Inheritance pattern of MUTYH-associated polyposis.

• A. Autosomal recessive
• B. X-linked
• C. Autosomal dominant
• D. Mitochondrial

Answer: (A)

MUTYH-associated polyposis is inherited in an autosomal recessive pattern because disease occurs when both copies of MUTYH are mutated. The condition stems from biallelic pathogenic variants, and individuals with a single mutated allele (carriers) are typically asymptomatic, with neglible or modest risk. As a result, affected people usually have two carrier parents, and siblings can be affected while the parents remain unaffected. This contrasts with X-linked inheritance (would involve transmission patterns through carrier mothers with more affected males), mitochondrial inheritance (maternal transmission to all children), or autosomal dominant inheritance (one mutated allele would usually be enough to cause disease, which is not how MAP presents).