Abstract：
Myotonia congenita (MC) is a rare genetic disease caused by mutations in the skeletal muscle chloride channel gene (CLCN1), encoding the voltage-gated chloride channel ClC-1 in skeletal muscle. Our study reported the clinical and molecular characteristics of six patients with MC and systematically review the literature on Chinese people. We retrospectively analyzed demographics, clinical features, family history, creatine kinase (CK), electromyography (EMG), treatment, and genotype data of our patients and reviewed the clinical data and CLCN1 mutations in literature. The median ages at examination and onset were 26.5 years (range 11-50 years) and 6.5 years (range 1.5-11 years), respectively, in our patients, and 21 years (range 3.5-65 years, n = 45) and 9 years (range 0.5-26 years, n = 50), respectively, in literature. Similar to previous reports, myotonia involved limb, lids, masticatory, and trunk muscles to varying degrees. Warm-up phenomenon (5/6), percussion myotonia (3/5), and grip myotonia (6/6) were common. Menstruation triggered myotonia in females, not observed in Chinese patients before. The proportion of abnormal CK levels (4/5) was higher than data from literature. Electromyography performed in six patients revealed myotonic changes (100%). Five novel CLCN1 mutations, including a splicing mutation (c.853 + 4A>G), a deletion mutation (c.2010_2014del), and three missense mutations (c.2527C>T, c.1727C>T, c.2017 G > C), were identified. The c.892 G > A (p.A298T) mutation was the most frequent mutation in the Chinese population. Our study expanded the clinical and genetic spectrum of patients with MC in the China. The MC phenotype in Chinese people is not different from that found in the West, while the genotype is different.
摘要：
先天性肌强直（MC）是一种罕见的遗传性疾病，由骨骼肌氯离子通道基因（CLCN1）突变引起，在骨骼肌中编码电压门控氯通道ClC-1。我们的研究报告了6例MC患者的临床和分子特征，并系统回顾了有关中国人的文献。我们回顾性分析了人口统计学，临床特征,家族史,肌酸激酶（CK），肌电图（EMG），治疗,和我们患者的基因型数据，并回顾了文献中的临床数据和CLCN1突变。检查和发病时的中位年龄为26.5岁（范围11-50岁）和6.5岁（范围1.5-11岁），分别,在我们的病人身上，和21年(范围3.5-65年，n=45)和9年(范围0.5-26年，n=50),分别,在文学中。与以前的报道类似，肌强直累及肢体，盖子,咀嚼,和不同程度的躯干肌肉。预热现象（5/6），打击乐肌强直（3/5），和抓地力肌强直（6/6）是常见的。月经引发女性肌强直，以前在中国患者中没有观察到。CK水平异常的比例（4/5）高于文献数据。对六名患者进行的肌电图检查显示肌强直变化（100％）。五个新的CLCN1突变，包括剪接突变（c.853+4A>G），缺失突变（c.2010_2014del），和三个错义突变(c.2527C>T，c.1727C>T，c.2017G>C)，已确定。c.892G>A（p。A298T）突变是中国人群中最常见的突变。我们的研究扩展了中国MC患者的临床和遗传谱。中国人的MC表型与西方没有什么不同，而基因型不同。
