Germline mutations in MLH1 and MSH2 account for approximately 90% of detected mutations in families with HNPCC where as mutations in MSH6 account for about 7%–10%, and PMS2 mutations in fewer than 5% of families with Hereditary nonpolyposis colorectal cancer and risk of developing colorectal cancer is also increased among MSH2 mutation carriers as compared with MLH1 mutation carriers [3]. The gene discussed is MSH2; the disease is colorectal cancer.