Background: Hereditary Hemochromatosis, once considered a monogenic disorder, is now seen as a polygenic disease, with clinical phenotype also influenced by several environmental factors. Besides the classic HFE gene, other genes involved in modulation of iron homeostasis and clinical phenotype include those coding for hemojuvelin and hepcidin (both responsible for Juvenile Hemochromatosis), ferroportin, and, possibly, H-ferritin.
Methods: we used DHPLC to scan mutations in the above mentioned genes in 55 consecutive patients recently referred to our tertiary care unit for iron overload disorders. Many of them had at least biochemical signs of iron overload not explained, or not completely explained, by classic or rare HFE mutations.
Main results: the −72 C→T variation in the promoter of hepcidin gene, near the putative TATA box, was found in a H63D heterozygous male with unexplained biochemical signs (serum ferritin 660 μg/L, TS 45%), who, rather, should have been protected by several previous blood donations. We recently found this new hepcidin mutation in a family from another cohort (Biasiotto et al., in press): genotype/phenotype correlation data were also consisting with a functional role of this mutation. Two other hepcidin variations were found in this series, the 108 G→A (new), and the 212 G→A. While the first appeared silent, familial study suggests that the second may be functional in association with C282Y. No new or functional variations were found in hemojuvelin or H-ferritin genes. Several polymorphisms were detected in the ferroportin gene, including two new sequence variations (−116 T→C in the promoter; 691+20C C→T in intron 4), that occurred in two unrelated subjects with wild-type HFE genotype. Their functional role is currently under investigation by extensive family studies and/or quantitative evaluation of hepatic iron by MRI/liver biopsy.
Conclusions: DHPLC scan of iron genes appears as a helpful tool for integrating clinical data in selected patients referring for suspected iron overload, as well as for rapid identification of new mutations.