We did not observe any consistent association between rs16969968 and smoking abstinence in this study. It is also worth noting that the direction of the association between rs16969968 and smoking abstinence in African Americans was in the opposite direction compared to the direction of effect observed in Caucasians (20). The ‘A’ allele of rs16969968 was associated lower abstinence with nicotine gum treatment and higher abstinence with placebo treatment in our study of African American smokers. In contrast, the ‘A’ allele of rs16969968 was associated with higher abstinence with nicotine replacement therapy and lower abstinence with placebo treatment in Caucasians (20). It is possible that different linkage disequilibrium/haplotype structures between African Americans and Caucasians contributes to this discrepancy. Overall, our smoking abstinence data and the relatively low prevalence of rs16969968 in African American would suggest that rs16969968 has very little pharmacogenetic importance in African American smokers.
