Familial cleidocranial dysplasia misdiagnosed as rickets over three generations

Cleidocranial dysplasia (CCD) is a rare autosomal dominant skeletal dysplasia characterized by hypoplastic clavicles, late closure of the fontanels, dental problems and other skeletal features. CCD is caused by mutations, deletions or duplications in runt-related transcription factor 2 (RUNX2), which encodes for a protein essential for osteoblast differentiation and chondrocyte maturation. We describe three familial cases of CCD, misdiagnosed as rickets over three generations. No mutations were detected on standard DNA sequencing of RUNX2, but a novel deletion was identified on quantitative polymerase chain reaction (qPCR) and multiple ligation-dependent probe amplification (MLPA). The present cases indicate that CCD could be misdiagnosed as rickets, leading to inappropriate treatment, and confirm that mutations in RUNX2 are not able to be identified on standard DNA sequencing in all CCD patients, but can be identified on qPCR and MLPA.