MLH1 and hereditary nonpolyposis colon cancer: Up to 20% of cases can be attributed to inherited mutations and these fall into two main groups; familial adenomatous polyposis (FAP) related to mutations in the APC gene and hereditary nonpolyposis colon cancer (HNPCC)—also known as Lynch syndrome—attributed to mutations in several DNA mismatch repair genes such as MSH2, MSH6, MLH1 and PMS2 [5,6].