潘蕾 陈亚秋 刘瑾 刘宏彦天津市妇女儿童保健中心(天津300070)
135例听力障碍大学生聋病易感基因检测结果分析
潘蕾陈亚秋刘瑾刘宏彦
天津市妇女儿童保健中心(天津300070)
【摘要】目的对听力障碍大学生进行聋病易感基因检测,了解常见聋病易感基因四个基因20个位点的突变情况,为耳聋的防治提供依据。方法应用基质辅助激光解析离子飞行时间质谱技术,通过采集末梢血检测135例听力障碍大学生的GJB2、GJB3、SLC26A4和线粒体12SrRNA基因的20个突变位点。结果135例受检者中77例存在基因突变,突变率为57.04%;杂合突变23例,纯合突变34例,复合杂合突变20例。c.235delC突变占GJB2基因突变的91.11%(41/ 45);c.IVS7-2A>G突变占SLC26A4基因突变的79.31%(23/29);12SrRNA基因仅检出3例m.1555A>G同质性突变;GJB3基因检出c.547G>A杂合突变1例。结论135例受检者中GJB2、GJB3、SLC26A4和线粒体12SrRNA基因突变率为57.04%;c.235delC是GJB2基因的常见突变位点;c.IVS7-2A>G是SLC26A4基因的常见突变位点;检出少数与氨基糖苷类药物耳毒性密切相关的线粒体12SrRNA基因突变;GJB3基因突变率不高。通过对听力障碍人群进行聋病易感基因检测,从分子诊断水平明确病因,进行耳聋靶向预防突变和遗传咨询,提高优生优育。
【关键词】耳聋;聋病易感基因;基因突变;遗传咨询
听力障碍是人类常见的致残疾病之一,发病率在1~3‰。2006年第二次全国残疾人抽样调查[1]推算我国现有听力残疾2004万人,患病率2.11%,其中单纯听力残疾患病率1.52%。由于50~70%的听力障碍与遗传因素有关[2,3],对育龄听力障碍人群进行聋病易感基因检测,既是基因学诊断,又可从遗传角度对听力障碍防控,降低其后代致残发生率。本文检测135例听力障碍大学生的聋病易感基因突变报告如下。
1.1研究对象
2015年正就读于天津某理工大学聋人工学院的135名听力障碍大学生,其中男生67人,女生68人,年龄最小18岁,最大27岁,平均21.17±1.747岁。所有学生了解本次检测的目的、方法,且自愿参加,并填写知情同意书。135人均持有当地残疾人联合会发放的《听力障碍残疾证》,无其他残疾,智力正常。
1.2研究方法
1.2.1标本采集
采集末梢指血于滤纸片上,避免污染,充分晾干,单片装袋,低温保存。
1.2.2检测方法
由华大基因检验所利用基质辅助激光解析离子飞行时间质谱技术,检测四个聋病易感基因[4-6]的20个位点,分别是GJB2基因(c.235delC,c.35delG,c.167delT,c.299_300delAT,c.176_191dell6)、GJB3基因(c.538C>T,c.547G>A)、SLC26A4基因(c.281C>T,c.589G>A,c.IVS7-2A>G,c.1174A>T,c.1226G >A,c.1229C>T,c.IVS15+5G>A,c.1975G>C,c.2027T>A,c.2162C>T,c.2168A>G)、线粒体12SrRNA基因(m.1555A>G,m.1494C>T)。
1.3统计学分析
采用SPSS16.0统计软件分析数据,不同性别突变率的差异采用χ2检验,P<0.05为差异有统计学意义。
2.1135名受检者中不同程度的基因突变77例,突变率57.04%。杂合突变23例,纯合突变34例,复合杂合突变20例,见表1。男生43例,女生34例,突变在性别上无统计学意义(χ2=2.769,P=0.096)。
2.277例基因突变个体中21例携带两个位点突变,其中2例出现在不同基因位点上,c.235delC杂合突变/ c.IVS7-2A>G纯合突变1例,c.176_191del16杂合突变/ c.IVS7-2A>G杂合突变1例。
2.3GJB2基因突变44例,占总受检人数的32.59% (44/135)。c.176_191del16杂合突变1例、纯合突变1例;c.235delC杂合突变13例、纯合突变19例;c.299_ 300delAT杂合突变1例;c.176_191del16/ c.235delC复合杂合突变1例;c.235delC/ c.299_300delAT复合杂合突变8例。
2.4GJB3基因突变1例,占总受检人数的0.74%(1/ 135),即c.547G>A杂合突变。
2.5线粒体12SrRNA基因突变3例,占总受检人数的2.22%(3/135),均为m.1555A>G同质性突变。
2.6SLC26A4基因突变27例,占总受检人数的20%(27/135)。c.IVS7-2A>G杂合突变4例、纯合突变10例;其余是杂合突变,分别为c.589G>A位点2例、c.IVS15+5G>A位点1例、c.1174A>T/ c.2168A>G复合杂合1例、c.1174A>T/ c.IVS7-2A>G复合杂合1例、c.1226G>A/ c.2168A>G复合杂合1例、c.1229C>T/ c.2168A>G复合杂合1例、c.1229C>T/ c.IVS7-2A>G复合杂合1例、c.1975G>C/ c.IVS7-2A>G复合杂合1例、c.2162C>T/ c.IVS7-2A>G复合杂合1例、c.2168A>G/ c.IVS7-2A>G复合杂合3例。
大部分听力障碍与遗传因素有关,通过对聋病易感基因的研究,目前已有100多个非综合征型耳聋基因座位定位,60多个基因被克隆或鉴定。据梁爽、李海波等[7-10]报道,GJB2、GJB3、SLC26A4、线粒体12SrRNA四个基因在中国聋人中所占耳聋比例是42~49%。本次检测135名听力障碍大学生的聋病易感基因突变率57.04%,突变发生率亦较高。基因突变的受检者中,54例纯合突变和复合杂合突变考虑与遗传因素有关,占总数的40%;23例单杂合突变,由于无家族史情况,不能确定其是否与遗传因素有关。
3.1GJB2基因
GJB2基因是最常见的聋病易感突变基因,与先天性重度耳聋有关。各国的GJB2突变率不同,代志瑶[11]报道我国占20.05%。本次检测的GJB2基因突变率最高,占32.59%;其中c.235delC突变占GJB2基因突变的91.11%(41/45),未发现c.35delG突变,这与文献[12-18]中报道的我国人群中该基因突变最多的位点是c.235delC相符。
3.2GJB3基因
GJB3基因与高频听力下降有关,属于常染色体显性或隐性遗传,可导致进行性或迟发型中度至极重度耳聋,其突变率不高[8,19,20],本次仅检测出1例。
3.3SLC26A4基因
SLC26A4基因是临床常见的大前庭水管综合征的致病基因,婴儿出生时听力正常,在感染或颅脑外伤等因素作用下可导致听力下降,应避免引起听力下降的高危因素,防止耳聋或耳聋加重。c.IVS7-2A>G是常见的SLC26A4基因突变位点[21,22],本次检测到的c.IVS7-2A>G突变占SLC26A4基因突变的79.31%(23/29)。
3.4线粒体12SrRNA
线粒体12SrRNA与氨基糖苷类药物的耳毒性密切相关,属母系遗传。本次受检者中仅有3例为此基因的m.1555A同质性突变,低于郭玉芬等[23]报道的9.50%。这部分受检者及家庭成员应终生不使用氨基糖苷类药物,避免“一针致聋”的发生,其家庭母系成员的婚育须进行遗传咨询。
表1 基因位点突变的检出情况[例(%)]Table 1 Detection of gene mutations[Cases(%)]
3.5GJB2和SLC26A4基因
GJB2和SLC26A4基因为常染色体隐性遗传,子代为纯合或复合杂合突变才表现出耳聋,本次检测的听力障碍学生中有21例杂合突变,则可能存在20个位点之外的基因位点突变。
同证婚配可增加遗传发生几率已成为共识,目前我国听力障碍人群在聋哑学校或福利机构中呈同证聚集状态[24],聋人之间存在普遍的同证婚配情况,对育龄聋人及其配偶的聋病易感基因检测和干预可减少下一代聋儿的出生,降低出生缺陷。由于基因具有地区、种族等差异性,通过对中国听力障碍人群的聋病易感基因检测,实现基因学诊断,尽可能揭示病因的同时,有针对性利用三级疾病预防降低聋儿的出生,提高优生优育。婚前检测聋病易感基因,遗传咨询、指导恋爱婚配和靶向预防;孕后对胎儿进行基因检测;产后即新生儿听力筛查和聋病易感基因检查。
通过本研究,对已检出耳聋致病基因的受检者,应避免同一基因突变者之间婚配。对未检出耳聋致病基因的受检者,可能是非遗传因素所致,但不能排除其存在20个位点以外的突变基因。纯合或复合杂合突变受检者,在明确基因学病因诊断后,对其后期进行遗传咨询、怀孕风险评估等具有非常重要的指导意义。对聋病易感基因携带者,有必要通过进一步的基因诊断来明确其是否存在其他致病基因或位点,亦或许可为单杂合突变致聋的研究提供依据。本次检测为基因正常的受检者,在除外环境因素外,仍有必要全基因测序,随着基因检验技术的不断提高,或许可发现新的耳聋致病基因和新位点,为今后更深入的基因学研究提出新的课题。
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·临床研究·
Analysis of deafness-related genes test results in135 deaf college students
PAN Lei,CHEN Yaqiu,LIU Jin,LIU Hongyan
Tianjin Women and Children’s Health Center,Tianjin,300070 Corresponding author:CHEN YaqiuEmail:qianyi3@sina.com
【Abstract】Objective To study prevalence of 20 mutations in four genes among college students with hearing impairment in order to detect deafness-related gene disorders and provide a basis for prevention and control of deafness.Methods Using Matrix assisted laser ion time-of-flight mass spectrometry,peripheral blood were collected from 135 deaf college students for detection of mutations in four gene,i.e.GJB2,GJB3,SLC26A4 and mitochondria 12SrRNA.Results The rate of mutations detection in the 135 subjects was 57.04%,including 23 cases of heterozygous mutations,34 cases of homozygous mutations and 20 cases of compound heterozygous mutations.The c.235 delC mutation accounted for 91.11%(41/45)of GJB2 gene mutations and c.IVS7-2A>G accounted for 79.31%(23/29)of SLC26A4 gene mutations.For the 12SrRNA gene,there were only 3 cases of homogeneity mutations of m.1555A locus.Check out 1 cases of heterozygous mutations of c.547G>A locus in GJB3 genes.Conclusions In the 135 cases,the rate of GJB2,GJB3,SLC26A4 and mitochondria 12SrRNA gene mutations was 57.04%.The c.235 delC mutation is the most common GJB2 gene mutation,while c.IVS7-2A>G is common in SLC26A4 gene mutations.There were only a few cases of mitochondria 12SrRNA gene mutation,which is closely related to aminoglycoside drugs ototoxicity.GJB3 gene mutations appear rare.Testing of deafness-related genes in patients with hearing loss will not only help provide clear etiology at the level of molecular diagnosis,but also targeted prevention and genetic counseling for deafness,as well as potentially improving the gene pool.
【Keywords】Deafness;Deaf disease susceptibility genes;Genetic mutations;Genetic counseling
【中图分类号】R764.43
【文献标识码】A
【文章编号】1672-2922(2016)03-365-5
DOI:10.3969 / j.issn.1672-2922.2016.03.010
作者简介:潘蕾,本科,研究方向:听力基因筛查
通讯作者:陈亚秋,Email:qianyi3@sina.com
收稿日期:(2016-03-28审核人:袁永一)