Kawamura Shuji, Ikeda Yoshio, Tomita Koji, Watanabe Nobuaki, Seki Kouichi
Department of Internal Medicine, Hyogo Prefectural Nishinomiya Hospital, Nishinomiya.
Intern Med. 2004 Mar;43(3):218-22. doi: 10.2169/internalmedicine.43.218.
Familial hypokalemic periodic paralysis is an autosomal dominant genetic muscle disease characterized by periodic attacks of muscle weakness associated with a decrease in serum potassium. There are two major missense mutation sites in the calcium channel alpha1 subunit (CACNA1S) gene in these patients. We recently encountered a 13-year-old Japanese boy who had collapsed following exercise and was found to have a low serum potassium level. Clinical and genetic studies including exploration of his family tree proved that he and his maternal relatives had the disease with the missense mutation, Arg528His (CGC --> CAC). However, his mother and grandmother had no symptoms of the disease, indicating reduced penetrance in female carriers. Sexual difference in the penetrance of this disease and the association between the clinical symptoms and the types of genetic defects are discussed.
家族性低钾性周期性麻痹是一种常染色体显性遗传肌肉疾病，其特征为与血清钾降低相关的周期性肌无力发作。这些患者的钙通道α1亚基（CACNA1S）基因中有两个主要的错义突变位点。我们最近遇到一名13岁的日本男孩，他在运动后晕倒，发现血清钾水平较低。包括探索其家族谱系在内的临床和基因研究证明，他和他的母系亲属患有该疾病且存在错义突变，即Arg528His（CGC --> CAC）。然而，他的母亲和祖母没有该疾病的症状，这表明女性携带者的外显率降低。本文讨论了该疾病外显率的性别差异以及临床症状与基因缺陷类型之间的关联。
