A Novel Mutation in the SCN4A Gene in a Japanese Family with Paramyotonia CongenitaSatoru Takahashi1*, Shiho Yamamoto1, Ryosuke Tanaka1, Akie Okayama1, Akiko Araki1, Hiroki Kajino2 and Hiroshi Azuma1
- Corresponding Author:
- Satoru Takahashi
Department of Pediatrics
Asahikawa Medical University
Asahikawa 078-8510, Japan
E-mail: [email protected]
Received date: August 22, 2014; Accepted dat: September 22, 2014; Published date: September 28, 2014
Citation: Takahashi S, Yamamoto S, Tanaka R, Okayama A, Araki A, et al. (2014) A Novel Mutation in the SCN4A Gene in a Japanese Family with Paramyotonia Congenita. J Neurol Neurophysiol 5:233. doi:10.4172/2155-9562.1000233
Copyright: © 2014 Takahashi S, et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
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 for docking with its inactivation particle.
This mutation may cause the defective inactivation of the channel. Our observation provides a new insight into the
genotype-phenotype correlation in sodium channel opathies.