APC and malignant colon neoplasm: Familial adenomatous polyposis (FAP) is an inherited autosomal dominant disorder due to mutation in the adenomatous polyposis coli (<i>APC</i>) gene that can cause iron deficiency anemia due to GI malignancy, most notably colon cancer. Variation of mutations within the <i>APC</i> gene can cause different forms of FAP, such as Gardner syndrome.