Anywhere from 5 to 10% [19] to as much as 15–30% [20] of CRC may be due to known hereditary conditions, including hereditary non-polyposis colorectal cancer (HNPCC; also known as Lynch syndrome, caused by mutations in mismatch DNA repair genes) and familial adenomatous polyposis (FAP, which is caused by mutations in the APC tumor suppressor gene). Here, APC is linked to hereditary nonpolyposis colon cancer.