[Genetics and physiopathology of hemochromatosis]

Thanks to the discovery of the HFE gene and of its mutations, it is now established that the most frequent form of hemochromatosis is related to homozygosity for the mutation C282Y, and that other types of hemochromatosis, unrelated to HFE mutations, do exist such as the juvenile hemochromatosis. From a pathophysiological standpoint, the C282Y mutation impairs HFE protein expression at the surface of the membrane and disturbs the cellular entry of iron (carried by circulating transferrin) into the cryptic duodenal cell. This, in turn, is likely to lead to an aberrant programmation of the degree of iron influx from the digestive lumen into the apical duodenal cells. The resulting hyperabsorption, which forms the basis of iron overload in hemochromatosis, is likely to implicate an overexpression of the transmembrane iron carrier DMT1. It is remarkable to observe that these major improvements in the knowledge of hemochomatosis have been accompanied by similar improvements in the understanding of normal iron metabolism.