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Marinakis NM, Svingou M, Papadimas GK, Papadopoulos C, Chroni E, Pons R, Pavlou E, Sarmas I, Kosma K, Apostolou P, Sofocleous C, Traeger-Synodinos J, Kekou K. Myotonia congenita in a Greek cohort: Genotype spectrum and impact of the CLCN1:c.501C > G variant as a genetic modifier. Muscle Nerve 2024. [PMID: 38855810 DOI: 10.1002/mus.28180] [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: 10/25/2023] [Revised: 05/18/2024] [Accepted: 05/24/2024] [Indexed: 06/11/2024]
Abstract
INTRODUCTION/AIMS Myotonia congenita (MC) is the most common hereditary channelopathy in humans. Characterized by muscle stiffness, MC may be transmitted as either an autosomal dominant (Thomsen) or a recessive (Becker) disorder. MC is caused by variants in the voltage-gated chloride channel 1 (CLCN1) gene, important for the normal repolarization of the muscle action potential. More than 250 disease-causing variants in the CLCN1 gene have been reported. This study provides an MC genotype-phenotype spectrum in a large cohort of Greek patients and focuses on novel variants and disease epidemiology, including additional insights for the variant CLCN1:c.501C > G. METHODS Sanger sequencing for the entire coding region of the CLCN1 gene was performed. Targeted segregation analysis of likely candidate variants in additional family members was performed. Variant classification was based on American College of Medical Genetics (ACMG) guidelines. RESULTS Sixty-one patients from 47 unrelated families were identified, consisting of 51 probands with Becker MC (84%) and 10 with Thomsen MC (16%). Among the different variants detected, 11 were novel and 16 were previously reported. The three most prevalent variants were c.501C > G, c.2680C > T, and c.1649C > G. Additionally, c.501C > G was detected in seven Becker cases in-cis with the c.1649C > G. DISCUSSION The large number of patients in whom a diagnosis was established allowed the characterization of genotype-phenotype correlations with respect to both previously reported and novel findings. For the c.501C > G (p.Phe167Leu) variant a likely nonpathogenic property is suggested, as it only seems to act as an aggravating modifying factor in cases in which a pathogenic variant triggers phenotypic expression.
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Affiliation(s)
- Nikolaos M Marinakis
- Laboratory of Medical Genetics, Medical School, St. Sophia's Children's Hospital, National and Kapodistrian University of Athens, Athens, Greece
- Research University Institute for the Study and Prevention of Genetic and Malignant Disease of Childhood, St. Sophia's Children's Hospital, National and Kapodistrian University of Athens, Athens, Greece
| | - Maria Svingou
- Laboratory of Medical Genetics, Medical School, St. Sophia's Children's Hospital, National and Kapodistrian University of Athens, Athens, Greece
| | - Giorgos-Konstantinos Papadimas
- Department of Neurology, Eginition Hospital, Medical School, National and Kapodistrian University of Athens, Athens, Greece
| | - Constantinos Papadopoulos
- Department of Neurology, Eginition Hospital, Medical School, National and Kapodistrian University of Athens, Athens, Greece
| | - Elisabeth Chroni
- Department of Neurology, School of Medicine, University of Patras, Rio-Patras, Greece
| | - Roser Pons
- First Department of Pediatrics, Medical School, St. Sophia's Children's Hospital, National and Kapodistrian University of Athens, Athens, Greece
| | - Evangelos Pavlou
- Department of Pediatrics, School of Medicine, Aristotle University of Thessaloniki, University General Hospital AHEPA, Thessaloniki, Greece
| | - Ioannis Sarmas
- Department of Neurology, Faculty of Medicine, University of Ioannina, Ioannina, Greece
| | - Konstantina Kosma
- Laboratory of Medical Genetics, Medical School, St. Sophia's Children's Hospital, National and Kapodistrian University of Athens, Athens, Greece
| | - Paraskevi Apostolou
- Human Molecular Genetics Laboratory, INRaSTES, National Center for Scientific Research "Demokritos", Athens, Greece
| | - Christalena Sofocleous
- Laboratory of Medical Genetics, Medical School, St. Sophia's Children's Hospital, National and Kapodistrian University of Athens, Athens, Greece
| | - Joanne Traeger-Synodinos
- Laboratory of Medical Genetics, Medical School, St. Sophia's Children's Hospital, National and Kapodistrian University of Athens, Athens, Greece
| | - Kyriaki Kekou
- Laboratory of Medical Genetics, Medical School, St. Sophia's Children's Hospital, National and Kapodistrian University of Athens, Athens, Greece
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Vinci M, Vitello GA, Greco D, Treccarichi S, Ragalmuto A, Musumeci A, Fallea A, Federico C, Calì F, Saccone S, Elia M. Next Generation Sequencing and Electromyography Reveal the Involvement of the P2RX6 Gene in Myopathy. Curr Issues Mol Biol 2024; 46:1150-1163. [PMID: 38392191 PMCID: PMC10887510 DOI: 10.3390/cimb46020073] [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: 12/27/2023] [Revised: 01/18/2024] [Accepted: 01/26/2024] [Indexed: 02/24/2024] Open
Abstract
Ion channelopathies result from impaired ion channel protein function, due to mutations affecting ion transport across cell membranes. Over 40 diseases, including neuropathy, pain, migraine, epilepsy, and ataxia, are associated with ion channelopathies, impacting electrically excitable tissues and significantly affecting skeletal muscle. Gene mutations affecting transmembrane ionic flow are strongly linked to skeletal muscle disorders, particularly myopathies, disrupting muscle excitability and contraction. Electromyography (EMG) analysis performed on a patient who complained of weakness and fatigue revealed the presence of primary muscular damage, suggesting an early-stage myopathy. Whole exome sequencing (WES) did not detect potentially causative variants in known myopathy-associated genes but revealed a novel homozygous deletion of the P2RX6 gene likely disrupting protein function. The P2RX6 gene, predominantly expressed in skeletal muscle, is an ATP-gated ion channel receptor belonging to the purinergic receptors (P2RX) family. In addition, STRING pathways suggested a correlation with more proteins having a plausible role in myopathy. No previous studies have reported the implication of this gene in myopathy. Further studies are needed on patients with a defective ion channel pathway, and the use of in vitro functional assays in suppressing P2RX6 gene expression will be required to validate its functional role.
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Affiliation(s)
| | | | | | | | | | | | | | - Concetta Federico
- Department of Biological, Geological and Environmental Sciences, University of Catania, Via Androne 81, 95124 Catania, Italy
| | | | - Salvatore Saccone
- Department of Biological, Geological and Environmental Sciences, University of Catania, Via Androne 81, 95124 Catania, Italy
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Lidonnici D, Brambilla P, Ravasio R, Zozulya-Weidenfeller A, Beiderbeck A, van Aswegen M, Oliveira R, Sansone VA. Expert Insights from a Delphi-driven Neurologists' Panel: Real-world Mexiletine use in Patients with Myotonic Disorders in Italy. J Neuromuscul Dis 2024; 11:411-423. [PMID: 38306059 DOI: 10.3233/jnd-230115] [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: 02/03/2024]
Abstract
Background Myotonic disorders, such as non-dystrophic myotonias (NDMs) and myotonic dystrophies (DMs) are characterized by a delay in muscle relaxation after a contraction stimulus. There is general consensus that protocols to treat myotonia need to be implemented. Objective Mexiletine is the only pharmacological agent approved for the symptomatic treatment of myotonia in adult patients with NDM and is considered to be the first-line treatment for DMs; however, its production in Italy was halted in 2022 making its availability to patients problematic. Methods A panel of 8 Italian neurologists took part in a two-round Delphi panel between June and October 2022, analyzing the current use of mexiletine in Italian clinical practice. Results The panelists assist 1126 patients (69% DM type1, 18% NDM and 13% DM type2). Adult NDM patients receive, on average, 400-600 mg of mexiletine hydrochloride (HCl) while adult DM patients receive 100-600 mg, per day in the long-term. The severity of symptoms is considered the main reason to start mexiletine treatment for both NDM and DM patients. Mexiletine is reckoned to have a clinical impact for both NDM and DM patients, but currently drug access is problematic. Conclusions Mexiletine treatment is recognized to have a role in the reduction of the symptomatic burden for NDM and DM patients. Patient management could be improved by facilitating access to therapy and developing new drug formulations.
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Affiliation(s)
| | | | | | | | | | | | | | - Valeria A Sansone
- The NEMO Center, Neurorehabilitation Unit, University of Milan, ASST Niguarda Hospital, Milan, Italy
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Khachatryan T, Shafie M, Abcede H, Shah J, Nagamine M, Granstein J, Yuki I, Golshani K, Suzuki S, Yu W. Rescue therapy after thrombectomy for large vessel occlusion due to underlying atherosclerosis: review of literature. Front Neurol 2023; 14:1181295. [PMID: 37396754 PMCID: PMC10313123 DOI: 10.3389/fneur.2023.1181295] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2023] [Accepted: 05/24/2023] [Indexed: 07/04/2023] Open
Abstract
In this review article, we summarized the current advances in rescue management for reperfusion therapy of acute ischemic stroke from large vessel occlusion due to underlying intracranial atherosclerotic stenosis (ICAS). It is estimated that 24-47% of patients with acute vertebrobasilar artery occlusion have underlying ICAS and superimposed in situ thrombosis. These patients have been found to have longer procedure times, lower recanalization rates, higher rates of reocclusion and lower rates of favorable outcomes than patients with embolic occlusion. Here, we discuss the most recent literature regarding the use of glycoprotein IIb/IIIa inhibitors, angioplasty alone, or angioplasty with stenting for rescue therapy in the setting of failed recanalization or instant/imminent reocclusion during thrombectomy. We also present a case of rescue therapy post intravenous tPA and thrombectomy with intra-arterial tirofiban and balloon angioplasty followed by oral dual antiplatelet therapy in a patient with dominant vertebral artery occlusion due to ICAS. Based on the available literature data, we conclude that glycoprotein IIb/IIIa is a reasonably safe and effective rescue therapy for patients who have had a failed thrombectomy or have residual severe intracranial stenosis. Balloon angioplasty and/or stenting may be helpful as a rescue treatment for patients who have had a failed thrombectomy or are at risk of reocclusion. The effectiveness of immediate stenting for residual stenosis after successful thrombectomy is still uncertain. Rescue therapy does not appear to increase the risk of sICH. Randomized controlled trials are warranted to prove the efficacy of rescue therapy.
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Affiliation(s)
- Tigran Khachatryan
- Department of Neurology, University of California, Irvine, Irvine, CA, United States
| | - Mohammad Shafie
- Department of Neurology, University of California, Irvine, Irvine, CA, United States
| | - Hermelinda Abcede
- Department of Neurology, University of California, Irvine, Irvine, CA, United States
| | - Jay Shah
- Department of Neurology, University of California, Irvine, Irvine, CA, United States
| | - Masaki Nagamine
- Department of Neurology, University of California, Irvine, Irvine, CA, United States
| | - Justin Granstein
- Department of Neurological Surgery, University of California, Irvine, Irvine, CA, United States
| | - Ichiro Yuki
- Department of Neurological Surgery, University of California, Irvine, Irvine, CA, United States
| | - Kiarash Golshani
- Department of Neurological Surgery, University of California, Irvine, Irvine, CA, United States
| | - Shuichi Suzuki
- Department of Neurological Surgery, University of California, Irvine, Irvine, CA, United States
| | - Wengui Yu
- Department of Neurology, University of California, Irvine, Irvine, CA, United States
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Díaz-Manera J, Urtizberea JA, Schey C, Kole A, von Gallwitz P, Whiting A, Foerster D, Zozulya-Weidenfeller A. Impact of restricted access to, and low awareness of, mexiletine on people with myotonia: a real-world European survey. Neuromuscul Disord 2023; 33:208-217. [PMID: 36706619 DOI: 10.1016/j.nmd.2022.12.008] [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: 04/28/2022] [Revised: 12/06/2022] [Accepted: 12/13/2022] [Indexed: 12/23/2022]
Abstract
Although mexiletine effectively treats myotonia, supply disruptions affected Europe between 2008-2018. MyoPath was a mixed-methods, cross-sectional, market research survey conducted January-June 2018 to evaluate consequences of limited access to/awareness of mexiletine in people with myotonia. Part A: qualitative structured interviews (clinicians; advocates for adult patients); Part B: quantitative online questionnaire completed by people with self-reported history of myotonia. Part A: Interviews (clinicians, n=12; patient advocates, n=5; 12 countries) indicated poor mexiletine awareness among general neurologists. Patients chose between living with myotonia (other treatments were generally unsatisfactory) or importing mexiletine. Part B: Questionnaire respondents, myotonic dystrophy (DM)1, n=213; DM2, n=128; non-dystrophic myotonia (NDM), n=41; other n=8; (11 countries). Of the respondents, 76/390 (20%) people with awareness of/access to mexiletine described profound improvements in myotonia and health-related quality of life following treatment. Respondents with NDM had greatest mexiletine experience (n=28/41). Mexiletine was associated with fewer falls, less muscle stiffness, increased mobility. Treatment interruptions worsened myotonia and were associated with fatigue, pain, dysphagia, breathing difficulty, impaired digestion, poor sleep. However, 36/54 (67%) of currently treated people expressed anxiety about mexiletine's availability: this finding was expected (MyoPath was undertaken before mexiletine's approval in NDM). MyoPath provides the largest European exploration of patients' views regarding impact of mexiletine on myotonia. Anticipated effects of mexiletine differ between people with different myotonic disorders: myotonia is the main symptom in NDM but one of many potential symptoms affecting those with DM. Nevertheless, findings indicate substantial harm caused to people with myotonia when mexiletine awareness/access is limited.
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Affiliation(s)
- Jordi Díaz-Manera
- John Walton Muscular Dystrophy Research Centre, Newcastle University International Centre for Life, Newcastle upon Tyne, United Kingdom.
| | | | - Carina Schey
- Department of Epidemiology, University of Groningen, Groningen, the Netherlands
| | - Anna Kole
- admedicum® Business for Patients GmbH & Co KG, Cologne, Germany
| | | | - Amy Whiting
- admedicum® Business for Patients GmbH & Co KG, Cologne, Germany
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Nan H, Wu Y, Cui S, Sun H, Wang J, Li Y, Meng L, Nagasaka T, Wu L. Coexistence of Charcot-Marie-Tooth 1A and nondystrophic myotonia due to PMP22 duplication and SCN4A pathogenic variants: a case report. BMC Neurol 2022; 22:17. [PMID: 34996390 PMCID: PMC8740465 DOI: 10.1186/s12883-021-02538-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2021] [Accepted: 12/27/2021] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Charcot-Marie-Tooth disease (CMT) is a genetically heterogeneous hereditary neuropathy, and CMT1A is the most common form; it is caused by a duplication of the peripheral myelin protein 22 (PMP22) gene. Mutations in the transient sodium channel Nav1.4 alpha subunit (SCN4A) gene underlie a diverse group of dominantly inherited nondystrophic myotonias that run the spectrum from subclinical myopathy to severe muscle stiffness, disabling weakness, or frank episodes of paralysis. CASE PRESENTATION We describe a Chinese family affected by both CMT1A and myotonia with concomitant alterations in both the PMP22 and SCN4A genes. In this family, the affected proband inherited the disease from his father in an autosomal dominant manner. Genetic analysis confirmed duplication of the PMP22 gene and a missense c.3917G > C (p. Gly1306Ala) mutation in SCN4A in both the proband and his father. The clinical phenotype in the proband showed the combined involvement of skeletal muscle and peripheral nerves. Electromyography showed myopathic changes, including myotonic discharges. MRI revealed the concurrence of neurogenic and myogenic changes in the lower leg muscles. Sural nerve biopsies revealed a chronic demyelinating and remyelinating process with onion bulb formations in the proband. The proband's father presented with confirmed subclinical myopathy, very mild distal atrophy and proximal hypertrophy of the lower leg muscles, pes cavus, and areflexia. CONCLUSION This study reports the coexistence of PMP22 duplication and SCN4A mutation. The presenting features in this family suggested that both neuropathy and myopathy were inherited in an autosomal dominant manner. The proband had a typical phenotype of sodium channel myotonia (SCM) and CMT1A. However, his father with the same mutations presented a much milder clinical phenotype. Our study might expand the genetic and phenotypic spectra of neuromuscular disorders with concomitant mutations.
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Affiliation(s)
- Haitian Nan
- Department of Neurology, Xuanwu Hospital, Capital Medical University, Beijing, China
| | - Yunqing Wu
- Department of Neurology, Beijing Tongren Hospital, Capital Medical University, Beijing, China
| | - Shilei Cui
- Department of Neurology, Beijing Tongren Hospital, Capital Medical University, Beijing, China
| | - Houliang Sun
- Department of Neurology, Beijing Tongren Hospital, Capital Medical University, Beijing, China
| | - Jiawei Wang
- Department of Neurology, Beijing Tongren Hospital, Capital Medical University, Beijing, China
| | - Ying Li
- Department of Neurology, Peking University First Hospital, Beijing, China
| | - Lingchao Meng
- Department of Neurology, Peking University First Hospital, Beijing, China
| | - Takamura Nagasaka
- Department of Neurology, University of Yamanashi, 1110 Shimokato, Chuo-city, Yamanashi, 409-3898, Japan
| | - Liyong Wu
- Department of Neurology, Xuanwu Hospital, Capital Medical University, Beijing, China.
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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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