Hemochromatosis and iron needs.

Although iron is an essential dietary requirement, the amount absorbed by the body is well regulated and depends on body iron stores and on dietary iron availability. There is very little iron excreted under normal conditions. Iron deficiency is a worldwide problem but iron overload, as seen in the inherited disease, hemochromatosis, is a major cause of morbidity in some Caucasian populations. This is a problem particularly where there is an adequate dietary iron intake and especially in males. A mutation has recently been described in an MHC Class l-like gene (HFE) that encodes for a protein (HFE) of 343 amino acids. The molecule contains a signal sequence peptide-binding region, alpha, and alpha(2) domains, and an immunoglobulinlike alpha(3) domain, in addition to a transmembrane region and a small cytoplasmic tail. It is a candidate gene for hemochromatosis. Several possibilities as to the function of this gene and the corresponding protein have been suggested but none has yet been confirmed. The mutation has been detected by several different groups in 80%-100% of subjects with the disease. However, in one study, 18%-20% of patients with the mutation did not exhibit significant iron overload. The discovery of this gene has important implications for both clinical studies and the elucidation of the pathways of iron metabolism.