We studied 18 genes known to be important in CRC susceptibility (APC, AXIN2, BMP4, BMPR1A, CHEK2, MLH1, MLH3, MSH2, MSH3, MSH6, MUTYH, PMS1, PTEN, SMAD4, STK11, STK11IP, TGFBR2, and TP53) and 18 genes suspected to play a role in CRC susceptibility (AXIN1, BLM, BUB1, CDH1, CDKN1B, CDKN2A, CTNNB1, FLCN, GALNT12, NUDT1, OGG1, PALB2, REQL5, SMAD1, SMAD2, SMAD3, TGFB1, and TGFBR1). This evidence concerns the gene SMAD4 and colorectal carcinoma.