Among the latter, the two most common are autosomal dominant disorders: the hereditary nonpolyposis CRC or Lynch syndrome, caused by inactivating mutations in one of four genes belonging to the mismatch repair system, namely MSH2, MLH1, MSH6, and PMS2 [37], and the familial adenomatous polyposis (FAP), due to germline mutations in the tumor suppressor gene adenomatous polyposis coli (APC) [38]. Here, PMS2 is linked to Familial adenomatous polyposis.