Lynch syndrome accounts for 1-5% of all colorectal cancer (CRC) patients [2-4] and associates with germline mutations in one of the DNA mismatch repair (MMR) genes including MLH1, MSH2, MSH6 and PMS2 (MIM: #120436, #609309, #600678, #600259, respectively). The gene discussed is MLH1; the disease is colorectal carcinoma.