Wednesday, February 27, 2019

FGF23 and its role in X-linked hypophosphatemia-related morbidity | Orphanet Journal of Rare Diseases | Full Text

FGF23 and its role in X-linked hypophosphatemia-related morbidity | Orphanet Journal of Rare Diseases | Full Text



Orphanet Journal of Rare Diseases

FGF23 and its role in X-linked hypophosphatemia-related morbidity

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Orphanet Journal of Rare Diseases201914:58
  • Received: 26 October 2018
  • Accepted: 30 January 2019
  • Published: 

Abstract

Background

X-linked hypophosphatemia (XLH) is an inherited disease of phosphate metabolism in which inactivating mutations of the Phosphate Regulating Endopeptidase Homolog, X-Linked (PHEX) gene lead to local and systemic effects including impaired growth, rickets, osteomalacia, bone abnormalities, bone pain, spontaneous dental abscesses, hearing difficulties, enthesopathy, osteoarthritis, and muscular dysfunction. Patients with XLH present with elevated levels of fibroblast growth factor 23 (FGF23), which is thought to mediate many of the aforementioned manifestations of the disease. Elevated FGF23 has also been observed in many other diseases of hypophosphatemia, and a range of animal models have been developed to study these diseases, yet the role of FGF23 in the pathophysiology of XLH is incompletely understood.

Methods

The role of FGF23 in the pathophysiology of XLH is here reviewed by describing what is known about phenotypes associated with various PHEX mutations, animal models of XLH, and non-nutritional diseases of hypophosphatemia, and by presenting molecular pathways that have been proposed to contribute to manifestations of XLH.

Results

The pathophysiology of XLH is complex, involving a range of molecular pathways that variously contribute to different manifestations of the disease. Hypophosphatemia due to elevated FGF23 is the most obvious contributor, however localised fluctuations in tissue non-specific alkaline phosphatase (TNAP), pyrophosphate, calcitriol and direct effects of FGF23 have been observed to be associated with certain manifestations.

Conclusions

By describing what is known about these pathways, this review highlights key areas for future research that would contribute to the understanding and clinical treatment of non-nutritional diseases of hypophosphatemia, particularly XLH.

Keywords

  • X-linked hypophosphatemia (XLH)
  • fibroblast growth factor 23 (FGF23)
  • phosphate regulating endopeptidase homolog, X-linked (PHEX)
  • hypophosphatemia
  • vitamin D deficiency
  • rickets
  • osteomalacia
  • bone dysplasia
  • ectopic calcification
  • muscle weakness
  • dental abscess
  • hearing impairment

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