RUNX2 and cleidocranial dysplasia 1: P10 and 2-month-old Csnk2bOsx mice displayed open calvarial fontanels, hypoplastic clavicles, and reduced body length (Fig. 3e–h and Supplementary Fig. 9a, b), similar to CCD seen in human patients with loss-of-function mutations in RUNX2 or mice with Runx2 haploinsufficiency1,6,7.