< 0.001; MNWS: F(1,177)=63.01, P < 0.001). The change in BQSU, but not MNWS, in response to the nicotine infusion session differed by rs31746 genotype (genotype by time point interaction: BQSU: F(1,175)= 5.37, P = 0.022) (Figure 3A). There was no significant main effect of rs31746 genotype on BQSU or MNWS. The interactive effect of genotype was similar for BQSU Factor 1, the urge to smoke for reward (F(1,175) = 4.40, P = 0.037), and BQSU Factor 2, the urge to smoke to relieve negative affect (F(1,175) = 4.68, P = 0.032). The withdrawal risk allele, rs31746*A, was associated with a greater percent reduction in the urge to smoking following the nicotine infusion session. The average percent reduction in total BQSU score by rs31746 genotype was 32% for AA, 19% for AG, and 11% for GG (Figure 3B). The association of genotype to change in BQSU score was significant after adjusting for baseline plasma cotinine and nicotine levels, and NMR (main effect of rs31746, P < 0.02). The effect was also consistent among EA and AA subjects when the two groups were analyzed separately (EA genotype by time point interaction for BQSU: F(1,85)= 2.87, P = 0.094; AA genotype by
