PDF(Pubmed)
Abstract：
Non-dystrophic myotonia (NDM) is a group of rare mono-genetic muscle disorders caused by skeletal muscle sodium or chloride channelopathies. These disorders are characterized by high muscle tone and the inability of the muscles to relax spontaneously after voluntary contraction. Myotonia congenita refers to a form of NDM that typically manifests during the later stages of childhood. It occurs as a result of genetic mutations affecting the chloride channels found in the sarcolemma membrane of skeletal muscles. Here, we present a case series of two male siblings born out of third-degree consanguineous union ages 10 and eight years, respectively, who presented with proximal muscle weakness and the characteristic \"Herculean body\" appearance. They demonstrated characteristic clinical diagnostic signs of myotonia. The diagnosis of myotonia congenita was confirmed through distinctive electromyography (EMG) findings, which were further supported by genetic testing revealing a homozygous mutation c.1445G>A in exon 13 of the CLCN1 gene, indicating autosomal recessive inheritance. This uncommon condition exhibits characteristic clinical manifestations and classical EMG findings, which are difficult to disregard once encountered. Genetic tests serve as a valuable tool to validate the diagnosis.
摘要：
非营养不良性肌强直（NDM）是一组罕见的由骨骼肌钠或氯通道病引起的单遗传肌肉疾病。这些疾病的特征是高肌肉张力和肌肉在随意收缩后不能自发放松。先天性肌强直是指通常在儿童后期表现的NDM形式。它是由于基因突变影响骨骼肌肌膜中发现的氯化物通道而发生的。这里,我们提供了一系列案例，其中包括两个年龄分别为10岁和8岁的三度近亲联盟出生的男性兄弟姐妹，分别,表现为近端肌肉无力和特征性的“难以捉摸的身体”外观。他们证明了肌强直的特征性临床诊断体征。先天性肌强直的诊断通过独特的肌电图（EMG）检查结果得到证实，遗传检测进一步支持了CLCN1基因第13外显子的纯合突变c.1445G>A，表明常染色体隐性遗传。这种罕见的情况表现出特征性的临床表现和经典的EMG表现，一旦遇到就很难忽视。基因测试是验证诊断的有价值的工具。
