Our analyses of consistency of association across populations and specificity of substance focused on correlates (r2=1.0 in the European population) of the common chromosome 8p11 variants rs6474412 and rs1451240 previously reported as having GWAS significant associations to nicotine dependence. The SNP Annotation and Proxy Search (SNAP) tool (15) using the 1000 Genomes CEU sample identified 18 additional SNPs that are highly correlated (r2=1.0) to these two SNPs in subjects of European ancestry. Only one SNP genotyped in our data, rs13273442, is highly correlated in both Europeans (r2=1.0) and in the African Yoruba (YRI) populations (r2≥0.89) to the two SNPs rs6474412 and rs1451240. The A allele displays a frequency of 0.25 in the European CEU reference sample and a frequency of 0.64 in the African YRI reference sample. Supplemental Table S3 provides information about the correlations in YRI for the 20 SNPs that are perfectly correlated in the CEU reference.
