Early studies of Runx2 in mice were hampered by lethality of Runx2 gene knockout; analysis of Runx2 heterozygous mice suggested a role for the transcription factor in tooth eruption via osteoclastogenesis, which mimicked eruption delays seen in cleidocranial dysplasia (CCD; OMIM# 119600) resulting from RUNX2 mutations (Kreiborg & Jensen, 2018). The gene discussed is RUNX2; the disease is cleidocranial dysplasia 1.