ARHR due to the DMP1 mutation is characterized by hypophosphatemia, osteomalacia, and poor bone and tooth development and structure and we have previously shown that FGF23 is elevated in osteocytes (Feng et al., 2006; Farrow et al., 2009) similar to what occurs in XLH (Liu et al., 2007; White et al., 2014). Here, FGF23 is linked to X-linked hypophosphatemia.