Lynch syndrome, also known as hereditary nonpolyposis colorectal cancer (HNPCC), is an inherited cancer syndrome caused by defect in one of the mismatch repair (MMR) genes—MLH1, MSH2, MSH6 and PMS2. It accounts for about 5% of all colorectal and endometrial cancers diagnosed [1,2]. The gene discussed is MLH1; the disease is hereditary nonpolyposis colon cancer.