A case of cleidocranial dysplasia with peculiar dental features: pathogenetic role of the RUNX2 mutation and long term follow-up.

This report deals with a case of Cleidocranial Dysplasia (CCD) associated to a rare mutation of the RUNX2 gene and a peculiar dental phenotype, namely no supernumerary teeth. The aim consists in evaluating the long-term follow-up after treatment and discussing the pathogenetic mechanism of the mutation. We have carried out a clinical evaluation after treatment and attempted to analyze the potential pathogenetic effect of the mutation, based upon the available experimental structure of RUNX family domain and the highly conserved homology of RUNX1-3. Clinically the treatment has led to tooth development in crowns an roots, correction of cross-bite and eruption of the central maxillary incisor. The structural analysis has pointed out impairment in the DNA binding capability of the mutant protein. The described mutation, c.391C>T (p.R131C) appears to influence both structure and function of the protein by hampering the interaction of RUNX2 with DNA. The impaired function could explain the peculiar reported CCD phenotype. The dental condition of our patient has largely improved after treatment.