Targeted ablation of the fgf-23 gene in mice disrupts calcium, phosphorus and 1,25 (OH)2D homeostasis [34], [48], giving rise to hypercalcemia, hyperphosphatemia and increased serum 1,25(OH)2D concentrations, the latter due to significantly increased renal expression of CYP27B1 mRNA and protein. This evidence concerns the gene CYP27B1 and hypercalcemia disease.