Angiotensin-converting enzyme gene polymorphisms and risk for sporadic Alzheimer's disease: a meta-analysis

Numerous studies have tested for associations between common polymorphisms of the angiotensin-converting enzyme gene and sporadic Alzheimer disease (SAD), but results have been inconclusive. Using meta-analysis, our study aimed to clarify the nature of the genetic risks contributed by the three polymorphisms (rs4291, rs4343, rs1800764) for developing SAD. Through searching of Pubmed, Embase, Alzgene and manually searching relevant references, a total of 14 articles with 26 independent studies were included. Odds ratios (ORs) with 95% confidence intervals (CIs) were used to assess the strength of the association studies. The heterogeneity across the studies was tested, as was publication bias. We observed significant association between SNP rs4291 and SAD using allelic comparison (OR = 1.08, 95% CI 1.03-1.14), homozygote comparison (OR = 1.16, 95% CI 1.04-1.30) and the recessive model (OR = 1.10, 95% CI 1.02-1.18). Association with SNP rs1800764 was revealed but it was not sufficiently robust to withstand the Benjamini-Hochberg method and stepdown Bonferroni correction. Significant association was not identified in the analysis for SNP rs4343. In subgroup analyses, the risk of SAD associated with SNP rs4291 appeared to be significant among Caucasians and in older cases (mean age ≥75 years). Our results confirmed a significant but modest association between SNP rs4291 and SAD susceptibility. Further study of the pathogenetic characteristics of this polymorphism and independent confirmation of the association in larger studies are warranted.