A new strategy for the treatment of X-linked hypophosphatemic rickets

Czech version

Authors: Ľ. Podracká ¹; M. Ilčík ²
Authors‘ workplace: Detská klinika Lekárskej fakulty Univerzity Komenského a Národného ústavu detských chorôb, Bratislava, Slovensko ¹; Rádiodiagnostické oddelenie Národného ústavu detských chorôb, Bratislava, Slovensko ²
Published in: Čes-slov Pediat 2021; 76 (7): 360-367.
Category: Original Papers

Overview

X-linked hypophosphataemia (XLH) is the most common hereditary hypophosphataemia with a prevalence of 1:20,000. The disease affects both sexes equally. XLH is manifested in childhood with typical clinical signs of rickets such as short stature, bone pain and skeletal deformities. The disease is characterized by the laboratory finding of chronic hypophosphatemia, normocalcemia and normal and/or only slightly elevated PTH.

The cause of XLH is a mutation in the PHEX gene (phosphate regulating endopeptitase). Mutations in the PHEX gene lead to significantly increased circulating concentrations of FGF23, a regulatory hormone (phosphatonin), resulting in decreased tubular phosphate reabsorption and impaired bone mineralization. Conventional treatment with phosphorus and calcitriol supplementation may be partially effective in some individuals, but has significant side effects. Targeted pathogenetic treatment with a monoclonal antibody (burosumab) is now available, which binds excess FGF-23 in the circulation and thus directly interferes with the pathogenetic mechanism of the disease.

We describe two rare cases of X-linked hypophosphatemic rickets successfully treated with burosumab.

Keywords:

X-linked hypophosphatemic rickets, PHEX gene, fibroblast growth factor 23, burosumab

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