Iron is a negative regulator of FGF23 levels, and iron deficiency increases FGF23 production independent of inflammation, probably by increasing the expression and stability of hypoxia-inducible factor 1α (HIF1α), which binds to hypoxia-responsive elements in the promoter region of Fgf23 and induces its transcription [47]. The gene discussed is FGF23; the disease is Iron deficiency anemia.