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Muacevic A, Adler JR. Chloride Channel Mutations Leading to Congenital Myotonia. Cureus 2022; 14:e32649. [PMID: 36540316 PMCID: PMC9759411 DOI: 10.7759/cureus.32649] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/17/2022] [Indexed: 12/23/2022] Open
Abstract
Congenital myotonia is a non-dystrophic musculoskeletal disease that causes abnormal muscle relaxation. The prevalence of congenital disorders is notably high in Iran, emphasizing the importance of genetic assessment in suspicious cases. In this study, we aim to report cases with the chloride channel gene, CLCN1, mutations leading to significant morbidity. This case report study investigated four patients from four families with clinically defined congenital myotonia. Inclusion criteria were increased creatinine kinase (CK) and muscle stiffness. We collected data regarding family history, age of onset, and current therapeutic plan. All patients underwent skeletal muscle electromyography, cardiological evaluation, spirometry study, and hematochemistry assessment, including but not limited to muscle enzyme levels. Afterward, DNA was extracted from peripheral blood. Subsequently, whole exome sequencing (WES) and Sanger sequencing were done to detect and confirm variants, respectively. Age of onset ranged from 1 to 12 years in these patients, which are years apart from their first visit to the clinic. The warm-up phenomenon was present in all of them. A variant of uncertain clinical significance was found. We recommend that future research projects should study the efficiency of collaboration between clinicians, molecular geneticists, and other healthcare providers in order to find out about unclear variants as quickly as possible.
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Woelfel C, Meurs K, Friedenberg S, DeBruyne N, Olby NJ. A novel mutation of the CLCN1 gene in a cat with myotonia congenita: Diagnosis and treatment. Vet Med (Auckl) 2022; 36:1454-1459. [PMID: 35815860 PMCID: PMC9308434 DOI: 10.1111/jvim.16471] [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: 03/23/2022] [Accepted: 05/27/2022] [Indexed: 11/29/2022]
Abstract
Case Description A 10‐month‐old castrated male domestic longhair cat was evaluated for increasing frequency of episodic limb rigidity. Clinical Findings The cat presented for falling over and lying recumbent with its limbs in extension for several seconds when startled or excited. Upon examination, the cat had hypertrophied musculature, episodes of facial spasm, and a short‐strided, stiff gait. Diagnostics Electromyography (EMG) identified spontaneous discharges that waxed and waned in amplitude and frequency, consistent with myotonic discharges. A high impact 8‐base pair (bp) deletion across the end of exon 3 and intron 3 of the chloride voltage‐gated channel 1 (CLCN1) gene was identified using whole genome sequencing. Treatment and Outcome Phenytoin treatment was initiated at 3 mg/kg po q24 h and resulted in long‐term improvement. Clinical Relevance This novel mutation within the CLCN1 gene is a cause of myotonia congenita in cats and we report for the first time its successful treatment.
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Affiliation(s)
- Christian Woelfel
- College of Veterinary Medicine, North Carolina State University, Raleigh, North Carolina, USA
| | - Kathryn Meurs
- College of Veterinary Medicine, North Carolina State University, Raleigh, North Carolina, USA
| | - Steven Friedenberg
- Veterinary Medical Center, University of Minnesota, Saint Paul, Minnesota, USA
| | - Nicole DeBruyne
- College of Veterinary Medicine, North Carolina State University, Raleigh, North Carolina, USA
| | - Natasha J Olby
- College of Veterinary Medicine, North Carolina State University, Raleigh, North Carolina, USA
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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: 21] [Impact Index Per Article: 5.3] [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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Hoppe K, Sartorius T, Chaiklieng S, Wietzorrek G, Ruth P, Jurkat-Rott K, Wearing S, Lehmann-Horn F, Klingler W. Paxilline Prevents the Onset of Myotonic Stiffness in Pharmacologically Induced Myotonia: A Preclinical Investigation. Front Physiol 2020; 11:533946. [PMID: 33329012 PMCID: PMC7719791 DOI: 10.3389/fphys.2020.533946] [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: 02/10/2020] [Accepted: 10/12/2020] [Indexed: 11/13/2022] Open
Abstract
Reduced Cl− conductance causes inhibited muscle relaxation after forceful voluntary contraction due to muscle membrane hyperexcitability. This represents the pathomechanism of myotonia congenita. Due to the prevailing data suggesting that an increased potassium level is a main contributor, we studied the effect of a modulator of a big conductance Ca2+- and voltage-activated K+ channels (BK) modulator on contraction and relaxation of slow- and high-twitch muscle specimen before and after the pharmacological induction of myotonia. Human and murine muscle specimens (wild-type and BK−/−) were exposed to anthracene-9-carboxylic acid (9-AC) to inhibit CLC-1 chloride channels and to induce myotonia in-vitro. Functional effects of BK-channel activation and blockade were investigated by exposing slow-twitch (soleus) and fast-twitch (extensor digitorum longus) murine muscle specimens or human musculus vastus lateralis to an activator (NS1608) and a blocker (Paxilline), respectively. Muscle-twitch force and relaxation times (T90/10) were monitored. Compared to wild type, fast-twitch muscle specimen of BK−/− mice resulted in a significantly decreased T90/10 in presence of 9-AC. Paxilline significantly shortened T90/10 of murine slow- and fast-twitch muscles as well as human vastus lateralis muscle. Moreover, twitch force was significantly reduced after application of Paxilline in myotonic muscle. NS1608 had opposite effects to Paxilline and aggravated the onset of myotonic activity by prolongation of T90/10. The currently used standard therapy for myotonia is, in some individuals, not very effective. This in vitro study demonstrated that a BK channel blocker lowers myotonic stiffness and thus highlights its potential therapeutic option in myotonia congenital (MC).
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Affiliation(s)
- Kerstin Hoppe
- Department of Anesthesiology, Intensive Care Medicine and Pain Therapy, Goethe University, Frankfurt University Hospital, Frankfurt, Germany.,Department of Anesthesiology, Intensive Care Medicine and Pain Therapy, Wuerzburg University Hospital, Wuerzburg, Germany
| | - Tina Sartorius
- Department of Pharmacology, Toxicology and Clinical Pharmacy, Institute of Pharmacy, University of Tuebingen, Tuebingen, Germany
| | - Sunisa Chaiklieng
- Division of Neurophysiology in the Center of Rare Diseases, Ulm University, Ulm, Germany.,Faculty of Public Health, Khon Kaen University, Muang Khon Kaen, Thailand
| | - Georg Wietzorrek
- Institute for Molecular and Cellular Pharmacology, Innsbruck Medical University, Innsbruck, Austria
| | - Peter Ruth
- Department of Pharmacology, Toxicology and Clinical Pharmacy, Institute of Pharmacy, University of Tuebingen, Tuebingen, Germany
| | - Karin Jurkat-Rott
- Division of Experimental Anesthesiology, University Medical Center Ulm, Ulm, Germany
| | - Scott Wearing
- Institute of Health and Biomedical Innovation, Queensland University of Technology, Brisbane, QLD, Australia.,Department of Conservative and Rehabilitation Orthopedics, Faculty of Sport and Health Science, Technical University of Munich, Munich, Germany
| | - Frank Lehmann-Horn
- Division of Neurophysiology in the Center of Rare Diseases, Ulm University, Ulm, Germany
| | - Werner Klingler
- Division of Neurophysiology in the Center of Rare Diseases, Ulm University, Ulm, Germany.,Institute of Health and Biomedical Innovation, Queensland University of Technology, Brisbane, QLD, Australia.,Department of Conservative and Rehabilitation Orthopedics, Faculty of Sport and Health Science, Technical University of Munich, Munich, Germany.,Department of Anesthesiology, Intensive Care Medicine and Pain Therapy, SRH Clinincs, Sigmaringen, Germany
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