Characteristic biochemical findings include hypophosphatemia, renal phosphate wasting, as indicated by a low calculated tubular reabsorption of phosphate (TRP) or low tubular maximum phosphate reabsorption rate (TmP/GFR), low or inappropriately normal 1,25(OH)2-vitamin D, and elevated or inappropriately normal FGF23 levels [6–8]. The gene discussed is FGF23; the disease is hypophosphatemia.