FGF23 and autosomal dominant hypophosphatemic rickets: High levels of FGF23 could also occur in Autosomal Dominant Hypophosphatemic Rickets (ADHR), which is caused by the inactive mutation in the proteolytic cleavage domain (RXXR cleavage motif) in FGF23, therefore the variation renders FGF23 resistant to proteolytic cleavage (Shimada et al., 2002).