Genetic mutations that impair hepcidin production or binding to ferroportin are associated with systemic iron overload (primary hemochromatosis) [12], while mutations in negative regulators of hepcidin (matriptase-2) cause iron refractory iron deficiency anaemia (IRIDA) due to inappropriately high hepcidin levels [13]. The gene discussed is SLC40A1; the disease is Tangier disease.