A recent observation has shown a genetic association between an intron
ic polymorphism in the Presenilin-1 (PS-1) gene and late onset Alzheim
er's disease (AD). The homozygosity of the 1 allele in the PS-1 gene w
as associated with a doubling of the risk for late onset AD. However,
contrasting results have been published. We analyzed the distribution
of the PS-1 intronic polymorphism in patients with sporadic AD and in
seven familial AD (FAD) families carrying pathogenetic mutations in th
e amyloid precursor protein (APP) and Presenilin (PS-1 and PS-2) genes
. Significant differences in PS-1 allele frequencies were observed in
the Presenilin genes mutated families but not in late onset AD patient
s and in APP mutated families. (C) 1997 Elsevier Science Ireland Ltd.