Among the known or classic CRC related genes (APC, AXIN2, BMPR1A, CHEK2, EPCAM, GREM1, MLH1, MSH2, MSH3, MSH6, MUTYH, NTHL1, PMS2, POLD1, POLE, PTEN, RPS20, SMAD4, STK11 or TP53 gene) mismatch repair (MMR) genes disease-causing variants were the most prevalent (16/20) in our cohort, accounting for 80.0% of all cases. This evidence concerns the gene NTHL1 and colorectal carcinoma.