In a multivariate model including the four expression traits and smoking, as well as age and gender, PTGDS (P = 5.7×10−4) and SASH1 (P = 0.012) remained significantly associated with the number of plaques whereas MMP25 (P = 0.09), WWC3 (P = 0.10) and smoking (P = 0.5) were no longer significant, suggesting that the association between smoking and atherosclerosis was mostly reflected (or mediated) by its effect on the expression of these four genes. This evidence concerns the gene PTGDS and atherosclerosis.