RUNX2 and cleidocranial dysplasia 1: Cleidocranial dysplasia (CCD) is a rare disorder of autosomal dominant inheritance characterized by delayed closure of the cranial sutures, hypoplastic or aplastic clavicles and multiple dental abnormalities.[1] This condition is usually caused by a mutation of the RUNX2 (Core Binding Factor-α1) gene, located at chromosome 6p21.