Mutations in different genes are responsible for the distinct types of non-classical HFE hemochromatosis, including hepcidin [43], [44] and hemojuvelin (type 2 or juvenile hemochromatosis - resulting from mutations in iron regulatory protein, hemojuvelin – HJV gene [45]), transferrin receptor 2 (type 3 hemochromatosis -TFR2 gene [46], [47]; and mutations in the iron exporter, ferroportin 1 [48] (mutated in type 4, the atypical dominant form of primary iron overload - SLC40A1 gene) [41], [42], [49]. The gene discussed is HJV; the disease is hemochromatosis type 3.