MUTYH-associated polyposis (also known as MAP) is caused by mutations in the MUTYH gene. The condition often results in dozens to hundreds of polyps in the colon and rectum, although some individuals develop colon cancer without any history of polyposis.
While the most common polyps seen are adenomas, other types of polyps can be found including serrated adenomas and hyperplastic polyps. In addition to the significantly increased risk for colon cancer, other risks include stomach polyps, duodenal polyps and duodenal cancer, as well as possibly uterine, ovarian, breast, bladder, thyroid, and skin cancers. Current guidelines recommend that individuals with MAP start colonoscopy screening no later than age 25-30. Other screening includes upper endoscopy, beginning at the age of 30-35. MAP is an autosomal recessive condition, where an individual inherits a mutated copy of the MUTYH gene from each parent (thus carrying two MUTYH mutations). While MAP is a rare cause of hereditary GI cancer, accounting for less than 1% of inherited colon cancers, 1-2% of individuals in the general population are MUTYH carriers (they have one mutated copy of the MUTYH gene). Being a MUTYH carrier is only believed to increase the risk for colon cancer when an individual has a first-degree relative (parent, sibling, or child) with colorectal cancer. The following resources can help you learn more about MUTYH-associated polyposis:
FORCE (Facing Hereditary Cancer Empowered): https://www.facingourrisk.org/
GeneReviews: https://www.ncbi.nlm.nih.gov/books/NBK107219/
InSiGHT (International Society for Gastrointestinal Hereditary Tumours): https://www.insight-group.org/
To find an inherited GI Cancer Genetics Clinic near you, check out the “Find a Clinic” page on the CGA-IGC website: https://www.cgaigc.com/find-a-clinic
