The MAF of rs16969968 differed significantly between racial groups, with 174 Caucasians having one ‘A’ allele and 45 having two alleles, while only six African Americans carried one copy of the ‘A’ allele. Accordingly, this SNP had a negligible effect on risk of smoking in the African American sample in the race-stratified analysis. Moveover, in four of the 25 SNPs, major and minor alleles were reversed in Caucasians and African Americans.
