Akie Okayama
Japan
Case Report
A Novel Mutation in the SCN4A Gene in a Japanese Family with Paramyotonia Congenita
Author(s): Satoru Takahashi, Shiho Yamamoto, Ryosuke Tanaka, Akie Okayama, Akiko Araki, Hiroki Kajino and Hiroshi AzumaSatoru Takahashi, Shiho Yamamoto, Ryosuke Tanaka, Akie Okayama, Akiko Araki, Hiroki Kajino and Hiroshi Azuma
Paramyotoniacongenita is an autosomal-dominant muscle disease caused by missense mutations in SCN4A, the
gene enconding the alpha subunit of skeletal muscle sodium channel. It is clinically characterized by paradoxical
myotonia, an attack of muscle stiffness that is aggravated by repeated activity, as well by cold-induced muscle
stiffness. We describe the clinical and genetic features of a Japanese family with Paramyotoniacongenita. Five
members of this family (four generations) were affected. Treatment with mexiletine, an antiarrhythmic drug that
inhibits inward sodium current, relieved their symptoms. We identified a novel SCN4A mutation (c.3470T>A,
p.Ile1157Asn) in the affected individuals. This mutation is located on the cytoplasmic loop connecting the transmembrane
segments S4 and S5 of domain 3 of the sodium channel, the site f.. View More»
