What’s new in hypophosphataemic rickets?

Although relatively uncommon individually, the various causes of hypophosphataemic rickets have provided an impetus for unravelling the mechanisms of phosphate homeostasis and bone mineralisation. Over the past 10 years, considerable advances have been made in establishing the gene mutations responsible for a number of the inherited causes and in understanding the mechanisms responsible for tumour-induced osteomalacia/rickets. The most exciting aspects of these discoveries have been the discovery of a whole new class of hormones or phosphatonins which are thought to control phosphate homoeostasis and 1 alpha-hydroxylase activity in the kidney, through a bone–kidney–intestinal tract axis. Although our understanding of the interrelationships is far from complete, it raises the possibilities of improved therapeutic agents in the long-term, and has resulted in improved diagnostic abilities in the short-term.