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He Y, Qiu Y, Xiong Y, Shen Y, Jiang K, Yi H, Huang P, Zhu Y, Zhu M, Zhou M, Hong D, Tan D. Clinical and genetic characteristics of myotonia congenita in Chinese population. Channels (Austin) 2024; 18:2349823. [PMID: 38720415 PMCID: PMC11086022 DOI: 10.1080/19336950.2024.2349823] [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: 11/15/2023] [Accepted: 03/22/2024] [Indexed: 05/12/2024] Open
Abstract
Myotonia congenita (MC) is a rare hereditary muscle disease caused by variants in the CLCN1 gene. Currently, the correlation of phenotype-genotype is still uncertain between dominant-type Thomsen (TMC) and recessive-type Becker (BMC). The clinical data and auxiliary examinations of MC patients in our clinic were retrospectively collected. Electromyography was performed in 11 patients and available family members. Whole exome sequencing was conducted in all patients. The clinical and laboratory data of Chinese MC patients reported from June 2004 to December 2022 were reviewed. A total of 11 MC patients were included in the study, with a mean onset age of 12.64 ± 2.73 years. The main symptom was muscle stiffness of limbs. Warm-up phenomenon and percussion myotonia were found in all patients. Electromyogram revealed significant myotonic charges in all patients and two asymptomatic carriers, while muscle MRI and biopsy showed normal or nonspecific changes. Fourteen genetic variants including 6 novel variants were found in CLCN1. Ninety-eight Chinese patients were re-analyzed and re-summarized in this study. There were no significant differences in the demographic data, clinical characteristics, and laboratory findings between 52 TMC and 46 BMC patients. Among the 145 variants in CLCN1, some variants, including the most common variant c.892 G>A, could cause TMC in some families and BMC in others. This study expanded the clinical and genetic spectrum of Chinese patients with MC. It was difficult to distinguish between TMC and BMC only based on the clinical, laboratory, and genetic characteristics.
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Affiliation(s)
- Yuting He
- Department of Neurology, The First Affiliated Hospital, Jiangxi Medical College, Nanchang University, Nanchang, China
| | - Yusen Qiu
- Department of Neurology, The First Affiliated Hospital, Jiangxi Medical College, Nanchang University, Nanchang, China
- Rare Disease Center, the First Affiliated Hospital, Jiangxi Medical College, Nanchang University, Nanchang, China
| | - Ying Xiong
- Department of Neurology, The First Affiliated Hospital, Jiangxi Medical College, Nanchang University, Nanchang, China
- Rare Disease Center, the First Affiliated Hospital, Jiangxi Medical College, Nanchang University, Nanchang, China
| | - Yu Shen
- Department of Neurology, The First Affiliated Hospital, Jiangxi Medical College, Nanchang University, Nanchang, China
| | - Kaiyan Jiang
- Department of Neurology, The First Affiliated Hospital, Jiangxi Medical College, Nanchang University, Nanchang, China
| | - Hancun Yi
- Department of Neurology, The First Affiliated Hospital, Jiangxi Medical College, Nanchang University, Nanchang, China
| | - Pengcheng Huang
- Department of Neurology, The First Affiliated Hospital, Jiangxi Medical College, Nanchang University, Nanchang, China
| | - Yu Zhu
- Department of Neurology, The First Affiliated Hospital, Jiangxi Medical College, Nanchang University, Nanchang, China
- Rare Disease Center, the First Affiliated Hospital, Jiangxi Medical College, Nanchang University, Nanchang, China
| | - Min Zhu
- Department of Neurology, The First Affiliated Hospital, Jiangxi Medical College, Nanchang University, Nanchang, China
- Rare Disease Center, the First Affiliated Hospital, Jiangxi Medical College, Nanchang University, Nanchang, China
| | - Meihong Zhou
- Department of Neurology, The First Affiliated Hospital, Jiangxi Medical College, Nanchang University, Nanchang, China
- Rare Disease Center, the First Affiliated Hospital, Jiangxi Medical College, Nanchang University, Nanchang, China
| | - Daojun Hong
- Department of Neurology, The First Affiliated Hospital, Jiangxi Medical College, Nanchang University, Nanchang, China
- Rare Disease Center, the First Affiliated Hospital, Jiangxi Medical College, Nanchang University, Nanchang, China
- Institute of Neurology, Jiangxi Academy of Clinical Medical Science, The First Affiliated Hospital, Jiangxi Medical College, Nanchang University, Nanchang, China
- Key Laboratory of Rare Neurological Diseases of Jiangxi Provincial Health Commission, Jiangxi Medical College, Nanchang University, Nanchang, China
| | - Dandan Tan
- Department of Neurology, The First Affiliated Hospital, Jiangxi Medical College, Nanchang University, Nanchang, China
- Rare Disease Center, the First Affiliated Hospital, Jiangxi Medical College, Nanchang University, Nanchang, China
- Institute of Neurology, Jiangxi Academy of Clinical Medical Science, The First Affiliated Hospital, Jiangxi Medical College, Nanchang University, Nanchang, China
- Key Laboratory of Rare Neurological Diseases of Jiangxi Provincial Health Commission, Jiangxi Medical College, Nanchang University, Nanchang, China
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Jacobsen LN, Stemmerik MG, Skriver SV, Pedersen JJ, Løkken N, Vissing J. Contractile properties and magnetic resonance imaging-assessed fat replacement of muscles in myotonia congenita. Eur J Neurol 2024; 31:e16207. [PMID: 38270354 DOI: 10.1111/ene.16207] [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: 08/14/2023] [Revised: 12/18/2023] [Accepted: 12/28/2023] [Indexed: 01/26/2024]
Abstract
BACKGROUND AND PURPOSE Myotonia congenita (MC) is a muscle channelopathy in which pathogenic variants in a key sarcolemmal chloride channel Gene (CLCN1) cause myotonia. This study used muscle magnetic resonance imaging (MRI) to quantify contractile properties and fat replacement of muscles in a Danish cohort of MC patients. METHODS Individuals with the Thomsen (dominant) and Becker (recessive) variants of MC were studied. Isometric muscle strength, whole-body MRI, and clinical data were collected. The degree of muscle fat replacement of thigh, calf, and forearm muscles was quantitively calculated on Dixon MRI as fat fractions (FFs). Contractility was evaluated as the muscle strength per contractile muscle cross-sectional area (PT/CCSA). Muscle contractility was compared with clinical data. RESULTS Intramuscular FF was increased and contractility reduced in calf and in forearm muscles compared with controls (FF = 7.0-14.3% vs. 5.3-9.6%, PT/CCSA = 1.1-4.9 Nm/cm2 vs. 1.9-5.8 Nm/cm2 [p < 0.05]). Becker individuals also showed increased intramuscular FF and reduced contractility of thigh muscles (FF = 11.9% vs. 9.2%, PT/CCSA = 1.9 Nm/cm2 vs. 3.2 Nm/cm2 [p < 0.05]). Individual muscle analysis showed that increased FF was limited to seven of 18 examined muscles (p < 0.05). There was a weak correlation between reduced contractility and severity of symptoms. CONCLUSIONS Individuals with MC have increased fat replacement and reduced contractile properties of muscles. Nonetheless, changes were small and likely did not impact clinically on their myotonic symptoms.
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Affiliation(s)
- Laura Nørager Jacobsen
- Copenhagen Neuromuscular Center, Department of Neurology, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
| | - Mads Godtfeldt Stemmerik
- Copenhagen Neuromuscular Center, Department of Neurology, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
| | - Sofie Vinther Skriver
- Copenhagen Neuromuscular Center, Department of Neurology, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
| | - Jonas Jalili Pedersen
- Copenhagen Neuromuscular Center, Department of Neurology, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
| | - Nicoline Løkken
- Copenhagen Neuromuscular Center, Department of Neurology, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
| | - John Vissing
- Copenhagen Neuromuscular Center, Department of Neurology, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
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Yadav J, Barnwal R, Kumar Mandal S, Prajapati B. Acetazolamide-responsive myotonia with a novel Ile239Thr mutation in SCN4A gene: a case report. Ann Med Surg (Lond) 2024; 86:1191-1195. [PMID: 38333241 PMCID: PMC10849450 DOI: 10.1097/ms9.0000000000001673] [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: 08/16/2023] [Accepted: 12/20/2023] [Indexed: 02/10/2024] Open
Abstract
Introduction and importance Sodium channel myotonia (SCM) belongs to the group of sodium channelopathies with mutations involving SCN4A gene. The main feature of sodium channel myotonia is pure myotonia without episodes of weakness or paralysis. One of the sodium channel myotonia has been classified as acetazolamide-responsive myotonia because of the effectiveness of acetazolamide as an antimyotonic drug. Case presentation The child presented with generalized muscle hypertrophy and stiffness involving arms, thighs, calves, chest, and back muscles with unusually prominent trapezius muscle. The parents described the warm-up phenomenon as an improvement in stiffness as the day passes and with repetitive action. Percussion myotonia was illustrated in the thenar eminence and trapezius muscle. Characteristic 'dive-bomber' sound was present in electromyography, and whole-exome sequencing revealed a novel Ile239Thr mutation in the SCN4A gene. Acetazolamide was prescribed for the condition, and regular follow-up shows an excellent clinical response. Clinical discussion This case presents a pure myotonic phenotype without episodes of weakness or paralysis. Generalized myotonia with muscle hypertrophy and demonstrating warm-up phenomenon resembles myotonia congenita (a chloride channelopathy). However, genetic analysis revealed a novel Ile239Thr mutation involving SCN4A gene indicating this case to be a sodium channelopathy. Conclusion This case limelight sodium channel myotonia with a novel Ile239Thr mutation in SCN4A gene that phenotypically resembles myotonia congenita but genetically belongs to sodium channelopathy highlighting the poor correlation between genotypes and phenotypes in non-dystrophic myotonia. Acetazolamide can be a safe and cost-effective antimyotonic drug in sodium channel myotonia.
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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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Brenes O, Pusch M, Morales F. ClC-1 Chloride Channel: Inputs on the Structure-Function Relationship of Myotonia Congenita-Causing Mutations. Biomedicines 2023; 11:2622. [PMID: 37892996 PMCID: PMC10604815 DOI: 10.3390/biomedicines11102622] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2023] [Revised: 08/11/2023] [Accepted: 08/24/2023] [Indexed: 10/29/2023] Open
Abstract
Myotonia congenita is a hereditary muscle disease mainly characterized by muscle hyperexcitability, which leads to a sustained burst of discharges that correlates with the magnitude and duration of involuntary aftercontractions, muscle stiffness, and hypertrophy. Mutations in the chloride voltage-gated channel 1 (CLCN1) gene that encodes the skeletal muscle chloride channel (ClC-1) are responsible for this disease, which is commonly known as myotonic chloride channelopathy. The biophysical properties of the mutated channel have been explored and analyzed through in vitro approaches, providing important clues to the general function/dysfunction of the wild-type and mutated channels. After an exhaustive search for CLCN1 mutations, we report in this review more than 350 different mutations identified in the literature. We start discussing the physiological role of the ClC-1 channel in skeletal muscle functioning. Then, using the reported functional effects of the naturally occurring mutations, we describe the biophysical and structural characteristics of the ClC-1 channel to update the knowledge of the function of each of the ClC-1 helices, and finally, we attempt to point out some patterns regarding the effects of mutations in the different helices and loops of the protein.
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Affiliation(s)
- Oscar Brenes
- Departamento de Fisiología, Escuela de Medicina, Universidad de Costa Rica, San José 11501-2060, Costa Rica;
- Centro de Investigación en Neurociencias (CIN), Universidad de Costa Rica, San José 11501-2060, Costa Rica
| | - Michael Pusch
- Istituto di Biofisica, Consiglio Nazionale delle Ricerche (CNR), Via De Marini 6, 16149 Genova, Italy
| | - Fernando Morales
- Instituto de Investigaciones en Salud (INISA), Universidad de Costa Rica, San José 11501-2060, Costa Rica
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Golinelli S, Fracassi F, Bianchi E, Pöppl ÁG, Miceli DD, Benedicenti L, De Marco V, Cook AK, Espada Castro L, Ramsey I, Seo KW, Cantile C, Gandini G, Hulsebosch SE, Feldman EC. Clinical features of muscle stiffness in 37 dogs with concurrent naturally occurring hypercortisolism. J Vet Intern Med 2023; 37:578-585. [PMID: 36798032 DOI: 10.1111/jvim.16620] [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: 02/07/2022] [Accepted: 12/14/2022] [Indexed: 02/18/2023] Open
Abstract
BACKGROUND Severe muscle stiffness (SMS) in dogs with hypercortisolism (HC) is uncommon. OBJECTIVES To evaluate signalment, presentation, treatments, and long-term outcomes of dogs with concurrent HC and SMS. ANIMALS Thirty-seven dogs. METHODS Medical records of dogs with HC and concurrent SMS were recruited from 10 institutions. Clinical information, test results, therapeutic responses, and survival times were reviewed. RESULTS All 37 dogs with HC and SMS had pituitary-dependent hypercortisolism (PDH); 36/37 weighed <20 kg. Signs and test results were typical of PDH aside from SMS, initially diagnosed in all 4 limbs in 9, pelvic limbs of 22, and thoracic limbs of 6 dogs. Hypercortisolism and SMS were diagnosed together in 3 dogs; HC 1-36 months before SMS in 23; SMS 1-12 months before HC in 11. Mitotane or trilostane, given to control HC in 36/37 dogs, improved or resolved HC signs in 28; SMS did not resolve, remaining static or worsening in 31/36 dogs, mildly improving in 5/19 dogs given additional therapies. Progression of SMS included additional limbs in 10 dogs and the masticatory muscles of 2. The median survival time from diagnosis of SMS was 965 days (range, 8-1188). CONCLUSIONS AND CLINICAL IMPORTANCE Concurrent SMS and HC is uncommon, possibly affecting only dogs with PDH. Development of SMS might occur before or after diagnosis of HC. Apart from SMS, the clinical picture and survival time of these dogs seem indistinguishable from those of dogs with HC in general. However, while muscle weakness usually resolves with HC treatment SMS does not.
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Affiliation(s)
- Stefania Golinelli
- Department of Veterinary Medical Sciences, University of Bologna, Bologna, Italy
| | - Federico Fracassi
- Department of Veterinary Medical Sciences, University of Bologna, Bologna, Italy
| | - Ezio Bianchi
- Department of Veterinary Medical Sciences, University of Parma, Parma, Italy
| | - Álan Gomes Pöppl
- Department of Animal Medicine, Faculty of Veterinary, Federal University of Rio Grande do Sul, Porto Alegre, Rio Grande do Sul, Brazil
| | - Diego Daniel Miceli
- Endocrinology Unit, School of Veterinary Medicine, University of Buenos Aires, Faculty of Veterinary Sciences, Buenos Aires, Argentina
| | - Leontine Benedicenti
- Department of Clinical Sciences and Advanced Medicine, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | | | - Audrey K Cook
- Department of Small Animal Clinical Sciences, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, Texas, USA
| | | | - Ian Ramsey
- School of Veterinary Medicine, University of Glasgow, Glasgow, UK
| | - Kyoung Won Seo
- Department of Veterinary Internal Medicine, College of Veterinary Medicine, Seoul National University, Seoul, South Korea
| | - Carlo Cantile
- Department of Veterinary Sciences, University of Pisa, Pisa, Italy
| | - Gualtiero Gandini
- Department of Veterinary Medical Sciences, University of Bologna, Bologna, Italy
| | - Sean E Hulsebosch
- Department of Medicine and Epidemiology, School of Veterinary Medicine, University of California, Davis, California, USA
| | - Edward C Feldman
- Department of Medicine and Epidemiology, School of Veterinary Medicine, University of California, Davis, California, USA
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Pedersen JJ, Stemmerik MG, Jacobsen LN, Skriver SV, Wilms GR, Duno M, Vissing J. Muscle fat replacement and contractility in patients with skeletal muscle sodium channel disorders. Sci Rep 2023; 13:2538. [PMID: 36782059 PMCID: PMC9925746 DOI: 10.1038/s41598-023-29759-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2022] [Accepted: 02/09/2023] [Indexed: 02/15/2023] Open
Abstract
Skeletal muscle sodium channel disorders give rise to episodic symptoms such as myotonia and/or periodic paralysis. Chronic symptoms with permanent weakness are not considered characteristic of the phenotypes. Muscle fat replacement represents irreversible damage that inevitably will impact on muscle strength. This study investigates muscle fat replacement and contractility in patients with pathogenic SCN4A variants compared to healthy controls. T1-weighted and 2-point Dixon MRI of the legs were conducted to assess fat replacement. Stationary dynamometry was used to assess muscle strength. Contractility was determined by maximal muscle contraction divided by cross-sectional muscle area. The average cross-sectional intramuscular fat fraction was greater in patients compared with controls by 2.5% in the calves (95% CI 0.74-4.29%, p = 0.007) and by 2.0% in the thighs (95% CI 0.75-3.2%, p = 0.003). Muscle contractility was less in patients vs. controls by 14-27% (p < 0.05). Despite greater fat fraction and less contractility, absolute strength was not significantly less. This study quantitatively documents greater fat fraction and additionally describes difference in muscle contractility in a large cohort of patients with skeletal muscle sodium channel disorders. The clinical impact of these abnormal findings is likely limited as muscle hypertrophy in the patients served to preserve absolute muscle strength. Subgroup analysis indicated significant difference in phenotype by genotype, however these findings lack statistical significance and serve as inspiration for future researchers to probe into the geno- phenotype relationship in these disorders.Trial registration: The study was registered at http://clinicaltrials.gov (identifier: NCT04808388).
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Affiliation(s)
- Jonas Jalili Pedersen
- Copenhagen Neuromuscular Center, Department of Neurology, Rigshospitalet, University of Copenhagen, Inge Lehmanns Vej 7-9, 2100, Copenhagen, Denmark.
| | - Mads Godtfeldt Stemmerik
- Copenhagen Neuromuscular Center, Department of Neurology, Rigshospitalet, University of Copenhagen, Inge Lehmanns Vej 7-9, 2100, Copenhagen, Denmark
| | - Laura Nørager Jacobsen
- Copenhagen Neuromuscular Center, Department of Neurology, Rigshospitalet, University of Copenhagen, Inge Lehmanns Vej 7-9, 2100, Copenhagen, Denmark
| | - Sofie Vinther Skriver
- Copenhagen Neuromuscular Center, Department of Neurology, Rigshospitalet, University of Copenhagen, Inge Lehmanns Vej 7-9, 2100, Copenhagen, Denmark
| | - Gustav Rhode Wilms
- Copenhagen Neuromuscular Center, Department of Neurology, Rigshospitalet, University of Copenhagen, Inge Lehmanns Vej 7-9, 2100, Copenhagen, Denmark
| | - Morten Duno
- Clinical Genetic Laboratory, Department of Biochemical Genetics, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
| | - John Vissing
- Copenhagen Neuromuscular Center, Department of Neurology, Rigshospitalet, University of Copenhagen, Inge Lehmanns Vej 7-9, 2100, Copenhagen, Denmark
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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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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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Treatment and Management of Disorders of Neuromuscular Hyperexcitability and Periodic Paralysis. Neuromuscul Disord 2022. [DOI: 10.1016/b978-0-323-71317-7.00018-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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Non-dystrophic myotonias: clinical and mutation spectrum of 70 German patients. J Neurol 2020; 268:1708-1720. [PMID: 33263785 PMCID: PMC8068660 DOI: 10.1007/s00415-020-10328-1] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2020] [Revised: 11/09/2020] [Accepted: 11/19/2020] [Indexed: 12/17/2022]
Abstract
Introduction Non-dystrophic myotonias (NDM) are heterogeneous diseases caused by mutations in CLCN1 and SCN4A. The study aimed to describe the clinical and genetic spectrum of NDM in a large German cohort. Methods We retrospectively identified all patients with genetically confirmed NDM diagnosed in our center. The following data were analyzed: demographics, family history, muscular features, cardiac involvement, CK, EMG, genotype, other tested genes, treatment perceived efficacy. Results 70 patients (age 40.2 years ± 14.9; 52.8% males) were included in our study (48 NDM-CLCN1, 22 NDM-SCN4A). The most frequent presenting symptoms were myotonia (NDM-CLCN1 83.3%, NDM-SCN4A 72.2%) and myalgia (NDM-CLCN1 57.4%, NDM-SCN4A 52.6%). Besides a more prominent facial involvement in NDM-SCN4A and cold-sensitivity in NDM-CLCN1, no other significant differences were observed between groups. Cardiac arrhythmia or conduction defects were documented in sixNDM-CLCN1 patients (three of them requiring a pacemaker) and one patient with NDM-SCN4A. CK was normal in 40% of patients. Myotonic runs in EMG were detected in 89.1% of CLCN1 and 78.9% of SCN4A. 50% of NDM-CLCN1 patients had the classic c.2680C>T (p.Arg894*) mutation. 12 new genetic variants are reported. About 50% of patients were not taking any anti-myotonic drug at the last follow-up. The anti-myotonic drugs with the best patient’s perceived efficacy were mexiletine and lamotrigine. Conclusion This study highlights the relevant clinical overlap between NDM-CLCN1 and NDM-SCN4A patients and warrants the use of early and broad genetic investigation for the precise identification of the NDM subtype. Besides the clinical and genetic heterogeneity, the limited response to current anti-myotonic drugs constitutes a continuing challenge. Supplementary Information The online version contains supplementary material available at 10.1007/s00415-020-10328-1.
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12
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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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13
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Farooque U, Cheema AY, Kumar R, Saini G, Kataria S. Primary Periodic Paralyses: A Review of Etiologies and Their Pathogeneses. Cureus 2020; 12:e10112. [PMID: 33005530 PMCID: PMC7523540 DOI: 10.7759/cureus.10112] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Periodic paralyses are a group of disorders characterized by episodes of muscle paralyses. They are mainly divided as primary (hereditary) and secondary (acquired) periodic paralyses. Primary periodic paralyses occur as a result of mutations in genes encoding subunits of muscle membrane channel proteins such as sodium, calcium, and potassium channels, resulting in impairment of their properties. Primary periodic paralyses are further classified on the basis of affected ion channels and other associated complications. Some of these periodic paralyses are hyperkalemic periodic paralysis (Na-channel mutation), hypokalemic periodic paralysis (Na- or Ca-channel mutation), Andersen’s syndrome (K-channel mutation), etc.
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14
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Meyer AP, Roggenbuck J, LoRusso S, Kissel J, Smith RM, Kline D, Arnold WD. Genotype-Phenotype Correlations and Characterization of Medication Use in Inherited Myotonic Disorders. Front Neurol 2020; 11:593. [PMID: 32670189 PMCID: PMC7332828 DOI: 10.3389/fneur.2020.00593] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2019] [Accepted: 05/22/2020] [Indexed: 11/13/2022] Open
Abstract
Introduction: Inherited myotonic disorders are genetically heterogeneous and associated with overlapping clinical features of muscle stiffness, weakness, and pain. Data on genotype-phenotype correlations are limited. In this study, clinical features and treatment patterns in genetically characterized myotonic disorders were compared. Methods: A retrospective chart review was completed in patients with genetic variants in CLCN1, SCN4A, DMPK, and CNBP to document clinical signs and symptoms, clinical testing, and antimyotonia medication use. Results: A total of 142 patients (27 CLCN1, 15 SCN4A, 89 DMPK, and 11 CNBP) were reviewed. The frequency of reported symptoms (stiffness, weakness, and pain) and electromyographic spontaneous activity were remarkably similar across genotypes. Most patients were not treated with antimyotonia agents, but those with non-dystrophic disorders were more likely to be on a treatment. Discussion: Among the features reviewed, we did not identify clinical or electrophysiological differences to distinguish CLCN1- and SCN4A-related myotonia. Weakness and pain were more prevalent in non-dystrophic disorders than previously identified. In addition, our results suggest that medical treatments in myotonic disorders may be under-utilized.
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Affiliation(s)
- Alayne P Meyer
- Division of Human Genetics, The Ohio State University, Columbus, OH, United States
| | - Jennifer Roggenbuck
- Division of Human Genetics, The Ohio State University, Columbus, OH, United States
| | - Samantha LoRusso
- Department of Neurology, The Ohio State University, Columbus, OH, United States
| | - John Kissel
- Department of Neurology, The Ohio State University, Columbus, OH, United States
| | - Rachel M Smith
- Department of Biomedical Informatics, Center for Biostatistics, The Ohio State University, Columbus, OH, United States
| | - David Kline
- Department of Biomedical Informatics, Center for Biostatistics, The Ohio State University, Columbus, OH, United States
| | - W David Arnold
- Department of Neurology, The Ohio State University, Columbus, OH, United States
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15
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Horie R, Kubota T, Koh J, Tanaka R, Nakamura Y, Sasaki R, Ito H, Takahashi MP. EF hand-like motif mutations of Nav1.4 C-terminus cause myotonic syndrome by impairing fast inactivation. Muscle Nerve 2020; 61:808-814. [PMID: 32129495 DOI: 10.1002/mus.26849] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2019] [Revised: 01/27/2020] [Accepted: 03/01/2020] [Indexed: 12/22/2022]
Abstract
INTRODUCTION Mutations of the voltage-gated sodium channel gene (SCN4A), which encodes Nav1.4, cause nondystrophic myotonia that occasionally is associated with severe apnea and laryngospasm. There are case reports of nondystrophic myotonia due to mutations in the C-terminal tail (CTerm) of Nav1.4, but the functional analysis is scarce. METHODS We present two families with nondystrophic myotonia harboring a novel heterozygous mutation (E1702del) and a known heterozygous mutation (E1702K). RESULTS The proband with E1702K exhibited repeated rhabdomyolysis, and the daughter showed laryngospasm and cyanosis. Functional analysis of the two mutations as well as another known heterozygous mutation (T1700_E1703del), all located on EF hand-like motif in CTerm, was conducted with whole-cell recording of heterologously expressed channel. All mutations displayed impaired fast inactivation. DISCUSSION The CTerm of Nav1.4 is vital for regulating fast inactivation. The study highlights the importance of accumulating pathological mutations of Nav1.4 and their functional analysis data.
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Affiliation(s)
- Riho Horie
- Department of Functional Diagnostic Science, Osaka University Graduate School of Medicine, Yamadaoka, Suita, Osaka, Japan
| | - Tomoya Kubota
- Department of Functional Diagnostic Science, Osaka University Graduate School of Medicine, Yamadaoka, Suita, Osaka, Japan
| | - Jinsoo Koh
- Department of Neurology, Wakayama Medical University, Kimiidera, Wakayama, Wakayama, Japan
| | - Rieko Tanaka
- Nanairo Kodomo Clinic, Fukiage, Wakayama, Wakayama, Japan
| | - Yuichiro Nakamura
- Department of Functional Diagnostic Science, Osaka University Graduate School of Medicine, Yamadaoka, Suita, Osaka, Japan
| | - Ryogen Sasaki
- Department of Neurology, Kuwana City Medical Center, Kotobukicho, Kuwana, Mie, Japan
| | - Hidefumi Ito
- Department of Neurology, Wakayama Medical University, Kimiidera, Wakayama, Wakayama, Japan
| | - Masanori P Takahashi
- Department of Functional Diagnostic Science, Osaka University Graduate School of Medicine, Yamadaoka, Suita, Osaka, Japan
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Morales F, Pusch M. An Up-to-Date Overview of the Complexity of Genotype-Phenotype Relationships in Myotonic Channelopathies. Front Neurol 2020; 10:1404. [PMID: 32010054 PMCID: PMC6978732 DOI: 10.3389/fneur.2019.01404] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2019] [Accepted: 12/23/2019] [Indexed: 12/11/2022] Open
Abstract
Myotonic disorders are inherited neuromuscular diseases divided into dystrophic myotonias and non-dystrophic myotonias (NDM). The latter is a group of dominant or recessive diseases caused by mutations in genes encoding ion channels that participate in the generation and control of the skeletal muscle action potential. Their altered function causes hyperexcitability of the muscle membrane, thereby triggering myotonia, the main sign in NDM. Mutations in the genes encoding voltage-gated Cl− and Na+ channels (respectively, CLCN1 and SCN4A) produce a wide spectrum of phenotypes, which differ in age of onset, affected muscles, severity of myotonia, degree of hypertrophy, and muscle weakness, disease progression, among others. More than 200 CLCN1 and 65 SCN4A mutations have been identified and described, but just about half of them have been functionally characterized, an approach that is likely extremely helpful to contribute to improving the so-far rather poor clinical correlations present in NDM. The observed poor correlations may be due to: (1) the wide spectrum of symptoms and overlapping phenotypes present in both groups (Cl− and Na+ myotonic channelopathies) and (2) both genes present high genotypic variability. On the one hand, several mutations cause a unique and reproducible phenotype in most patients. On the other hand, some mutations can have different inheritance pattern and clinical phenotypes in different families. Conversely, different mutations can be translated into very similar phenotypes. For these reasons, the genotype-phenotype relationships in myotonic channelopathies are considered complex. Although the molecular bases for the clinical variability present in myotonic channelopathies remain obscure, several hypotheses have been put forward to explain the variability, which include: (a) differential allelic expression; (b) trans-acting genetic modifiers; (c) epigenetic, hormonal, or environmental factors; and (d) dominance with low penetrance. Improvements in clinical tests, the recognition of the different phenotypes that result from particular mutations and the understanding of how a mutation affects the structure and function of the ion channel, together with genetic screening, is expected to improve clinical correlation in NDMs.
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Affiliation(s)
- Fernando Morales
- Instituto de Investigaciones en Salud, Universidad de Costa, San José, Costa Rica
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17
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Becker's myotonia: novel mutations and clinical variability in patients born to consanguineous parents. Acta Neurol Belg 2018; 118:567-572. [PMID: 29480456 DOI: 10.1007/s13760-018-0893-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2017] [Accepted: 02/05/2018] [Indexed: 01/30/2023]
Abstract
Myotonia congenita is an inherited muscle disease present from childhood that is characterized by impaired muscle relaxation after contraction resulting in muscle stiffness; moreover, skeletal striated muscle groups may be involved. Myotonia congenita occurs due to chloride (Cl) channel mutations that reduce the stabilizing Cl conductance, and it is caused by mutations in the CLCN1 gene. This paper describes four patients from two different healthy consanguineous Turkish families with muscle stiffness and easy fatigability. A genetic investigation was performed. Mutation analyses showed a homozygous p.Tyr150* (c.450C > A) mutation in patients 1, 2 and 3 and a homozygous p.Leu159Cysfs*11 (c.475delC) mutation in patient 4 in the CLCN1 gene. These mutations have never been reported before and in silico analyses showed that the mutations were disease causing. They may be predicted to cause nonsense-mediated mRNA decay. Our data expand the spectrum of CLCN1 mutations and provide insights for genotype-phenotype correlations of myotonia congenita.
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18
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Nondystrophic Myotonic Disorders. Neuromuscul Disord 2018. [DOI: 10.1007/978-981-10-5361-0_27] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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19
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Yamamoto J, Hokkoku K, Hatanaka Y, Sakoda S, Yuan JH, Sonoo M. An unusual case of sodium channel myotonia with transient weakness upon initiating movements which is characteristic in Becker disease. Rinsho Shinkeigaku 2017; 57:287-292. [PMID: 28552867 DOI: 10.5692/clinicalneurol.cn-000980] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
We reported a 32-year-old man who was a sporadic case of myotonic syndrome with muscle stiffness or transient weakness of limbs upon initiating movements after rest. On examination, he showed painless myotonia with warm-up phenomenon, Hercules-like hypertrophic musculature and myotonic discharges in EMG. The clinical findings resembled to those of Becker disease rather than Thomsen disease. But electrodiagnosis suggested sodium channel myotonia instead of chloride channelopathy. Genetic testing detected a novel missense mutation (p.V1166A) in the SCN4A gene but not in the CLCN1 gene. Transient weakness upon initiating movements is usually observed in Becker disease but rare in Thomsen disease, which is not reported in sodium channel myotonia so far. He was probably the first case of sodium channel myotonia with transient weakness upon initiating movements, which was confirmed by 10 Hz repetitive nerve stimulation test as depolarization block.
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Affiliation(s)
- Junpei Yamamoto
- Department of Neurology, Teikyo University School of Medicine
| | - Keiichi Hokkoku
- Department of Neurology, Teikyo University School of Medicine
| | - Yuki Hatanaka
- Department of Neurology, Teikyo University School of Medicine
| | - Shunichi Sakoda
- Department of Neurology and Geriatrics, Kagoshima University Graduate School of Medical and Dental Sciences
| | - Jun-Hui Yuan
- Department of Neurology and Geriatrics, Kagoshima University Graduate School of Medical and Dental Sciences
| | - Masahiro Sonoo
- Department of Neurology, Teikyo University School of Medicine
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20
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Lian M, Law HY, Lee CG, Chong SS. Defining the performance parameters of a rapid screening tool for myotonic dystrophy type 1 based on triplet-primed PCR and melt curve analysis. Expert Rev Mol Diagn 2016; 16:1221-1232. [PMID: 27665623 DOI: 10.1080/14737159.2016.1241145] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
BACKGROUND DMPK CTG-repeat expansions that cause myotonic dystrophy type 1 (DM1) can be detected more rapidly, cost-effectively, and simply by combining triplet-primed PCR (TP-PCR) with melting curve analysis (MCA). We undertook a detailed technical validation study to define the optimal operational parameters for performing bidirectional TP-PCR MCA assays. METHODS We determined the assays' analytic specificity and sensitivity, assessed the effect of reaction volumes, DNA diluents, and common contaminants on melt peak temperature, determined the assays' sensitivity in detecting low-level mosaicism for repeat expansion, and evaluated their performance on two real-time PCR platforms. RESULTS Both assays were highly specific and sensitive, and performed optimally under a broad range of parameters. Bidirectional TP-PCR MCA analysis also reduces the risk of generating false-negative results associated with the rare CCG-interruptions that may be present at either end of expanded alleles. CONCLUSION The DMPK TP-PCR MCA is a highly specific, sensitive, and significantly cost-saving screening tool for DM1.
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Affiliation(s)
- Mulias Lian
- a Khoo Teck Puat - National University Children's Medical Institute , National University Health System , Singapore , Singapore
| | - Hai-Yang Law
- b Department of Pediatric Medicine , KK Women's and Children's Hospital , Singapore , Singapore.,c Pediatrics Academic Clinical Program , Duke-NUS Graduate Medical School , Singapore , Singapore
| | - Caroline G Lee
- d Department of Biochemistry, Yong Loo Lin School of Medicine , National University of Singapore , Singapore , Singapore.,e Cancer and Stem Cell Biology Program , Duke-NUS Graduate Medical School , Singapore , Singapore.,f Division of Medical Sciences , National Cancer Center , Singapore , Singapore
| | - Samuel S Chong
- a Khoo Teck Puat - National University Children's Medical Institute , National University Health System , Singapore , Singapore.,g Department of Pediatrics, Yong Loo Lin School of Medicine , National University of Singapore , Singapore , Singapore.,h Department of Laboratory Medicine , National University Hospital, National University Health System , Singapore , Singapore
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21
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Liu XL, Huang XJ, Luan XH, Zhou HY, Wang T, Wang JY, Chen SD, Tang HD, Cao L. Mutations of SCN4A gene cause different diseases: 2 case reports and literature review. Channels (Austin) 2016; 9:82-7. [PMID: 25839108 DOI: 10.1080/19336950.2015.1012945] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
SCN4A encodes the Nav1.4 channel and mutations in SCN4A lead to different ionic channelopathies. In this study, one sporadic individual of periodic paralysis, one paramyotonia family and 200 normal healthy controls are enrolled. Genomic DNA was extracted from peripheral blood leukocytes, followed by polymerase chain reaction and DNA sequencing of candidate genes, including SCN4A and CACNA1S. As a result, heterozygous mutations c.2024G>A (R675Q) and c.1333G>A (V445M) of gene SCN4A were identified in the hypokalemic periodic paralysis patient and the paramyotonia congenita family respectively. Both mutations were not detected in healthy controls. Compared with reported cases, patients with mutation R675Q usually do not present hypokalemic periodic paralysis but hyperkalemic or normokalemic periodic paralysis. The mutation V445M was first reported in Chinese patients with nondystrophic myotonias. In addition, we carried out literature review by summarizing clinical features of the 2 mutations and establish the genotype-phenotype correlations to provide guidance for diagnosis.
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Affiliation(s)
- Xiao-li Liu
- a Department of Neurology ; Rui Jin Hospital & Rui Jin Hospital North ; Shanghai Jiao Tong University School of Medicine ; Shanghai , China
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22
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The Myotonic Plot Thickens: Electrical Myotonia in Antimuscle-Specific Kinase Myasthenia Gravis. Case Rep Neurol Med 2016; 2015:242691. [PMID: 26770848 PMCID: PMC4681818 DOI: 10.1155/2015/242691] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2015] [Accepted: 11/22/2015] [Indexed: 11/18/2022] Open
Abstract
Electrical myotonia is known to occur in a number of inherited and acquired disorders including myotonic dystrophies, channelopathies, and metabolic, toxic, and inflammatory myopathies. Yet, electrical myotonia in myasthenia gravis associated with antibodies against muscle-specific tyrosine kinase (MuSK) has not been previously reported. We describe two such patients, both of whom had a typical presentation of proximal muscle weakness with respiratory failure in the context of a significant electrodecrement in repetitive nerve stimulation. In both cases, concentric needle examination revealed electrical myotonia combined with myopathic motor unit morphology and early recruitment. These findings suggest that MuSK myasthenia should be included within the differential diagnosis of disorders with electrical myotonia.
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23
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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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Yoshinaga H, Sakoda S, Shibata T, Akiyama T, Oka M, Yuan JH, Takashima H, Takahashi MP, Kitamura T, Murakami N, Kobayashi K. Phenotypic variability in childhood of skeletal muscle sodium channelopathies. Pediatr Neurol 2015; 52:504-8. [PMID: 25724373 DOI: 10.1016/j.pediatrneurol.2015.01.014] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/10/2014] [Revised: 01/21/2015] [Accepted: 01/22/2015] [Indexed: 10/24/2022]
Abstract
BACKGROUND Mutations of the SCN4A gene cause several skeletal muscle channelopathies and overlapping forms of these disorders. However, the variability of the clinical presentation in childhood is confusing and not fully understood among pediatric neurologists. PATIENTS We found three different mutations (p.V445M, p.I693L, and a novel mutation, p.V1149L) in SCN4A but not in the CLCN1 gene. The patient with p.V445M showed the clinical phenotype of sodium channel myotonia, but her clear symptoms did not appear until 11 years of age. Her younger sister and mother, who have the same mutation, displayed marked intrafamilial phenotypic heterogeneity from mild to severe painful myotonia with persistent weakness. The patient with p.I693L exhibited various symptoms that evolved with age, including apneic episodes, tonic muscular contractions during sleep, fluctuating severe episodic myotonia, and finally episodic paralyses. The patient with the novel p.V1149L mutation exhibited episodic paralyses starting at 3 years of age, and myotonic discharges were detected at 11 years of age for the first time. CONCLUSION The present cohort reveals the complexity, variability, and overlapping nature of the clinical features of skeletal muscle sodium channelopathies. These are basically treatable disorders, so it is essential to consider genetic testing before the full development of a patient's condition.
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Affiliation(s)
- Harumi Yoshinaga
- Department of Child Neurology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama, Japan.
| | - Shunichi Sakoda
- Department of Neurology and Geriatrics, Kagoshima University Graduate School of Medical and Dental Sciences, Kagoshima, Japan
| | - Takashi Shibata
- Department of Child Neurology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama, Japan
| | - Tomoyuki Akiyama
- Department of Child Neurology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama, Japan
| | - Makio Oka
- Department of Child Neurology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama, Japan
| | - Jun-Hui Yuan
- Department of Neurology and Geriatrics, Kagoshima University Graduate School of Medical and Dental Sciences, Kagoshima, Japan
| | - Hiroshi Takashima
- Department of Neurology and Geriatrics, Kagoshima University Graduate School of Medical and Dental Sciences, Kagoshima, Japan
| | - Masanori P Takahashi
- Department of Neurology, Osaka University Graduate School of Medicine, Osaka, Japan
| | - Tetsuro Kitamura
- Department of Pediatrics, Nipponkokan Fukuyama Hospital, Hiroshima, Japan
| | - Nagako Murakami
- Department of Pediatrics, Nipponkokan Fukuyama Hospital, Hiroshima, Japan
| | - Katsuhiro Kobayashi
- Department of Child Neurology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama, Japan
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Efficient and Highly Sensitive Screen for Myotonic Dystrophy Type 1 Using a One-Step Triplet-Primed PCR and Melting Curve Assay. J Mol Diagn 2015; 17:128-35. [DOI: 10.1016/j.jmoldx.2014.10.001] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2014] [Revised: 10/15/2014] [Accepted: 10/22/2014] [Indexed: 01/22/2023] Open
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Paroxysmal kinesigenic dyskinesia and myotonia congenita in the same family: coexistence of a PRRT2 mutation and two CLCN1 mutations. Neurosci Bull 2014; 30:1010-1016. [PMID: 25205014 DOI: 10.1007/s12264-014-1467-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2014] [Accepted: 04/28/2014] [Indexed: 10/24/2022] Open
Abstract
Paroxysmal kinesigenic dyskinesia (PKD) and myotonia congenita (MC) are independent disorders that share some clinical features. We aimed to investigate the sequences of PRRT2 and CLCN1 in a proband diagnosed with PKD and suspected MC. Clinical evaluation and auxiliary examinations were performed. Direct sequencing of the entire coding regions of the PRRT2 and CLCN1 genes was conducted. Haplotype analysis confirmed the relationships among the family members. The proband suffered choreoathetosis attacks triggered by sudden movements, and lower-limb weakness and stiffness that worsened in cold weather. Carbamazepine monotherapy completely controlled his choreoathetosis and significantly relieved his limb weakness and stiffness. His father, when young, had similar limb stiffness, while his mother and brother were asymptomatic. Genetic analysis revealed that the proband and his father harbored a PRRT2 c.649dupC mutation, and CLCN1 c.1723C>T and c.2492A>G mutations. His brother carried only the two CLCN1 mutations. None of these mutations were identified in his mother and 150 unrelated controls. This is the first report showing the coexistence of PRRT2 and CLCN1 mutations. Our results also indicate that both the PRRT2 and CLCN1 genes need to be screened if we fail to identify PRRT2 mutations in PKD patients or CLCN1 mutations in MC patients.
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Borges AS, Barbosa JD, Resende LAL, Mota LSLS, Amorim RM, Carvalho TL, Garcia JF, Oliveira-Filho JP, Oliveira CMC, Souza JES, Winand NJ. Clinical and molecular study of a new form of hereditary myotonia in Murrah water buffalo. Neuromuscul Disord 2013; 23:206-13. [PMID: 23339992 DOI: 10.1016/j.nmd.2012.11.008] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2012] [Revised: 11/04/2012] [Accepted: 11/12/2012] [Indexed: 10/27/2022]
Abstract
Hereditary myotonia caused by mutations in CLCN1 has been previously described in humans, goats, dogs, mice and horses. The goal of this study was to characterize the clinical, morphological and genetic features of hereditary myotonia in Murrah buffalo. Clinical and laboratory evaluations were performed on affected and normal animals. CLCN1 cDNA and the relevant genomic region from normal and affected animals were sequenced. The affected animals exhibited muscle hypertrophy and stiffness. Myotonic discharges were observed during EMG, and dystrophic changes were not present in skeletal muscle biopsies; the last 43 nucleotides of exon-3 of the CLCN1 mRNA were deleted. Cloning of the genomic fragment revealed that the exclusion of this exonic sequence was caused by aberrant splicing, which was associated with the presence of a synonymous SNP in exon-3 (c.396C>T). The mutant allele triggered the efficient use of an ectopic 5' splice donor site located at nucleotides 90-91 of exon-3. The predicted impact of this aberrant splicing event is the alteration of the CLCN1 translational reading frame, which results in the incorporation of 24 unrelated amino acids followed by a premature stop codon.
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Affiliation(s)
- Alexandre S Borges
- Department of Veterinary Clinical Science, College of Veterinary Medicine and Animal Science, Univ Estadual Paulista (UNESP), Botucatu, Brazil.
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Richman DP, Yu Y, Lee TT, Tseng PY, Yu WP, Maselli RA, Tang CY, Chen TY. Dominantly inherited myotonia congenita resulting from a mutation that increases open probability of the muscle chloride channel CLC-1. Neuromolecular Med 2012; 14:328-37. [PMID: 22790975 DOI: 10.1007/s12017-012-8190-1] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2012] [Accepted: 06/22/2012] [Indexed: 10/28/2022]
Abstract
Myotonia congenita-inducing mutations in the muscle chloride channel CLC-1 normally result in reduced open probability (P (o)) of this channel. One well-accepted mechanism of the dominant inheritance of this disease involves a dominant-negative effect of the mutation on the function of the common-gate of this homodimeric, double-barreled molecule. We report here a family with myotonia congenita characterized by muscle stiffness and clinical and electrophysiologic myotonic phenomena transmitted in an autosomal dominant pattern. DNA sequencing of DMPK and ZNF9 genes for myotonic muscular dystrophy types I and II was normal, whereas sequencing of CLC-1 encoding gene, CLCN1, identified a single heterozygous missense mutation, G233S. Patch-clamp analyses of this mutant CLC-1 channel in Xenopus oocytes revealed an increased P (o) of the channel's fast-gate, from ~0.4 in the wild type to >0.9 in the mutant at -90 mV. In contrast, the mutant exhibits a minimal effect on the P (o) of the common-gate. These results are consistent with the structural prediction that the mutation site is adjacent to the fast-gate of the channel. Overall, the mutant could lead to a significantly reduced dynamic response of CLC-1 to membrane depolarization, from a fivefold increase in chloride conductance in the wild type to a twofold increase in the mutant-this might result in slower membrane repolarization during an action potential. Since expression levels of the mutant and wild-type subunits in artificial model cell systems were unable to explain the disease symptoms, the mechanism leading to dominant inheritance in this family remains to be determined.
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Affiliation(s)
- David P Richman
- Department of Neurology and Center for Neuroscience, University of California, Davis, CA 95616, USA.
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Kokunai Y, Goto K, Kubota T, Fukuoka T, Sakoda S, Ibi T, Doyu M, Mochizuki H, Sahashi K, Takahashi MP. A sodium channel myotonia due to a novel SCN4A mutation accompanied by acquired autoimmune myasthenia gravis. Neurosci Lett 2012; 519:67-72. [PMID: 22617007 DOI: 10.1016/j.neulet.2012.05.023] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2012] [Revised: 04/19/2012] [Accepted: 05/07/2012] [Indexed: 10/28/2022]
Abstract
Mutations of the voltage gated sodium channel gene (SCN4A) are responsible for non-dystrophic myotonia including hyperkalemic periodic paralysis, paramyotonia congenita, and sodium channel myotonia, as well as congenital myasthenic syndrome. In vitro functional analyses have demonstrated the non-dystrophic mutants to show a gain-of-function defect of the channel; a disruption of fast inactivation, an enhancement of activation, or both, while the myasthenic mutation presents a loss-of function defect. This report presents a case of non-dystrophic myotonia that is incidentally accompanied with acquired myasthenia. The patient presented a marked warm-up phenomenon of myotonia but the repeated short exercise test suggested mutations of the sodium channel. The genetic analysis identified a novel mutation, G1292D, of SCN4A. A functional study of the mutant channel revealed marked enhancement of activation and slight impairment of fast inactivation, which should induce muscle hyperexcitability. The effects of the alteration of channel function to the myasthenic symptoms were explored by using stimulation of repetitive depolarization pulses. A use-dependent channel inactivation was reduced in the mutant in comparison to normal channel, thus suggesting an opposing effect to myasthenia.
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Affiliation(s)
- Yosuke Kokunai
- Department of Neurology, Osaka University Graduate School of Medicine, Osaka, Japan
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Gurgel-Giannetti J, Senkevics AS, Zilbersztajn-Gotlieb D, Yamamoto LU, Muniz VP, Pavanello RCM, Oliveira AB, Zatz M, Vainzof M. Thomsen or Becker myotonia? A novel autosomal recessive nonsense mutation in the CLCN1 gene associated with a mild phenotype. Muscle Nerve 2012; 45:279-83. [PMID: 22246887 DOI: 10.1002/mus.22252] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
We describe a large Brazilian consanguineous kindred with 3 clinically affected patients with a Thomsen myotonia phenotype. They carry a novel homozygous nonsense mutation in the CLCN1 gene (K248X). None of the 6 heterozygote carriers show any sign of myotonia on clinical evaluation or electromyography. These findings confirm the autosomal recessive inheritance of the novel mutation in this family, as well as the occurrence of phenotypic variability in the autosomal recessive forms of myotonia.
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Affiliation(s)
- Juliana Gurgel-Giannetti
- Centro de Estudos do Genoma Humano-IB-USP, Biosciences Institute, University of São Paulo, R. do Matão, 277, Sala 220, CEP 05508-900 São Paulo, Brazil
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Ratbi I, Elalaoui SC, Escudero A, Kriouile Y, Molano J, Sefiani A. Moroccan consanguineous family with Becker myotonia and review. Ann Indian Acad Neurol 2012; 14:307-9. [PMID: 22346025 PMCID: PMC3271475 DOI: 10.4103/0972-2327.91963] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2010] [Revised: 11/05/2010] [Accepted: 12/02/2010] [Indexed: 11/23/2022] Open
Abstract
Myotonia congenita is a genetic muscle disorder characterized by clinical and electrical myotonia, muscle hypertrophy, and stiffness. It is inherited as either autosomal-dominant or –recessive, known as Thomsen and Becker diseases, respectively. These diseases are distinguished by the severity of their symptoms and their patterns of inheritance. Becker disease usually appears later in childhood than Thomsen disease and causes more severe muscle stiffness and pain. Mutations in the muscular voltage-dependent chloride channel gene (CLCN1), located at 7q35, have been found in both types. We report here the case of a Moroccan consanguineous family with a myotonic autosomal-recessive condition in two children. The molecular studies showed that the patients reported here are homozygous for mutation p.Gly482Arg in the CLCN1 gene. The parents were heterozygote carriers for mutation p.Gly482Arg. This diagnosis allowed us to provide an appropriate management to the patients and to make a genetic counselling to their family.
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Affiliation(s)
- Ilham Ratbi
- Human Genomic Center, Faculty of medicine and pharmacy, University Mohammed V Souissi, Rabat, Morocco
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Yoshinaga H, Sakoda S, Good JM, Takahashi MP, Kubota T, Arikawa-Hirasawa E, Nakata T, Ohno K, Kitamura T, Kobayashi K, Ohtsuka Y. A novel mutation in SCN4A causes severe myotonia and school-age-onset paralytic episodes. J Neurol Sci 2012; 315:15-9. [PMID: 22257501 DOI: 10.1016/j.jns.2011.12.015] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2011] [Revised: 11/30/2011] [Accepted: 12/22/2011] [Indexed: 11/30/2022]
Abstract
Mutations in the pore-forming subunit of the skeletal muscle sodium channel (SCN4A) are responsible for hyperkalemic periodic paralysis, paramyotonia congenita and sodium channel myotonia. These disorders are classified based on their cardinal symptoms, myotonia and/or paralysis. We report the case of a Japanese boy with a novel mutation of SCN4A, p.I693L, who exhibited severe episodic myotonia from infancy and later onset mild paralytic attack. He started to have apneic episodes with generalized hypertonia at age of 11 months, then developed severe episodic myotonia since 2 years of age. He presented characteristic generalized features which resembled Schwarz-Jampel syndrome. After 7 years old, paralytic episodes occurred several times a year. The compound muscle action potential did not change during short and long exercise tests. Functional analysis of the mutant channel expressed in cultured cell revealed enhancement of the activation and disruption of the slow inactivation, which were consistent with myotonia and paralytic attack. The severe clinical features in his infancy may correspond to myotonia permanence, however, he subsequently experienced paralytic attacks. This case provides an example of the complexity and overlap of the clinical features of sodium channel myotonic disorders.
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Affiliation(s)
- Harumi Yoshinaga
- Department of Child Neurology, Okayama University Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences, Okayama, Japan.
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Conravey A, Santana-Gould L. Myotonia congenita and myotonic dystrophy: surveillance and management. Curr Treat Options Neurol 2011; 12:16-28. [PMID: 20842486 DOI: 10.1007/s11940-009-0055-z] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
OPINION STATEMENT Myotonia can be treated both pharmacologically and by lifestyle modifications. Cell membrane stabilizers are the medications most commonly used for symptomatic treatment of myotonia. Most patients do not require treatment for the myotonia itself, unless it is severe, but physicians must be aware of anesthesia risks in both myotonia congenita and myotonic dystrophy. A mainstay of management of myotonic dystrophy is the surveillance and treatment of its various systemic complications.
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Affiliation(s)
- Allison Conravey
- Department of Pediatrics, Tulane University, 1430 Tulane Avenue, SL-37, New Orleans, LA, 70112, USA,
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Kiesewetter IS, Tipold A, Baumgärtner W, Schenk HC. Potassium-aggravated muscle stiffness in 12 cats. J Am Vet Med Assoc 2011; 238:1026-31. [PMID: 21492046 DOI: 10.2460/javma.238.8.1026] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
CASE DESCRIPTION 12 European shorthair cats (6 males and 6 females; age range, 2 months to 3 years) from 1 household were evaluated for clinical signs of recurrent and progressive muscle spasticity. Genetic relationships among the cats were suspected but were not known. CLINICAL FINDINGS Physical examination of all cats revealed a thin to mildly emaciated body condition and signs of suppurative rhinitis. Results of neurologic evaluations revealed no abnormalities in any cats at rest, but exercise- and stress-induced episodes of muscle spasticity were observed. Results of hematologic (7/12 cats) and CSF (4) analysis, diagnostic imaging (including radiography [7] and magnetic resonance imaging [4]), electromyography (4), motor nerve conduction tests (4), screening for metabolic storage diseases (4), provocation tests via exercise in a cold (4°C [39.2°F]) environment (7), and gross pathological and histologic examination (5) revealed no abnormalities that could potentially explain the clinical signs. However, consumption of a potassium-enriched diet resulted in severe aggravation of clinical signs in 7 of 7 cats, leading to a diagnosis of potassium-aggravated muscle stiffness. TREATMENT AND OUTCOME 5 cats were euthanized after initial examination because of poor physical condition and severe clinical signs. Spasticity in the 7 remaining cats was improved during a 6-week follow-up period as they reduced their own activity. Further investigation and treatment were declined. CLINICAL RELEVANCE Channelopathies are rarely recognized diseases in domestic animals. In addition to conventional diagnostic evaluation methods, provocation tests in a clinical environment can be used in the assessment of channelopathies.
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Affiliation(s)
- Iris S Kiesewetter
- Department of Small Animal Medicine and Surgery, University of Veterinary Medicine Hannover Foundation, Germany
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Jurkat-Rott K, Lerche H, Lehmann-Horn F. Muskuläre Kanalopathien. DER NERVENARZT 2011; 82:511-20; quiz 521. [DOI: 10.1007/s00115-011-3269-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
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37
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Sun C, Van Ghelue M, Tranebjaerg L, Thyssen F, Nilssen Ø, Torbergsen T. Myotonia congenita and myotonic dystrophy in the same family: coexistence of a CLCN1 mutation and expansion in the CNBP (ZNF9) gene. Clin Genet 2011; 80:574-80. [DOI: 10.1111/j.1399-0004.2010.01616.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
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39
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Kornblum C, Lutterbey GG, Czermin B, Reimann J, von Kleist-Retzow JC, Jurkat-Rott K, Wattjes MP. Whole-body high-field MRI shows no skeletal muscle degeneration in young patients with recessive myotonia congenita. Acta Neurol Scand 2010; 121:131-5. [PMID: 20047568 DOI: 10.1111/j.1600-0404.2009.01228.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
BACKGROUND Muscle magnetic resonance imaging (MRI) is the most sensitive method in the detection of dystrophic and non-dystrophic abnormalities within striated muscles. We hypothesized that in severe myotonia congenita type Becker muscle stiffness, prolonged transient weakness and muscle hypertrophy might finally result in morphologic skeletal muscle alterations reflected by MRI signal changes. AIM OF THE STUDY To assess dystrophic and/or non-dystrophic alterations such as fatty or connective tissue replacement and muscle edema in patients with severe recessive myotonia congenita. METHODS We studied three seriously affected patients with myotonia congenita type Becker using multisequence whole-body high-field MRI. All patients had molecular genetic testing of the muscle chloride channel gene (CLCN1). RESULTS Molecular genetic analyses demonstrated recessive CLCN1 mutations in all patients. Two related patients were compound heterozygous for two novel CLCN1 mutations, Q160H and L657P. None of the patients showed skeletal muscle signal changes indicative of fatty muscle degeneration or edema. Two patients showed muscle bulk hypertrophy of thighs and calves in line with the clinical appearance. CONCLUSIONS We conclude that (i) chloride channel dysfunction alone does not result in skeletal muscle morphologic changes even in advanced stages of myotonia congenita, and (ii) MRI skeletal muscle alterations in myotonic dystrophy must be clear consequences of the dystrophic disease process.
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Affiliation(s)
- C Kornblum
- Department of Neurology, University of Bonn, Bonn, Germany.
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Jarecki BW, Piekarz AD, Jackson JO, Cummins TR. Human voltage-gated sodium channel mutations that cause inherited neuronal and muscle channelopathies increase resurgent sodium currents. J Clin Invest 2009; 120:369-78. [PMID: 20038812 DOI: 10.1172/jci40801] [Citation(s) in RCA: 105] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2009] [Accepted: 11/10/2009] [Indexed: 11/17/2022] Open
Abstract
Inherited mutations in voltage-gated sodium channels (VGSCs; or Nav) cause many disorders of excitability, including epilepsy, chronic pain, myotonia, and cardiac arrhythmias. Understanding the functional consequences of the disease-causing mutations is likely to provide invaluable insight into the roles that VGSCs play in normal and abnormal excitability. Here, we sought to test the hypothesis that disease-causing mutations lead to increased resurgent currents, unusual sodium currents that have not previously been implicated in disorders of excitability. We demonstrated that a paroxysmal extreme pain disorder (PEPD) mutation in the human peripheral neuronal sodium channel Nav1.7, a paramyotonia congenita (PMC) mutation in the human skeletal muscle sodium channel Nav1.4, and a long-QT3/SIDS mutation in the human cardiac sodium channel Nav1.5 all substantially increased the amplitude of resurgent sodium currents in an optimized adult rat-derived dorsal root ganglion neuronal expression system. Computer simulations indicated that resurgent currents associated with the Nav1.7 mutation could induce high-frequency action potential firing in nociceptive neurons and that resurgent currents associated with the Nav1.5 mutation could broaden the action potential in cardiac myocytes. These effects are consistent with the pathophysiology associated with the respective channelopathies. Our results indicate that resurgent currents are associated with multiple channelopathies and are likely to be important contributors to neuronal and muscle disorders of excitability.
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Affiliation(s)
- Brian W Jarecki
- Department of Pharmacology and Toxicology, Stark Neurosciences Research Institute, Indiana University School of Medicine, 950 Walnut Street, Indianapolis, Indiana 46202, USA
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Skeletal muscle channelopathies: new insights into the periodic paralyses and nondystrophic myotonias. Curr Opin Neurol 2009; 22:524-31. [PMID: 19571750 DOI: 10.1097/wco.0b013e32832efa8f] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
PURPOSE OF REVIEW To summarize advances in our understanding of the clinical phenotypes, genetics, and molecular pathophysiology of the periodic paralyses, the nondystrophic myotonias, and other muscle channelopathies. RECENT FINDINGS The number of pathogenic mutations causing periodic paralysis, nondystrophic myotonias, and ryanodinopathies continues to grow with the advent of exon hierarchy analysis strategies for genetic screening and better understanding and recognition of disease phenotypes. Recent studies have expanded and clarified the role of gating pore current in channelopathy pathogenesis. It has been shown that the gating pore current can account for the molecular and phenotypic diseases observed in the muscle sodium channelopathies, and, given that homologous residues are affected in mutations of calcium channels, it is possible that pore leak represents a pathomechanism applicable to many channel diseases. Improvements in treatment of the muscle channelopathies are on the horizon. A randomized controlled trial has been initiated for the study of mexiletine in nondystrophic myotonias. The class IC antiarrhythmia drug flecainide has been shown to depress ventricular ectopy and improve exercise capacity in patients with Andersen-Tawil syndrome. SUMMARY Recent studies have expanded our understanding of gating pore current as a disease-causing mechanism in the muscle channelopathies and have allowed new correlations to be drawn between disease genotype and phenotype.
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Parness J, Bandschapp O, Girard T. The Myotonias and Susceptibility to Malignant Hyperthermia. Anesth Analg 2009; 109:1054-64. [DOI: 10.1213/ane.0b013e3181a7c8e5] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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Kubota T, Kinoshita M, Sasaki R, Aoike F, Takahashi MP, Sakoda S, Hirose K. New mutation of the Na channel in the severe form of potassium-aggravated myotonia. Muscle Nerve 2009; 39:666-73. [PMID: 19347921 DOI: 10.1002/mus.21155] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Myotonia manifests in several hereditary diseases, including hyperkalemic periodic paralysis (HyperPP), paramyotonia congenita (PMC), and potassium-aggravated myotonia (PAM). These are allelic disorders originating from missense mutations in the gene that codes the skeletal muscle sodium channel, Nav1.4. Moreover, a severe form of PAM has been designated as myotonia permanens. A new mutation of Nav1.4, Q1633E, was identified in a Japanese family presenting with the PAM phenotype. The proband suffered from cyanotic attacks during infancy. The mutated amino acid residue is located on the EF-hand calcium-binding motif in the intracellular C-terminus. A functional analysis of the mutant channel using the voltage-clamp method revealed disruption of fast inactivation, a slower rate of current decay, and a depolarized shift in the voltage dependence of availability. This study has identified a new mutation of PAM with a severe phenotype and emphasizes the importance of the C-terminus for fast inactivation of the sodium channel. Muscle Nerve 39: 666-673, 2009.
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Affiliation(s)
- Tomoya Kubota
- Department of Neurology, Osaka University Graduate School of Medicine, Osaka, Japan
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Dupré N, Chrestian N, Bouchard JP, Rossignol E, Brunet D, Sternberg D, Brais B, Mathieu J, Puymirat J. Clinical, electrophysiologic, and genetic study of non-dystrophic myotonia in French-Canadians. Neuromuscul Disord 2009; 19:330-4. [DOI: 10.1016/j.nmd.2008.01.007] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2007] [Revised: 01/17/2008] [Accepted: 01/25/2008] [Indexed: 10/22/2022]
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Trip J, de Vries J, Drost G, Ginjaar HB, van Engelen BGM, Faber CG. Health status in non-dystrophic myotonias: close relation with pain and fatigue. J Neurol 2009; 256:939-47. [PMID: 19252786 PMCID: PMC2698970 DOI: 10.1007/s00415-009-5049-y] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2008] [Revised: 10/29/2008] [Accepted: 01/20/2009] [Indexed: 12/02/2022]
Abstract
To determine self-reported health status in non-dystrophic myotonias (NDM) and its relationship to painful myotonia and fatigue. In a cross-sectional study, 32 NDM patients with chloride and 30 with sodium channelopathies, all off treatment, completed a standardised interview, the fatigue assessment scale (FAS), and the 36-item Short-Form Health Survey (SF-36). Beside formal assessment of pain, assessment of painful or painless myotonia was determined. The domain scores of the SF-36 were compared with Dutch community scores. Apart from the relationship among SF-36 scores and (1) painful myotonia and (2) fatigue, regression analyses in both NDM groups were conducted to determine the strongest determinants of the SF-36 domains general health perception, physical component (PCS) and mental component summary (MCS). All physically oriented SF-36 domains in both NDM groups (P ≤ 0.01) and social functioning in the patients with sodium channelopathies (P = 0.048) were substantially lower relative to the Dutch community scores. The patients with painful myotonia (41.9%) scored substantially (P < 0.05) lower on most SF-36 domains than the patients without painful myotonia (58.1%). Fatigued patients (53.2%) scored substantially lower (P ≤ 0.01) on all SF-36 domains than their non-fatigued counterparts (46.8%). The regression analysis showed that fatigue was the strongest predictor for the general-health perception and painful myotonia for the physical-component summary. None of the patients showed below-norm scores on the domain mental-component summary. The impact of NDM on the physical domains of patients’ health status is substantial, and particularly painful myotonia and fatigue tend to impede their physical functioning.
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Affiliation(s)
- J Trip
- Department of Neurology, Maastricht University Medical Centre, P.O. Box 5800, 6202 AZ, Maastricht, The Netherlands.
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Affiliation(s)
- Abhijit Das
- Department of Neurology, Sree Chitra Tirunal Institute for Medical Sciences and Technology, Trivandrum, Kerala, India
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Thomas J, Tarleton J, Baker SK. Recessive CLCN1
mutation presenting as thomsen disease. Muscle Nerve 2008; 38:1515-1517. [DOI: 10.1002/mus.21121] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Neuromuscular and mitochondrial disorders: what is relevant to the anaesthesiologist? Curr Opin Anaesthesiol 2008; 21:350-5. [PMID: 18458553 DOI: 10.1097/aco.0b013e3282f82bcc] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
PURPOSE OF REVIEW The review provides an up-to-date information to the anaesthesiologist about the more frequent and important neuromuscular disorders for which new basic insights or clinical implications have been reported. RECENT FINDINGS The findings include the mechanisms of the hyperkalemia after succinylcholine in patients with upregulation of acetylcholine receptors. New insights into the mechanism of malignant hyperthermia-like reactions such as rhabdomyolysis during anaesthesia in patients with Duchenne muscular dystrophy have been published. The importance of mitochondrial defects and the effect of agents used in anaesthesia on mitochondrial function are also highlighted. SUMMARY The increased understanding of the genetics and pathophysiology of common muscle disorders may lead to a decrease in life-threatening complications related to surgery and anaesthesia. However, there is still a lack of prospective clinical studies to determine which is the safest anaesthetic technique for these patients.
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Burgunder JM, Huifang S, Beguin P, Baur R, Eng CS, Seet RC, Lim EC, Ong BK, Hunziker W, Sigel E. Novel chloride channel mutations leading to mild myotonia among Chinese. Neuromuscul Disord 2008; 18:633-40. [DOI: 10.1016/j.nmd.2008.05.007] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2007] [Revised: 05/10/2008] [Accepted: 05/15/2008] [Indexed: 10/21/2022]
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Abstract
OBJECTIVE To review the current knowledge about primary periodic paralyses (PPs). RESULTS Periodic paralyses are a heterogeneous group of disorders, clinically characterized by episodes of flaccid muscle weakness, occurring at irregular intervals. PPs are divided into primary (hereditary) and secondary (acquired) forms of which the secondary PPs are much more common than the primary PPs. Primary PPs are due to mutations in genes encoding for subunits of channel proteins of the skeletal muscle membrane, such as the muscular sodium, potassium or calcium channels, or the SCL4A1 protein. Primary PPs include entities such as hyperkalemic PP, hypokalemic PP, paramyotonia congenita von Eulenburg, Andersen's syndrome, thyrotoxic PP, distal renal tubular acidosis, X-linked episodic muscle weakness syndrome and congenital myasthenic syndromes. Attacks of weakness or myotonia may be triggered or enhanced by vigorous exercise, cold, potassium-rich food, emotional stress, drugs such as glucocorticosteroids, insulin or diuretics, or pregnancy. Depending on the pathomechanism, episodes of weakness may respond to mild exercise, ingestion of potassium, carbohydrates, salbutamol, calcium gluconate, thiazide diuretics, carboanhydrase inhibitors, such as acetazolamide or dichlorphenamine, and episodes may be prevented by avoidance of potassium-rich food, or drugs, which increase serum potassium. CONCLUSION This review presents and discusses current knowledge and recent advances in the etiology, molecular genetics, genotype-phenotype correlations, pathogenesis, diagnosis and treatment of primary PPs.
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Affiliation(s)
- J Finsterer
- Neurological Department, Krankenanstalt Rudolfstiftung, Vienna, Austria.
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