For follow-up analyses (stage 2), we genotyped 35 SNPs drawn from the most significantly associated independent loci. We defined signals at two SNPs to be independent of each other if the SNPs were in low LD (r2 < 0.3) or if they were >1 Mb apart. In some cases, the SNP with the strongest signal of association at a locus could not be genotyped for technical reasons, and we substituted another SNP that was strongly correlated with the original SNP in the HapMap CEU sample (Supplementary Note). Because SNP selection was based on an earlier version of the meta-analysis and because some SNPs failed primer design, not all of the top signals were represented among the 35 SNPs. Among the SNPs that were followed up, the highest stage 1 P value was 6.9 × 10−4.
