Hemojuvelin (Hjv, also known as RGMc), a protein belonging to the repulsive-guidance molecule (RGM) family, was originally identified as the affected gene in several families with severe early onset iron overload and reduced levels of hepcidin.[3] Hepcidin, a transcriptionally regulated peptide hormone, is produced in the liver[4] and modulates intestinal iron absorption and macrophage iron release[5]–[7]. The gene discussed is HAMP; the disease is Tangier disease.