FGF23 has been associated with a number of human diseases, including X-linked hypophosphatemia (XLH), autosomal dominant hypophosphatemic rickets (ADHR), chronic kidney disease (CKD), familial tumoral calcinosis, McCune-Albright syndrome, and fibrous dysplasia of bone [25–29]. The gene discussed is FGF23; the disease is autosomal dominant hypophosphatemic rickets.