COL4A1 and coronary artery disorder: TCF21 and AHR appeared to be highly related when co-expression network was visualized with all other CAD GWAS implicated genes, localizing in a cluster of extracellular matrix gene COL4A1 and growth factor receptor PDGFR, and distinct from a cluster of lipid genes (LPA, APOA5, APOB, APOA1) (Fig 1D).