One of the two most common forms of hereditary colorectal cancer. FAP is an autosomal dominant found in adolescents who present with abdominal pain, diarrhea and rectal bleeding. A carpet of pre-cancerous growths, usually in the colon, progresses to colorectal cancer. The mutant gene is adenomatous polyposis coli (APC); about 740 different mutations in this gene have been identified with simultaneous loss of heterozygosity or mutation to the p53 tumor suppressor gene. There is some evidence for a paternal age effect. Aka familial polyposis of the colon (FPC).

Cf. colon cancer, hereditary nonpolyposis.