familial adenomatous polyposis


polyposis

 [pol″ĭ-po´sis] the formation of numerous polyps.familial polyposis (familial adenomatous polyposis (FAP)) a hereditary condition marked by multiple adenomatous polyps with high malignant potential, lining the intestinal mucosa, especially that of the colon. Polyps are first seen around puberty, and by age 35 years 95 per cent of patients have polyps. Without colectomy, colon cancer is inevitable. Extracolonic manifestations may also be present. It occurs as part of several different conditions, including gardner's, peutz-jeghers, canada-cronkhite, and turcot's syndromes.

familial adenomatous polyposis (FAP),

[MIM*175100] polyposis that usually begins in childhood; polyps increase in number, causing symptoms of chronic colitis; pigmented retinal lesions are frequently found; carcinoma of the colon almost invariably develops in untreated cases; autosomal dominant inheritance, caused by mutation in the adenomatous polyposis coli gene (APC) on 5q. In Gardner syndrome, which is allelic to FAP, there are extracolonic changes (desmoid tumors, osteomas, jaw cysts). Synonym(s): adenomatous polyposis coli, familial polyposis coli, multiple intestinal polyposis (1)

familial adenomatous polyposis

Familial polyposis An AD condition affecting ±50,000–US, characterized by progressive development of hundreds of adenomatous colorectal polyps; progression to cancer Molecular pathology APC gene on chromosome 5q21 is mutated in FAP, which may also be mutated in sporadic colorectal tumors Diagnosis Allele-specific expression assay, in vitro synthesized protein assay Treatment Sulindac

fa·mi·li·al ad·e·nom·a·tous pol·y·po·sis

(FAP) (fă-mil'ē-ăl ad'ĕ-nō'mă-tŭs pol'i-pō'sis) Polyposis of the colon that usually begins in childhood; polyps increase in number, causing symptoms of chronic colitis; pigmented retinal lesions are frequently found; carcinoma of the colon almost invariably develops in untreated cases; autosomal dominant inheritance, caused by mutation in the adenomatous polyposis coli gene (APC) on 5q. In Gardner syndrome, which is allelic to FAP, there are extracolonic changes (desmoid tumors, osteomas, jaw cysts).
Synonym(s): adenomatous polyposis coli, familial polyposis coli.

familial adenomatous polyposis

An autosomal dominant genetic disorder featuring multiple ADENOMAS of the colon and rectum, desmoids, osteomas and sebaceous cysts. The condition is causes by a mutation on the adenomatous polyposis coli (APC) gene on the long arm of chromosome 5 and carries a strong risk of malignancy. About 12 per cent of people with the gene develop a cancer of the upper intestinal tract, usually a cancer at the point where the bile and pancreatic ducts enter the small intestine (the ampulla of Vater). The APC gene is large with about 100,000 base pairs but of which only about one tenth are exons. It is a tumour suppressor gene, and the mutation allows tumours to arise. In people with familial adenomatous popyposis the normal allele of the pair is deleted.