Familial adenomatous polyposis (FAP) is the most common adenomatous polyposis syndrome. It is an autosomal dominant inherited disorder characterized by the early onset of hundreds to thousands of adenomatous polyps throughout the colon. If left untreated, all patients with this syndrome will develop colon cancer by age 35-40 years. Approximately 1 in 10,000 babies born live will have FAP resulting from a germline adenomatous polyposis coli (APC) mutation. Because this is an autosomal-dominant condition, males and females are equally affected by this disease. There do not appear to be significant racial, ethnic, or geographical differences in the incidence of FAP, nor do environmental factors appear to affect the disease incidence.