PMS2 and hereditary nonpolyposis colon cancer: The most common type, Lynch syndrome (also known as hereditary nonpolyposis colorectal cancer, or HNPCC), is characterized by germline mutations in the DNA mismatch repair (MMR) genes (MLH1, MSH2, MSH6 and PMS2) or deletion of the 3’ end of EPCAM. Estimated cancer risks associated with germline mutations vary widely by gene and study and range from 10-83% for CRC and 16-62% for endometrial cancers [2–4].