MUTYH-associated polyposis compared to FAP: inheritance pattern and surveillance focus.

• A. MUTYH is autosomal dominant with many polyps; more aggressive than FAP
• B. They are identical in inheritance and management
• C. MUTYH-associated polyposis does not increase colon cancer risk
• D. MUTYH-associated polyposis is autosomal recessive with fewer polyps; surveillance focuses on colonoscopy frequency and polyp management, with colectomy considered for cancer risk similar to FAP in selected cases

Answer: (D)

This question tests how MUTYH-associated polyposis is inherited and how its surveillance differs from classic FAP. MUTYH-associated polyposis is autosomal recessive, meaning a person typically needs mutations in both copies of MUTYH to manifest the condition. Clinically, it usually presents with fewer polyps than classic FAP, and while there is an elevated risk of colorectal cancer, the pattern and burden are different from FAP. Because the polyp burden is generally lower, colonoscopic surveillance is tailored toward regular, frequent monitoring with careful polyp removal, rather than the near-constant risk seen in FAP. Colectomy is considered when cancer risk is high or when polyposis becomes extensive, but this decision is made in a way similar to FAP for selected cases, rather than as a default in MAP.

The other statements misstate inheritance, polyp burden, or cancer risk: MAP is not autosomal dominant; its cancer risk is real and clinically relevant; and its management is not identical to FAP but shares some principles, with attention to the different inheritance and polyp load.