PMS2 and Lynch syndrome: Lynch syndrome, or hereditary nonpolyposis CRC, is caused by an inherited alteration in one of the MMR genes (MLH1 (OMIM,120436), MSH2 (OMIM, 609309), MSH6 (OMIM, 600678), PMS2 (OMIM, 600259) and EPCAM (OMIM, 185535)).