The p-value for the GABRA2 A2-4 (G-T-A) haplotype (p=0.00019) can be compared to that for the 6-SNP H8 haplotype: T-G-C-G-T-A (Table 4), which includes rs1497571, rs10938426, rs10033451, rs567926, rs279869, and rs279837, and yielded a p-value of 0.0033) (OR=2.63; 95%CI=1.32-5.54). It should be noted that the 6-SNP H8 haplotype was the only 6-SNP haplotype carrying the A2-4 (GTA) GABRA2 haplotype associated to AD. The GABRG1 component (G1-1, TGC) of this 6-SNP haplotype did not show any association to AD alone (Table 2). In conclusion, the findings reported here in an AA sample are globally consistent with the findings obtained previously by Covault et al., (2008) in EAs. Specifically, it appears that GABRG1 and GABRA2 genes are interrelated or that independent risk loci for AD exist in each of them. Previous studies have suggested an association of AD with either GABRA2 (Covault et al., 2004; Edenberg et al., 2004; Lappalainen et al., 2005) or GABRG1 (Covault et al., 2008; Enoch et al., 2009) markers. In our study, GABRA2 haplotypes accounted for most of the association signal and joint effects of the two
