[Molecular genetic aspects of the susceptibility to develop idiopathic epilepsy]

There are more than 40 clinical types of epilepsy classified according to aetiology and/or mode of clinical onset. The term idiopathic epilepsy is reserved for cases with convulsions but no detectable structural lesions of the brain or neurological anomalies.

In spite of many studies confirming the importance of genetic factors in the occurrence of idiopathic epilepsy, these appear to be complex and probably involve a locus of variable expression or several loci with similar phenotype expression (epistaxis). Also, environmental factors have variable effects. In recent years the principal genes involved in susceptibility to develop epilepsy have been mapped. In this way one mitochondrial and three autosomic genes have been cloned as responsible for the development of certain forms of this disorder. Also several studies of genetic linkage have given evidence, sometimes inconsistent, regarding the influence of another five loci in the susceptibility to develop epilepsy (6p21.2, 6q23-25, 8q24, 8p, 10q). On occasions the same locus has been linked with different forms of epilepsy, and on other occasions one form of epilepsy has been shown to be linked to several loci.