Attenuated familial adenomatous polyposis (AFAP) is a mild form of familial adenomatous polyposis characterized by the presence of fewer than 100 adenomatous colonic polyps, a more proximal colonic location, a delayed age of colorectal cancer (CRC) onset and a more limited expression of the extracolonic features. The disease is attenuated familial adenomatous polyposis (MONDO_0016362, a Monarch Disease Ontology id). Also known as: AAPC, AFAP, HFAS, attenuated FAP, attenuated adenomatous polyposis coli, attenuated familial polyposis coli, hereditary flat adenoma syndrome.