外胚叶发育不全基因A突变导致家族性非综合征型先天缺牙的初步研究

Preliminary study of familial nonsyndromic tooth agenesis caused by ectodysplasin A mutation

目的 寻找非综合征型先天缺牙(non-syndromic tooth agenesis,NSTA)家系的致病基因,探讨其发病机制。方法 获得医院伦理审批及患者与家属知情同意,收集先证者及其家系主要成员的临床资料,采集外周静脉血,提取DNA,利用全外显子测序技术进行基因检测,运用Sanger测序验证筛查出的致病基因,运用生物信息学工具分析突变蛋白的三维结构,并与野生型进行比较分析。结果 该家系2名患者为表兄弟关系,家系中无其他先天多数牙缺失的患者,除先天缺失多颗牙外,2名患者无明显毛发异常、无指/趾异常、无出汗异常等其他外胚叶组织的异常表现。通过对此家系中的患者及主要成员进行基因测序,发现与该家系相关的突变基因是一种新的外胚叶发育不全基因A(ectodysplasin A,EDA)的错义突变c.983C>T(p.Pro328Leu),导致对应编码的氨基酸从脯氨酸(Pro)变为亮氨酸(Leu)。对该突变位点进行保守性分析发现,该位点具有高度保守性,通过三维构建模发现该位点蛋白结构发生了改变。结论 首次发现EDA基因新的错义突变位点c.983C>T(p.Pro328Leu)与非综合征型先天缺牙有关,扩大了EDA基因的突变谱。

Objective To explore the pathogenic genes in a Chinese family affected by nonsyndromic tooth agenesis so as to study the pathogenesis of oligodontia.Methods Hospital ethical approval and informed consent of the patients and family members were obtained.Clinical data of the proband and close family members were collected,peripheral venous blood was collected,and DNA was extracted.Gene sequencing was performed through whole-exome sequencing,and then the screened pathogenic genes were verified by Sanger sequencing.The three-dimensional structure of the mutant proteins was analyzed and compared with the wild-type using bioinformatics tools.Results The two patients with congenital majority tooth loss in this family were cousins,and there were no other patients with congenital majority tooth loss in the family.Besides congenital multiple tooth loss,the two patients had no obvious hair abnormalities,finger/toe abnormalities,sweating abnormalities or other abnormal manifestations of ectodermal tissue.We found a mutant gene that in this family by carrying out gene sequencing of the patients and their close family members.A novel EDA(ectodysplasin A) missense mutation c.983CT(p.Pro328Leu) was identified,which changed the encoded amino acid from proline(Pro)to leucine(Leu).Analysis of the mutation site showed that the site was highly conserved,and three-dimensional structure modeling also found that it changed the structure of EDA.Conclusion A novel EDA missense variant(c.983CT,p.Pro328Leu) was first identified in a Chinese family with nonsyndromic tooth agenesis,extending the mutation spectrum of the EDA gene.