Meta-analyses of GWAS results. We performed fixed-effect meta-analysis for each smoking phenotype by computing pooled inverse-variance-weighted β-coefficients, s.e. and Z scores for each SNP.37 All GWAS results were corrected via genomic control before the meta-analysis. The study-specific lambda values utilized in this step ranged from 1.01 to 1.08 for SI (Supplementary Table 1). Heterogeneity across studies was investigated using the I2 statistic.38 The results presented herein are corrected by a second GC correction based on λ of the meta-analyses (λ<1.02). A significance threshold of P<5 × 10−8 was considered to indicate genome-wide significance. Linkage disequilibrium statistics for the largest of the STOMP cohorts (Women's Health Initiative, n=8208) were calculated using DPRIME (http://www.phs.wfubmc.edu/public/bios/gene/downloads.cfm). Linkage disequilibrium statistics for CEU and YRI were obtained from HapMap phase 2 33. Statistical power analysis was performed using QUANTO.39
