目的：对遗传性乳光牙本质患者进行临床表型分析，检测基因变异；对患牙的组织形态进行电子显微镜观察，并对其元素含量进行能谱分析。方法:募集1例遗传性乳光牙本质患者，进行病史采集和临床检查，采集血液样本提取DNA，PCR扩增DSPP基因编码区并测序，测序结果与数据库比对；收集患牙样本进行组织形态的电子显微镜观察和成分组成的能谱分析，并与正常对照牙齿相比较。结果:患者有典型的乳光牙本质临床表现，即牙齿变色、磨损、髓腔和根管闭锁等，且伴发釉质发育不全和骨性反牙合表现。在DSPP基因中发现16个基因变异位点(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)， 经分析均为多态性位点，患牙的组织结构和成分组成与对照牙差别明显。扫描电子显微镜下，患牙牙本质小管数目减少，排列稀疏不规则，釉牙本质界失去了典型的扇贝样外形。能谱分析结果为患牙中镁元素含量（0.615 0%±0.261 6%）比对照牙（1.283 3%±0.322 1%）低，差异有统计学意义(P=0.040)；患牙中钙元素含量较对照牙高（34.865 0%±0.388 9% vs. 29.221 7%±2.248 4%），差异有统计学意义(P=0.015)；患牙钙磷比比值为1.981 2±0.019 3，而对照牙为1.775 9±0.111 6，差异有统计学意义(P=0.049);患牙碳元素和氧元素含量减低、磷元素含量增高，但差异没有统计学意义。结论:遗传性乳光牙本质的表型分析、基因变异检测和组织学观察结果扩大了该疾病的表型谱，可为进一步的基因和组织学研究提供参考。

Objective： 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. Methods: 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. Results: 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. Conclusion: 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.