source: St. Jude Children's Research Hospital

Don’t be discouraged by the children’s hospital authorship, this article still has plenty of information for adults too. This article provides a decent introduction to F.A.P., with bonus points for having separate guidelines for adults and children with F.A.P.  –  FAPvoice

From the author:

Familial adenomatous polyposis is a condition that mostly affects the digestive system. People with familial adenomatous polyposis typically develop abnormal tissue growths in the large and small intestines. These growths are called polyps. If not removed, some of these polyps can become cancerous over time. For this reason, people with familial adenomatous polyposis are at high risk to develop colon cancer and other digestive system cancers at a young age. Besides polyps, people with familial adenomatous polyposis are at increased risk to develop other tumors or cancers, and they may have other physical findings.