As if coinciding with these changes, αKlotho was first reported in 1997, a deficiency of which results in an aging phenotype [1], and fibroblast growth factor 23 (FGF23), which causes a form of rickets and hypophosphatemia in bone metastasis, was identified in the early 2000s [2,3]. The gene discussed is FGF23; the disease is hypophosphatemia.