source: Northwell Health summary/abstract:
Familial adenomatous polyposis (FAP) is also known as familial polyposis coli, adenomatous polyposis coli or Gardner syndrome. Mutations in a tumor suppressor gene called APC, located on chromosome five, causes most cases of FAP. The APC gene is a tumor suppressor gene, which usually has the job of controlling cell growth and cell death. Everyone has two APC genes (one on each chromosome number five). When a person has an altered, or mutated, APC gene, their risk of developing polyps and risk of cancer increases. Without intervention, nearly all people who have a mutation in the APC gene that causes the classic form of FAP will develop colorectal polyps by age 40 or 50.