Open AccessMolecular basis of renal disease. X-linked hypophosphataemia: a homologous disorder in humans and mice
Author(s) -
Harriet S. Tenenhouse
Publication year - 1999
Publication title -
nephrology, dialysis, transplantation/nephrology dialysis transplantation
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.654
H-Index - 168
eISSN - 1460-2385
pISSN - 0931-0509
DOI - 10.1093/ndt/14.2.333
Subject(s) - phex , hypophosphatemia , hypophosphatemic rickets , endocrinology , positional cloning , medicine , osteomalacia , rickets , homeostasis , kidney , mutant , biology , vitamin d and neurology , biochemistry , gene
X-linked hypophosphatemia is an inherited disorder of phosphate (Pi) homeostasis characterized by growth retardation, rickets and osteomalacia, hypophosphataemia, and aberrant renal Pi reabsorption and vitamin D metabolism. Studies in murine Hyp and Gy homologues have identified a specific defect in Na+-Pi cotransport at the brush border membrane, abnormal regulation of 1,25-dihydroxyvitamin D3 (1,25(OH)2D) synthesis and degradation, and an intrinsic defect in bone mineralization. The mutant gene has been identified in XLH patients, by positional cloning, and in Hyp and Gy mice, and was designated PHEX/Phex to signify a PHosphate-regulating gene with homology to Endopeptidases on the X chromosome. PHEX/Phex is expressed in bones and teeth but not in kidney and efforts are under way to elucidate how loss of PHEX/Phex function elicits the mutant phenotype. Based on its homology to endopeptidases, it is postulated that PHEX/Phex is involved in the activation or inactivation of a peptide hormone(s) which plays a key role in the regulation of bone mineralization, renal Pi handling and vitamin D metabolism.