Genetic factors play an increasingly recognized role in idiopathic epilepsies. Positional cloning strategies in multigenerational families with autosomal dominant transmission have revealed several genes. Most of epilepsy-genes encode ion channels subunits or receptors for neurotransmitters: voltage-gated potassium channels (KCNQ2, KCNQ3) for benign familial neonatal seizures; voltage-gated sodium channel subunits (SCN1B, SCN1A, SCN2A) in generalized epilepsy with febrile seizures plus (GEFS +), severe myoclonic epilepsy of infancy or Dravet syndrome and benign familial neonatal-infantile seizures; nicotinic acetylcholine receptor subunits (CHRNA4, CHRNA2, CHRNB2) in autosomal dominant nocturnal frontal lobe epilepsy, and GABA A receptor subunits for GEFS+ and autosomal dominant juvenile myoclonic epilepsy.