These results indicate that FGF23 processing appears to be severely impaired in Furinosb-/- mice under conditions of iron deficiency as these mice maintained in the circulation a 1:1 ratio (i.e., 100%) of intact over C-terminal FGF23 and very low level of cleaved FGF23 (Figures 2G, H). This evidence concerns the gene FGF23 and Iron deficiency anemia.