Original Article The association of three BACE1 gene polymorphisms (exon5 C/G, intron 5 T/G and 3'UTR T/A) with sporadic Alzheimer's disease susceptibility: a meta-analysis

Despite biological support for a role of Beta-site APP-cleaving enzyme 1 (BACE1) in sporadic Alzheimer's disease (SAD), studies about the BACE1 genetic polymorphisms in SAD are inconsistent. To explore whether the BACE1 polymorphisms confers susceptibility to SAD, the current meta-analysis was conducted to evaluate the gene- disease association in relevant studies. The serious databases were researched to identify studies. The association between BACE1 (exon5 C/G, intron 5 T/G or 3'UTR T/A) polymorphism and SAD risk was evaluated by odds ratios (ORs) together with their 95% confidence intervals (CIs). The combined results showed no significant difference in all models on the basis of all studies for BACE1 (exon5 C/G, intron 5 T/G or 3'UTR T/A) polymorphisms. When subgroup analysis was performed based on ethnicity and the epsilon 4 allele of apolipoprotein E (APOEe4) carriers status, significant associations were demonstrated (CC versus CG+GG: OR=1.37, 95% CI=1.04-1.82, P=0.03<0.05 and CC versus CG: OR=1.49, 95% CI=1.11-2.01, P=0.01<0.05) for APOEe4 carriers status. The pooled results sug- gest the BACE1 (exon5 C/G, intron 5 T/G or 3'UTR T/A) polymorphism could be not a risk factor for SAD. However, individuals with CC genotype have higher risk of SAD with APOEe4 carrier status, and gene-gene interaction might affect on the association. Further studies with large sample size, especially in subgroup analysis, should be done to confirm these findings.