While previous studies have found that both haplotype blocks were associated with AD, this study only found significant associations between the SNP in the 3′ haplotype block (rs1497571) and alcohol use and low response to alcohol. Given that the sample size and resulting statistical power is lower in this study compared with previous large-scale trials, as demonstrated by the power analysis reported in Table 2, this discrepancy might suggest that the signal for the 3′ SNP is strong enough to be detected, while power may be simply inadequate for detecting an association for the rs1391166 SNP. Certainly, the lack of association for rs1391166 in this study should not be viewed as a strong contradiction of previous findings of an association between that haplotype block and AD considering the difference in statistical power and phenotypes between this study and previous reports.
