Generalized epilepsy with febrile seizures plus (GEFS+) is a syndromic autosomal dominant disorder where affected individuals can exhibit numerous epilepsy phenotypes.[1] GEFS+ can persist beyond early childhood (i.e., 6 years of age). GEFS+ is also now believed to encompass three other epilepsy disorders: severe myoclonic epilepsy of infancy (SMEI), which is also known as Dravet's syndrome, borderline SMEI (SMEB), and intractable epilepsy of childhood (IEC).[2][3] There are at least six types of GEFS+, delineated by their causative gene. Known causative gene mutations are in the sodium channel ¦Á subunit genes SCN1A, an associated ¦Â subunit SCN1B, and in a GABAA receptor ¦Ã subunit gene, in GABRG2 and there is another gene related with calcium channel the PCDH19 which is also known as Epilepsy Female with Mental Retardation.[4] Penetrance for this disorder is estimated at 60%.[5]

Reference
Wiki: Intractable childhood epilepsy with generalized tonic-clonic seizures