FGF23 and X-linked hypophosphatemia: The genetic disorders X-linked hypophosphatemia (XLH), autosomal dominant hypophosphatemic rickets (ADHR), and autosomal recessive hypophosphatemic rickets 1,2 and 3 (ARHR1, ARHR2 and ARHR3), are all examples of the FGF23-mediated kind, as is the acquired tumour induced osteomalacia (TIO) [19,20,21,22,23,24,25,26].