Kbus/Idr,a mutant mouse strain with skeletal abnormalities and hypophosphatemia: Identification as an allele of 'Hyp'

Background: the endopeptidase encoded by phex (phosphate-regulating gene with homologies to endopeptidases linked to the x chromosome) is critical for regulation of bone matrix mineralization and phosphate homeostasis. phex has been identified from analyses of human x-linked hypophosphatemic rickets and hyp mutant mouse models. we here demonstrated a newly established dwarfism-like kbus/idr mouse line to be a novel hyp model. methods. histopathological and x-ray examination with cross experiments were performed to characterize kbus/idr. rt-pcr-based and exon-directed pcr screening performed to identify the presence of genetic alteration. biochemical assays were also performed to evaluate activity of alkaline phosphatase. results: kbus/idr,characterized by bone mineralization defects,was found to be inherited in an x chromosome-linked dominant manner. rt-pcr experiments showed that a novel mutation spanning exon 16 and 18 causing hypophosphatemic rickets. alkaline phosphatase activity,as an osteoblast marker,demonstrated raised levels in the bone marrow of kbus/idr independent of the age. conclusions: kbus mice should serve as a useful research tool exploring molecular mechanisms underlying aberrant phex-associated pathophysiological phenomena. © 2011 moriyama et al; licensee biomed central ltd.