少汗性外胚层发育不良患者EDA基因突变检测及表型分析

目的: 在少汗性外胚层发育不良(hypohidrotic ectodermal dysplasia,HED)患者中检测ectodysplasin A(EDA)基因突变,汇总并分析携带EDA基因突变的HED患者的缺失恒牙分布特点及全身临床表现。方法: 对临床收集到的12个HED家系进行遗传病史采集、全身系统性检查和口内检查,通过采集先证者及其家族成员的外周静脉血或唾液样本,提取基因组DNA,聚合酶链式反应(polymerase chain reaction,PCR)扩增EDA基因编码区并进行Sanger测序,与正常人群的EDA基因序列(NM_001399.5)进行比对,筛查突变。利用突变功能预测、保守性分析、蛋白结构预测分析突变的功能影响,根据《美国医学遗传学和基因组学会遗传变异致病性分级指南》评估突变的致病性。总结EDA基因突变的HED患者的全身表型、缺失恒牙牙位,对比分析不同牙位缺失率的差异。结果: 在12个HED家系中发现8个家系分别携带8个EDA基因突变:c.164T>C(p.Leu55Pro)、c.457C>T(p.Arg153Cys)、c.466C>T(p.Arg156Cys)、c.584G>A(p.Gly195Glu)、c.619delG(p.Gly207Profs*73)、c.673C>T(p.Pro225Ser)、c.676C>T(p.Gln226*)和c.905T>G(p.Phe302Cys),其中,c.164T>C(p.Leu55Pro)、c.619delG(p.Gly207Profs*73)、c.673C>T(p.Pro225Ser)、c.676C>T(p.Gln226*)和 c.905T>G(p.Phe302Cys)为新检出的突变。本研究发现的EDA基因突变的HED患者均为男性,其平均缺失恒牙数目为(13.86±4.49)颗,其中上颌平均缺失恒牙数目为(13.14±5.76)颗,缺失率为73.02%,下颌平均缺失恒牙数目为(14.57±3.05)颗,缺失率为80.95%。牙列左、右侧同名牙缺失数目差异无统计学意义(P>0.05)。上颌侧切牙、上颌第二前磨牙和下颌侧切牙缺失率高,而上颌中切牙、上颌第一磨牙和下颌第一磨牙缺失率低。结论: 本研究在HED患者中检测出EDA基因致病突变,总结EDA基因突变的HED患者缺失恒牙规律,丰富了HED患者的EDA基因突变谱和表型谱,为遗传诊断和产前咨询提供了新的证据。

Detection of EDA gene mutation and phenotypic analysis in patients with hypohidrotic ectodermal dysplasia

Objective: To detect the ectodysplasin A (EDA) gene mutation in patients with hypohidro-tic ectodermal dysplasia (HED), and to analyze the distribution pattern of missing permanent teeth and the systemic manifestation of HED patients with EDA gene mutation.Methods: Twelve HED families were enrolled from clinic for genetic history collection, systemic physical examination and oral examination. Peripheral blood or saliva samples were collected from the probands and the family members to extract genomic DNA. PCR amplification and Sanger sequencing were utilized to detect the EDA gene variations, which were compared with the normal sequence (NM_001399.5). The functional impact of EDA gene variants was then evaluated by functional prediction of mutation, conservation analysis and protein structure prediction. The pathogenicity of each EDA gene variation was assessed according to the stan-dards and guidelines of the American College of Medical Genetics and Genomics (ACMG). The systemic phenotype and missing permanent tooth sites of HED patients with EDA gene mutations were summarized, and the missing rate of each tooth position was analyzed and compared.Results: Eight out of twelve HED families were identified to carry EDA gene mutations, including: c.164T>C(p.Leu55Pro); c.457C>T(p.Arg153Cys); c.466C>T(p.Arg156Cys); c. 584G>A(p.Gly195Glu); c.619delG(p.Gly207Profs*73); c.673C>T(p.Pro225Ser); c.676C>T(p.Gln226*) and c.905T>G(p.Phe302Cys). Among them, c.164T>C(p.Leu55Pro); c.619delG(p.Gly207Profs*73); c.673C>T(p.Pro225Ser); c.676C>T(p.Gln226*) and c.905T>G(p.Phe302Cys) were novel mutations. The HED patients with EDA gene mutations in this study were all male. Our results showed that the average number of missing permanent teeth was 13.86±4.49, the average number of missing permanent teeth in the upper jaw was 13.14±5.76, the missing rate was 73.02%. And in the lower jaw, the average number of missing permanent teeth was 14.57±3.05, the missing rate was 80.95%. There was no significant difference in the number of missing teeth between the left and right sides of the permanent dentition (P>0.05). Specifi-cally, the maxillary lateral incisors, the maxillary second premolars and the mandibular lateral incisors were more likely to be missing, while the maxillary central incisors, the maxillary and mandibular first molars had higher possibility of persistence.Conclusion: This study detected novel EDA gene pathogenic variants and summarized the distribution pattern of missing permanent teeth of HED patients, thus enriched the variation and phenotype spectrum of EDA gene, and provided new clinical evidence for genetic diagnosis and prenatal consultation.