Familial adenomatous polyposis


Familial adenomatous polyposis (FAP) is an inherited genetic condition that causes the growth of hundreds to thousands of polyps (abnormal mushroom-shaped growths of tissue) in a patient's lower intestine (including the colon and rectum). Polyps may be seen in a patient's upper intestine as well. About one in 30,000 people is affected with FAP.
Polyps usually begin to grow in patients at about age 10 to 12. Initially, these polyps do not cause symptoms in most patients. However, they greatly increase the risk of colon cancer, in which cells in the colon divide uncontrollably and develop into tumors. Almost all patients with FAP develop colon cancer by age 40.
FAP is known to be caused by mutations in a gene called adenomatous polyposis coli or APC (APC). This gene contains the genetic code for making the APC protein, which regulates growth in normally functioning cells. Mutations in the APC gene can result in an abnormal APC protein that cannot properly control cell growth. This leads to the formation of polyps in patients with FAP.
If the polyps are removed before cancer develops, patients may greatly reduce their risk of developing cancer. If colon cancer does develop, it can be life-threatening. However, it can be treated in a number of ways, including surgery, radiation therapy, and chemotherapy.

Related Terms

Adenomatous polyposis coli, APC gene, APC protein, colon cancer, cyst, desmoid tumor, FAP, hereditary polyposis of the colon, inherited genetic condition, intestinal cancer, MUTYH gene, MYH glycosylase, polyp, rectal cancer.