frequently display symptoms that are uncommon in adult disease. Any child presenting with abnormal gait, leg cramps, or strabismus, especially if intermittent, should prompt examination for myotonia. Those with sodium channel disease should be monitored for respiratory or bulbar complications. Neonatal hypotonia can herald periodic paralysis. Early diagnosis is essential for children to reach their full educational potential.
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Affiliation(s)
- Emma Matthews
- Medical Research Council Center for Neuromuscular Diseases, University College London and National Hospital for Neurology and Neurosurgery, London, UK.
| | - Arpana Silwal
- Dubowitz Neuromuscular Center and MRC Center for Neuromuscular Diseases, UCL Great Ormond Street Institute of Child Health, London, UK
| | - Richa Sud
- Neurogenetics Unit, Institute of Neurology, London, UK
| | - Michael G Hanna
- Medical Research Council Center for Neuromuscular Diseases, University College London and National Hospital for Neurology and Neurosurgery, London, UK
| | - Adnan Y Manzur
- Dubowitz Neuromuscular Center and MRC Center for Neuromuscular Diseases, UCL Great Ormond Street Institute of Child Health, London, UK
| | - Francesco Muntoni
- Dubowitz Neuromuscular Center and MRC Center for Neuromuscular Diseases, UCL Great Ormond Street Institute of Child Health, London, UK
| | - Pinki Munot
- Dubowitz Neuromuscular Center and MRC Center for Neuromuscular Diseases, UCL Great Ormond Street Institute of Child Health, London, UK
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17
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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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18
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King EC, Patel V, Anand M, Zhao X, Crump SM, Hu Z, Weisleder N, Abbott GW. Targeted deletion of Kcne3 impairs skeletal muscle function in mice. FASEB J 2017; 31:2937-2947. [PMID: 28356343 DOI: 10.1096/fj.201600965rr] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2016] [Accepted: 03/13/2017] [Indexed: 11/11/2022]
Abstract
KCNE3 (MiRP2) forms heteromeric voltage-gated K+ channels with the skeletal muscle-expressed KCNC4 (Kv3.4) α subunit. KCNE3 was the first reported skeletal muscle K+ channel disease gene, but the requirement for KCNE3 in skeletal muscle has been questioned. Here, we confirmed KCNE3 transcript and protein expression in mouse skeletal muscle using Kcne3-/- tissue as a negative control. Whole-transcript microarray analysis (770,317 probes, interrogating 28,853 transcripts) findings were consistent with Kcne3 deletion increasing gastrocnemius oxidative metabolic gene expression and the proportion of type IIa fast-twitch oxidative muscle fibers, which was verified using immunofluorescence. The down-regulated transcript set overlapped with muscle unloading gene expression profiles (≥1.5-fold change; P < 0.05). Gastrocnemius K+ channel α subunit remodeling arising from Kcne3 deletion was highly specific, involving just 3 of 69 α subunit genes probed: known KCNE3 partners KCNC4 and KCNH2 (mERG) were down-regulated, and KCNK4 (TRAAK) was up-regulated (P < 0.05). Functionally, Kcne3-/- mice exhibited abnormal hind-limb clasping upon tail suspension (63% of Kcne3-/- mice ≥10-mo-old vs. 0% age-matched Kcne3+/+ littermates). Whereas 5 of 5 Kcne3+/+ mice exhibited the typical biphasic decline in contractile force with repetitive stimuli of hind-limb muscle, both in vivo and in vitro, this was absent in 6 of 6 Kcne3-/- mice tested. Finally, myoblasts isolated from Kcne3-/- mice exhibit faster-inactivating and smaller sustained outward currents than those from Kcne3+/+ mice. Thus, Kcne3 deletion impairs skeletal muscle function in mice.-King, E. C., Patel, V., Anand, M., Zhao, X., Crump, S. M., Hu, Z., Weisleder, N., Abbott, G. W. Targeted deletion of Kcne3 impairs skeletal muscle function in mice.
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Affiliation(s)
- Elizabeth C King
- Department of Pharmacology, Weill Medical College of Cornell University, New York, New York, USA
| | - Vishal Patel
- Department of Physiology and Biophysics, University of Medicine and Dentistry of New Jersey-Robert Wood Johnson Medical School, Piscataway, New Jersey, USA
| | - Marie Anand
- Department of Pharmacology, School of Medicine, University of California, Irvine, California, USA.,Department of Physiology and Biophysics, School of Medicine, University of California, Irvine, Irvine, California, USA
| | - Xiaoli Zhao
- Department of Physiology and Biophysics, University of Medicine and Dentistry of New Jersey-Robert Wood Johnson Medical School, Piscataway, New Jersey, USA
| | - Shawn M Crump
- Department of Pharmacology, School of Medicine, University of California, Irvine, California, USA.,Department of Physiology and Biophysics, School of Medicine, University of California, Irvine, Irvine, California, USA
| | - Zhaoyang Hu
- Department of Pharmacology, School of Medicine, University of California, Irvine, California, USA.,Department of Physiology and Biophysics, School of Medicine, University of California, Irvine, Irvine, California, USA
| | - Noah Weisleder
- Department of Physiology and Biophysics, University of Medicine and Dentistry of New Jersey-Robert Wood Johnson Medical School, Piscataway, New Jersey, USA;
| | - Geoffrey W Abbott
- Department of Pharmacology, School of Medicine, University of California, Irvine, California, USA; .,Department of Physiology and Biophysics, School of Medicine, University of California, Irvine, Irvine, California, USA
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19
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Gusella JF. 2016 William Allan Award: Human Disease Research: Genetic Cycling and Re-cycling. Am J Hum Genet 2017; 100:387-394. [PMID: 28257685 DOI: 10.1016/j.ajhg.2017.01.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
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20
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Zostawa J, Adamczyk J, Sowa P, Adamczyk-Sowa M. The influence of sodium on pathophysiology of multiple sclerosis. Neurol Sci 2017; 38:389-398. [PMID: 28078565 PMCID: PMC5331099 DOI: 10.1007/s10072-016-2802-8] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2016] [Accepted: 12/19/2016] [Indexed: 01/06/2023]
Abstract
Multiple sclerosis (MS) is a chronic, inflammatory, autoimmune disease of the central nervous system, and is an important cause of disability in young adults. In genetically susceptible individuals, several environmental factors may play a partial role in the pathogenesis of MS. Some studies suggests that high-salt diet (>5 g/day) may contribute to the MS and other autoimmune disease development through the induction of pathogenic Th17 cells and pro-inflammatory cytokines in both humans and mice. However, the precise mechanisms of pro-inflammatory effect of sodium chloride intake are not yet explained. The purpose of this review was to discuss the present state of knowledge on the potential role of environmental and dietary factors, particularly sodium chloride on the development and course of MS.
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Affiliation(s)
- Jacek Zostawa
- Department of Neurology in Zabrze, Medical University of Silesia, ul. 3-go Maja 13-15, 41-800, Zabrze, Poland
| | - Jowita Adamczyk
- Department of Neurology in Zabrze, Medical University of Silesia, ul. 3-go Maja 13-15, 41-800, Zabrze, Poland.
| | - Paweł Sowa
- Department of Otorhinolaryngology and Oncological Laryngology, Medical University of Silesia, ul. C. Skłodowskiej 10, 41-800, Zabrze, Poland
| | - Monika Adamczyk-Sowa
- Department of Neurology in Zabrze, Medical University of Silesia, ul. 3-go Maja 13-15, 41-800, Zabrze, Poland
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21
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Benhammou JN, Phan J, Lee H, Ghassemi K, Parsons W, Grody WW, Pisegna JR. A Sodium Channel Myotonia Presenting with Intermittent Dysphagia as a Manifestation of a Rare SCN4A Variant. J Mol Neurosci 2016; 61:312-314. [PMID: 28012096 DOI: 10.1007/s12031-016-0878-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2016] [Accepted: 12/15/2016] [Indexed: 11/28/2022]
Abstract
The voltage gated sodium channel SCN4A mutations account for non-dystrophic myotonia and include a heterogeneous group of conditions that include hyperkalemic periodic paralysis, paramyotonica congenita, potassium-aggravated myotonia, and hypokalemic periodic paralysis type 2. This case report proposes that a rare variant p.Pro1629Leu in SCN4A can cause a skeletal muscle deficit with intermittent dysphagia.
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Affiliation(s)
- Jihane N Benhammou
- Division of Digestive Diseases, Department of Medicine, and Departments of Pathology & Laboratory Medicine and Human Genetics, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA.,Division of Gastroenterology, Hepatology and Parenteral Nutrition, VA Greater Los Angeles Healthcare System (691/111C), 11301 Wilshire Blvd, Los Angeles, CA, 90073, USA
| | - Jennifer Phan
- Division of Digestive Diseases, Department of Medicine, and Departments of Pathology & Laboratory Medicine and Human Genetics, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA.,Division of Gastroenterology, Hepatology and Parenteral Nutrition, VA Greater Los Angeles Healthcare System (691/111C), 11301 Wilshire Blvd, Los Angeles, CA, 90073, USA
| | - Hane Lee
- Division of Digestive Diseases, Department of Medicine, and Departments of Pathology & Laboratory Medicine and Human Genetics, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA.,Division of Gastroenterology, Hepatology and Parenteral Nutrition, VA Greater Los Angeles Healthcare System (691/111C), 11301 Wilshire Blvd, Los Angeles, CA, 90073, USA
| | - Kevin Ghassemi
- Division of Digestive Diseases, Department of Medicine, and Departments of Pathology & Laboratory Medicine and Human Genetics, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA.,Division of Gastroenterology, Hepatology and Parenteral Nutrition, VA Greater Los Angeles Healthcare System (691/111C), 11301 Wilshire Blvd, Los Angeles, CA, 90073, USA
| | - William Parsons
- Division of Digestive Diseases, Department of Medicine, and Departments of Pathology & Laboratory Medicine and Human Genetics, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA.,Division of Gastroenterology, Hepatology and Parenteral Nutrition, VA Greater Los Angeles Healthcare System (691/111C), 11301 Wilshire Blvd, Los Angeles, CA, 90073, USA
| | - Wayne W Grody
- Division of Digestive Diseases, Department of Medicine, and Departments of Pathology & Laboratory Medicine and Human Genetics, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA.,Division of Gastroenterology, Hepatology and Parenteral Nutrition, VA Greater Los Angeles Healthcare System (691/111C), 11301 Wilshire Blvd, Los Angeles, CA, 90073, USA
| | - Joseph R Pisegna
- Division of Digestive Diseases, Department of Medicine, and Departments of Pathology & Laboratory Medicine and Human Genetics, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA. .,Division of Gastroenterology, Hepatology and Parenteral Nutrition, VA Greater Los Angeles Healthcare System (691/111C), 11301 Wilshire Blvd, Los Angeles, CA, 90073, USA.
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22
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D'Mello S, Shum L. A review of the use of mexiletine in patients with myotonic dystrophy and non-dystrophic myotonia. Eur J Hosp Pharm 2016; 23:359-363. [PMID: 31156883 DOI: 10.1136/ejhpharm-2015-000839] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2016] [Revised: 05/18/2016] [Accepted: 05/24/2016] [Indexed: 11/03/2022] Open
Abstract
Introduction Myotonia is found in a number of muscle diseases, including myotonic dystrophy and non-dystrophic myotonia. The resulting symptoms of myotonia can interfere with daily activities such as walking or climbing the stairs. Due to the rarity of both these conditions, pharmacological treatment of myotonia is largely anecdotal and is led by specialist clinicians who tend to favour the use of mexiletine, a class 1b antiarrhythmic sodium antagonist. Objective To identify and review randomised controlled trials in order to assess the efficacy and safety of use of mexiletine in myotonic dystrophy and non-dystrophic myotonia for two different patient cases. Search methods The literature search was conducted using MEDLINE, EMBASE and The Cochrane Library (from January 1990 to December 2014). Specialist neurology centres were also contacted. Selection criteria All randomised controlled trials between January 1990 and December 2014 which compared the use of mexiletine for the treatment of myotonia in patients who suffer from myotonic dystrophy and non-dystrophic were included in this review. Primary outcome: reduction of clinical myotonia. Results Two randomised controlled trials were included for review. Both studies are underpowered; however, there is evidence to support the use of mexiletine for the improvement of clinical myotonia. Conclusions Larger randomised controlled trials are required, which look at the functional effect of myotonia as a primary outcome (ie, stair test) and the long-term use of mexiletine. This is needed to establish the ongoing efficacy and safety of the long-term use of mexiletine in the management of myotonia.
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Affiliation(s)
- Simon D'Mello
- Pharmacy Department, St George's University Hospitals NHS Foundation Trust, London, UK
| | - Ling Shum
- Pharmacy Department, Lewisham and Greenwich NHS Trust, London, UK.,Pharmacy Department, Guy's and St Thomas' NHS Foundation Trust, London, UK
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23
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Shimomura T, Irie K, Fujiyoshi Y. Molecular determinants of prokaryotic voltage-gated sodium channels for recognition of local anesthetics. FEBS J 2016; 283:2881-95. [DOI: 10.1111/febs.13776] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2016] [Revised: 05/22/2016] [Accepted: 06/06/2016] [Indexed: 11/28/2022]
Affiliation(s)
- Takushi Shimomura
- Cellular and Structural Physiology Institute (CeSPI); Nagoya University; Japan
| | - Katsumasa Irie
- Cellular and Structural Physiology Institute (CeSPI); Nagoya University; Japan
- Graduate School of Pharmaceutical Science; Nagoya University; Japan
| | - Yoshinori Fujiyoshi
- Cellular and Structural Physiology Institute (CeSPI); Nagoya University; Japan
- Graduate School of Pharmaceutical Science; Nagoya University; Japan
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24
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Abstract
Myotonia (muscle stiffness) is a symptom of several inherited diseases in humans and also in animals. It is due to muscle membrane hyperexcitability, which, in turn, can be caused by mutations in plasma membrane ion channels. The skeletal muscle chloride channel CLC-1 provides the major part of muscle membrane conductance and is important for keeping this membrane close to its resting voltage. Mutations in CLC-1 can cause both recessive (Becker) and dominant (Thomsen) forms of myotonia. Some of these mutations have been introduced into the functional cDNA and analyzed in the Xenopus oocyte expression system. From these studies, it was concluded that CLC-1 functions as a homooligomer with probably four subunits. Dominant mutant subunits are assumed to associate with wild-type ones, leading to their inactivation. The principle disease-causing mechanism of dominant mutations is a drastic alteration in the voltage dependence of CLC-1 gating. Some mutations in CLC-1 can be inherited either recessively or dominantly, probably depending on the genetic background. These studies point to the important role of CLC-1 in muscle physiology and provide interesting insights into the structure and function of this gene family of voltage-gated chloride channels. NEUROSCIENTIST 2:225-232, 1996
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Affiliation(s)
- Klaus Steinmeyer
- Institute for Molecular Neuropathobiology Center for
Molecular Neurobiology (ZMNH) Hamburg University Hamburg
| | - Thomas J. Jentsch
- Institute for Molecular Neuropathobiology Center for
Molecular Neurobiology (ZMNH) Hamburg University Hamburg
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25
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Abstract
PURPOSE OF REVIEW This is an update on skeletal muscle sodium channelopathies since knowledge in the field have dramatically increased in the past years. RECENT FINDING The relationship between two phenotypes and SCN4A has been confirmed with additional cases that remain extremely rare: severe neonatal episodic laryngospasm mimicking encephalopathy, which should be actively searched for since patients respond well to sodium channel blockers; congenital myasthenic syndromes, which have the particularity to be the first recessive Nav1.4 channelopathy. Deep DNA sequencing suggests the contribution of other ion channels in the clinical expressivity of sodium channelopathies, which may be one of the factors modulating the latter. The increased knowledge of channel molecular structure, the quantity of sodium channel blockers, and the availability of preclinical models would permit a most personalized choice of medication for patients suffering from these debilitating neuromuscular diseases. SUMMARY Advances in the understanding of the molecular structure of voltage-gated sodium channels, as well as availability of preclinical models, would lead to improved medical care of patients suffering from skeletal muscle, as well as other sodium channelopathies.
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26
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27
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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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28
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Ramakrishna H, O’Hare M, Mookadam F, Gutsche JT, Shah R, Augoustides JG. Sudden Cardiac Death and Disorders of the QT Interval: Anesthetic Implications and Focus on Perioperative Management. J Cardiothorac Vasc Anesth 2015; 29:1723-33. [DOI: 10.1053/j.jvca.2015.07.026] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/20/2015] [Indexed: 12/19/2022]
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29
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Bergareche A, Bednarz M, Sánchez E, Krebs CE, Ruiz-Martinez J, De La Riva P, Makarov V, Gorostidi A, Jurkat-Rott K, Marti-Masso JF, Paisán-Ruiz C. SCN4A pore mutation pathogenetically contributes to autosomal dominant essential tremor and may increase susceptibility to epilepsy. Hum Mol Genet 2015; 24:7111-20. [PMID: 26427606 DOI: 10.1093/hmg/ddv410] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2015] [Accepted: 09/25/2015] [Indexed: 12/19/2022] Open
Abstract
Essential tremor (ET) is the most prevalent movement disorder, affecting millions of people in the USA. Although a positive family history is one of the most important risk factors for ET, the genetic causes of ET remain unknown. In an attempt to identify genetic causes for ET, we performed whole-exome sequencing analyses in a large Spanish family with ET, in which two patients also developed epilepsy. To further assess pathogenicity, site-directed mutagenesis, mouse and human brain expression analyses, and patch clamp techniques were performed. A disease-segregating mutation (p.Gly1537Ser) in the SCN4A gene was identified. Posterior functional analyses demonstrated that more rapid kinetics at near-threshold potentials altered ion selectivity and facilitated the conductance of both potassium and ammonium ions, which could contribute to tremor and increase susceptibility to epilepsy, respectively. In this report, for the first time, we associated the genetic variability of SCN4A with the development of essential tremor, which adds ET to the growing list of neurological channelopathies.
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Affiliation(s)
- Alberto Bergareche
- Movement Disorders Unit, Department of Neurology Hospital Universitario Donostia San Sebastián Guipuzcoa Spain, Biodonostia Research Institute, Area of Neurosciences, Centro de Investigación Biomédica en Red para Enfermedades Neurodegenerativas (CIBERNED), Carlos III Health Institute, Madrid, Spain
| | - Marcin Bednarz
- Division of Neurophysiology, Ulm University, Albert-Einstein-Allee 11, 89070 Ulm, Germany
| | | | | | - Javier Ruiz-Martinez
- Movement Disorders Unit, Department of Neurology Hospital Universitario Donostia San Sebastián Guipuzcoa Spain, Biodonostia Research Institute, Area of Neurosciences, Centro de Investigación Biomédica en Red para Enfermedades Neurodegenerativas (CIBERNED), Carlos III Health Institute, Madrid, Spain
| | - Patricia De La Riva
- Movement Disorders Unit, Department of Neurology Hospital Universitario Donostia San Sebastián Guipuzcoa Spain, Biodonostia Research Institute, Area of Neurosciences, Centro de Investigación Biomédica en Red para Enfermedades Neurodegenerativas (CIBERNED), Carlos III Health Institute, Madrid, Spain
| | - Vladimir Makarov
- Human Oncology and Pathogenesis Program, Memorial Sloan-Kettering Cancer Center, 1275 York Ave, New York, NY 10065, USA
| | - Ana Gorostidi
- Movement Disorders Unit, Department of Neurology Hospital Universitario Donostia San Sebastián Guipuzcoa Spain, Biodonostia Research Institute, Area of Neurosciences, Centro de Investigación Biomédica en Red para Enfermedades Neurodegenerativas (CIBERNED), Carlos III Health Institute, Madrid, Spain
| | - Karin Jurkat-Rott
- Division of Neurophysiology, Ulm University, Albert-Einstein-Allee 11, 89070 Ulm, Germany
| | - Jose Felix Marti-Masso
- Movement Disorders Unit, Department of Neurology Hospital Universitario Donostia San Sebastián Guipuzcoa Spain, Biodonostia Research Institute, Area of Neurosciences, Department of Neurosciences University of the Basque Country, EHU-UPV San Sebastián Gipuzkoa Spain, Centro de Investigación Biomédica en Red para Enfermedades Neurodegenerativas (CIBERNED), Carlos III Health Institute, Madrid, Spain
| | - Coro Paisán-Ruiz
- Department of Neurology, Department of Psychiatry, Department of Genetics and Genomic Sciences, Friedman Brain Institute, Mindich Child Health and Development Institute, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, New York, NY 10029, USA and
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30
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Dick IE, Limpitikul WB, Niu J, Banerjee R, Issa JB, Ben-Johny M, Adams PJ, Kang PW, Lee SR, Sang L, Yang W, Babich J, Zhang M, Bazazzi H, Yue NC, Tomaselli GF. A rendezvous with the queen of ion channels: Three decades of ion channel research by David T Yue and his Calcium Signals Laboratory. Channels (Austin) 2015; 10:20-32. [PMID: 26176690 DOI: 10.1080/19336950.2015.1051272] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
David T. Yue was a renowned biophysicist who dedicated his life to the study of Ca(2+) signaling in cells. In the wake of his passing, we are left not only with a feeling of great loss, but with a tremendous and impactful body of work contributed by a remarkable man. David's research spanned the spectrum from atomic structure to organ systems, with a quantitative rigor aimed at understanding the fundamental mechanisms underlying biological function. Along the way he developed new tools and approaches, enabling not only his own research but that of his contemporaries and those who will come after him. While we cannot hope to replicate the eloquence and style we are accustomed to in David's writing, we nonetheless undertake a review of David's chosen field of study with a focus on many of his contributions to the calcium channel field.
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Affiliation(s)
- Ivy E Dick
- a Calcium Signals Laboratory; Department of Biomedical Engineering ; Johns Hopkins University School of Medicine ; Baltimore , MD USA
| | - Worawan B Limpitikul
- a Calcium Signals Laboratory; Department of Biomedical Engineering ; Johns Hopkins University School of Medicine ; Baltimore , MD USA
| | - Jacqueline Niu
- a Calcium Signals Laboratory; Department of Biomedical Engineering ; Johns Hopkins University School of Medicine ; Baltimore , MD USA
| | - Rahul Banerjee
- a Calcium Signals Laboratory; Department of Biomedical Engineering ; Johns Hopkins University School of Medicine ; Baltimore , MD USA
| | - John B Issa
- a Calcium Signals Laboratory; Department of Biomedical Engineering ; Johns Hopkins University School of Medicine ; Baltimore , MD USA
| | - Manu Ben-Johny
- a Calcium Signals Laboratory; Department of Biomedical Engineering ; Johns Hopkins University School of Medicine ; Baltimore , MD USA
| | - Paul J Adams
- a Calcium Signals Laboratory; Department of Biomedical Engineering ; Johns Hopkins University School of Medicine ; Baltimore , MD USA.,b Kwantlen Polytechnic University ; Surrey , BC Canada
| | - Po Wei Kang
- a Calcium Signals Laboratory; Department of Biomedical Engineering ; Johns Hopkins University School of Medicine ; Baltimore , MD USA
| | - Shin Rong Lee
- a Calcium Signals Laboratory; Department of Biomedical Engineering ; Johns Hopkins University School of Medicine ; Baltimore , MD USA
| | - Lingjie Sang
- a Calcium Signals Laboratory; Department of Biomedical Engineering ; Johns Hopkins University School of Medicine ; Baltimore , MD USA
| | - Wanjun Yang
- a Calcium Signals Laboratory; Department of Biomedical Engineering ; Johns Hopkins University School of Medicine ; Baltimore , MD USA
| | - Jennifer Babich
- a Calcium Signals Laboratory; Department of Biomedical Engineering ; Johns Hopkins University School of Medicine ; Baltimore , MD USA
| | - Manning Zhang
- a Calcium Signals Laboratory; Department of Biomedical Engineering ; Johns Hopkins University School of Medicine ; Baltimore , MD USA
| | - Hojjat Bazazzi
- a Calcium Signals Laboratory; Department of Biomedical Engineering ; Johns Hopkins University School of Medicine ; Baltimore , MD USA
| | - Nancy C Yue
- a Calcium Signals Laboratory; Department of Biomedical Engineering ; Johns Hopkins University School of Medicine ; Baltimore , MD USA
| | - Gordon F Tomaselli
- a Calcium Signals Laboratory; Department of Biomedical Engineering ; Johns Hopkins University School of Medicine ; Baltimore , MD USA.,c Division of Cardiology; Department of Medicine ; Johns Hopkins University School of Medicine ; Baltimore , MD USA
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31
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Corrochano S, Männikkö R, Joyce PI, McGoldrick P, Wettstein J, Lassi G, Raja Rayan DL, Blanco G, Quinn C, Liavas A, Lionikas A, Amior N, Dick J, Healy EG, Stewart M, Carter S, Hutchinson M, Bentley L, Fratta P, Cortese A, Cox R, Brown SDM, Tucci V, Wackerhage H, Amato AA, Greensmith L, Koltzenburg M, Hanna MG, Acevedo-Arozena A. Novel mutations in human and mouse SCN4A implicate AMPK in myotonia and periodic paralysis. ACTA ACUST UNITED AC 2014; 137:3171-85. [PMID: 25348630 PMCID: PMC4240299 DOI: 10.1093/brain/awu292] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Mutations in the skeletal muscle channel (SCN4A), encoding the Nav1.4 voltage-gated sodium channel, are causative of a variety of muscle channelopathies, including non-dystrophic myotonias and periodic paralysis. The effects of many of these mutations on channel function have been characterized both in vitro and in vivo. However, little is known about the consequences of SCN4A mutations downstream from their impact on the electrophysiology of the Nav1.4 channel. Here we report the discovery of a novel SCN4A mutation (c.1762A>G; p.I588V) in a patient with myotonia and periodic paralysis, located within the S1 segment of the second domain of the Nav1.4 channel. Using N-ethyl-N-nitrosourea mutagenesis, we generated and characterized a mouse model (named draggen), carrying the equivalent point mutation (c.1744A>G; p.I582V) to that found in the patient with periodic paralysis and myotonia. Draggen mice have myotonia and suffer from intermittent hind-limb immobility attacks. In-depth characterization of draggen mice uncovered novel systemic metabolic abnormalities in Scn4a mouse models and provided novel insights into disease mechanisms. We discovered metabolic alterations leading to lean mice, as well as abnormal AMP-activated protein kinase activation, which were associated with the immobility attacks and may provide a novel potential therapeutic target.
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Affiliation(s)
| | - Roope Männikkö
- 2 UCL Institute of Neurology, MRC Centre for Neuromuscular Diseases, London, UK
| | - Peter I Joyce
- 1 MRC Mammalian Genetics Unit, Harwell, Oxfordshire, UK
| | - Philip McGoldrick
- 2 UCL Institute of Neurology, MRC Centre for Neuromuscular Diseases, London, UK
| | - Jessica Wettstein
- 3 University of Aberdeen, Institute of Medical Sciences, Scotland, UK
| | - Glenda Lassi
- 4 Department of Neuroscience and Brain Technologies, Istituto Italiano di Tecnologia, Genova, Italy
| | - Dipa L Raja Rayan
- 2 UCL Institute of Neurology, MRC Centre for Neuromuscular Diseases, London, UK
| | | | - Colin Quinn
- 6 Brigham and Women's Hospital, Harvard Medical School, Boston, US
| | - Andrianos Liavas
- 2 UCL Institute of Neurology, MRC Centre for Neuromuscular Diseases, London, UK
| | | | - Neta Amior
- 2 UCL Institute of Neurology, MRC Centre for Neuromuscular Diseases, London, UK
| | - James Dick
- 2 UCL Institute of Neurology, MRC Centre for Neuromuscular Diseases, London, UK
| | - Estelle G Healy
- 2 UCL Institute of Neurology, MRC Centre for Neuromuscular Diseases, London, UK
| | | | - Sarah Carter
- 1 MRC Mammalian Genetics Unit, Harwell, Oxfordshire, UK
| | | | - Liz Bentley
- 1 MRC Mammalian Genetics Unit, Harwell, Oxfordshire, UK
| | - Pietro Fratta
- 2 UCL Institute of Neurology, MRC Centre for Neuromuscular Diseases, London, UK
| | - Andrea Cortese
- 7 Mondino National Institute of Neurology Foundation, IRCCS, Pavia, Italy
| | - Roger Cox
- 1 MRC Mammalian Genetics Unit, Harwell, Oxfordshire, UK
| | | | - Valter Tucci
- 4 Department of Neuroscience and Brain Technologies, Istituto Italiano di Tecnologia, Genova, Italy
| | | | - Anthony A Amato
- 6 Brigham and Women's Hospital, Harvard Medical School, Boston, US
| | - Linda Greensmith
- 2 UCL Institute of Neurology, MRC Centre for Neuromuscular Diseases, London, UK
| | - Martin Koltzenburg
- 2 UCL Institute of Neurology, MRC Centre for Neuromuscular Diseases, London, UK
| | - Michael G Hanna
- 2 UCL Institute of Neurology, MRC Centre for Neuromuscular Diseases, London, UK
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Mutational Consequences of Aberrant Ion Channels in Neurological Disorders. J Membr Biol 2014; 247:1083-127. [DOI: 10.1007/s00232-014-9716-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2014] [Accepted: 07/25/2014] [Indexed: 12/25/2022]
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Statland JM, Barohn RJ. Muscle channelopathies: the nondystrophic myotonias and periodic paralyses. Continuum (Minneap Minn) 2014; 19:1598-614. [PMID: 24305449 DOI: 10.1212/01.con.0000440661.49298.c8] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
PURPOSE OF REVIEW The muscle channelopathies are a group of rare inherited diseases caused by mutations in muscle ion channels. Mutations cause an increase or decrease in muscle membrane excitability, leading to a spectrum of related clinical disorders: the nondystrophic myotonias are characterized by delayed relaxation after muscle contraction, causing muscle stiffness and pain; the periodic paralyses are characterized by episodes of flaccid muscle paralysis. This review describes the clinical characteristics, molecular pathogenesis, and treatments of the nondystrophic myotonias and periodic paralyses. RECENT FINDINGS Advances have been made in both the treatment and our understanding of the molecular pathophysiology of muscle channelopathies: (1) a recent controlled trial showed that mexiletine was effective for reducing symptoms and signs of myotonia in nondystrophic myotonia; (2) the mechanisms by which hypokalemic periodic paralysis leads to a depolarized but unexcitable sarcolemma membrane have been traced to a novel gating pore current; and (3) an association was demonstrated between mutations in a potassium inward rectifier and patients with thyrotoxic periodic paralysis. SUMMARY The muscle channelopathies are an expanding group of muscle diseases caused by mutations in sodium, chloride, potassium, and calcium ion channels that result in increased or decreased muscle membrane excitability. Recognizing patients with channelopathies and confirming the diagnosis is important, as treatment and management strategies differ based on mutation and clinical phenotype.
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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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Bandschapp O, Iaizzo PA. Pathophysiologic and anesthetic considerations for patients with myotonia congenita or periodic paralyses. Paediatr Anaesth 2013; 23:824-33. [PMID: 23802937 DOI: 10.1111/pan.12217] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 05/29/2013] [Indexed: 12/13/2022]
Abstract
Myotonia congenita and periodic paralyses are hereditary skeletal muscle channelopathies. In these disorders, various channel defects in the sarcolemma lead to a severely disturbed membrane excitability of the affected skeletal muscles. The clinical picture can range from severe myotonic reactions (e.g., masseter spasm, opisthotonus) to attacks of weakness and paralysis. Provided here is a short overview of the pathomechanisms behind such wide-ranging phenotypic presentations in these patients, followed by recommendations concerning the management of anesthesia in such populations.
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Affiliation(s)
- Oliver Bandschapp
- Department of Anesthesia, Surgical Intensive Care, Prehospital Emergency Medicine and Pain Therapy, University Hospital Basel, Basel, Switzerland.
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Akimoto T, Masuda A, Yotsu-Yamashita M, Hirokawa T, Nagasawa K. Synthesis of saxitoxin derivatives bearing guanidine and urea groups at C13 and evaluation of their inhibitory activity on voltage-gated sodium channels. Org Biomol Chem 2013; 11:6642-9. [DOI: 10.1039/c3ob41398e] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
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Gandolfi B, Gruffydd-Jones TJ, Malik R, Cortes A, Jones BR, Helps CR, Prinzenberg EM, Erhardt G, Lyons LA. First WNK4-hypokalemia animal model identified by genome-wide association in Burmese cats. PLoS One 2012; 7:e53173. [PMID: 23285264 PMCID: PMC3532348 DOI: 10.1371/journal.pone.0053173] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2012] [Accepted: 11/26/2012] [Indexed: 11/18/2022] Open
Abstract
Burmese is an old and popular cat breed, however, several health concerns, such as hypokalemia and a craniofacial defect, are prevalent, endangering the general health of the breed. Hypokalemia, a subnormal serum potassium ion concentration ([K+]), most often occurs as a secondary problem but can occur as a primary problem, such as hypokalaemic periodic paralysis in humans, and as feline hypokalaemic periodic polymyopathy primarily in Burmese. The most characteristic clinical sign of hypokalemia in Burmese is a skeletal muscle weakness that is frequently episodic in nature, either generalized, or sometimes localized to the cervical and thoracic limb girdle muscles. Burmese hypokalemia is suspected to be a single locus autosomal recessive trait. A genome wide case-control study using the illumina Infinium Feline 63K iSelect DNA array was performed using 35 cases and 25 controls from the Burmese breed that identified a locus on chromosome E1 associated with hypokalemia. Within approximately 1.2 Mb of the highest associated SNP, two candidate genes were identified, KCNH4 and WNK4. Direct sequencing of the genes revealed a nonsense mutation, producing a premature stop codon within WNK4 (c.2899C>T), leading to a truncated protein that lacks the C-terminal coiled-coil domain and the highly conserved Akt1/SGK phosphorylation site. All cases were homozygous for the mutation. Although the exact mechanism causing hypokalemia has not been determined, extrapolation from the homologous human and mouse genes suggests the mechanism may involve a potassium-losing nephropathy. A genetic test to screen for the genetic defect within the active breeding population has been developed, which should lead to eradication of the mutation and improved general health within the breed. Moreover, the identified mutation may help clarify the role of the protein in K+ regulation and the cat represents the first animal model for WNK4-associated hypokalemia.
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Affiliation(s)
- Barbara Gandolfi
- Department of Population Health and Reproduction, University of California Davis, Davis, California, United States of America
| | | | - Richard Malik
- Centre for Veterinary Education, University of Sydney, Sydney, Australia
| | - Alejandro Cortes
- Department of Population Health and Reproduction, University of California Davis, Davis, California, United States of America
| | - Boyd R. Jones
- Institute of Veterinary, Animal & Biomedical Sciences, Massey University, Palmerston North, New Zealand
| | - Chris R. Helps
- Molecular Diagnostic Unit, University of Bristol, Langford, Bristol, United Kingdom
| | - Eva M. Prinzenberg
- Institute of Animal Breeding & Genetics, Justus Liebig University, Giessen, Germany
| | - George Erhardt
- Institute of Animal Breeding & Genetics, Justus Liebig University, Giessen, Germany
| | - Leslie A. Lyons
- Department of Population Health and Reproduction, University of California Davis, Davis, California, United States of America
- * E-mail:
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Statland JM, Bundy BN, Wang Y, Trivedi JR, Raja Rayan D, Herbelin L, Donlan M, McLin R, Eichinger KJ, Findlater K, Dewar L, Pandya S, Martens WB, Venance SL, Matthews E, Amato AA, Hanna MG, Griggs RC, Barohn RJ. A quantitative measure of handgrip myotonia in non-dystrophic myotonia. Muscle Nerve 2012; 46:482-9. [PMID: 22987687 DOI: 10.1002/mus.23402] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
INTRODUCTION Non-dystrophic myotonia (NDM) is characterized by myotonia without muscle wasting. A standardized quantitative myotonia assessment (QMA) is important for clinical trials. METHODS Myotonia was assessed in 91 individuals enrolled in a natural history study using a commercially available computerized handgrip myometer and automated software. Average peak force and 90% to 5% relaxation times were compared with historical normal controls studied with identical methods. RESULTS Thirty subjects had chloride channel mutations, 31 had sodium channel mutations, 6 had DM2 mutations, and 24 had no identified mutation. Chloride channel mutations were associated with prolonged first handgrip relaxation times and warm-up on subsequent handgrips. Sodium channel mutations were associated with prolonged first handgrip relaxation times and paradoxical myotonia or warm-up, depending on underlying mutations. DM2 subjects had normal relaxation times but decreased peak force. Sample size estimates are provided for clinical trial planning. CONCLUSION QMA is an automated, non-invasive technique for evaluating myotonia 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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Amarteifio E, Nagel AM, Weber MA, Jurkat-Rott K, Lehmann-Horn F. Hyperkalemic periodic paralysis and permanent weakness: 3-T MR imaging depicts intracellular 23Na overload--initial results. Radiology 2012; 264:154-63. [PMID: 22509051 DOI: 10.1148/radiol.12110980] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
PURPOSE To assess whether myoplasmic ionic sodium (Na+) is increased in muscles of patients with hyperkalemic periodic paralysis (HyperPP) with 3-T sodium 23 (23Na) magnetic resonance (MR) imaging and to evaluate the effect of medical treatment on sodium-induced muscle edema. MATERIALS AND METHODS This study received institutional review board approval; written informed consent was obtained. Proton (hydrogen 1 [1H]) and 23Na MR of both calves were performed in 12 patients with HyperPP (mean age, 48 years±14 [standard deviation]) and 12 healthy volunteers (mean age, 38 years±12) before and after provocation (unilateral cooling, one calf). 23Na MR included spin-density, T1-weighted, and inversion-recovery (IR) sequences. Total sodium concentration and normalized signal intensities (SIs) were evaluated within regions of interest (ROIs). Muscle strength was measured with the British Medical Research Council (MRC) grading scale. Five patients underwent follow-up MR after diuretic treatment. RESULTS During rest, mean myoplasmic Na+ concentration was significantly higher in HyperPP with permanent weakness (40.7 μmol/g±3.9) compared with HyperPP with transient weakness (31.3 μmol/g±4.8) (P=.004). Mean SI in 23Na IR MR was significantly higher in HyperPP with permanent weakness (0.83±0.04; median MRC, grade 4; range, 3-5) compared with HyperPP without permanent weakness (0.67±0.05; median MRC, grade 5; range, 4-5) (P=.002). Provocation reduced muscle strength in HyperPP (before provocation, median MRC, 5; range, 3-5; after provocation, median MRC, 3; range, 1-4) and increased SI in 23Na IR from 0.75±0.09 to 0.86±0.10 (P=.004). Spin-density and T1-weighted sequences were less sensitive, particularly to cold-induced Na+ changes. 23Na IR SI remained unchanged in volunteers (0.53±0.06 before and 0.54±0.06 after provocation, P=.3). Therapy reduced mean SI in 23Na IR sequence from 0.85±0.04 to 0.64±0.11. CONCLUSION 23Na MR imaging depicts increased myoplasmic Na+ in HyperPP with permanent weakness. Na+ overload may cause muscle degeneration developing with age. 23Na MR imaging may have potential to aid monitoring of medical treatment that reduces this overload.
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Affiliation(s)
- Erick Amarteifio
- Department of Diagnostic and Interventional Radiology, University Hospital of Heidelberg, Im Neuenheimer Feld 110, D-69120 Heidelberg, Germany.
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Glaaser IW, Osteen JD, Puckerin A, Sampson KJ, Jin X, Kass RS. Perturbation of sodium channel structure by an inherited Long QT Syndrome mutation. Nat Commun 2012; 3:706. [PMID: 22426227 PMCID: PMC3518026 DOI: 10.1038/ncomms1717] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2011] [Accepted: 01/31/2012] [Indexed: 12/22/2022] Open
Abstract
The cardiac voltage-gated sodium channel (NaV1.5) underlies impulse conduction in the heart and its depolarization-induced inactivation is essential in control of the duration of the QT interval of the electrocardiogram (ECG). Perturbation of Nav1.5 inactivation by drugs or inherited mutation can underlie and trigger cardiac arrhythmias. The carboxy terminus plays an important role in channel inactivation, but complete structural information on its predicted structural domain is unknown. Here we measure interactions between the functionally critical distal C-T alpha helix (H6) and the proximal structured EF hand motif using transition metal ion FRET. We measure distances at three loci along H6 relative to an intrinsic tryptophan, demonstrating the proximal-distal interaction in a contiguous carboxy terminus polypeptide. Using these data together with the existing NaV1.5 carboxy terminus NMR structure, we construct a model of the predicted structured region of the carboxy terminus. An arrhythmia associated H6 mutant which impairs inactivation decreases FRET, indicating destabilization of the distal-proximal intramolecular interaction. These data provide a structural correlate to the pathological phenotype of the mutant channel.
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Affiliation(s)
- Ian W Glaaser
- Department of Pharmacology, College of Physicians and Surgeons of Columbia University, Columbia University Medical Center, 630 W 168th Street, New York, NY 10032, USA
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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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Shinohara R, Akimoto T, Iwamoto O, Hirokawa T, Yotsu-Yamashita M, Yamaoka K, Nagasawa K. Synthesis of skeletal analogues of saxitoxin derivatives and evaluation of their inhibitory activity on sodium ion channels Na(V)1.4 and Na(V)1.5. Chemistry 2011; 17:12144-52. [PMID: 21922571 DOI: 10.1002/chem.201101058] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2011] [Revised: 07/20/2011] [Indexed: 12/19/2022]
Abstract
Skeletal analogues of saxitoxin (STX) that possess a fused-type tricyclic ring system, designated FD-STX, were synthesized as candidate sodium ion channel modulators. Three kinds of FD-STX derivatives 4a-c with different substitution at C13 were synthesized, and their inhibitory activity on sodium ion channels was examined by means of cell-based assay. (-)-FD-STX (4a) and (-)-FD-dcSTX (4b), which showed moderate inhibitory activity, were further evaluated by the use of the patch-clamp method in cells that expressed Na(V)1.4 (a tetrodotoxin-sensitive sodium channel subtype) and Na(V)1.5 (a tetrodotoxin-resistant sodium channel subtype). These compounds showed moderate inhibitory activity towards Na(V)1.4, and weaker inhibitory activity towards Na(V)1.5. Uniquely, however, the inhibition of Na(V)1.5 by (-)-FD-dcSTX (4b) was "irreversible".
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Affiliation(s)
- Ryoko Shinohara
- Tokyo University of Agriculture and Technology, Department of Biotechnology and Life Science, Koganei, Tokyo 184-8588, Japan
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Simkin D, Léna I, Landrieu P, Lion-François L, Sternberg D, Fontaine B, Bendahhou S. Mechanisms underlying a life-threatening skeletal muscle Na+ channel disorder. J Physiol 2011; 589:3115-24. [PMID: 21521764 DOI: 10.1113/jphysiol.2011.207977] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Myotonia is an intrinsic muscular disorder caused by muscle fibre hyperexcitability, which produces a prolonged time for relaxation after voluntary muscle contraction or internal mechanical stimulation. Missense mutations in skeletal muscle genes encoding Cl− or Na+ channels cause non-dystrophic myotonias.Mutations of the SCN4A gene that encodes the skeletal voltage-gated Na+ channel Nav1.4 can produce opposing phenotypes leading to hyperexcitable or inexcitable muscle fibres. Nav1.4 mutations result in different forms of myotonias that can be found in adults. However, the recently reported myotonic manifestations in infants have been shown to be lethal. This was typically the case for children suffering from severe neonatal episodic laryngospasm (SNEL). A novel Nav1.4 channel missense mutation was found in these children that has not yet been analysed. In this study, we characterize the functional consequences of the new A799S Na+ channel mutation that is associated with sodium channel myotonia in newborn babies. We have used mammalian cell expression and patch-clamp techniques to monitor the channel properties.We found that the A799S substitution changes several biophysical properties of the channel by causing a hyperpolarizing shift of the steady-state activation, and slowing the kinetics of fast inactivation and deactivation. In addition, the single channel open probability was dramatically increased, contributing hence to a severe phenotype. We showed that substitutions at position 799 of the Nav1.4 channel favoured the channel open state with sustained activity leading to hyperexcitability of laryngeal muscles that could be lethal during infancy.
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Affiliation(s)
- Dina Simkin
- University of Nice Sophia-Antipolis, and UMR 6097 CNRS-TIANP, Nice, France
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Abstract
Inherited ion channel mutations can affect the entire nervous system. Many cause paroxysmal disturbances of brain, spinal cord, peripheral nerve or skeletal muscle function, with normal neurological development and function in between attacks. To fully understand how mutations of ion channel genes cause disease, we need to know the normal location and function of the channel subunit, consequences of the mutation for biogenesis and biophysical properties, and possible compensatory changes in other channels that contribute to cell or circuit excitability. Animal models of monogenic channelopathies increasingly help our understanding. An important challenge for the future is to determine how more subtle derangements of ion channel function, which arise from the interaction of genetic and environmental influences, contribute to common paroxysmal disorders, including idiopathic epilepsy and migraine, that share features with rare monogenic channelopathies.
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Affiliation(s)
- Dimitri M Kullmann
- Institute of Neurology, University College London, Queen Square, London WC1N3BG, United Kingdom.
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Sodium channelopathies of skeletal muscle result from gain or loss of function. Pflugers Arch 2010; 460:239-48. [PMID: 20237798 PMCID: PMC2883924 DOI: 10.1007/s00424-010-0814-4] [Citation(s) in RCA: 84] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2010] [Revised: 02/19/2010] [Accepted: 02/23/2010] [Indexed: 10/31/2022]
Abstract
Five hereditary sodium channelopathies of skeletal muscle have been identified. Prominent symptoms are either myotonia or weakness caused by an increase or decrease of muscle fiber excitability. The voltage-gated sodium channel NaV1.4, initiator of the muscle action potential, is mutated in all five disorders. Pathogenetically, both loss and gain of function mutations have been described, the latter being the more frequent mechanism and involving not just the ion-conducting pore, but aberrant pores as well. The type of channel malfunction is decisive for therapy which consists either of exerting a direct effect on the sodium channel, i.e., by blocking the pore, or of restoring skeletal muscle membrane potential to reduce the fraction of inactivated channels.
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Burgunder JM, Finsterer J, Szolnoki Z, Fontaine B, Baets J, Van Broeckhoven C, Di Donato S, De Jonghe P, Lynch T, Mariotti C, Schöls L, Spinazzola A, Tabrizi SJ, Tallaksen C, Zeviani M, Harbo HF, Gasser T. EFNS guidelines on the molecular diagnosis of channelopathies, epilepsies, migraine, stroke, and dementias. Eur J Neurol 2010; 17:641-8. [DOI: 10.1111/j.1468-1331.2010.02985.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Zhou H, Lillis S, Loy RE, Ghassemi F, Rose MR, Norwood F, Mills K, Al-Sarraj S, Lane RJM, Feng L, Matthews E, Sewry CA, Abbs S, Buk S, Hanna M, Treves S, Dirksen RT, Meissner G, Muntoni F, Jungbluth H. Multi-minicore disease and atypical periodic paralysis associated with novel mutations in the skeletal muscle ryanodine receptor (RYR1) gene. Neuromuscul Disord 2010; 20:166-73. [PMID: 20080402 DOI: 10.1016/j.nmd.2009.12.005] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2009] [Revised: 12/06/2009] [Accepted: 12/15/2009] [Indexed: 11/26/2022]
Abstract
The skeletal muscle ryanodine receptor plays a crucial role in excitation-contraction (EC) coupling and is implicated in various congenital myopathies. The periodic paralyses are a heterogeneous, dominantly inherited group of conditions mainly associated with mutations in the SCN4A and the CACNA1S genes. The interaction between RyR1 and DHPR proteins underlies depolarization-induced Ca(2+) release during EC coupling in skeletal muscle. We report a 35-year-old woman presenting with signs and symptoms of a congenital myopathy at birth and repeated episodes of generalized, atypical normokalaemic paralysis in her late teens. Genetic studies of this patient revealed three heterozygous RYR1 substitutions (p.Arg2241X, p.Asp708Asn and p.Arg2939Lys) associated with marked reduction of the RyR1 protein and abnormal DHPR distribution. We conclude that RYR1 mutations may give rise to both myopathies and atypical periodic paralysis, and RYR1 mutations may underlie other unresolved cases of periodic paralysis with unusual features.
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Affiliation(s)
- Haiyan Zhou
- Dubowitz Neuromuscular Centre, UCL Institute of Child Health & Great Ormond Street Hospital for Children, London, UK
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