MLH1 and Familial adenomatous polyposis: In inherited CRC, defects in the tumor suppressor gene APC is a well-known cause of familial adenomatous polyposis (FAP), and hereditary nonpolyposis CRC (HNPCC) is due to germline mutations on DNA mismatch repair (MMR) genes such as MLH1 and MSH2 [7, 8].