| [ Summary ] |
The concentration of serum phosphorous is regulated by many factors such as PTH, 1,25-dihydroxy vitamin D, growth hormone, PTHrP and so on. X-linked hypophosphatemic rickets is characterized by hypophosphatemia, decreased reabsorption of phosphorus by the renal tubule. The genetic defect for this disorder is in a gene termed PHEX, wich encodes for neutral endopeptidase presumed to be responsible for degradation of an as-yet-unidentified systemic phosphaturic hormone, phosphatonin. The defective PHEX gene product in X-linked hypophosphatemic rickets permits phosphatonin to inhibit renal phosphate absorption, de spite persitent hypophosphatemia. Recent report de scribed that FGF-23 inhibits renal tubular phosphate transport and was a PHEX substrate. FGF-23 was possible candidate for phosphatonin. |