Forty-three SNPs in the NTAD gene cluster were selected (cf. Gelernter et al., 2006). These 43 SNPs (Figure 1(A)) were designated in sequence order (from the 5′ end of NCAM1 to the 5′ end of DRD2) as N1-N17 (mapped to NCAM1, 5′ to 3′), N18-N19 and T1-T2 (intergenic between NCAM1 and TTC12), T3-T9 (mapped to TTC12, 5′ to 3′), T10 (intergenic between TTC12 and ANKK1), A1-A7 (mapped to ANKK1, 5′ to 3′), D1-D4 (mapped to DRD2, 3′ to 5′), and D5-D7 (intergenic, 5′ to DRD2; for details refer to online supplemental Table 1). SNPs were genotyped as described previously (Gelernter et al., 2006). In addition, 37 ancestry informative markers (AIMs), as discussed in Yang et al. (2005a, 2005b), including 36 short tandem repeat (STR) markers and one SNP (rs2814778) in the Duffy antigen (FY) gene were genotyped in all cases and controls to infer ancestry. Two markers did not pass the HWE test. They are SNP N4 (p-value = 7.6×10−5) only in the control sample and SNP A4 (p-value = 2.3×10−6) only in the AD-only sample. Since causal variants in
