THE GENETICS OF IDIOPATHIC GENERALIZED EPILEPSIES OF ADOLESCENT ONSET- DIFFERENCES BETWEEN JUVENILE MYOCLONIC EPILEPSY AND EPILEPSY WITH RANDOM GRAND-MAL AND WITH AWAKENING GRAND-MAL

Both linkage and association studies provide strong evidence that a ge ne locus on chromosome 6 is involved in the expression of juvenile myo clonic epilepsy (JME), an adolescent-onset form of primary idiopathic generalized epilepsy (IGE). This epilepsy-related gene locus, designat ed EJM-1, may also influence the expression of other forms of IGE. We report here evidence that at least one form of epilepsy that is simila r to JME-pure, adolescent-onset grand mal epilepsy in which the seizur es occur at any time during waking-is not linked to the EJM-1 locus. H owever, we also have evidence that another form of pure, adolescent-on set grand mal that occurs on awakening is linked to the EJM-1 locus an d may be genetically the same as JME. This work suggests that clinical ly similar epileptic syndromes may have different genetic bases and un derscores the critical importance of careful clinical observations in studying the genetics of the epilepsies.