非综合征型耳聋GJB2基因和mtDNA 12SrRNA A1555G位点的突变分析

目的:分析南京聋校散发性耳聋患者GJB2基因突变率和线粒体DNA(mtDNA)12SrRNA A1555G基因突变率.方法:收集聋校学生135名和健康对照人群162名外周血样本,PCR扩增GJB2和mtDNA 12SrRNA基因,通过限制性内切酶酶切鉴定突变热点,对PCR产物直接测序进行突变确定.结果:对GJB2检测结果显示:散发性耳聋患者样本中发现9种碱基改变(V27I、E114G、I203T V37I、176-191del16、235delC、299-300delAT、T123N和504insGCAA),其中235delC为主要突变方式,携带率为27.41%,其中纯合突变18例,杂合突变19例;162例正常对照中发现了15种碱基改变,其中4种为常见多态.散发聋135例和正常对照162例共计297例样本中未发现有mtDNA 12SrRNA A1555G位点突变存在;结论:GJB2基因突变是引起散发性非综合征耳聋患者听力损失发生的重要原因,不同人种GJB2基因的突变热点存在差异,235delC是GJB2基因在中国人中的主要致病突变位点;GJB2基因在人群中存在较多类型的突变和较多形式的多态性;在散发性耳聋中mtDNA 12SrRNA A1555G位点的突变率明显低于全国平均水平.

Analysis of GJB2 gene and mtDNA A1555G mutation in non-syndromic hearing loss patients

Objective:To determine the prevalence and characteristics of deafness-causing mutations in Connexin26(Cx26,GJB2)gene and mitochondrial DNA A1555G with non-syndromic hearing impairment(NSHI).Methods:The peripheral blood samples were obtained from the students of Nanjing Deaf-Blind School and healthy people in Jiangsu province.Using polymerase chain reaction(PCR),the code region of mitochondrial DNA and GJB2 gene were amplified.The GJB2 235delC mutation and mtDNA A1555G mutation was distinguished by restricted enzyme digestion.All of the subjects were sequenced.Results:Fifteen kinds of polymorphism about GJB2 gene,were found in 162 cases of controls and 9 kinds of pathologic mutations of GJB2 gene(V27I,E114G,I203T,V37I,176-191del16,235delC,299-300delAT,T123N and 504insGCAA) were identified in 135 patients.GJB2 235delC is the main pathogenic mutation site in GJB2 gene,which was found in 37cases(18 cases were homozygosis,19 cases were heterozygosis).The mitochondrial DNA A1555G mutation was not found in those subjects.Conclusion:The mutation of Cx26 genes is much responsible for non-syndromic hearing impairment in this region.Our data support the view that specific combinations of GJB2 mutation exist in different populations.235delC is the main pathogenic mutation site in GJB2 gene in Chinese.The incidence of mtDNA 12SrRNA A1555G mutation in the deaf population of Nanjing,Jiangsu Province is lower than the average level of the general Chinese deaf population.