MSH2 and Lynch syndrome: Patients with Lynch syndrome have a pathogenic variant in one of the mismatch repair (MMR) genes, MLH1 (OMIM# 120436), MSH2 (OMIM# 609309), MSH6 (OMIM# 600678), and PMS2 (OMIM# 600259), or deletions in the EPCAM (OMIM# 185535).