Data from tumor-induced osteomalacia (TIO), familial tumoral calcinosis (FTC), and X-linked hypophosphatemic rickets studies have demonstrated the role of FGFR1 and its ligand FGF23 in tightly regulating phosphate balance in conjunction with the parathyroid hormone [9,13]. The gene discussed is FGF23; the disease is thyroid cancer, nonmedullary, 2.