Clinical and molecular characteristics of myotonia congenita in China: Case series and a literature review

Li, Yifan; Li, Mao; Wang, Zhenfu; Yang, Fei; Wang, Hongfen; Bai, Xufeng; Sun, Bei; Chen, Siyu; Huang, Xusheng

doi:10.1080/19336950.2022.2041292

Cited by 5 publications

(3 citation statements)

References 41 publications

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“…The most frequently reported mutations for a recently published Chinese cohort were c.892 G>A (p.Ala298Thr), c.1679T>C (p.Met560Thr) and c.1657A>T (p.Ile553Phe) similar to the Japanese study. As discussed, the frequency of dominant and recessive forms and identified mutations display geographical differences [ 30 ].…”

Section: Discussionmentioning

confidence: 99%

Clinical and Genetic Spectrum of Myotonia Congenita in Turkish Children

Tunçer

Sanrı

AYDIN

et al. 2023

JND

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Background: Myotonia congenita is the most common form of nondystrophic myotonia and is caused by Mendelian inherited mutations in the CLCN1 gene encoding the voltage-gated chloride channel of skeletal muscle. Objective: The study aimed to describe the clinical and genetic spectrum of Myotonia congenita in a large pediatric cohort. Methods: Demographic, genetic, and clinical data of the patients aged under 18 years at time of first clinical attendance from 11 centers in different geographical regions of Türkiye were retrospectively investigated. Results: Fifty-four patients (mean age:15.2 years (±5.5), 76% males, with 85% Becker, 15% Thomsen form) from 40 families were included. Consanguineous marriage rate was 67%. 70,5% of patients had a family member with Myotonia congenita. The mean age of disease onset was 5.7 (±4.9) years. Overall 23 different mutations (2/23 were novel) were detected in 52 patients, and large exon deletions were identified in two siblings. Thomsen and Becker forms were observed concomitantly in one family. Carbamazepine (46.3%), mexiletine (27.8%), phenytoin (9.3%) were preferred for treatment. Conclusions: The clinical and genetic heterogeneity, as well as the limited response to current treatment options, constitutes an ongoing challenge. In our cohort, recessive Myotonia congenita was more frequent and novel mutations will contribute to the literature.

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Section: Discussionmentioning

confidence: 99%

Clinical and Genetic Spectrum of Myotonia Congenita in Turkish Children

Tunçer

Sanrı

AYDIN

et al. 2023

JND

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“…CLCN1 encodes the voltage-gated chloride channel (ClC-1), which is important for the normal repolarization of muscle action potential 7 and more than 250 variants have been reported to date, including deletions, insertions, splicing, nonsense and missense variants. 4,[8][9][10][11] Of those, 210 are linked to Becker disease, 25 to Thomsen and 15 to both the dominant and recessive forms, complicating final interpretation and genotype-phenotype correlations. [12][13][14] Differential diagnosis may be further complicated by variants in SCN4A, a gene responsible mainly for nondystrophic myotonias, including paramyotonia (PM; MIM no.…”

Section: Introductionmentioning

confidence: 99%

“…Pathogenic or likely pathogenic variants in the chloride voltage‐gated channel 1 ( CLCN1 ) gene, located on chromosome 7q34, cause both types of MC. CLCN1 encodes the voltage‐gated chloride channel (ClC‐1), which is important for the normal repolarization of muscle action potential 7 and more than 250 variants have been reported to date, including deletions, insertions, splicing, nonsense and missense variants 4,8–11 . Of those, ~210 are linked to Becker disease, 25 to Thomsen and 15 to both the dominant and recessive forms, complicating final interpretation and genotype–phenotype correlations 12–14 .…”

Section: Introductionmentioning

confidence: 99%

Myotonia congenita in a Greek cohort: Genotype spectrum and impact of the CLCN1:c.501C > G variant as a genetic modifier

Marinakis,

Svingou,

Papadimas

et al. 2024

Muscle and Nerve

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Introduction/AimsMyotonia congenita (MC) is the most common hereditary channelopathy in humans. Characterized by muscle stiffness, MC may be transmitted as either an autosomal dominant (Thomsen) or a recessive (Becker) disorder. MC is caused by variants in the voltage‐gated chloride channel 1 (CLCN1) gene, important for the normal repolarization of the muscle action potential. More than 250 disease‐causing variants in the CLCN1 gene have been reported. This study provides an MC genotype–phenotype spectrum in a large cohort of Greek patients and focuses on novel variants and disease epidemiology, including additional insights for the variant CLCN1:c.501C > G.MethodsSanger sequencing for the entire coding region of the CLCN1 gene was performed. Targeted segregation analysis of likely candidate variants in additional family members was performed. Variant classification was based on American College of Medical Genetics (ACMG) guidelines.ResultsSixty‐one patients from 47 unrelated families were identified, consisting of 51 probands with Becker MC (84%) and 10 with Thomsen MC (16%). Among the different variants detected, 11 were novel and 16 were previously reported. The three most prevalent variants were c.501C > G, c.2680C > T, and c.1649C > G. Additionally, c.501C > G was detected in seven Becker cases in‐cis with the c.1649C > G.DiscussionThe large number of patients in whom a diagnosis was established allowed the characterization of genotype–phenotype correlations with respect to both previously reported and novel findings. For the c.501C > G (p.Phe167Leu) variant a likely nonpathogenic property is suggested, as it only seems to act as an aggravating modifying factor in cases in which a pathogenic variant triggers phenotypic expression.

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Yanoff,

Sassani

2025

Ocular Pathology

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Clinical and molecular characteristics of myotonia congenita in China: Case series and a literature review

Cited by 5 publications

References 41 publications

Clinical and Genetic Spectrum of Myotonia Congenita in Turkish Children

Clinical and Genetic Spectrum of Myotonia Congenita in Turkish Children

Myotonia congenita in a Greek cohort: Genotype spectrum and impact of the CLCN1:c.501C > G variant as a genetic modifier

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