These 75 SNPs were selected to include the same SNPs used to cover this region in our previous publications [9, 10, 20]. Forty-nine of the genotyped SNPs lie between 76642961 bp and 76722642 bp, encompassing CHRNA5-CHRNA3-CHRNB4 and the 2kb flanking either side (5′ of CHRNA5 and 5′ of CHRNB4), matching the dbSNP definition of in or near a gene. These SNPs provide good coverage of the 72 SNPs in this region that are common (minor allele frequency (MAF) ≥ 0.05) in either the HapMap CEU or YRI samples. Of the 61 SNPs that have MAF ≥ 5% in CEU, 54 (93%) are tagged by at least one genotyped SNP at an r2 ≥ 0.8 according to CEU LD data; all 61 are tagged at an r2 ≥ 0.5. Of the 65 SNPs in this region that have MAF ≥ 5% in YRI, 46 (71%) are tagged at an r2 ≥ 0.8 in the YRI LD data; 60 (92%) are tagged at an r2 ≥ 0.5 (HapMap release 23a). Twenty-six additional SNPs flanking the cluster or in IREB2, LOC123688, and PSMA4 were included because of the high r2 extending from CHRNA5-CHRNA3-CHRNB4.
