Surgical Management and Evaluation of the Craniofacial Growth and Morphology in Cleidocranial Dysplasia

A novel single-base deletion of the RUNX Family Transcription Factor 2 gene associated with cleidocranial dysplasia

Cleidocranial dysplasia (CCD) is a rare, autosomal dominant hereditary disorder characterized by skeletal malformations and dental abnormalities. The purpose of this study was to explore the functional role of a novel mutation in the pathogenesis of CCD. Genomic DNA was extracted from peripheral blood mononuclear cells collected from family members of a Chinese patient with CCD. An analysis of their RUNX Family Transcription Factor 2 (RUNX2) gene sequences was performed by PCR amplification and Sanger sequencing. The function of the mutant RUNX2 was studied by bioinformatics, real-time PCR, western blotting, and subcellular localization analysis. Sanger sequencing identified a novel single-base deletion (NM_001024630.4:c.132delG;NP_001019801.3: Val45Trpfs^* 99) in the RUNX2 gene present in the Chinese patient with CCD. In vitro, functional studies showed altered protein localization and increased expression of mutant RUNX2 mRNA and mutant Runt-related transcription factor 2 (RUNX2). Luciferase reporter assay demonstrated that the novel RUNX2 mutations significantly increased the transactivation activity of RUNX2 on the osteocalcin gene promoter. In conclusion, we identified a patient with sporadic CCD carrying a novel deletion/frameshift mutation of the RUNX2 gene and performed screening and functional analyses to determine the cause of the CCD phenotype. This study provides new insights into the pathogenesis of CCD.3.

Cleidocranial dysplasia, a rare skeletal disorder with failure of the cranial closure: case-based update

BACKGROUND AND AIM

Cleidocranial dysplasia is a rare disorder of skeletal development that mainly promotes, among other malformations, inadequate development of clavicles and failure in cranial closure. In this affection, the role of neurosurgery in addressing cranial defects is rarely discussed.

MATERIAL AND METHODS

We conducted an extensive review of the literature using the PubMed database, giving a greater focus to publications in the field of neurosurgery. Additionally, we report a case of a 2-year-old female child with cleidocranial dysplasia.

RESULTS

In our review, we encountered several cases of orthodontic implications but a few cases on cranial defect approach.

CONCLUSION

The articles present literature that is unanimous on the recommendation of expectant conduct in children since the cranial block can occur spontaneously, even if the delayed form. In our approach, we opted for an expected strategy concerning the cranial defect, using a helmet made for brain protection. We also made the referral for multidisciplinary monitoring of pediatrics, neuropediatrics, ophthalmology, dentistry, and orthopedics.

Cleidocranial dysplasia

We present a 4-year-old girl with persistent anterior fontanelle and narrow sloping shoulders. The X-ray imaging revealed widely open anterior fontanelle, supernumerary teeth, and absence of clavicles. Therefore, the diagnosis was cleidocranial dysplasia, which is a rare autosomal dominant skeletal disease, caused by the mutation in the gene on 6p21 encoding transcription factor CBFA1 (runt-related transcription factor 2-RUNX2). The girl remains under close surveilance, her anterior fontanelle closed spontaneously at the age of 9 years.

Gene-Expression Analysis Identifies IGFBP2 Dysregulation in Dental Pulp Cells From Human Cleidocranial Dysplasia

Cleidocranial dysplasia (CCD) is an autosomal dominant disorder affecting osteoblast differentiation, chondrocyte maturation, skeletal morphogenesis, and tooth formation. Dental phenotype in CCD include over-retained primary teeth, failed eruption of permanent teeth, and supernumerary teeth. The underlying mechanism is unclear. We previously reported one CCD patient with allelic RUNX2 deletion (CCD-011). In the current study, we determined the transcriptomic profiles of dental pulp cells from this patient compared to one sex-and-age matched non-affected individual. Next Generation RNA sequencing revealed that 60 genes were significantly dysregulated (63% upregulated and 27% downregulated). Among them, IGFBP2 (insulin-like growth factor binding protein-2) was found to be upregulated more than twofold in comparison to control cells. Stable overexpression of RUNX2 in CCD-011 pulp cells resulted in the reduction of IGFBP2. Moreover, ALPL expression was up-regulated in CCD-011 pulp cells after introduction of normal RUNX2. Promoter analysis revealed that there are four proximal putative RUNX2 binding sites in -1.5 kb IGFBP2 promoter region. Relative luciferase assay confirmed that IGFBP2 is a direct target of RUNX2. Immunohistochemistry demonstrated that IGFBP2 was expressed in odontoblasts but not ameloblasts. This report demonstrated the importance of RUNX2 in the regulation of gene profile related to dental pulp cells and provided novel insight of RUNX2 into the negative regulation of IGFBP2.