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Elaraby NM, Ahmed HA, Dawoud H, Ashaat NA, Azmy A, Galal ER, Elhusseny Y, Awady HE, Metwally AM, Ashaat EA. Clinical and molecular characterization of myotonia congenita using whole-exome sequencing in Egyptian patients. Mol Biol Rep 2024; 51:766. [PMID: 38877370 DOI: 10.1007/s11033-024-09646-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2024] [Accepted: 05/16/2024] [Indexed: 06/16/2024]
Abstract
BACKGROUND Myotonia Congenita (MC) is a rare disease classified into two major forms; Thomsen and Becker disease caused by mutations in the CLCN1 gene, which affects muscle excitability and encodes voltage-gated chloride channels (CLC-1). While, there are no data regarding the clinical and molecular characterization of myotonia in Egyptian patients. METHODS Herein, we report seven Egyptian MC patients from six unrelated families. Following the clinical diagnosis, whole-exome sequencing (WES) was performed for genetic diagnosis. Various in silico prediction tools were utilized to interpret variant pathogenicity. The candidate variants were then validated using Sanger sequencing technique. RESULTS In total, seven cases were recruited. The ages at the examination were ranged from eight months to nineteen years. Clinical manifestations included warm-up phenomenon, hand grip, and percussion myotonia. Electromyography was performed in all patients and revealed myotonic discharges. Molecular genetic analysis revealed five different variants. Of them, we identified two novel variants in the CLCN1 gene ( c.1583G > C; p.Gly528Ala and c.2203_2216del;p.Thr735ValfsTer57) and three known variants in the CLCN1 and SCN4A gene. According to in silico tools, the identified novel variants were predicted to have deleterious effects. CONCLUSIONS As the first study to apply WES among Egyptian MC patients, our findings reported two novel heterozygous variants that expand the CLCN1 mutational spectrum for MC diagnosis. These results further confirm that genetic testing is essential for early diagnosis of MC, which affects follow-up treatment and prognostic assessment in clinical practice.
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Affiliation(s)
- Nesma M Elaraby
- Medical Molecular Genetics Department, Human Genetics and Genome Research Institute, National Research Centre, Dokki, Cairo, Egypt.
| | - Hoda A Ahmed
- Medical Molecular Genetics Department, Human Genetics and Genome Research Institute, National Research Centre, Dokki, Cairo, Egypt
| | - Heba Dawoud
- Pediatric Department, Tanta University, Gharbia, Egypt
| | - Neveen A Ashaat
- Professor of Human Genetics, Ain Shams University, Cairo, Egypt
| | - Ashraf Azmy
- Child Health Department, Medical Research and Clinical Studies Institute, National Research Centre, Dokki, Cairo, Egypt
| | - Eman Reda Galal
- Biochemistry and Molecular Biology Department, Faculty of Pharmacy (Girls), Al-Azhar University, Cairo, Egypt
| | - Yasmine Elhusseny
- Lecturer of Medical Biochemistry and Molecular Biology, School of Medicine, Newgiza University, Giza, Egypt
| | - Heba El Awady
- Pediatric Department, Fayoum University Hospitals, Fayoum, Egypt
| | - Ammal M Metwally
- Community Medicine Research Department/Medical Research, Clinical Studies Institute/National Research Centre (Affiliation ID: 60014618), Dokki, Cairo, Egypt
| | - Engy A Ashaat
- Clinical Genetics Department, Human Genetics and Genome Research Institute, National Research Centre, Cairo, Egypt
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Vicino A, Brugnoni R, Maggi L. Diagnostics in skeletal muscle channelopathies. Expert Rev Mol Diagn 2023; 23:1175-1193. [PMID: 38009256 DOI: 10.1080/14737159.2023.2288258] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2023] [Accepted: 11/22/2023] [Indexed: 11/28/2023]
Abstract
INTRODUCTION Skeletal muscle channelopathies (SMCs) are a heterogenous group of disorders, caused by mutations in skeletal ion channels leading to abnormal muscle excitability, resulting in either delayed muscle relaxation (myotonia) which characterizes non-dystrophic myotonias (NDMs), or membrane transient inactivation, causing episodic weakness, typical of periodic paralyses (PPs). AREAS COVERED SMCs include myotonia congenita, paramyotonia congenita, and sodium-channel myotonia among NDMs, and hyper-normokalemic, hypokalemic, or late-onset periodic paralyses among PPs. When suspecting an SMC, a structured diagnostic approach is required. Detailed personal and family history and clinical examination are essential, while neurophysiological tests should confirm myotonia and rule out alternative diagnosis. Moreover, specific electrodiagnostic studies are important to further define the phenotype of de novo cases and drive molecular analyses together with clinical data. Definite diagnosis is achieved through genetic testing, either with Sanger sequencing or multigene next-generation sequencing panel. In still unsolved patients, more advanced techniques, as exome-variant sequencing or whole-genome sequencing, may be considered in expert centers. EXPERT OPINION The diagnostic approach to SMC is still mainly based on clinical data; moreover, definite diagnosis is sometimes complicated by the difficulty to establish a proper genotype-phenotype correlation. Lastly, further studies are needed to allow the genetic characterization of unsolved patients.
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Affiliation(s)
- Alex Vicino
- Neurology IV Unit, Neuroimmunology and Neuromuscular Diseases, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy
- Nerve-Muscle Unit, Neurology Service, Department of Clinical Neurosciences, Lausanne University Hospital and University of Lausanne, Lausanne, Switzerland
| | - Raffaella Brugnoni
- Neurology IV Unit, Neuroimmunology and Neuromuscular Diseases, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy
| | - Lorenzo Maggi
- Neurology IV Unit, Neuroimmunology and Neuromuscular Diseases, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy
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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: 9] [Impact Index Per Article: 3.0] [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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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: 18] [Impact Index Per Article: 6.0] [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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Taminato T, Mori-Yoshimura M, Miki J, Sasaki R, Sato N, Oya Y, Nishino I, Takahashi Y. Paramyotonia Congenita with Persistent Distal and Facial Muscle Weakness: A Case Report with Literature Review. J Neuromuscul Dis 2020; 7:193-201. [PMID: 32083589 DOI: 10.3233/jnd-190440] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
BACKGROUND Paramyotonia congenita (PC; OMIM 168300) is a non-dystrophic myotonia caused by mutations in the SCN4A gene. Transient muscle stiffness, usually induced by exposure to cold and aggravated by exercise, is the predominant clinical symptom, and interictal persistent weakness is uncommon. CASE REPORT We report a family with a history of PC accompanied by persistent hand muscle weakness with masticatory muscle involvement. Persistent weakness was exacerbated with age, and MR analysis showed marked atrophy of temporal, masseter, and finger flexor muscles with fatty replacement. The PC causative mutation T1313M in the SCN4A gene was prevalent in the family. Administration of acetazolamide chloride improved clinical symptoms and the results of cold and short exercise tests. Phenotypic variation within the family was remarkable, as the two younger affected patients did not present with persistent weakness or muscle atrophy. CONCLUSIONS PC associated with the T1313M mutation is a possible cause of persistent distal hand weakness.
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Affiliation(s)
- Tomoya Taminato
- Department of Neurology, National Center Hospital, National Center of Neurology and Psychiatry, Tokyo, Japan
| | - Madoka Mori-Yoshimura
- Department of Neurology, National Center Hospital, National Center of Neurology and Psychiatry, Tokyo, Japan
| | - Jun Miki
- Department of Neurology, Saku Central Hospital, Nagano Prefectural Federation of Agricultural Cooperatives for Health and Welfare, Nagano, Japan
| | - Ryogen Sasaki
- Department of Neurology, Kuwana City Medical Center, Mie, Japan
| | - Noriko Sato
- Department of Radiology, National Center Hospital, National Center of Neurology and Psychiatry, Tokyo, Japan
| | - Yasushi Oya
- Department of Neurology, National Center Hospital, National Center of Neurology and Psychiatry, Tokyo, Japan
| | - Ichizo Nishino
- Department of Genome Medicine Development, Medical Genome Center, National Center of Neurology and Psychiatry, Tokyo, Japan.,Department of Neuromuscular Research, National Institute of Neuroscience, National Center of Neurology and Psychiatry, Tokyo, Japan
| | - Yuji Takahashi
- Department of Neurology, National Center Hospital, National Center of Neurology and Psychiatry, Tokyo, Japan
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Stunnenberg BC, LoRusso S, Arnold WD, Barohn RJ, Cannon SC, Fontaine B, Griggs RC, Hanna MG, Matthews E, Meola G, Sansone VA, Trivedi JR, van Engelen BG, Vicart S, Statland JM. Guidelines on clinical presentation and management of nondystrophic myotonias. Muscle Nerve 2020; 62:430-444. [PMID: 32270509 PMCID: PMC8117169 DOI: 10.1002/mus.26887] [Citation(s) in RCA: 46] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2020] [Revised: 04/01/2020] [Accepted: 04/04/2020] [Indexed: 12/26/2022]
Abstract
The nondystrophic myotonias are rare muscle hyperexcitability disorders caused by gain-of-function mutations in the SCN4A gene or loss-of-function mutations in the CLCN1 gene. Clinically, they are characterized by myotonia, defined as delayed muscle relaxation after voluntary contraction, which leads to symptoms of muscle stiffness, pain, fatigue, and weakness. Diagnosis is based on history and examination findings, the presence of electrical myotonia on electromyography, and genetic confirmation. In the absence of genetic confirmation, the diagnosis is supported by detailed electrophysiological testing, exclusion of other related disorders, and analysis of a variant of uncertain significance if present. Symptomatic treatment with a sodium channel blocker, such as mexiletine, is usually the first step in management, as well as educating patients about potential anesthetic complications.
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Affiliation(s)
- Bas C. Stunnenberg
- Department of Neurology, Radboud University Medical Center, Nijmegen, the Netherlands
| | - Samantha LoRusso
- Department of Neurology, Ohio State University Wexner Medical Center, Columbus, Ohio
| | - W. David Arnold
- Department of Neurology, Ohio State University Wexner Medical Center, Columbus, Ohio
| | - Richard J. Barohn
- Department of Neurology, University of Kansas Medical Center, Kansas City, Kansas
| | - Stephen C. Cannon
- Department of Physiology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, California
| | - Bertrand Fontaine
- Assistance Publique-Hôpitaix de Paris, Sorbonne Université, INSERM, Service of Neuro-Myology and UMR 974, Institute of Myology, University Hospital Pitié-Salpêtrière, Paris, France
| | - Robert C. Griggs
- Department of Neurology, University of Rochester, Rochester, New York
| | - Michael G. Hanna
- MRC Centre for Neuromuscular Diseases, Department of Neuromuscular diseases, UCL Queen Square Institute of Neurology, United Kingdom
| | - Emma Matthews
- MRC Centre for Neuromuscular Diseases, Department of Neuromuscular diseases, UCL Queen Square Institute of Neurology, United Kingdom
| | - Giovanni Meola
- Department of Neurorehabilitation Sciences, Casa Cura Policlinico, Milan, Italy
- Department of Biomedical Sciences for Health, University of Milan, Milan, Italy
| | - Valeria A. Sansone
- Department of Biomedical Sciences for Health, University of Milan, Milan, Italy
- Neurorehabilitation Unit, University of Milan, NEuroMuscular Omnicentre (NEMO), Fondazione Serena Onlus, Milan, Italy
| | - Jaya R. Trivedi
- Department of Neurology and Neurotherapeutics, UT Southwestern Medical Center, Dallas, Texas
| | | | - Savine Vicart
- Assistance Publique-Hôpitaix de Paris, Sorbonne Université, INSERM, Service of Neuro-Myology and UMR 974, Institute of Myology, University Hospital Pitié-Salpêtrière, Paris, France
| | - Jeffrey M. Statland
- Department of Neurology, University of Kansas Medical Center, Kansas City, Kansas
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7
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Westra D, Schouten MI, Stunnenberg BC, Kusters B, Saris CGJ, Erasmus CE, van Engelen BG, Bulk S, Verschuuren-Bemelmans CC, Gerkes EH, de Geus C, van der Zwaag PA, Chan S, Chung B, Barge-Schaapveld DQCM, Kriek M, Sznajer Y, van Spaendonck-Zwarts K, van der Kooi AJ, Krause A, Schönewolf-Greulich B, de Die-Smulders C, Sallevelt SCEH, Krapels IPC, Rasmussen M, Maystadt I, Kievit AJA, Witting N, Pennings M, Meijer R, Gillissen C, Kamsteeg EJ, Voermans NC. Panel-Based Exome Sequencing for Neuromuscular Disorders as a Diagnostic Service. J Neuromuscul Dis 2019; 6:241-258. [PMID: 31127727 DOI: 10.3233/jnd-180376] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
BACKGROUND Neuromuscular disorders (NMDs) are clinically and genetically heterogeneous. Accurate molecular genetic diagnosis can improve clinical management, provides appropriate genetic counseling and testing of relatives, and allows potential therapeutic trials. OBJECTIVE To establish the clinical utility of panel-based whole exome sequencing (WES) in NMDs in a population with children and adults with various neuromuscular symptoms. METHODS Clinical exome sequencing, followed by diagnostic interpretation of variants in genes associated with NMDs, was performed in a cohort of 396 patients suspected of having a genetic cause with a variable age of onset, neuromuscular phenotype, and inheritance pattern. Many had previously undergone targeted gene testing without results. RESULTS Disease-causing variants were identified in 75/396 patients (19%), with variants in the three COL6-genes (COL6A1, COL6A2 and COL6A3) as the most common cause of the identified muscle disorder, followed by variants in the RYR1 gene. Together, these four genes account for almost 25% of cases in whom a definite genetic cause was identified. Furthermore, likely pathogenic variants and/or variants of uncertain significance were identified in 95 of the patients (24%), in whom functional and/or segregation analysis should be used to confirm or reject the pathogenicity. In 18% of the cases with a disease-causing variant of which we received additional clinical information, we identified a genetic cause in genes of which the associated phenotypes did not match that of the patients. Hence, the advantage of panel-based WES is its unbiased approach. CONCLUSION Whole exome sequencing, followed by filtering for NMD genes, offers an unbiased approach for the genetic diagnostics of NMD patients. This approach could be used as a first-tier test in neuromuscular disorders with a high suspicion of a genetic cause. With uncertain results, functional testing and segregation analysis are needed to complete the evidence.
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Affiliation(s)
- Dineke Westra
- Department of Human Genetics, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Meyke I Schouten
- Department of Human Genetics, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Bas C Stunnenberg
- Department of Neurology, Donders Institute for Brain, Cognition, and Behavior, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Benno Kusters
- Department of Pathology, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Christiaan G J Saris
- Department of Neurology, Donders Institute for Brain, Cognition, and Behavior, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Corrie E Erasmus
- Department of Pediatric Neurology, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Baziel G van Engelen
- Department of Neurology, Donders Institute for Brain, Cognition, and Behavior, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Saskia Bulk
- Service de Génétique Humaine, CHU de Liège, Liège, Belgium
| | | | - E H Gerkes
- Department of Genetics, University Medical Center Groningen, Groningen, The Netherlands
| | - Christa de Geus
- Department of Genetics, University Medical Center Groningen, Groningen, The Netherlands
| | - P A van der Zwaag
- Department of Genetics, University Medical Center Groningen, Groningen, The Netherlands
| | - Sophelia Chan
- Department of Pediatrics and Adolescent Medicine, LKS Faculty of Medicine, The University of Hong Kong, Hong Kong
| | - Brian Chung
- Department of Pediatrics and Adolescent Medicine, LKS Faculty of Medicine, The University of Hong Kong, Hong Kong
| | | | - Marjolein Kriek
- Department of Clinical Genetics, Leiden University Medical Center, Leiden, The Netherlands
| | - Yves Sznajer
- Center de Génétique Humaine, Clinique Universitaires Saint Luc, Bruxelles, Belgium
| | | | - Anneke J van der Kooi
- Department of Neurology, Amsterdam Medical Center, Amsterdam UMC, University of Amsterdam, Neuroscience institute, Amsterdam, The Netherlands
| | - Amanda Krause
- Division of Human Genetics, National Health Laboratory Service and School of Pathology, Faculty of Health Sciences, The University of the Witwatersrand, Johannesburg, South Africa
| | | | | | - Suzanne C E H Sallevelt
- Department of Clinical Genetics, Maastricht University Medical Center+, Maastricht, The Netherlands
| | - Ingrid P C Krapels
- Department of Clinical Genetics, Maastricht University Medical Center+, Maastricht, The Netherlands
| | - Magnhild Rasmussen
- Department of Child Neurology and Unit for Congenital and Inherited Neuromuscular Disorders, Oslo University Hospital, Oslo, Norway
| | - Isabelle Maystadt
- Center de Génétique Humaine, Institut de Pathologie et de Génétique, Gosselies, Belgium
| | - Anneke J A Kievit
- Department of Clinical Genetics, Erasmus University Medical Center, Rotterdam, The Netherlands
| | - Nanna Witting
- Department of Neurology, Rigshospitalet, Copenhagen, Denmark
| | - Maartje Pennings
- Department of Human Genetics, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Rowdy Meijer
- Department of Human Genetics, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Christian Gillissen
- Department of Human Genetics, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Erik-Jan Kamsteeg
- Department of Human Genetics, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Nicol C Voermans
- Department of Neurology, Donders Institute for Brain, Cognition, and Behavior, Radboud University Medical Center, Nijmegen, The Netherlands
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Kokunai Y, Dalle C, Vicart S, Sternberg D, Pouliot V, Bendahhou S, Fournier E, Chahine M, Fontaine B, Nicole S. A204E mutation in Na v1.4 DIS3 exerts gain- and loss-of-function effects that lead to periodic paralysis combining hyper- with hypo-kalaemic signs. Sci Rep 2018; 8:16681. [PMID: 30420713 PMCID: PMC6232142 DOI: 10.1038/s41598-018-34750-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2018] [Accepted: 10/25/2018] [Indexed: 12/11/2022] Open
Abstract
Periodic paralyses (PP) are characterized by episodic muscle weakness and are classified into the distinct hyperkalaemic (hyperPP) and hypokalaemic (hypoPP) forms. The dominantly-inherited form of hyperPP is caused by overactivity of Nav1.4 - the skeletal muscle voltage-gated sodium channel. Familial hypoPP results from a leaking gating pore current induced by dominant mutations in Nav1.4 or Cav1.1, the skeletal muscle voltage-gated calcium channel. Here, we report an individual with clinical signs of hyperPP and hypokalaemic episodes of muscle paralysis who was heterozygous for the novel p.Ala204Glu (A204E) substitution located in one region of Nav1.4 poor in disease-related variations. A204E induced a significant decrease of sodium current density, increased the window current, enhanced fast and slow inactivation of Nav1.4, and did not cause gating pore current in functional analyses. Interestingly, the negative impact of A204E on Nav1.4 activation was strengthened in low concentration of extracellular K+. Our data prove the existence of a phenotype combining signs of hyperPP and hypoPP due to dominant Nav1.4 mutations. The hyperPP component would result from gain-of-function effects on Nav1.4 and the hypokalemic episodes of paralysis from loss-of-function effects strengthened by low K+. Our data argue for a non-negligible role of Nav1.4 loss-of-function in familial hypoPP.
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Affiliation(s)
- Yosuke Kokunai
- Inserm U1127, CNRS UMR 7225, Sorbonne Universités, UPMC Univ Paris 06 UMR S 1127, Institut du Cerveau et de la Moelle épinière (ICM), F-75013, Paris, France
| | - Carine Dalle
- Inserm U1127, CNRS UMR 7225, Sorbonne Universités, UPMC Univ Paris 06 UMR S 1127, Institut du Cerveau et de la Moelle épinière (ICM), F-75013, Paris, France
| | - Savine Vicart
- Inserm U1127, CNRS UMR 7225, Sorbonne Universités, UPMC Univ Paris 06 UMR S 1127, Institut du Cerveau et de la Moelle épinière (ICM), F-75013, Paris, France
- AP-HP, Hôpital Universitaire Pitié-Salpétrière, National Reference Center for Channelopathies, F-75013, Paris, France
| | - Damien Sternberg
- Inserm U1127, CNRS UMR 7225, Sorbonne Universités, UPMC Univ Paris 06 UMR S 1127, Institut du Cerveau et de la Moelle épinière (ICM), F-75013, Paris, France
- AP-HP, Hôpital Universitaire Pitié-Salpétrière, National Reference Center for Channelopathies, F-75013, Paris, France
| | - Valérie Pouliot
- Centre de recherche CERVO, Institut Universitaire en Santé Mentale de Québec, Quebec City, QC, G1J 2G3, Canada
- Department of Medicine, Université Laval, Quebec City, QC, G1K 7P4, Canada
| | - Said Bendahhou
- CNRS UMR7370, LP2M, Labex ICST, University Nice Sophia-Antipolis, Faculté de Médecine, Nice, France
| | - Emmanuel Fournier
- Inserm U1127, CNRS UMR 7225, Sorbonne Universités, UPMC Univ Paris 06 UMR S 1127, Institut du Cerveau et de la Moelle épinière (ICM), F-75013, Paris, France
- AP-HP, Hôpital Universitaire Pitié-Salpétrière, National Reference Center for Channelopathies, F-75013, Paris, France
| | - Mohamed Chahine
- Centre de recherche CERVO, Institut Universitaire en Santé Mentale de Québec, Quebec City, QC, G1J 2G3, Canada
- Department of Medicine, Université Laval, Quebec City, QC, G1K 7P4, Canada
| | - Bertrand Fontaine
- Inserm U1127, CNRS UMR 7225, Sorbonne Universités, UPMC Univ Paris 06 UMR S 1127, Institut du Cerveau et de la Moelle épinière (ICM), F-75013, Paris, France.
- AP-HP, Hôpital Universitaire Pitié-Salpétrière, National Reference Center for Channelopathies, F-75013, Paris, France.
| | - Sophie Nicole
- Inserm U1127, CNRS UMR 7225, Sorbonne Universités, UPMC Univ Paris 06 UMR S 1127, Institut du Cerveau et de la Moelle épinière (ICM), F-75013, Paris, France.
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9
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Bayless-Edwards L, Winston V, Lehmann-Horn F, Arinze P, Groome JR, Jurkat-Rott K. Na V1.4 DI-S4 periodic paralysis mutation R222W enhances inactivation and promotes leak current to attenuate action potentials and depolarize muscle fibers. Sci Rep 2018; 8:10372. [PMID: 29991727 PMCID: PMC6039468 DOI: 10.1038/s41598-018-28594-5] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2018] [Accepted: 06/20/2018] [Indexed: 01/24/2023] Open
Abstract
Hypokalemic periodic paralysis is a skeletal muscle disease characterized by episodic weakness associated with low serum potassium. We compared clinical and biophysical effects of R222W, the first hNaV1.4 domain I mutation linked to this disease. R222W patients exhibited a higher density of fibers with depolarized resting membrane potentials and produced action potentials that were attenuated compared to controls. Functional characterization of the R222W mutation in heterologous expression included the inactivation deficient IFM/QQQ background to isolate activation. R222W decreased sodium current and slowed activation without affecting probability. Consistent with the phenotype of muscle weakness, R222W shifted fast inactivation to hyperpolarized potentials, promoted more rapid entry, and slowed recovery. R222W increased the extent of slow inactivation and slowed its recovery. A two-compartment skeletal muscle fiber model revealed that defects in fast inactivation sufficiently explain action potential attenuation in patients. Molecular dynamics simulations showed that R222W disrupted electrostatic interactions within the gating pore, supporting the observation that R222W promotes omega current at hyperpolarized potentials. Sodium channel inactivation defects produced by R222W are the primary driver of skeletal muscle fiber action potential attenuation, while hyperpolarization-induced omega current produced by that mutation promotes muscle fiber depolarization.
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Affiliation(s)
| | - Vern Winston
- Department of Biological Sciences, Idaho State University, 83209, Pocatello, ID, USA
| | | | - Paula Arinze
- Department of Biological Sciences, Idaho State University, 83209, Pocatello, ID, USA
| | - James R Groome
- Department of Biological Sciences, Idaho State University, 83209, Pocatello, ID, USA.
| | - Karin Jurkat-Rott
- Department of Neuroanesthesiology, Clinic for Neurosurgery, Ulm University, Guenzburg, Germany
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