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MYH (MUTYH)-associated polyposis

Epidemiology: - 0.5-1.0% of the population Pathology: - defects in DNA base excision repair - familial polyposis syndrome with fewer adenomas than adenomatous polyposis coli (FAP) - most patients have 20-100 adenomatous polyps - some patients can develop colorectal cancer with few or no synchronous adenomas - mean age of colorectal cancer onset is 52 years - serratated polyps as well as adenomatous polyps may occur - risk of duodenal cancer is 4% Genetics: - associated with defects in the MYH gene - autosomal recessive - test both parents prior to testing children [1] - heterozygous & homozygous forms - MYH mutations predispose to somatic alterations in APC Clinical manifestations: - colorectal polyps Laboratory: - MUTYH gene mutation Special laboratory: - colonoscopy at 25 years of age - survelliance every 2-3 years - upper GI endoscopy with side-view examination of duodenal papilla at age 35 - survelliance every 3-5 years Complications: - colorectal carcinoma, gastric cancer

Related

MUTYH gene mutation

General

adenomatous polyposis syndrome

References

  1. Medical Knowledge Self Assessment Program (MKSAP) 16, 17, 18. American College of Physicians, Philadelphia 2012, 2015, 2018.
  2. Hegde M, Ferber M, Mao R et al ACMG technical standards and guidelines for genetic testing for inherited colorectal cancer (Lynch syndrome, familial adenomatous polyposis, and MYH-associated polyposis). Genet Med. 2014 Jan;16(1):101-16. PMID: 24310308