Defects in the pathways that regulate hepcidin produce disease: relative reductions in hepcidin underlie most forms of hereditary hemochromatosis15, ineffective erythropoiesis suppresses hepcidin contributing to iron loading in thalassemia16, 17 and inflammation elevates hepcidin leading to anemia of inflammation18. The gene discussed is HAMP; the disease is anemia (phenotype).