赤峰市特教学校耳聋患者GJB2和GJB3及GJB6基因突变分析

目的:利用基因诊断的方法调查内蒙古自治区赤峰市特教学校非综合征耳聋患者的常见分子病因,对GJB2、GJB3、GJB6基因编码区突变进行分析.方法:调查对象来自赤峰市特教学校非综合征耳聋患者134例(耳聋组),对照组为中国北方地区(北京、河北、内蒙、山西)听力正常者100例.所有受检者均采集外周血并提取DNA,首先进行GJB2基因编码区测序,对携带GJB2单杂合突变的患者进一步检查GJB6 del(GJB6-D13S1830)突变并进行GJB6编码区测序.对除GJB2基因、线粒体A1555G突变相关性耳聋及前庭水管扩大综合征外的分子病因不明的91例非综合征耳聋患者进行GJB3基因编码区测序.结果:134例非综合征耳聋患者及100例正常对照中共检测到6种GJB2基因新的突变方式.耳聋组41例携带GJB2病理性突变,其中双等位基因突变22例,单等位基因突变19例,在GJB2单等位基因突变的耳聋患者中未检测到GJB6 del(GJB6-D13S1830)及编码区其他突变;对照组4例携带GJB2基因病理性突变.在91例分子病因不明的耳聋患者及100例正常对照中共检测到3种GJB3基因新的突变方式.耳聋组2例携带GJB3基因病理性突变,均为杂合子,其中1例同时携带GJB2单等位基因突变235delC;对照组1例携带GJB3基因病理性突变.结论:通过GJB2、GJB6、GJB3基因编码区突变分析为赤峰市特教学校16.42%(22/134)的非综合征耳聋学生明确了分子病因;新发现的突变和多态丰富了中国人GJB2、GJB3基因突变及多态性图谱,为深入开展耳聋基因筛查奠定了基础.

Mutation analysis of GJB2,GJB3 and GJB6 gene in deaf population from special educational school of Chifeng city

Objective:To investigate the genetic causes of nonsymdromic deaf patients in special educational school of Chifeng city,Inner Mongolia by genetic screening testing method.This study focused on analyzing mutations of coding sequence of GJB2,GJB3 and GJB6 gene.Method:DNA were extracted out from peripheral blood of 134 nonsyndromic deaf probands of Chifeng special educational school and 100 normal hearing controls in Northern China.First,GJB2 gene mutation was analyzed by direct sequencing for its only exon in the open reading frame.Individuals found with heterozygous GJB2 mutation were given further testing for GJB6 del(GJB6-D13S1830) and direct sequencing for its exon.In 91 probands with unknown genetic cause(excluding probands who carried mtDNA A1555G mutation and GJB2 gene biallele mutation and probands who were diagnosed as enlarged vestibular aqueduct by temporal CT),GJB3 gene mutation was analyzed by direct sequencing for its exon.Result:The sequencing results revealed that forty-one cases carried GJB2 mutation,of which twenty-two were homozygous or compound heterozygous and nineteen were heterozygous.Further testing for GJB6 del(GJB6-D13S1830) and analysis of its coding sequence in GJB2 heterozygous cases showed no positive result.Four subjects in control group carried pathogentic mutation of GJB2 gene.Six types of novel variants of GJB2 gene were detected.Of the 91 deaf probands with unknown etiology,two probands were found carrying heterozygous pathogentic mutation of GJB3 gene,one of whom also carried GJB2 235delC heterozygous mutation.One subjects in the control group carried pathogentic mutation of GJB3 gene.Three types of novel variants of GJB3 gene were found.Conclusion:By screening GJB2,GJB3 and GJB6 gene,we found 32.1% probands carrying GJB2,GJB3,and GJB6 mutations and we are able to determine genetic cause related to these three genes from one family for 16.42 percent of nonsyndromic deaf probands in special educational school of Chifeng city.The discovery of novel variants of GJB2 and GJB3 gene makes the mutational and polymorphic spectrum more plentiful in Chinese population.