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 loci. Inspection of the LD patterns in EA and AA populations (Ittiwut et al., 2008) suggests that the effects of these two loci are very difficult to disentangle, by study of EA samples alone. Because there is much less LD in AAs, we sought to distinguish effects of the two loci by studying association with AD in this population group. We found evidence for association with markers in both genes, but the evidence for GABRA2 was much stronger. This demonstrates the utility of using a low-LD population to resolve an issue of fine-scale LD mapping.
