RUNX2 and cleidocranial dysplasia 1: The development of calvaria in the newborn was retarded similar to <i>Runx2</i> <sup>+/-</sup> mice, which showed cleidocranial dysplasia, but it was much less affected than in <i>Runx2</i> <sup>+/-</sup> mice at 8 weeks of age, and the suture mesenchymal cell proliferation increased.