Abstract: Cleidocranial dysplasia (CCD) is a rare genetic disorder. The clinical manifestation usually is cranial, clavicular, and dental hypoplasia, with an unusual coronoid process. We report two patients who had elongate coronoid process and one patient who had a novel mutation in the RUNX2 gene (NM_001024630:exon5:c.586_587del AG).

Key words: cleidocranial dysplasia, autosomal dominant inheritance, mandibular coronoid process, gene mutation