Abstract
X-linked hypophosphatemia is caused by mutations in transmembrane endopeptidase gene on the X chromosome (PHEX gene). This situation results in fibroblast growth factor 23 (FGF23) excess, leading to renal phosphate wasting and 1α-hydroxylase suppression.
Chronic hypophosphatemia causes impaired bone mineralization and rickets in children's growing skeleton (osteomalacia in adults). Conventional therapy consists of active vitamin D and supplementation of phosphate in multiple oral doses per day.
This therapy is asociated with some improvement in clinical symptoms but not normal phosphatemia and the disease is insufficiently controlled. At present time, the new therapeutic option is introduced: burosumab is fully human monoclonal recombinant antibody against FGF23.
Burosumab binds to FGF23 with inactivation its phosphaturic effect. Increased calcitriol formation stimulates phosphate gut absorption.
Phosphate homeostasis could be restored.