X-linked hypophosphatemic rickets and craniosynostosis.
Bone mineralization is possible via complex interactions among fibroblast growth factor 23 (FGF23), phosphate-regulating gene with homologies to endopeptidases on the X-chromosome (PHEX), and matrix extracellular phosphoglycoprotein. A loss-of-function mutation in PHEX disrupts this interaction leading to hypophosphatemic rickets. X-linked hypophosphatemic (XLH) rickets is the most common form of metabolic rickets, and there have been reports linking XLH rickets to craniosynostosis. A clinical report of a patient with XLH rickets and craniosynostosis is presented with a review of literature. A review of physiology of bone mineralization reveals that, at high levels, there is cross-binding of FGF23 with FGF receptors 2 and 3 at the cranial sutures. This may be the reason for the common association of craniosynostosis and XLH rickets. There are complex interactions of proteins required for mineralization, proteins inhibiting mineralization, bone remodeling, and bone-renal phosphate homeostasis. Clarification of this pathway and reproducibility in a mouse model may pave the way for medical prevention of craniosynostosis in rickets.
Murthy
Ananth S
AS
Section of Plastic Surgery, Children's National Medical Center, George Washington University, Washington, DC 20010, USA. amurthy@cnmc.org
D016723:Bone Remodeling / Q000235:genetics; D016025:Bone Transplantation / Q000379:methods; D002113:Calcification, Physiologic / Q000235:genetics; D003393:Cranial Sutures / Q000601:surgery; D003398:Craniosynostoses / Q000209:etiology* / Q000601:surgery; D003399:Craniotomy / Q000379:methods; D005091:Exons / Q000235:genetics; D053098:Familial Hypophosphatemic Rickets / Q000150:complications* / Q000235:genetics; D000089703:Fibroblast Growth Factor-23; D005346:Fibroblast Growth Factors / Q000235:genetics; D005500:Follow-Up Studies; D040181:Genetic Diseases, X-Linked; D006706:Homeostasis / Q000502:physiology; D006801:Humans; D007231:Infant, Newborn; D019586:Intracranial Hypertension / Q000209:etiology; D008297:Male; D009154:Mutation / Q000235:genetics; D009777:Occipital Bone / Q000601:surgery; D053402:PHEX Phosphate Regulating Neutral Endopeptidase / Q000235:genetics; D010294:Parietal Bone / Q000601:surgery; D014364:Tryptophan / Q000235:genetics
C000717427:FGF23 protein, human; C000717428:Fgf23 protein, mouse; D005346:Fibroblast Growth Factors; D000089703:Fibroblast Growth Factor-23; D014364:Tryptophan; D053402:PHEX Phosphate Regulating Neutral Endopeptidase; C506231:PHEX protein, human