Adjustment for ever-smoking status in the stage 1 data (Table 3) did not show materially different effect-size estimates for the associations with the sentinel SNPs in TNS1, GSTCD, HTR4, AGER, THSD4 or HHIP. Similarly, adjustments for a quantitative measure of lifetime smoking exposure (pack-years) did not show substantially different effect-size estimates for the identified SNP associations (data not shown). We also tested the associations of the top SNPs in TNS1, GSTCD, HTR4, AGER and THSD4 separately in ever-smokers and never-smokers (Supplementary Table 4); all P values were >0.05 for tests of interaction between smoking status and these SNPs on lung function.
