Two of these modifier genes are HFE (H= high FE = Fe, iron homestasis regulator) related with type 1 hemochromatosis [67] and TMPRSS6 (transmembrane serine protease 6) coding for the matriptase 2 and causative of iron refractory iron deficiency anemia (IRIDA) [68]. This evidence concerns the gene TMPRSS6 and hemochromatosis type 1.