Iron overload in the era of molecular biology.

Identification of the HFE gene and its C282Y and H63D mutations has improve d the classification of iron overload disorders. Inherited hemochromatosis is due mainly or perhaps only, to C282Y homozygosity, whereas nonhemochroma tosis forms of iron overload are due to other HFE mutations and are usually responsible for mild overload precipitated by another factor such as cirrh osis or insulin-resistance. In practice, the diagnosis of inherited hemochr omatosis rests on demonstration of homozygosity for the C282Y mutation; in this setting, the role of liver biopsy is to evaluate the prognosis by look ing for fibrosis. In patients who are not homozygous for the C282Y mutation but have severe iron overload, causes other than hemochromatosis should be looked for before the extremely remote possibility of nonC282Y-related hem ochromatosis is considered; here, liver biopsy remains of considerable diag nostic usefulness.