These data suggest that both MEPE and OPN are involved in impaired tooth mineralization associated with XLH, possibly through different effects on the mineralization process.
Finally, additional studies are required to establish the molecular mechanisms of FGF23 and MEPE actions on kidney and bone, as well as to confirm the role of these and other potential "phosphatonins," such as frizzled related protein-4, in the pathogenesis of the renal and skeletal phenotypes in XLH and TIO.