Juvenile myoclonic epilepsy

Juvenile myoclonic epilepsy, also known as Janz syndrome or impulsive petit mal, is a hereditary, idiopathic generalized form of epilepsy that accounts for an estimated five to ten percent of all epilepsy cases. It typically first appears between the ages of twelve and eighteen with myoclonic seizures that most often occur after waking, in the evening, or when a person is sleep-deprived, and it is also marked by generalized tonic-clonic seizures, with a minority of patients also experiencing absence seizures. The condition was first described by Theodore Herpin in 1857, and research since the 1990s has identified more than twenty chromosomal loci and multiple genes associated with it, leading some researchers to describe it as a spectrum disorder given how genetically and clinically varied it is.