Approach to Lynch Syndrome for the Gastroenterologist.

Lynch syndrome is an autosomal-dominant hereditary cancer syndrome. Mutations in mismatch repair genes, including MLH1, MSH2, MSH6, and PMS2, are implicated in the pathogenesis of the syndrome through microsatellite instability (MSI) and a rapid adenoma-carcinoma sequence. The primary methodologies for diagnosis include clinical criteria (Amsterdam I/II, Revised Bethesda Guidelines), computational models, and genetic testing (MSI, immunohistochemistry, germline testing). Universal genetic testing of colorectal cancers has gained popularity as a method to identify high-risk individuals and to offer appropriate cancer surveillance, psychological reassurance, and family planning. Management includes short-interval surveillance with colonoscopy in those without colorectal cancer and colectomy for those with cancer. Long-term chemoprevention with aspirin may improve mortality.