Muscle channelopathies

Suetterlin, KJ; Hanna, MG

doi:10.1002/9781118777329.ch116

Muscle channelopathies

Lookup NU author(s): Dr Karen Suetterlin ORCiD, Professor Michael Hanna

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Abstract

The skeletal muscle channelopathies are a rare group of genetic dis-orders whose muscular manifestations range from pure myotonia to myotonia with episodes of weakness or flaccid paralysis to episodes of weakness or flaccid paralysis alone. The non-dystropic myotonias (NDMs) include myotonia congenital (MC), paramyotonia congenita (PMC), and sodium channel myotonia (SCM). Mutations can be inherited in a dominant or recessive manner and for some mutations both modes of inheritance have been observed. MC and SCM are caused by missense mutations in SCN4A, the gene encoding the alpha subunit of the skeletal muscle voltage-gated sodium channel. The common pathomechanism for the attacks of weakness in primary periodic paralyses is prolonged sarcolemmal depolarization inactivating mutant and wild-type sodium channels with subsequent failure of action potential propagation. Improved understanding of the pathogenesis of the skeletal muscle channelopathies has translated into better patient care and new therapeutics are in the developmental pipeline.