Several issues prompted us to carry out the present meta-analysis. First, it is difficult to determine the effect of the minor allele without using a large sample, which can most readily be obtained by meta-analysis. Second, rates of AD differ across population subgroups, even within Asian populations, and this is further complicated because of the consequences of differing sampling strategies. Third, many new studies have been reported from various populations in recent years since the previous meta-analyses (Luczak et al. 2006; Zintzaras et al. 2006). Therefore, based on these factors together with the well known critical role of the gene product in alcohol and acetaldehyde metabolism and the fact that the SNP is known to alter protein activity, we performed a comprehensive meta-analysis of the ALDH2 gene with AD as well as alcohol-induced diseases including alcohol liver disease, cirrhosis, and pancreatitis, based on all identifiable published studies in both English and Chinese publications, to update the association and to compare the results with those previously described.
