PMS2 and Leigh syndrome: Lynch syndrome is caused by germline mutations in the DNA mismatch repair genes (MMR genes) MLH1, MSH2, MSH6 and PMS2 or deletion of the EPCAM gene (epithelial cell adhesion molecule), which causes MSH2 inactivation.11Women with LS have 43% to 57% risk for endometrial carcinoma during their lifetime.12An individual is generally considered to have LS if they have a pathogenic variant in one of the MMR genes, regardless of having been diagnosed with an associated cancer.13