Another important novel finding was made in 2000, when bone-derived hormone Fibroblast Growth Factor-23 (FGF23) was found to cause autosomal dominant hypophosphataemic rickets (ADHR), which provided the underlying mechanism for the previously unknown “phosphaturic factor” causing hypophosphataemia (2, 3). The gene discussed is FGF23; the disease is autosomal dominant hypophosphatemic rickets.