Epilepsy and ionic channels

Ion channels play critical roles in a broad range of physiological processes. In particular, they represent a common basis for the excitable properties of different tissues. Consequently, ion channels of many different types have been implicated in several human genetic disorders of the heart, brain and skeletal muscle. An increasing number of genes encoding neurotransmitter- or voltage-gated ion channel subunits have proved to be mutated in various idiopathic human epilepsies as well as in different animal models. The epilepsies could thus be considered as one of many paroxysmal disorders that are due to mutations in ion channel genes, the so-called channelopathies. However, recent data supported the hypothesis that other genes with different properties could also be responsible for human idiopathic epilepsies, thus opening new and exciting areas of research. Effort is still needed to identify the genes responsible for the large variety of other epileptic disorders inherited as Mendelian traits and evaluate the role of these genes in the more common and polygenic forms. Defining the genetic bases of the latter will also require that exhaustive association studies are performed. These studies may help understand the pathophysiology of human epilepsies and represent the first step towards the discovery of new therapeutic targets, as exemplified in the case of the KCNQ potassium channels.