Cleidocranial dysplasia (CCD) is an autosomal-dominant heritable skeletal disease caused by heterozygous mutations in the RUNX2 gene. Here, the RUNX2 gene was analyzed within a CCD family from China, and a novel missense mutation (c. 475G --> C [p.G159R]) was identified. Normal and mutant RUNX2 expression vectors were then constructed and expressed transiently in NIH3T3 cells. Immunofluorescent staining and Western blotting showed that wild-type RUNX2 protein was localized exclusively in the nucleus; however, the mutant protein was found in both the nucleus and the cytoplasm, which demonstrated that transport of the RUNX2 mutant into the nucleus was disturbed by the G159R mutation. Therefore, we suggest that G159 is very important to promote RUNX2 nuclear localization. According to clinical analysis, the patient displays severe dysplasia of bones and relatively low-grade craniofacial abnormality, and we infer that G159 may be vital for normal skeletal development, other than control of tooth number. These findings confirm that mutations in the RUNX2 gene are associated with the pathogenesis of CCD across different ethnic backgrounds.
Various methods of using skeletal anchorage for the intrusion of overerupted maxillary molars have been reported; however, it is difficult to intrude the overerupted upper second molars because of the low bone density in the region of the tuberosity. This article illustrates a new treatment method using partial fixed edgewise appliances and miniscrews to intrude the overerupted upper second molars. The miniscrews were applied to reinforce the anchorage of the upper first molar. The intrusive force was generated by the Ni-Ti wire. The clinical results showed a significant intrusion effect without root resorption or periodontal problems. This report demonstrates that the combination of partial conventional fixed appliances with miniscrews is a simple and effective treatment option to intrude overerupted upper second molars, especially in situations where miniscrews cannot be inserted directly next to the second molar.
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