Gene–environment (smoking) interaction in the TSS cohort. (A) Boxplot of log-transformed, outlier-removed, and age- and sex-adjusted PLG levels against smoking. (B) Boxplot of PLG levels against smoking status and genotypes of the top SNP, rs4252129. (C) Boxplot of PLG levels against smoking status and the genotype combinations of the top 2 independent SNPs, rs4252129 and rs1084651.