located in an intron in CHRNA3 (Figure S3, middle panel). Conditioning on rs16969968 and rs7170068 left no residual signal in this region (Figure S3, bottom panel). It is notable that earlier dissection of the 15q25.1 region has suggested a third distinct signal for smoking quantity, marked by rs588765, apparent upon adjustment for rs16969968910. However, this signal was not identified in three previous large GWAS meta-analyses after conditioning on rs16969968134, and was not apparent in our data, before or after adjustment for rs16969968 (p = 0.10; pc = 1.18 × 10−3).
