MYASTHENIA & RELATED DISORDERS: P.36 Novel SCN4A mutations causing mild myotonic phenotype

Abstract

Mutations in the sodium channel gene, SCN4A, encoding the Nav1.4 voltage-gated sodium channel, are well known causes of the skeletal muscle channelopathies: periodic paralyses (hyperkalemic, normokalemic, and hypokalemic periodic paralysis), paramyotonia congenita and other forms of myotonia. In addition, rare recessive SCN4A mutations have been associated with congenital myasthenic myopathy and congenital myopathy with hypotonia. To date over 40 dominant mutations in SCN4A have been reported to cause variable phenotypes depending on the type and location of the mutations.