All DNA samples were genotyped on the Illumina Human 1M beadchip. After extensive data cleaning and quality control procedures, described in detail elsewhere (Bierut et al., 2010), a total of 948,658 SNPs were analyzed in the primary GWAS. For the purpose of this study we focused the analyses on the 21 SNPs covering the CRHR1 gene, which is approximately 51.55 kb in length and maps to 17q21.31. Two SNPs (rs4792882 and rs16940655) did not have sufficient genotypic variance (< 2% minor allele frequency; MAF) and were therefore excluded, leaving a total of 19 SNPs for analyses. SNPs gene location, chromosomal position, allele frequency, and Hardy-Weinberg Equilibrium (HWE) are presented in Table 2.
