No significant association between a PS-1 intronic polymorphism and dementia in Down's syndrome

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.