SNP rs10517626 within the TDO2 (tryptophan 2,3,-dioxygenase) gene was also found to be noteworthy and has similar patterns of effects at EOT and at 6-month follow-up. Specifically, at EOT there is a genetic effect enhancing quit rates for each additional minor allele (OR = 1.81; 95% CI 1.10–2.99; P = 0.01) with the treatment effect being more effective within those individuals carrying the minor allele (OR = 3.98; 95% CI 1.60–9.91) when compared with the treatment effect within individuals with the WT genotype (OR = 1.39; 95% CI 0.84–2.31). The difference in treatment effects by genotype is suggestive of an observed P-value from the interaction test of 4.26 × 10−2. Additional polymorphisms at EOT are indicated in ADCYAP1 and HTR1B or at 6-month follow-up in CDK5 and FOSB, but none are consistent with the analyses at both time points.
