Rare hereditary hemochromatosis comprises the rare forms of hereditary hemochromatosis (HH), a group of diseases characterized by excessive tissue iron deposition. These rare forms are hemochromatosis type 2 (juvenile), type 3 (TFR2-related), and type 4 (ferroportin disease) (see these terms). Hemochromatosis type 1 (also called classic hemochromatosis; see this term) is not a rare disease. The disease is Orphanet rare-disease nomenclature id Orphanet_220489 (Rare hereditary hemochromatosis). Also known as: Iron overload disease.