source: MD Anderson Cancer Center summary/abstract:
Familial Adenomatous Polyposis (FAP) is a genetic condition where affected individuals will develop hundreds to thousands of polyps (abnormal, mushroom- read more
like growths) throughout their gastrointestinal (GI) tract beginning at a young age (usually as a teenager or young adult). These polyps are usually found in the large intestine (colon and rectum), but they can develop in the stomach and small intestine as well. The polyps that form in the large intestine are known as adenomas. Adenomas are considered to be precancerous. In addition, individuals with FAP may also develop other features outside of the gastrointestinal tract.