MUTYH-associated polyposis (also known as MYH-associated polyposis) is an autosomal recessive polyposis syndrome. ^[1] The disorder is caused by mutations in both alleles (genetic copies) of the DNA repair gene, MUTYH. The MUTYH gene encodes a base excision repair protein, which corrects oxidative damage to DNA. Affected individuals have an increased risk of colorectal cancer, precancerous colon polyps ( adenomas) and an increased risk of several additional cancers. About 1–2 percent of the population possess a mutated copy of the MUTYH gene, and less than 1 percent of people have the MUTYH-associated polyposis syndrome. The presence of 10 or more colon adenomas should prompt consideration of MUTYH-associated polyposis, familial adenomatous polyposis and similar syndromes. ^[2]

Signs and symptoms

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Pathophysiology

MUTYH-associated polyposis is caused by a mutation of the MUTYH gene, which is located on chromosome 1. ^[3] The condition may be caused by identical mutations affecting both copies of the gene (biallelic mutations) or where each allele is affected by different mutations ( compound heterozygote). ^[3]

Treatment

Treatment is similar to familial adenomatous polyposis, which varies based on the extent of polyps.^{[ citation needed]}

All first degree relatives of individuals with the condition should undergo screening for MUTYH-associated polyposis. ^[3] To identify risk for future offspring, screening should be offered to spouses of individuals affected by MUTYH-associated polyposis. ^[3] If the spouse is a carrier of a mutation in MUTYH, then genetic counseling should be offered to the children as they approach adulthood.^{[ citation needed]}

Epidemiology

Without surveillance or screening, between 80 and 90% of individuals with MUTYH-associated polyposis develop colorectal cancer. ^[4]

References