Evidence of genetic heterogeneity among the nondystrophic myotonias.

Ptacek, L J; Ziter, F A; Roberts, J W; Leppert, M F · Neurology · 1992

case_report · Level V

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Abstract

Recent in vitro electrophysiologic studies have demonstrated abnormal sodium channel gating in muscle from patients with Thomsen's disease and have called the chloride hypothesis into question. Abnormal sodium channel function, like myotonia, is a feature common to Thomsen's disease and several myotonias that are genetically linked to a chromosome-17q sodium channel locus. We present a pedigree segregating an allele for Thomsen's disease that is unlinked to this sodium channel locus, thus constituting evidence of genetic heterogeneity among the nondystrophic myotonias.

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