and the second one was 0.042 (HIST1H2AE expression, smoking and rs16891378). This first genome-wide exploration of interaction between cis eSNPs and risk factors on gene expression therefore suggests that the two sources of variability mostly act additively on expression. This is illustrated for eQTLs affected by smoking in Figure 5 . It must be noted however that despite the large size of this study, its power may nevertheless be insufficient to assess weak interaction.
