What is the inheritance pattern of MUTYH-associated polyposis?

What is the inheritance pattern of MUTYH-associated polyposis?

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

Answer: (C)

MAP is inherited in autosomal recessive fashion: you need mutations in both copies of the MUTYH gene to develop the condition. Typically, affected individuals have two mutated MUTYH alleles (homozygous or compound heterozygous), and each parent is a carrier with one mutated copy but usually no disease. This explains why the condition often appears in siblings rather than every generation, and it carries about a 25% recurrence risk when both parents are carriers. Carriers with a single MUTYH mutation may have a modestly increased colorectal cancer risk, but they do not typically present with the polyposis pattern seen in MAP. This pattern differs from autosomal dominant conditions (where one mutated copy is enough) and from X-linked or mitochondrial inheritance, which show different sex-linked or maternal transmission patterns.

MAP is inherited in autosomal recessive fashion: you need mutations in both copies of the MUTYH gene to develop the condition. Typically, affected individuals have two mutated MUTYH alleles (homozygous or compound heterozygous), and each parent is a carrier with one mutated copy but usually no disease. This explains why the condition often appears in siblings rather than every generation, and it carries about a 25% recurrence risk when both parents are carriers. Carriers with a single MUTYH mutation may have a modestly increased colorectal cancer risk, but they do not typically present with the polyposis pattern seen in MAP. This pattern differs from autosomal dominant conditions (where one mutated copy is enough) and from X-linked or mitochondrial inheritance, which show different sex-linked or maternal transmission patterns.