COMMON SUBTYPES OF IDIOPATHIC GENERALIZED EPILEPSIES - LACK OF LINKAGE TO D20S19 CLOSE TO CANDIDATE LOCI (EBN1, EEGV1) ON CHROMOSOME-20

Hereditary factors play a major role in the etiology of idiopathic gen eralized epilepsies (IGEs). A trait locus (EBN1) for a rare subtype of IGEs, the benign neonatal familial convulsions, and a susceptibility gene (EEGV1) for the common human low-voltage electroencephalogram hav e been mapped close together with D20S19 to the chromosomal region 20q 13.2. Both loci are potential candidates for the susceptibility to IGE spectra with age-related onset beyond the neonatal period, The presen t study tested the hypothesis that a putative susceptibility locus lin ked to D20S19 predisposes to spectra of IGEs with age-related onset fr om childhood to adolescence, Linkage analyses were conducted in 60 fam ilies ascertained through IGE patients with juvenile myoclonic epileps y, juvenile absence epilepsy or childhood absence epilepsy, Our result s provide evidence against linkage of a putative susceptibility gene f or four hierarchically broadened IGE spectra with D20S19 assuming tent ative single-locus genetic models, The extent of an ''exclusion region '' (led scores below - 2) varied from 0.5 cM up to 22 cM on either sid e of D20S19 depending on the trait assumed, These results are contrary to the expectation that a susceptibility gene in vicinity to D20S19 c onfers a common major gene effect to the expression of IGE spectra wit h age-related onset from childhood to adolescence. (C) 1996 Wiley-Liss , Inc.