Familial Adenomatous Polyposis---FAP

Familial adenomatous polyposis (FAP) is a rare genetic condition associated with the growth of dozens to hundreds of polyps (abnormal growths or tumors) in the gastrointestinal (GI) tract. In FAP, the polyps are called adenomas, which typically begin to form in late childhood or early adolescence. If the entire colon is not removed, almost everyone who is diagnosed with FAP inevitably develops colorectal cancer by the age of 40-50 years.

FAP is caused by a defective gene called adenomatous polyposis coli (APC) that can cause of group of polyposis conditions with similar features:

• Gardner syndrome: A form of familial adenomatous polyposis (FAP) that causes multiple colorectal polyps and different types of tumors — both cancerous and non-cancerous.
• Turcot syndrome: A condition often associated with FAP. Children with this syndrome have multiple adenomatous polyps, an increased risk of colorectal cancer and an increased risk of brain cancer.
• Attenuated FAP (AFAP): A milder kind of FAP characterized by fewer polyps and the development of colorectal cancer at a later age. Less than 10 percent of families with FAP have an attenuated form.
• MYH Gene: An autosomal recessive condition in which both parents have to be carriers. Each individual offspring has a 25 percent risk of inheriting the condition.

FAP is an autosomal dominant condition, meaning that it can be passed down through families. If a child inherits the gene from one parent, there is a 50 percent they will have FAP. In some instances, FAP is not inherited but rather the result of a gene change, known as a mutation.

FAP may also cause other abnormal growths or lesions in other areas of the body, such as the thyroid, eyes, bone, teeth, brain, liver and skin. These can be either benign (non-cancerous) or malignant (cancerous) lesions.