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
• heterozygous & homozygous forms
• MYH mutations predispose to somatic alterations in APC

Clinical manifestations

• colorectal polyps

Laboratory

• MUTYH gene mutation

Diagnostic procedures

• 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

More general terms

• adenomatous polyposis syndrome

Additional terms

• MUTYH gene mutation