粤西部分地区耳聋患者耳聋基因检测结果分析

目的通过对常见致聋基因的筛查,初步了解粤西肇庆市和云浮市地区耳聋患者耳聋基因突变情况及特点。方法在相关人员知情同意的情况下,对肇庆市和云浮市地区92例非综合征型耳聋患者进行外周静脉血采集,提取基因组DNA,应用PCR-反向点杂交技术(PCR-RDB法)对4个常见耳聋基因的16个热点突变位点进行检测,同时对GJB2基因的全外显子和线粒体12S rRNA基因进行Sanger测序。结果92例受检者中,33例为GJB2基因基因变异,其中携带致病突变有18例(包括纯合,复合杂合或杂合致病突变),突变频率为19.57%(18/92),其中c.109G>A和c.235delC等位基因频率分别为9.78%(18/184)和3.26%(6/184),共占检出的GJB2基因致病等位基因数的66.67%(24/36),因此c.109G>A和c.235delC是该地区GJB2基因上的两个热点突变;检出9例SLC26A4基因突变(包括纯合,复合杂合或杂合致病突变),突变频率为9.78%(9/92),主要为c.919-2A>G;线粒体DNA(mitochondria DNA,mtDNA 12S rRNA),未检出m.1555A>G点突变或m.1494C>T,但检出2例罕见的致聋的突变m.1027A>G和m.1452T>C。另外,检出1例m.1236C>T,截止到2018年9月未见文献报道。GJB3基因未检出突变。结论GJB2基因突变是引起粤西肇庆市和云浮地区耳聋学生听力障碍的主要原因,其中,c.109G>A和c.235delC为GJB2基因最主要的突变位点,而c.919-2A>G则是SLC26A4基因最常见的突变位点。对该地区听力障碍患者进行了四个热点耳聋基因检测,让30.43%(28/92)患者明确了其分子病因,同时给其提供了详细的遗传咨询服务,这将有利于本地区的耳聋防治。

Analysis of Deafness Gene Test Results in Hearing Loss Patients from Western Guangdong Province

Objective Common deafness gene screening was performed in Zhaoqing city and Yunfu city in western Guangdong province to understand the genetic etiology of hearing loss and its characteristics in the region.Methods After obtaining informed consents,peripheral blood samples were collected from 92 patients with non-syndrome hearing loss from to extract genomic DNA and screen for 16 mutation sites of four common deafness genes by polymerase chain reaction-reverse dot blotting(PCR-RDB).Sanger sequences were used to analyze the coding region of the GJB2 gene and Mitochondrial DNA(mtDNA)12 S rRNA.Results Among the 92 subjects,33 had mutated alleles of the GJB2 gene,including disease-causing mutations(homozygote and compound heterozygote)in 18(19.57%),and 9(9.78%)had SLC26 A4 gene mutation(c.919-2 A>G),but no m.1555 A>G or m.1494 C>T mutations in mtDNA 12 S rRNA or GJB3 gene mutations.For the GJB2 gene,the allele frequency for c.109 G>A was 9.78%(18/184)and 3.26%(6/184)for c.235 delC,respectively.Rare homozygous mutations of mtDNA 12 S rRNA(i.e.m.1027 A>G and m.1452 T>C)were detected in 2 cases,as well as a novel homozygote mutation(m.1236 C>T)in one patient.In total,deafness causing mutations were detected in 28 patients(30.43%)who(and their family members)acquired definite molecular etiology diagnosis and effective genetic counseling,aimed to help prevent and treat hearing loss.Conclusion GJB2 and SLC26 A4 are the two main deafness genes causing hearing loss in the Zhaoqing/Yunfu area,with c.109 G>A and c.235 delC being the two major mutations of the GJB2 gene and c.919-2 A>G the most common mutant form of the SLC26 A4 gene.