Mutations in the RUNX2 gene have been implicated in CCD [3]—evidence showing that the main pathogenic gene involved in CCD is RUNX2. Deletion, insertion, missense, nonsense, splice-site, and frameshift mutations are the most common types of RUNX2 mutations reported to cause CCD [4]. Here, RUNX2 is linked to cleidocranial dysplasia 1.