RUNX2 and cleidocranial dysplasia 1: Clinical genetic studies have demonstrated that haplo-insufficiency of the RUNX2 gene is associated with cleidocranial dysplasia (CCD) in humans, an autosomal dominant disease characterized by systemic skeletal anomalies, causing shortening of the face, abnormalities in the permanent dentition, as well as stature effects in affected individuals19–24.