Deficient nasal bone growth in the X-linked hypophosphataemic (HYP) mouse and its implication in craniofacial growth

Mice bearing the mutant Hyp gene are characterized by craniofacial abnormalities secondary to their metabolic bone disease. X-ray cephalograms were taken of 40 normal and 29 Hyp mice at 1, 2, 3 and 4 weeks of age in one group and at weeks 6, 9 and 12 in a second. Hyp mice exhibited shorter skulls, shorter mandibles antero-posteriorly and a compressed upper face height. Both the fronto-nasal and the premaxillo-maxillary sutures in the Hyp mice were deformed and failed to close by 12 weeks of age. The deficient linear growth of the nasal bone was the most important measured variable contributing to the overall difference in the skull morphology between Hyp and normal mice. Thus this animal model is promising for elucidating the regulatory mechanisms affecting craniofacial growth.