Polymorphisms in the presenilin 1 and presenilin 2 genes and risk for sporadic Alzheimer's disease

We examined the possible involvement of polymorphisms of the presenilin I ( PS1) and presenilin 2 (PS2) genes in the risk for sporadic Alzheimer's dise ase (AD), either through an independent effect or through interaction with the existing apolipoprotein E (ApoE) risk, in 211 AD cases and 188 age-matc hed control subjects. No significant differences were obtained in any of th e comparisons relating the effect of the PS1 and PS2 polymorphisms; thus, t hese polymorphisms do not appear to be sufficient risk factors by themselve s for sporadic AD. Although the ApoE epsilon 4 genotype is the only definit e predictor of risk, homozygosity for either the 1 allele of the PS1 or the C allele of the PS2 genes may increase the risk conferred by the presence of an ApoE epsilon 4 allele. Additionally, combination of PS1/11 and PS2/CC genotypes might have a small synergistic effect on the risk for AD. (C) 19 99 Elsevier Science B.V. All rights reserved.