This chapter provides an overview of the prototype X-linked hypophosphatemic disease (XLH). The chapter discusses key elements central to the pathophysiology of XLH and its related disorders, including the putative function of the mutated endopeptidase PHEX and the substances that appear to be important candidates for mediation of the disease. The chapter reviews the biochemistry of FGF23 with respect to its role in the related disorder, autosomal-dominant hypophosphatemic rickets (ADHR). Clinical features of related disorders, including ADHR, hereditary hypophosphatemic rickets with hypercalciuria (HHRH), and tumor-induced osteomalacia (TIO) are compared to those observed in XLH. XLH is one of the most common bone diseases seen in children. XLH is characterized by renal phosphate wasting leading to hypophosphatemia and low or normal concentrations of 1,25-dihydroxyvitamin D [1,25(OH)2D], an inappropriate response to hypophosphatemia. In children, the disorder first becomes apparent with the development of rickets, skeletal deformities, short stature, and dental abscesses. In adults, manifestations of XLH include osteomalacia, degenerative joint disease, enthesopathy, bone and joint pain, and continued dental disease.
ASJC Scopus subject areas
- Biochemistry, Genetics and Molecular Biology(all)