title: Effect of gene dose and parental origin on bone histomorphometry in X-linked Hyp mice.
abstract: X-linked hypophosphatemia (XLH) is characterized by rickets and osteomalacia and arises from mutations in the Phex and PHEX genes in mice (Hyp) and humans, respectively. The present study was undertaken to examine the effect of gene dose on the skeletal phenotype using a histomorphometric approach. Metrical traits (vertebral length, growth plate thickness, cancellous osteoid volume per bone volume, and cancellous, endocortical, and periosteal osteoid thickness) were compared in caudal vertebrae of mutant female (Hyp/+, Hyp/Hyp) and male (Hyp/Y) mice and their normal female (+/+) and male (+/Y) littermates. Mutant animals had trait values that differed significantly from those of normal animals. However, with the exception of vertebral length and cancellous osteoid thickness, values were not significantly different between the three mutant genotypes. We also examined the effect of gamete-of-origin on histomorphometric parameters in obligate Hyp/+ females derived from male or female transmitting parents. The metrical trait values in both groups of Hyp/+ mice were similar, with the exception of vertebral length and cancellous osteoid volume per bone volume. In summary, we demonstrate that the amount of osteoid per bone volume is similar in the three mutant genotypes and conclude that the extent and magnitude of the mineralization defect is fully dominant and likely not affected by gene dose. The differences in vertebral length in the mutants suggest that rickets and osteomalacia are not the only causes of decreased vertebral growth in Hyp mice and that Phex protein may influence bone growth and mineralization by distinct pathways.
authors.affiliation: Department of Biology, McGill University, Montreal, Quebec H3A 1B1, Canada.
authors.forename: Z Q
authors.initials: ZQ
authors.lastname: Qiu
authors.forename: R
authors.initials: R
authors.lastname: Travers
authors.forename: F
authors.initials: F
authors.lastname: Rauch
authors.forename: F H
authors.initials: FH
authors.lastname: Glorieux
authors.forename: C R
authors.initials: CR
authors.lastname: Scriver
authors.forename: H S
authors.initials: HS
authors.lastname: Tenenhouse
mesh_terms: D000818:Animals; D001842:Bone and Bones / Q000378:metabolism / Q000473:pathology*; D001947:Breeding; D005260:Female; D018628:Gene Dosage; D040181:Genetic Diseases, X-Linked / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D005838:Genotype; D007015:Hypophosphatemia, Familial / Q000097:blood / Q000235:genetics* / Q000378:metabolism / Q000473:pathology*; D008297:Male; D051379:Mice; D008817:Mice, Mutant Strains; D008822:Mice, Transgenic; D009154:Mutation / Q000235:genetics; D053402:PHEX Phosphate Regulating Neutral Endopeptidase; D010710:Phosphates / Q000097:blood; D011506:Proteins / Q000235:genetics* / Q000378:metabolism*; D014960:X Chromosome / Q000235:genetics
chemical_list: D010710:Phosphates; D011506:Proteins; D053402:PHEX Phosphate Regulating Neutral Endopeptidase; C506232:Phex protein, mouse