Pitfalls in the genetic diagnosis of hereditary hemochromatosis

The widespread use of the genotype assay that identifies the common C282Y m utation in the HFE gene has allowed an earlier diagnosis to be made in many subjects. A significant number of these patients may have no evidence of p henotypic disease and have a normal serum ferritin level. This phenomenon i s more common when the genotype assay is used to screen populations rather than higher-risk groups such as family members of a proband with hereditary hemochromatosis. Moreover, patients with significant iron overload may be wild type for the C282Y mutation and have no other demonstrable mutation of the HFE gene. The HFE genotype assay has recently been found to give a fal se-positive C282Y homozygous result in half of the subjects in one populati on screening study due to the presence of a single nucleotide polymorphism (SNP) that interfered with primer binding in the PCR assay; The problem may be overcome by using alternate primers. A number of other groups have conf irmed the finding but in a much smaller number of subjects, whereas others found that their assays were not affected by the SNP, The use of the HFE ge notype assay as the sole diagnostic criterion for hereditary hemochromatosi s is not recommended. The genotype assay should be used as an adjunct to th e established methods of demonstrating iron overload and be viewed as a pre dictor of either the presence of iron overload or the subsequent developmen t of iron overload during an individual's lifetime.