Advances on the genetics of Mendelian idiopathic epilepsies

Genetic factors play an increasingly recognized role in idiopathic epilepsies. Since 1995, positional cloning strategies in multigenerational families with autosomal dominant transmission have revealed 11 genes (KCNQ2, KCNQ3, CHRNA4, CHRNA2, CHRNB2, SCN1B, SCN1A, SCN2A, GABRG2, GABRA1, and LGI1) and numerous loci for febrile seizures and epilepsies. To date, all genes with the exception of LGI1, encode neuronal ion channel or neurotransmitter receptor subunits. Molecular approaches have revealed great genetic heterogeneity, with most genes remaining to be identified. One of the major challenges is now to understand phenotype-genotype correlations. This review focuses on the current knowledge on the molecular basis of these rare mendelian autosomal dominant forms of idiopathic epilepsies.