Presenilin-1 (PS-1) intronic polymorphism is claimed to be a risk factor fo
r Alzheimer's disease (AD). The effect of PS-1 polymorphism on AD neuropath
ology of adults with Down's syndrome (DS) was studied by genotyping 26 deme
nted and 36 non-demented DS adults and comparing these findings with those
of two non-mentally retarded control groups (young and elderly). A total of
30.8% of the demented and 38.9% of the non-demented DS adults were homozyg
ous for allele 1. Frequencies for the 1-1 genotype in young and elderly con
trols were respectively 36.9% and 27.7%. No statistically significant diffe
rences were found in either allelic or genotypic distributions of the PS-1
polymorphism between demented and non-demented DS adults and the control gr
oups.