The clinical features of 101 patients with idiopathic generalized epilepsy beginning in adolescence were studied by standardized interview at the Department of Neurology, Austin Hospital, and the Department of Medicine, The University of Melbourne, Australia. Nonconvulsive seizures (myoclonic or absence) occurred in 84 patients, of whom 75 also had generalized tonic clonic seizures (GTCS). GTCS occurred alone in 17 patients. A group with myoclonic but not absence seizures (21 patients) corresponded to the ILAE syndrome of juvenile myoclonic epilepsy. A group with absence but not myoclonic seizures (37) resembled juvenile absence epilepsy. A group of 26 patients shared the features of juvenile myoclonic and juvenile absence epilepsies. Epilepsy with GTCS on awakening was not a specific entity. Seven patients with only GTCS, occurring neither on awakening nor in the evening period of relaxation, were not included in the current ILAE syndrome classification. 
COMMENT. The authors conclude that some patients with idiopathic generalized epilepsy of adolescence are not included in the current ILAE syndromic classification and those that correspond to classified syndromes show overlap, suggesting genetic relationships. A substantial group of patients shared features of both juvenile myoclonic and juvenile absence epilepsies.