[Genetic hypophosphatemia: recent advances in physiopathogenic concept].
Renal proximal tubular reabsorption of phosphate and intestinal absorption both regulate phosphate homeostasis. Brush-border membrane Npt2a cotransporter is the key element in proximal tubular P (i) reabsorption. Inactivating mutations of Npt2a cause bone demineralisation and urolithiasis. An excess of a phosphaturic factor, called "Phosphatonin", could modulate phosphate reabsorption by inhibition on Npt2a. Inactivating mutation of PHEX, an endopeptidase-membrane coding gene, is responsible for X-linked Hypophosphatemia (XLH), because of an impaired degradation of phosphatonine by PHEX product. Autosomic Dominant Hypophosphatemic Rickets (ADHR) is explained by a mutation preventing FGF23 (one of the best identified phosphatonines) from cleavage. According recent data, FGF23, MEPE (Matrix Extracellular Phosphoglycoprotein) et FRP4 (frizzled related protein-4) are 3 putative "phosphatonines".
Beraud
G
G
Service d'Endocrinologie et Métabolisme, 6, rue du Pr. Laguesse, Centre hospitalo-universitaire, 59037 Lille Cedex, France.
Perimenis
P
P
Velayoudom
Fr-L
FL
Wemeau
J-L
JL
Vantyghem
M-Chr
MC
D000042:Absorption; D000089703:Fibroblast Growth Factor-23; D040181:Genetic Diseases, X-Linked; D006706:Homeostasis; D006801:Humans; D017674:Hypophosphatemia / Q000235:genetics* / Q000503:physiopathology; D007015:Hypophosphatemia, Familial; D007408:Intestinal Absorption; D007687:Kidney Tubules, Proximal / Q000378:metabolism; D009154:Mutation; D010710:Phosphates / Q000378:metabolism
C000717427:FGF23 protein, human; D010710:Phosphates; D000089703:Fibroblast Growth Factor-23