These GWAS have provided insights into the biological basis of CRC, highlighting the role of genes within the bone morphogenetic protein signalling pathway (BMP2, BMP4, GREM1 and SMAD7)4, 11 and some candidate genes (e.g. CDH1/CDH3), as well as genes not previously implicated in CRC (e.g. POLD3, TERC, CDKN1A and SHROOM2)5, 6. Here, SMAD7 is linked to colorectal carcinoma.