利用全外显子测序技术发现BTK基因新生突变

Whole-exome sequencing identifies a de novo mutation in BTK

目的利用全外显子测序技术,对疑似X-连锁无丙种球蛋白血症患儿及父母进行测序,发现致病基因突变并明确临床诊断,探讨基因型与临床表型之间的关系及分子诊断的意义。方法提取疑似X-连锁无丙种球蛋白血症患儿及其父母外周血,应用全外显子组捕获高通量测序筛查患儿及父母基因组DNA。通过生物信息学分析,结合dbSNP、千人基因组、ExAC、gnomAD数据库分析变异频率,确定突变位点,用Sanger测序法进行验证。结果通过全外显子测序,在患儿BTK基因中找到一个新发错义杂合突变c.1781G >A(p.G594E),该位点位于已报道的热点位置,其父母此位点为正常基因型。结合临床表型和基因检测结果,该患儿被确诊为X-连锁无丙种球蛋白血症。结论本研究明确了X-连锁无丙种球蛋白血症临床表型和该BTK突变位点的相关性。通过全外显子测序技术成功鉴定了BTK基因的突变,强调了该技术在儿童先天性免疫缺陷病的明确诊断和遗传咨询中的实用性。

Objective:Using whole-exome sequencing(WES),we aim to identify sequence variants in patients who are suspected to suffer from X-linked agammaglobulinemia(XLA),and to explore the relationship between genotype and clinical phenotype. Methods:Peripheral blood samples from a patient with XLA and his parents(trio)were collected and genomic DNAs were extracted to conduct trio-WES. Variant frequency was evaluated using dbSNP,1000 Genomes Project,Ex AC,and gnom AD Database. The candidate variants were further validated by PCR and Sanger sequencing. Results:By whole-exome sequencing,we found a de novo missense heterozygous mutation c.1781 G >A(p.G594 E)in the BTK gene of the patient. This variant is located in a reported mutation hotspot. Conclusion:We identified the de novo p.G594 E variant of BTK gene was the causative mutation of XLA. This emphasizes the practical application of trio-WES in diagnosing rare diseases which is important for genetic conseling.