The discovery of the HFE gene has improved classification and diagnosis of
iron overload. Most patients with a phenotypic diagnosis of haemochromatosi
s are homozygote for the C282Y mutation. Among those with other genotypes,
only compound heterozygotes, who present the C282Y mutation on one chromoso
me and the H63D on the other, may present with haemochromatosis, but with a
low penetrance and a mild expression. Other patients usually present with
another cause of iron overload, such as insulin resistance, alcoholic liver
disease or liver cirrhosis. The practical management of haemochromatosis h
as been greatly modified, since liver biopsy is no more necessary for diagn
osis in C282Y homozygotes, and is only needed for exclusion of cirrhosis, F
amily screening has also greatly benefited from genotyping.