[The diagnosis of hemochromatosis in the era of the gene]. / Le diagnostic de l'hémochromatose à l'heure du gène.

ABSTRACT

The discovery of the hemochromatosis gene has deeply changed and simplified the diagnosis of the disease. In a given individual, establishing the diagnosis relies, from now on, on a simple blood sample showing the couple elevated transferrin saturation and homozygous C282Y mutation (= C282Y +/+). Liver biopsy should only be performed when iron overload is massive in order to detect cirrhosis (or bridging fibrosis), i.e. in a prognostic view. Practically, liver biopsy is confined to the following two situations when the C282Y +/+ patient exhibits hepatomegaly and/or an increase in serum transaminases and/or a serum ferritin level above 1,000 micrograms/L; whenever, despite a strong bio-clinical suspicion of iron overload, genetic testing does not show the expected homozygosity for C282Y. At the family level, evaluating the risk for hemochromatosis is now "instantaneous" thanks to genetic testing. One must, however, keep in mind in interpreting the data of the family members that clinical expression of the homozygous status is not constant; heterozygosity for C282Y does not per se lead to significant iron overload, but may constitute a co-factor exacerbating (or increasing the risk of) other hepatic or non hepatic diseases. Heterozygosity exposes also to the risk of homozygosity among the offspring; this knowledge of C282Y status must be balanced by the negative impact from the standpoint of possible societal genetic discrimination.