Leaky channels make weak muscles.

Mutations in the skeletal muscle voltage-gated calcium channel (CaV1.1) have been associated with hypokalemic periodic paralysis, but how the pathogenesis of this disorder relates to the functional consequences of mutations was unclear. In this issue of the JCI, Wu and colleagues recapitulate the disease by generating a novel knock-in CaV1.1 mutant mouse and use this model to investigate the cellular and molecular features of pathogenesis. They demonstrated an aberrant muscle cell current conducted through the CaV1.1 voltage-sensor domain (gating pore current) that explains an abnormally depolarized muscle membrane and the failure of muscle action potential firing during challenge with agents known to provoke periodic paralysis. Their work advances understanding of molecular and cellular mechanisms underlying an inherited channelopathy.