d) not be using other tobacco products; and e) not be pregnant or nursing. In both studies, the average number of cigarettes per day was computed from a daily diary and a first morning urine sample was collected from each subject. In these studies, the frequency of the rs16969968 A allele was 0.35 in European Americans and 0.10 in African Americans. The genotype frequencies were consistent with Hardy Weinberg equilibrium (African Americans, p>0.05; Caucasians, p=0.01). Concordance rates across the ∼15% blinded duplicate samples genotyped were 97−100% and the genotyping call rate was 100%.
