Meta-analysis of aldehyde dehydrogenase 2 gene polymorphism and Alzheimer's disease in East Asians.

Background: The association of genetic polymorphism of mitochondrial aldehyde dehydrogenase 2 ( ALDH2 ) and Alzheimer's disease (AD) has been controversial and has been investigated only in several small-sample studies. In the present study, we performed a meta-analysis to evaluate the cross-sectional association of ALDH2 variants and AD risk in East Asian populations. Methods: Trials were retrieved through MEDLINE, EMBASE, J-STAGE and the China National Knowledge Internet databases (from January 1, 1994 to November 1, 2010) without any restriction on language. Data were abstracted by a standardized protocol. Results: We found four studies of 821AD patients and 1380 healthy controls that qualified for the analysis. The variant ALDH2 genotype GA/AA was not associated with increased AD risk (odds ratio (OR) = 1.35; 95% confidence interval (CI) = 0.75-2.42; p = 0.32), even after stratification for the status of apolipoprotein E epsilon 4 allele. However, in the subgroup analyses, the association was significant for men (OR = 1.72; 95% CI = 1.10-2.67; p = 0.02). Conclusions: This study adds to the evidence that ALDH2 GA/AA genotype increases the risk of AD among East Asian men, although the effect size is moderate.