GTR Home > Conditions/Phenotypes > Turcot syndrome


Lynch syndrome, caused by a germline pathogenic variant in a mismatch repair gene and associated with tumors exhibiting microsatellite instability (MSI), is characterized by an increased risk for colon cancer and cancers of the endometrium, ovary, stomach, small intestine, hepatobiliary tract, urinary tract, brain, and skin. In individuals with Lynch syndrome the following life time risks for cancer are seen: 52%-82% for colorectal cancer (mean age at diagnosis 44-61 years); 25%-60% for endometrial cancer in women (mean age at diagnosis 48-62 years); 6% to 13% for gastric cancer (mean age at diagnosis 56 years); and 4%-12% for ovarian cancer (mean age at diagnosis 42.5 years; approximately 30% are diagnosed before age 40 years). The risk for other Lynch syndrome-related cancers is lower, though substantially increased over general population rates. [from GeneReviews]

Associated genes

Clinical features


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Go to complete MedGen record for Turcot syndrome

Practice guidelines

  • ASCO/ESMO, 2015
    Hereditary colorectal cancer syndromes: American Society of Clinical Oncology Clinical Practice Guideline endorsement of the familial risk-colorectal cancer: European Society for Medical Oncology Clinical Practice Guidelines.
  • ACMG/NSGC, 2015
    A practice guideline from the American College of Medical Genetics and Genomics and the National Society of Genetic Counselors: referral indications for cancer predisposition assessment.
  • NSGC, 2004
    Genetic cancer risk assessment and counseling: recommendations of the national society of genetic counselors.

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