High Quality Content by WIKIPEDIA articles! Juvenile myoclonic epilepsy (JME), also known as Janz syndrome, is a fairly common form of idiopathic generalized epilepsy, representing 5-10% of all epilepsies. This disorder typically first manifests itself between the ages of 12 and 18 with myoclonus occurring early in the morning. Most patients also have tonic-clonic seizures and many also have absence seizures. Linkage studies have demonstrated at least 6 loci for JME, 4 with known causative genes. Most of these genes are ion channels with the one non-ion channel gene having been shown to affect ion channel currents.