Case-control study of presenilin-1 intronic polymorphism in sporadic early and late onset Alzheimer's disease.

OBJECTIVE: Presenilin-1 is a major causative gene for early onset familial Alzheimer's disease, and the apolipoprotein E epsilon4 allele is a major genetic risk factor known to influence late onset and sporadic early onset Alzheimer's disease. The presenilin-1 1/1 genotype has recently been reported to be associated with sporadic Alzheimer's disease. The purpose of this study is to determine whether Alzheimer's disease is associated with presenilin-1 gene polymorphism and the apolipoprotein E genotype in an extended case-control study.
METHODS: An examination was conducted on 217 patients with Alzheimer's disease, along with an equal number of age and sex matched controls derived from the same community in a Japanese population, by using a chi2 test for homogeneity and a logistic regression analysis. A meta-analysis of data from the literature on allele frequencies in Alzheimer's disease and control populations was used for comparison with the Japanese allele frequencies obtained in this study.
RESULTS: The presenilin-1 allele-1 frequencies were similar in patients with early onset Alzheimer's disease (0.61) and younger controls (0.61), and in those with late onset Alzheimer's disease (0.63) and elderly controls (0. 63). We found no evidence for a possible association between the presenilin-1 polymorphism and the apolipoprotein E epsilon4 allele. However, the meta-analysis showed that the association between the presenilin-1 1/1 genotype and Alzheimer's disease was significant (Peto odds ratio=1.16, 95% confidence interval=1.04-1.31).
CONCLUSIONS: These results suggest a subtle but positive association of presenilin-1 gene polymorphism with Alzheimer's disease, although Japanese data in this study which failed to support such a relation would indicate an ethnic variation.