Symptoms of familial adenomatous polyposis (FAP)
- FAP is an autosomal-dominant, non–sex-linked disease in which more than 100 adenomatous polyps affect the colon and rectum.
- FAP is caused by mutation in the adenomatous polyposis coli (APC) gene on the long arm of chromosome 5 at the 5q21-q22 locus.
- The APC protein is a tumor suppressor that, when mutated, fails to bind beta-catenin and allows for unregulated cellular growth.
- One third of patients present as the propositus case (presumed mutation) with no prior family history.
- The disease invariably leads to invasive colon cancer if not treated. The average age at diagnosis of colon cancer is 39 years compared with 65 years for routine colon cancer.
