et al., 2004) to enhance coverage of the CHRN genes. Third, we chose additional SNPs to fine-map the strong association signals already seen in the CHRNA5-CHRNA3-CHRNB4 and CHRNB3-CHRNA6 clusters. Prior to analysis, all SNPs were required to have call rates ≥ 98%. SNPs having r2 ≥ 0.8 with CHRN SNPs (e.g. in IREB2, LOC123688, and PSMA4 which flank the CHRNA5-CHRNA3-CHRNB4 cluster) were also included in the final analysis set of 226 SNPs, of which 118 are newly genotyped by CIDR. Map positions and genomic annotations were obtained from the National Center for Biotechnology Information (NCBI) Human Reference Build 36.2 and dbSNP build 127.
