Intrafamilial variation in hereditary hemochromatosis.

A review of 57 families with hereditary hemochromatosis revealed three pairs of HLA-identical, sex-matched siblings in which the younger sibling demonstrated considerably more iron loading than the older sibling. Liver biopsy, chemical hepatic iron determination, iron absorption studies, and number of venesections required were used to support these observations. Nineteen pairs of HLA identical, sex-matched siblings homozygous for hemochromatosis were found in which the iron loading was more marked in the older sibling. There was no evidence of blood loss, difference in alcohol consumption, or dietary iron loading to explain the increased iron loading in the younger sibling. These three families demonstrate that the rate of iron accumulation may vary within a family and that the extent of iron loading in hereditary hemochromatosis is not solely dependent on the duration of iron accumulation.