Channelopathies: ion channel defects linked to heritable clinical disorders

Electrical signals are critical for the function of neurones, muscle cells, and cardiac myocytes. Proteins that regulate electrical signalling in these cells, including voltage gated ion channels, are logical sites where abnormality might lead to disease. Genetic and biophysical approaches are being used to show that several disorders result from mutations in voltage gated ion channels. Understanding gained from early studies on the pathogenesis of a group of muscle diseases that are similar in their episodic nature (periodic paralysis) showed that these disorders result from mutations in a gene encoding a voltage gated Na(+) channel. Their characterisation as channelopathies has served as a paradigm for other episodic disorders. For example, migraine headache and some forms of epilepsy have been shown to result from mutations in voltage gated Ca(2+) channel genes, while long QT syndrome is known to result from mutations in either K(+) or Na(+) channel genes. This article reviews progress made in the complementary fields of molecular genetics and cellular electrophysiology which has led to a better understanding of voltage gated ion channelopathies in humans and mice.