Zhang Zhenwei, Xu Xinran, Gao Xuejun, Dong Yanmei, Tian Hua
Department of Cariology and Endodontology, Peking University School and Hospital of Stomatology & National Center for Stomatology & National Clinical Research Center for Oral Diseases & National Engineering Research Center of Oral Biomaterials and Digital Medical Devices, Beijing 100081, China.
Department of Conservative Dentistry and Endodontics 2, Shanghai Stomatological Hospital & School of Stomatology; Shanghai Key Laboratory of Craniomaxillofacial Development and Diseases, Fudan University, Shanghai 200001, China.
Beijing Da Xue Xue Bao Yi Xue Ban. 2025 Feb 18;57(1):13-18. doi: 10.19723/j.issn.1671-167X.2025.01.003.
To analyze gene mutation found in a pedigree with clinical features and inheritable pattern consistent with amelogenesis imperfecta (AI) in China, and to study the relationship between its genotype and phenotype.
Clinical and radiological features were recorded for the affected individuals. Peripheral venous blood samples of the patient and family members were collected for further study, and the genomic DNA was extracted to identify the pathogenic gene. Whole exome sequencing (WES) was performed to analyze the possible pathogenic genes, and Sanger sequencing was performed for validation. SIFT and PolyPhen-2 were used to predict and analyze the mutation effect. Comparison of RELT amino acids across different species were performed by using Uniprot website. In addition, the three-dimen-sional structures of the wild type and mutant proteins were predicted by Alphafold 2.
The proband exhibited typical hypocalcified AI, with heavy wear, soft enamel, rough and discolored surface, and partial enamel loss, while his parents didn ' t have similar manifestations. WES and Sanger sequencing results indicated that the proband carries a homozygous frameshift mutation in gene, NM_032871.3: c.1169_1170del, and both of his parents were carriers. This mutation was predicted to be pathogenic by SIFT and PolyPhen-2. Up to now, there were 11 mutation sites in gene were reported to be associated with AI, and all of the patients exhibited with hypocalcified AI. Compared with the wild-type RELT protein, the mutant protein p. Pro390fs35 conformation terminated prematurely, affecting the normal function of the protein.
Through phenotype analysis, gene sequencing, and functional prediction of a Chinese family with typical amelogenesis imperfecta, this study found that gene frameshift mutation can lead to protein dysfunction in AI patients. Further research will focus on the role and mechanism of RELT in enamel development at the molecular and animal levels, providing molecular biology evidence for the genetic counseling, prenatal diagnosis, and early prevention and treatment of AI.
分析中国一个家系中发现的基因突变，该家系具有与牙釉质发育不全（AI）一致的临床特征和遗传模式，并研究其基因型与表型之间的关系。
记录受累个体的临床和影像学特征。采集患者及其家庭成员的外周静脉血样本进行进一步研究，提取基因组DNA以鉴定致病基因。进行全外显子组测序（WES）以分析可能的致病基因，并进行Sanger测序进行验证。使用SIFT和PolyPhen-2预测和分析突变效应。通过Uniprot网站对不同物种的RELT氨基酸进行比较。此外，使用Alphafold 2预测野生型和突变型蛋白质的三维结构。
先证者表现出典型的低钙化型AI，磨损严重，牙釉质软，表面粗糙且变色，部分牙釉质缺失，而其父母没有类似表现。WES和Sanger测序结果表明，先证者在基因NM_032871.3中携带纯合移码突变：c.1169_1170del，其父母均为携带者。该突变被SIFT和PolyPhen-2预测为致病突变。截至目前，该基因中有11个突变位点被报道与AI相关，所有患者均表现为低钙化型AI。与野生型RELT蛋白相比，突变蛋白p.Pro390fs35构象提前终止，影响了蛋白质的正常功能。
通过对一个具有典型牙釉质发育不全的中国家系进行表型分析、基因测序和功能预测，本研究发现该基因移码突变可导致AI患者蛋白质功能障碍。进一步的研究将聚焦于RELT在牙釉质发育中的分子和动物水平的作用及机制，为AI的遗传咨询、产前诊断及早期防治提供分子生物学依据。
