APC gene

Role in cancer

Familial adenomatous polyposis (FAP) is caused by an inherited, inactivating mutation in the APC gene. More than 800 mutations in the APC gene have been identified in families with classic and attenuated types of familial adenomatous polyposis. Most of these mutations cause the production of an APC protein that is abnormally short and presumably nonfunctional. This short protein cannot suppress the cellular overgrowth that leads to the formation of polyps, which can become cancerous. The most common mutation in familial adenomatous polyposis is a deletion of five bases in the APC gene. This mutation changes the sequence of amino acids in the resulting APC protein beginning at position 1309. Mutations in the APC gene have also been found to lead to the development of desmoid tumors in FAP patients.