An autosomal dominant disorder caused by pathogenic variants in the APC gene, characterized by the development of colorectal adenomatous polyposis, a very high risk of colorectal cancer and other extracolonic manifestations including both classic and attenuated familial adenomatous polyposis (FAP). The disease is familial adenomatous polyposis 1 (Monarch Disease Ontology term MONDO_0021056). Also known as: APC-related adenomatous polyposis, FAP1, adenoma, periampullary, somatic.