[Genetic variants analysis and histological observation of teeth in a patient with hereditary opalescent dentin]

To analyze the clinical characteristics and the genetic cause of a Chinese patient with hereditary opalescent dentin, and to make an observation of the histologic and elemental features of the affected teeth.

We enrolled a patient affected with hereditary opalescent dentin. The medical history was collected and clinical examinations were performed for the phenotypic analyses. The blood sample was collected for DNA extraction and PCRs of the coding sequence of DSPP were done for sanger sequencing. The teeth samples were collected for histological evaluation and elemental analysis.

The patient showed typical clinical manifestations of opalescent dentin and had enamel dysplasia and skeletal class III malocclusion. Several polymorphisms (c.727G>A, c.897A>G, c.2053_2054ins18bp, c.2548G>A, c.2645_2646ins9bp, c.2706T>C, c.2878A>G, c.3004A>G, c.3069_3086del18bp, c.3249A>C, c.3264T>C, c.3266_3400del135bp, c.3418A>G, c.3454G>A, c.3461_3462ins18bp, c.3606C>T) but no pathogenic mutations were identified in DSPP. The histological analyses of the patient's teeth showed characteristic abnormalities that were significantly different from normal teeth. The dentin tubules of the affected teeth were decreased in number and sparsed in arrangement, while in the control teeth, they were more regular. The enamel-dentin junction of the affected teeth was abnormal in its less scallopped outline compared with the control teeth under the scanning electronic microscopy. The Mg proportion of the patient's teeth (0.615 0%±0.261 6%) was lower than that of the control teeth (1.283 3%±0.322 1%), the P value was 0.040. The Ca proportion was the higher compared with the control teeth (34.865 0%±0.388 9% vs. 29.221 7%±2.248 4%), the P value was 0.015. The Ca/P ration of the patient's teeth was 1.981 2±0.019 3, which was higher than that of control teeth (1.775 9±0.111 6), the P value was 0.049. The differences of Mg, Ca proportion and Ca/P ration between the affected teeth and the control teeth were significant. The C and O proportion of the patient's teeth were lower and the P proportion was higher compared with the control teeth, however, the differences were not significant.

Our study of clinical manifestation analysis, genetic variants sequencing and histological observation has enlarged the phenotypic spectrum of hereditary opalescent dentin, and the genetic and histological results would contribute to further studies.