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Talarico M, Fortunato F, Labalme A, Januel L, Chatron N, Sanlaville D, Sammarra I, Gagliardi M, Procopio R, Valentino P, Annesi G, Lesca G, Gambardella A. Idiopathic generalized epilepsy in a family with SCN4A-related myotonia. Epilepsia Open 2024; 9:951-959. [PMID: 38544349 PMCID: PMC11145607 DOI: 10.1002/epi4.12920] [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: 09/11/2023] [Revised: 02/01/2024] [Accepted: 02/04/2024] [Indexed: 06/04/2024] Open
Abstract
OBJECTIVES Myotonia is a clinical sign typical of a group of skeletal muscle channelopathies, the non-dystrophic myotonias. These disorders are electrophysiologically characterized by altered membrane excitability, due to specific genetic variants in known causative genes (CLCN1 and SCN4A). Juvenile Myoclonic Epilepsy (JME) is an epileptic syndrome identified as idiopathic generalized epilepsy, its genetics is complex and still unclarified. The co-occurrence of these two phenotypes is rare and the causes likely have a genetic background. In this study, we have genetically investigated an Italian family in which co-segregates myotonia, JME, or abnormal EEG without seizures was observed. METHODS All six individuals of the family, 4 affected and 2 unaffected, were clinically evaluated; EMG and EEG examinations were performed. For genetic testing, Exome Sequencing was performed for the six family members and Sanger sequencing was used to confirm the candidate variant. RESULTS Four family members, the mother and three siblings, were affected by myotonia. Moreover, EEG recordings revealed interictal generalized sharp-wave discharges in all affected individuals, and two siblings were affected by JME. All four affected members share the same identified variant, c.644 T > C, p.Ile215Thr, in SCN4A gene. Variants that could account for the epileptic phenotype alone, separately from the myotonic one, were not identified. SIGNIFICANCE These results provide supporting evidence that both myotonic and epileptic phenotypes could share a common genetic background, due to variants in SCN4A gene. SCN4A pathogenic variants, already known to be causative of myotonia, likely increase the susceptibility to epilepsy in our family. PLAIN LANGUAGE SUMMARY This study analyzed all members of an Italian family, in which the mother and three siblings had myotonia and epilepsy. Genetic analysis allowed to identify a variant in the SCN4A gene, which appears to be the cause of both clinical signs in this family.
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Affiliation(s)
- Mariagrazia Talarico
- Department of Medical and Surgical Sciences, Institute of NeurologyUniversity Magna GraeciaCatanzaroItaly
| | - Francesco Fortunato
- Department of Medical and Surgical Sciences, Institute of NeurologyUniversity Magna GraeciaCatanzaroItaly
| | | | - Louis Januel
- Genetics DepartmentHospices Civils de LyonLyonFrance
| | - Nicolas Chatron
- Genetics DepartmentHospices Civils de LyonLyonFrance
- GENDEV Team, CRNL, INSERM U1028, CNRS UMR 5292UCBL1LyonFrance
| | - Damien Sanlaville
- Genetics DepartmentHospices Civils de LyonLyonFrance
- GENDEV Team, CRNL, INSERM U1028, CNRS UMR 5292UCBL1LyonFrance
| | - Ilaria Sammarra
- Department of Medical and Surgical Sciences, Institute of NeurologyUniversity Magna GraeciaCatanzaroItaly
| | - Monica Gagliardi
- Department of Medical and Surgical Sciences, Neuroscience Research CenterMagna Graecia UniversityCatanzaroItaly
| | - Radha Procopio
- Department of Medical and Surgical Sciences, Institute of NeurologyUniversity Magna GraeciaCatanzaroItaly
| | - Paola Valentino
- Department of Medical and Surgical Sciences, Institute of NeurologyUniversity Magna GraeciaCatanzaroItaly
| | - Grazia Annesi
- Institute for Biomedical Research and InnovationNational Research CouncilCosenzaItaly
| | - Gaetan Lesca
- Genetics DepartmentHospices Civils de LyonLyonFrance
- GENDEV Team, CRNL, INSERM U1028, CNRS UMR 5292UCBL1LyonFrance
| | - Antonio Gambardella
- Department of Medical and Surgical Sciences, Institute of NeurologyUniversity Magna GraeciaCatanzaroItaly
- Department of Medical and Surgical Sciences, Neuroscience Research CenterMagna Graecia UniversityCatanzaroItaly
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Zou X, Zhang Z, Lu H, Zhao W, Pan L, Chen Y. Functional effects of drugs and toxins interacting with Na V1.4. Front Pharmacol 2024; 15:1378315. [PMID: 38725668 PMCID: PMC11079311 DOI: 10.3389/fphar.2024.1378315] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2024] [Accepted: 04/08/2024] [Indexed: 05/12/2024] Open
Abstract
NaV1.4 is a voltage-gated sodium channel subtype that is predominantly expressed in skeletal muscle cells. It is essential for producing action potentials and stimulating muscle contraction, and mutations in NaV1.4 can cause various muscle disorders. The discovery of the cryo-EM structure of NaV1.4 in complex with β1 has opened new possibilities for designing drugs and toxins that target NaV1.4. In this review, we summarize the current understanding of channelopathies, the binding sites and functions of chemicals including medicine and toxins that interact with NaV1.4. These substances could be considered novel candidate compounds or tools to develop more potent and selective drugs targeting NaV1.4. Therefore, studying NaV1.4 pharmacology is both theoretically and practically meaningful.
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Affiliation(s)
- Xinyi Zou
- Zhejiang Provincial Key Laboratory of Resources Protection and Innovation of Traditional Chinese Medicine, College of Food and Health, Zhejiang Agriculture and Forestry University, Hangzhou, China
| | - Zixuan Zhang
- Zhejiang Provincial Key Laboratory of Resources Protection and Innovation of Traditional Chinese Medicine, College of Food and Health, Zhejiang Agriculture and Forestry University, Hangzhou, China
| | - Hui Lu
- Zhejiang Provincial Key Laboratory of Resources Protection and Innovation of Traditional Chinese Medicine, College of Food and Health, Zhejiang Agriculture and Forestry University, Hangzhou, China
| | - Wei Zhao
- Zhejiang Provincial Key Laboratory of Resources Protection and Innovation of Traditional Chinese Medicine, College of Food and Health, Zhejiang Agriculture and Forestry University, Hangzhou, China
| | - Lanying Pan
- Key Laboratory of Artificial Organs and Computational Medicine in Zhejiang Province, Shulan International Medical College, Zhejiang Shuren University, Hangzhou, China
| | - Yuan Chen
- Zhejiang Provincial Key Laboratory of Resources Protection and Innovation of Traditional Chinese Medicine, College of Food and Health, Zhejiang Agriculture and Forestry University, Hangzhou, China
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Campanale C, Laghetti P, Saltarella I, Altamura C, Canioni E, Iosa E, Maggi L, Brugnoni R, Tacconi P, Desaphy JF. A c.1775C > T Point Mutation of Sodium Channel Alfa Subunit Gene (SCN4A) in a Three-Generation Sardinian Family with Sodium Channel Myotonia. J Neuromuscul Dis 2024; 11:725-734. [PMID: 38427496 DOI: 10.3233/jnd-230134] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/03/2024]
Abstract
Background 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. Methods Next-generation sequencing including the CLCN1 and SCN4A genes was performed in patients with clinical neuromuscular disorders. Electromyography, Short Exercise Test, in vivo and in vitro electrophysiology, site-directed mutagenesis and heterologous expression were collected. Results A heterozygous point mutation (c.1775C > T, p.Thr592Ile) of muscle voltage-gated sodium channel α subunit gene (SCN4A) has been identified in five female patients over three generations, in a family with non-dystrophic myotonia. The muscle stiffness and myotonia involve mainly the face and hands, but also affect walking and running, appearing early after birth and presenting a clear cold sensitivity. Very hot temperatures, menstruation and pregnancy also exacerbate the symptoms; muscle pain and a warm-up phenomenon are variable features. Neither paralytic attacks nor post-exercise weakness has been reported. Muscle hypertrophy with cramp-like pain and increased stiffness developed during pregnancy. The symptoms were controlled with both mexiletine and acetazolamide. The Short Exercise Test after muscle cooling revealed two different patterns, with moderate absolute changes of compound muscle action potential amplitude. Conclusions The p.Thr592Ile mutation in the SCN4A gene identified in this Sardinian family was responsible of clinical phenotype of myotonia.
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Affiliation(s)
- Carmen Campanale
- Department of Precision and Regenerative Medicine, Section of Pharmacology, School of Medicine, University of Bari Aldo Moro, Bari, Italy
| | - Paola Laghetti
- Department of Precision and Regenerative Medicine, Section of Pharmacology, School of Medicine, University of Bari Aldo Moro, Bari, Italy
| | - Ilaria Saltarella
- Department of Precision and Regenerative Medicine, Section of Pharmacology, School of Medicine, University of Bari Aldo Moro, Bari, Italy
| | - Concetta Altamura
- Department of Precision and Regenerative Medicine, Section of Pharmacology, School of Medicine, University of Bari Aldo Moro, Bari, Italy
| | - Eleonora Canioni
- Neurology IV - Neuroimmunology and Neuromuscular Diseases Unit, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy
| | - Emanuele Iosa
- Neurology IV - Neuroimmunology and Neuromuscular Diseases Unit, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy
| | - Lorenzo Maggi
- Neurology IV - Neuroimmunology and Neuromuscular Diseases Unit, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy
| | - Raffaella Brugnoni
- Neurology IV - Neuroimmunology and Neuromuscular Diseases Unit, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy
| | - Paolo Tacconi
- Centro Regionale per la Sclerosi Multipla, Ospedale Binaghi, Cagliari, Italy
| | - Jean-François Desaphy
- Department of Precision and Regenerative Medicine, Section of Pharmacology, School of Medicine, University of Bari Aldo Moro, Bari, Italy
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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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Vacchiano V, Brugnoni R, Campanale C, Imbrici P, Dinoi G, Canioni E, Laghetti P, Saltarella I, Altamura C, Maggi L, Liguori R, Donadio V, Desaphy JF. Coexistence of SCN4A and CLCN1 mutations in a family with atypical myotonic features: A clinical and functional study. Exp Neurol 2023; 362:114342. [PMID: 36720299 DOI: 10.1016/j.expneurol.2023.114342] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2022] [Revised: 01/12/2023] [Accepted: 01/26/2023] [Indexed: 01/30/2023]
Abstract
Non-dystrophic myotonias include several entities with possible clinical overlap, i.e. myotonia congenita caused by CLCN1 gene mutations, as well as paramyotonia congenita and sodium channel myotonia caused by SCN4A gene mutations. Herein, we describe the clinical features of five relatives affected by clinical and neurophysiological myotonia, with an aspecific and mixed phenotype. Next-generation sequencing identified the novel p.K1302R variant in SCN4A and the p.H838P variant in CLCN1. Segregation of the two mutations with the disease was confirmed by genotyping affected and non-affected family members. Patch-clamp experiments showed that sodium currents generated by p.K1302R and WT hNav1.4 were very similar. Mutant channel showed a small negative shift (5 mV) in the voltage-dependence of activation, which increased the likelihood of the channel to open at more negative voltages. The p.H838P mutation caused a reduction in chloride current density and a small voltage-dependence shift towards less negative potentials, in agreement with its position into the CBS2 domain of the C-terminus. Our results demonstrated that the mild functional alterations induced by p.K1302R and p.H838P in combination may be responsible for the mixed myotonic phenotypes. The K1302R mutant was sensitive to mexiletine and lamotrigine, suggesting that both drugs might be useful for the K1302R carriers.
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Affiliation(s)
- Veria Vacchiano
- IRCSS Istituto delle Scienze Neurologiche di Bologna, Bologna, Italy.
| | - Raffaella Brugnoni
- Neuroimmunology and Neuromuscular Diseases Unit, Fondazione IRCCS Istituto Neurologico Carlo Besta, Italy
| | - Carmen Campanale
- Dept. of Precision and Regenerative Medicine, School of Medicine, University of Bari Aldo Moro, Bari, Italy
| | - Paola Imbrici
- Dept. of Pharmacy - Drug Sciences, University of Bari Aldo Moro, Bari, Italy
| | - Giorgia Dinoi
- Dept. of Pharmacy - Drug Sciences, University of Bari Aldo Moro, Bari, Italy
| | - Eleonora Canioni
- Neuroimmunology and Neuromuscular Diseases Unit, Fondazione IRCCS Istituto Neurologico Carlo Besta, Italy
| | - Paola Laghetti
- Dept. of Precision and Regenerative Medicine, School of Medicine, University of Bari Aldo Moro, Bari, Italy
| | - Ilaria Saltarella
- Dept. of Precision and Regenerative Medicine, School of Medicine, University of Bari Aldo Moro, Bari, Italy
| | - Concetta Altamura
- Dept. of Precision and Regenerative Medicine, School of Medicine, University of Bari Aldo Moro, Bari, Italy
| | - Lorenzo Maggi
- Neuroimmunology and Neuromuscular Diseases Unit, Fondazione IRCCS Istituto Neurologico Carlo Besta, Italy
| | - Rocco Liguori
- IRCSS Istituto delle Scienze Neurologiche di Bologna, Bologna, Italy
| | - Vincenzo Donadio
- IRCSS Istituto delle Scienze Neurologiche di Bologna, Bologna, Italy
| | - Jean-François Desaphy
- Dept. of Precision and Regenerative Medicine, School of Medicine, University of Bari Aldo Moro, Bari, Italy
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Rigamonti A, Mantero V, Peverelli L, Pagliarani S, Lucchiari S, Comi G, Gibertini S, Salmaggi A. p.Asn1180Ile mutation of SCN4A gene in an Italian family with myopathy and myotonic syndrome. Neurol Sci 2021; 42:5359-5363. [PMID: 34378097 DOI: 10.1007/s10072-021-05537-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2021] [Accepted: 08/01/2021] [Indexed: 11/28/2022]
Abstract
INTRODUCTION Mutations of the skeletal muscle sodium channel gene SCN4A are associated with several neuromuscular disorders including hyper/hypokaliemic periodic paralysis, paramyotonia congenita and sodium channel myotonia. These disorders are distinguished from dystrophic myotonias by the absence of progressive weakness and extramuscular systemic involvement. METHODS We present an Italian family with 2 subjects carrying a p.Asn1180Ile mutation in SCN4A gene showing a peculiar clinical picture characterized by the association of myopathic features and myotonia. RESULTS The clinical, electromyographic and histological findings of these patients are reported. The possible pathogenicity of the mutation was tested by three different software, all giving positive results. DISCUSSION This is the first report of a dominant, heterozygous mutation in SCN4A causing a complex phenotype of non-congenital myopathy and myotonic syndrome. We suggest that, in patients with myotonia and myopathy not related to dystrophic myotonias, the sequence analysis of SCN4A gene should be performed.
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Affiliation(s)
- Andrea Rigamonti
- Neurology Unit, Ospedale A. Manzoni, ASST Lecco, Via Dell'Eremo 9-11, 23900, Lecco, Italy.
| | - Vittorio Mantero
- Neurology Unit, Ospedale A. Manzoni, ASST Lecco, Via Dell'Eremo 9-11, 23900, Lecco, Italy
| | - Lorenzo Peverelli
- Neurology Unit, Ospedale Maggiore di Lodi, ASST Lodi, Largo Donatori del Sangue 1, 26900, Lodi, Italy
| | - Serena Pagliarani
- Dino Ferrari Centre, Neuroscience Section, Department of Pathophysiology and Transplantation (DEPT), University of Milan, Via F. Sforza 35, 20122, Milano, Italy
| | - Sabrina Lucchiari
- Dino Ferrari Centre, Neuroscience Section, Department of Pathophysiology and Transplantation (DEPT), University of Milan, Via F. Sforza 35, 20122, Milano, Italy
| | - Giacomo Comi
- Neuromuscular and Rare Diseases Unit, Foundation IRCSS Ca' Granda Ospedale Maggiore Policlinico, Via F. Sforza 35, 20122, Milano, Italy
| | - Sara Gibertini
- Muscle Cell Biology Laboratory, Neuromuscular Diseases and Neuroimmunology Unit, Fondazione IRCCS Istituto Neurologico "C. Besta", Via Celoria 11, 20133, Milano, Italy
| | - Andrea Salmaggi
- Neurology Unit, Ospedale A. Manzoni, ASST Lecco, Via Dell'Eremo 9-11, 23900, Lecco, 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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