Ion channel mutations affecting muscle and brain.

Voltage-gated ion channels control many aspects of signal transduction in both muscle and nerve. These channels are finely tuned, and either increased or decreased channel activity can adversely affect function. In skeletal muscle, mutations in ion channel genes have been shown to cause both myotonic discharges and episodic paralysis. In cardiac muscle, mutations in related ion channels can produce repolarization defects and fatal arrhythmias. During the past 2 years, a new chapter in the channelopathy story has been opened with the identification of ion channel mutations in the brain that cause disorders ranging from episodic ataxia to epilepsy.