Congenital intrinsic factor deficiency (IFD) is a rare disorder of vitamin B12 (cobalamin) absorption that is characterized by megaloblastic anemia and neurological abnormalities. The disease is Congenital intrinsic factor deficiency (Orphanet_332). Also known as: Congenital pernicious anemia, Gastric intrinsic factor deficiency, Hereditary juvenile meganoblastic anemia due to intrinsic factor deficiency, IFD, Intrinsic factor deficiency.