Review of the Lynch syndrome: history, molecular genetics, screening, differential diagnosis, and medicolegal ramifications

More than one million patients will manifest colorectal cancer (CRC) this year of which, conservatively, approximately 3% (approximately 30,700 cases) will have Lynch syndrome (LS), the most common hereditary CRC predisposing syndrome. Each case belongs to a family with clinical needs that require genetic counseling, DNA testing for mismatch repair genes (most frequently MLH1 or MSH2) and screening for CRC. Colonoscopy is mandated, given CRC's proximal occurrence (70-80% proximal to the splenic flexure). Due to its early age of onset (average 45 years of age), colonoscopy needs to start by age 25, and because of its accelerated carcinogenesis, it should be repeated every 1 to 2 years through age 40 and then…

• CU
  Creighton University
• ND
  Nebraska Department of Health and Human Services
• NC
  National Cancer Institute