A genome-wide scan of a large family with juvenile myoclonic epilepsy (JME), seen at the All India Institute of Medical Sciences, New Delhi, was conducted to test an hypothesis that 2 loci, one predisposing to generalized tonic clonic seizures (GTCS) and a second to myoclonic seizures (MS), would be present within the JME syndrome. A new locus for GTCS was identified at 10q25-q26, and analyses of this locus performed in 10 additional JME families showed evidence for linkage in 4. The findings show that this novel locus confers susceptibility to GTCS within the syndrome of JME. 
COMMENT. These findings show that a locus on chromosome 10q25-q26 confers susceptibility to GTCS within the genetic syndrome of juvenile myoclonic epilepsy. In support of the theory of two loci, one for GTCS and another for MS, within the JME syndrome is the clinical pattern of different ages of onset for these seizures. The syndrome commonly presents with absence seizures between 5 and 16 years, myoclonic jerks follow about 4 years later, usually around age 15 years, and GTCS are the last to appear, and mainly on awakening (Ped Neur Briefs June 1993) .