Type 1: Mutations of the HFE (human homeostatic iron regulator) gene Type 2 (juvenile hemochromatosis): Mutations in the HJV (hemojuvelin BMP co-receptor) and HAMP (hepcidin antimicrobial peptide) genes Type 3: Mutations in the TFR2 (transferrin receptor 2) gene Type 4 (ferroportin disease): Mutations in the SLC40A1 (solute carrier family 40 member 1) gene Other much rarer genetic disorders can cause hepatic iron overload, but the clinical picture is usually dominated by symptoms and signs due to failure of other organs (eg, anemia in hypotransferrinemia or atransferrinemia, or neurologic defects in aceruloplasminemia).