A multidisciplinary approach for the diagnosis of hypocalcified amelogenesis imperfecta in two Chilean families

Abstract

Objective. The purpose of this study was to conduct a multidisciplinary analysis of a specific type of tooth enamel disturbance (amelogenesis imperfecta) affecting two Chilean families to obtain a precise diagnosis and to investigate possible underlying mutations. Materials and methods. Two non-related families affected with amelogenesis imperfecta were evaluated with clinical, radiographic and histopathological methods. Furthermore, pedigrees of both families were constructed and the presence of eight mutations in the enamelin gene (ENAM) and three mutations in the enamelysin gene (MMP-20) were investigated by PCR and direct sequencing. Results. In the two affected patients, the dental malformation presented as soft and easily disintegrated enamel and exposed dark dentin. Neither of the affected individuals presented with a dental and skeletal open bite. Histologically, a high level of an organic matrix with prismatic organization was found. Genetic analysis indicated that the condition is autosomal recessive in one family and either autosomal recessive or due to a new mutation in the other family. Molecular mutational analysis revealed that none of the eight mutations previously described in the ENAM gene or the three mutations in the MMP-20 gene were present in the probands. Conclusion . A multidisciplinary analysis allowed for a diagnosis of hypocalcified amelogenesis imperfecta, Witkop type III, which was unrelated to previously described mutations in the ENAM or MMP-20 genes.

Key Words::

• amelogenesis imperfecta
• enamel malformation
• hypocalcified enamel

Acknowledgements

This study was supported by the project PRI-ODO 07/3, which is sponsored by a fellowship from the School of Postgraduate Studies of the Faculty of Dentistry, and by the project FIOUCh 09-01 of Faculty of Dentistry, University of Chile. The economic costs of DNA sequencing services were contributed by the Centre of Biotechnology of the Faculty of Sciences of the University of Chile.

Declaration of interest: The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.