Genetically, CCD is caused by a mutation in the osteoblast-specific transcription-factor-encoding gene, RUNX2, localised on Chromosome 6p21, which comprises a region size of 223 kb (Chr6:45328317-45551082) and consists of eight exons [10,11,12,13]. This evidence concerns the gene RUNX2 and cleidocranial dysplasia 1.