FGF23 and Hypocalcemia: Liu et al.19 showed that Dmp1 or Phex knockout leads to the elevation of FGF23 and, as a result, to hypophosphatemic rickets.19 This was not the case in our model, where serum analysis showed reduced levels of FGF23, hyperphosphatemia and hypocalcemia followed by high levels of PTH and low levels of osteoprotegerin (OPG), indicating that bone resorption was taking place (Supplementary Table 3).