Hereditary colorectal cancers are caused by highly penetrant mutations, such as those involved in tumour suppression or in the DNA mismatch repair system, including Hereditary Nonpolyposis Colorectal Cancer (HNPCC), Familial Adenomatous Polyposis (FAP), MYH-associated polyposis, and the rare hamartomatous polyposis syndromes [5]. The gene discussed is MUTYH; the disease is Familial adenomatous polyposis.