With the PGMDR method, we analyzed interactions for all possible combinations of two to seven SNPs within the CHRNA5/A3/B4 cluster. Table 6 shows the best interactive model for three ND measures in the AA and pooled samples. In the AA sample, we found the best interaction model for three loci (i.e., rs578776, rs3743078, and rs1317286 in CHRNA3) with a P value of 0.045 for HSI and 0.003 for FTND. For the four-locus model (i.e., rs684513 and rs615470 in CHRNA5; rs1317286 in CHRNA3; rs12441088 in CHRNB4), P values of 0.002 for SQ, 0.016 for HSI, and 0.041 for FTND were identified. Finally, for the six-locus model (i.e., rs684513 and rs621849 in CHRNA5; rs578776, rs1317286, and rs12914385 in CHRNA3; rs12441088 in CHRNB4), P values of 0.005 for SQ, 0.003 for HSI, and 0.044 for FTND were noted. All three models remained significant at the experiment-wide level for at least one ND measure.
