[Genetics of epilepsy].

Epilepsy is a common neurological disease and encompasses a variety of disorders with paroxysms. Although there is a genetic component in the pathogenesis of epilepsy, the molecular mechanisms of this syndrome remain poorly understood. The identification of genes responsible for human epilepsy was first documented in progressive myoclonic epilepsy (EPM) because of their clear inheritance and phenotypic presentation. EPM is characterized by frequent myoclonic jerks and cumulative neurological deterioration and includes MERRF, a mitochondrial disease and DRPLA, a triplet disorder. The genes responsible for EPM seem to participate in the maintenance of cell viability. Genetic defects have been recently identified also for some familial epilepsy in which the phenotypes are similar to common idiopathic epilepsies. Defects of neuronal nicotinic acetylcholine receptor, a ligand-gated ion channel, caused nocturnal frontal lobe epilepsy. Mutations of two K(+)-channel genes were identified in benign familial neonatal convulsions. Mutations in the voltage-gated Na(+)-channel alpha 1, 2 and beta 1 and the GABAA receptor gamma 2 subunit genes were found as a cause of dominant epilepsy with febrile seizures plus, a clinical subset of febrile seizures. Abnormalities of Na(+)-channel alpha 1 subunit were also associated with severe myoclonic epilepsy in infancy. Other genes encoding ion channels expressed in the brain were also found to be associated with other familial epilepsy. This line of evidence suggests the involvement of channels expressed in the brain in the pathogenesis of certain idiopathic epilepsy, albeit there are a few exceptions that abnormalities of non-channel molecules have been found to be associated with idiopathic epilepsy.