Consistent with previous reports, the majority of Runx2+/− mice exhibited developmental anomalies resembling the CCD phenotype described by Otto and colleagues (eg, hypoplastic clavicles, wide sutures, and delayed membranous bone ossification resulting in open anterior and posterior fontanelles as well as wide cranial sutures)(4) (Fig. 3A, B). Here, RUNX2 is linked to cleidocranial dysplasia 1.