The upregulation of serum FGF23 results in hyperphosphaturia, hypophosphatemia, and decreased levels of calcitriol due to the inhibitory effect on renal 25-hydroxyvitamin D3 1-α-hydroxylase with the resultant hypo-mineralization of calcified tissues, such as bone and teeth (3). This evidence concerns the gene FGF23 and hypophosphatemia.