Hepatic iron concentration, fibrosis and response to venesection associated with the A77D and V162del “loss of function” mutations in ferroportin disease

Abstract

Ferroportin disease is an autosomal dominant form of hemochromatosis associated with siderosis in cells of the mononuclear phagocyte system and, to varying degrees, in hepatocytes. Ferroportin was investigated as a candidate gene in two pedigrees with hyperferritinaemia and siderosis in mononuclear phagocytes. The entire ferroportin coding region was sequenced and hepatic iron concentration, histology and response to treatment were determined. The results were compared with previously reported cases. The A77D mutation was detected in patient 1, his father (patient 2) and his brother (patient 3), who had portal fibrosis. The V162del mutation was detected in patient 4, who developed anemia after the third weekly venesection. While the disease is rare, A77D and V162del are the most common ferroportin mutations in Caucasians. The spectrum of clinical expression of these two mutations was reviewed in all cases described to date. These mutations were associated with fibrosis in about a third of cases. For A77D and V162del, this analysis confirms that the threshold hepatic iron concentration for development of fibrosis may be higher than for classical hemochromatosis. These two mutations, which both decreased iron export in cell culture studies, give rise to similar patterns of clinical expression and morbidity, although the highest hepatic iron concentrations have been observed with A77D. It is important for clinicians to consider ferroportin disease in cases where there are features of iron overload unrelated to HFE, autosomal dominant inheritance and/or iron deposition in mononuclear phagocytes.