title: Hypophosphatemic rickets.
abstract: OBJECTIVE
  Description of the recent advances on the regulation of phosphate metabolism, gene mutations, and new approaches to treatment in patients with hypophosphatemic rickets.
  
  
  RESULTS
  Fibroblast growth factor 23 (FGF23) overproduction may be a primary cause of hypophosphatemic rickets. Inactivating mutations of phosphate-regulating gene with homologies to endopeptidases on the X chromosome, dentin matrix acidic phosphoprotein 1, and ectonucleotide pyrophosphatase/phosphodiesterase 1 are associated with X-linked hypophosphatemic rickets, autosomal recessive hypophosphatemic rickets 1, and autosomal recessive hypophosphatemic rickets 2, respectively. Activating mutations of FGF23 gene is the cause of autosomal dominant hypophosphatemic rickets. Iron deficiency may affect autosomal dominant hypophosphatemic rickets phenotype by regulating FGF23 production.Current treatment with activated vitamin D metabolites and oral inorganic phosphate salts may partially correct skeletal lesions and linear growth in patients with hypophosphatemic rickets. However, some patients have poor improvement by the current treatment.
  
  
  CONCLUSIONS
  Identification of the causative mutation in patients with hypophosphatemic rickets may be useful to confirm the diagnosis and probably for prognosis. Inhibition of FGF23 overproduction by anti-FGF23 neutralizing antibodies could be a future approach for treatment of patients with FGF23-dependent hypophosphatemic rickets.
authors.affiliation: Pediatric Unit I, Department of Obstetrics, Gynecology and Pediatrics, University-Hospital, Pisa, Italy. g.baroncelli@med.unipi.it
authors.forename: Giampiero I
authors.initials: GI
authors.lastname: Baroncelli
authors.forename: Benedetta
authors.initials: B
authors.lastname: Toschi
authors.forename: Silvano
authors.initials: S
authors.lastname: Bertelloni
mesh_terms: D000818:Animals; D057134:Antibodies, Neutralizing / Q000235:genetics*; D004252:DNA Mutational Analysis; D053098:Familial Hypophosphatemic Rickets / Q000175:diagnosis* / Q000188:drug therapy / Q000235:genetics; D005260:Female; D000089703:Fibroblast Growth Factor-23; D005346:Fibroblast Growth Factors / Q000235:genetics*; D040181:Genetic Diseases, X-Linked; D006801:Humans; D007501:Iron; D008297:Male; D051379:Mice; D009154:Mutation; D010710:Phosphates / Q000008:administration & dosage / Q000494:pharmacology*; D011379:Prognosis; D014807:Vitamin D / Q000008:administration & dosage / Q000494:pharmacology*
chemical_list: D057134:Antibodies, Neutralizing; C000717427:FGF23 protein, human; C000717428:Fgf23 protein, mouse; D010710:Phosphates; D014807:Vitamin D; D005346:Fibroblast Growth Factors; D000089703:Fibroblast Growth Factor-23; D007501:Iron