A novel muscle sodium channel mutation causes painful congenital myotonia.
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Rosenfeld J, Sloan-Brown K, George AL Jr
A novel muscle sodium channel mutation causes painful congenital myotonia.
Ann Neurol. 1997 Nov;42(5):811-4.
- PubMed ID
- 9392583 [ View in PubMed]
- Abstract
Mutations in the skeletal muscle voltage-gated sodium channel alpha-subunit gene (SCN4A) have been associated with a spectrum of inherited nondystrophic myotonias and periodic paralyses. Most disease-associated SCN4A alleles occur in portions of the gene that encode the third and fourth repeat domains with the conspicuous absence of mutations in domain 1. Here we describe a family segregating an unusual autosomal dominant congenital myotonia associated with debilitating pain especially severe in the intercostal muscles. A novel SCN4A mutation causing the replacement of Val445 in the sixth transmembrane segment of domain 1 with methionine was discovered in all affected individuals and is the likely genetic basis for the syndrome. Myotonia was resistant to treatment; however, the most severely affected family member responded dramatically to the sodium channel blocking agent flecainide.