Coronary artery disease (CAD) is a leading cause of morbidity and mortality worldwide1,2. Although 58 genomic regions have been associated with CAD to date3–9, most of the heritability is unexplained9, indicating additional susceptibility loci await identification. An efficient discovery strategy may be larger-scale evaluation of promising associations suggested by genome-wide association studies (GWAS). Hence, we genotyped 56,309 participants using a targeted gene array derived from earlier GWAS results and meta-analysed results with 194,427 participants previously genotyped to give a total of 88,192 CAD cases and 162,544 controls. We identified 25 new SNP-CAD-associations (P < 5x10-8, in fixed effects meta-analysis) from 15 genomic regions, including SNPs in or near genes involved in cellular adhesion, leucocyte migration and atherosclerosis (PECAM1, rs1867624), coagulation and inflammation (PROCR, rs867186 [p.Ser219Gly]) and vascular smooth muscle cell differentiation (LMOD1, rs2820315). Correlation of these regions with cell type-specific gene expression and plasma protein levels shed light on potential novel disease mechanisms.

Background Common diseases such as coronary heart disease (CHD) are complex in etiology. The interaction of genetic susceptibility with lifestyle factors may play a prominent role. However, gene-environment interactions for CHD have been difficult to identify. Here, we investigate interaction of smoking behavior, a potent lifestyle factor, with genotypes that have been shown to associate with CHD risk. Methods We analyzed data on 60,919 CHD cases and 80,243 controls from 29 studies for gene-smoking interactions for genetic variants at 45 loci previously reported to associate with CHD risk. We also studied 5 loci associated with smoking behavior. Study specific gene-smoking interaction effects were calculated and pooled using fixed-effects meta-analyses. Interaction analyses were declared to be significant at a P-value < 1.0×10−3 (Bonferroni correction for 50 tests). Results We identified novel gene-smoking interaction for a variant upstream of the ADAMTS7 gene. Every T allele of rs7178051 was associated with lower CHD risk by 12% in never-smokers (P-value: 1.3×10−16) compared to 5% in ever-smokers (P-value: 2.5×10−4) translating to a 60% loss of CHD protection conferred by this allelic variation in people who smoked tobacco (Interaction P-value: 8.7×10−5). The protective T allele at rs7178051 was also associated with reduced ADAMTS7 expression in human aortic endothelial cells and lymphoblastoid cell lines. Exposure of human coronary artery smooth muscle cells to cigarette smoke extract led to induction of ADAMTS7. Conclusions Allelic variation at rs7178051 that associates with reduced ADAMTS7 expression confers stronger CHD protection in “never-smokers” compared to “ever-smokers”. Increased vascular ADAMTS7 expression may contribute to the loss of CHD protection in smokers.