GJB2 mutation spectrum in deaf population in a typical southeastern area of China

Mutations in GJB2 gene are the most frequently found mutations in patients with nonsyndromic hearing impairment. However, the spectrum and prevalence of mutations in this gene vary among different ethnic groups. In China, 30,000 infants are born with congenital hearing impairment annually. In order to provide appropriate genetic testing and counseling to the families, we investigated the molecular etiology of nonsyndromic deafness in 103 unrelated school children attending Nantong School for the Deaf and Mute in Jiangsu Province, China. The coding exon of the GJB2 gene was PCR amplified and sequenced. Sixty two GJB2 mutant alleles were identified in 35.9% (37/103) of the patients. Twenty five patients carried two pathogenic mutations and 12 patients carried one mutant allele. The 235delC was the most common mutation accounting for 69.4% (43/62) of GJB2 mutant alleles.The GJB2 mutant alleles accounted for 30.1% (62/206) of all chromosomes responsible for nonsyndromic hearing impairment. Testing of the 3 most prevalent deleterious frame shift mutations in this cohort detected 100% of all GJB2 mutant alleles. These results demonstrate that an effective genetic testing of GJB2 gene for patients and families with nonsyndromic hearing impairment is possible.     

江苏南通地区非综合征性耳聋GJB2基因突变分析

目的 研究南通地区非综合征性耳聋GJB2基因突变情况。方法 收集南通地区海安县和如皋县聋哑学校学生100名和健康对照组50名，利用PCR扩增及限制性内切酶酶切分析初筛GJB2 235delC突变者，然后再行DNA直接测序。结果 耳聋组中共发现三种突变：235delC、176—191del16、299—300delAT。235delC是主要突变方式．约30％的患者携带此突变；299—300delAT和176-191del16突变检出率分别为9％和8％。对照组未发现这些突变。结论 南通地区非综合征性耳聋GJB2基因突变率较高，因此在南通地区进行广泛的生育前耳聋基因筛查工作有重要意义。     

安阳市特教学校重度感音性聋分子病因学分析--GJB2 235delC突变和线粒体DNA 12SrRNA A1555G突变筛查报告

目的 调查河南省安阳地区重度感音神经性耳聋聋病分子病因学情况。方法对安阳市聋哑学校160名学生进行耳聋病因问卷调查、纯音听阈测试。对其中154名非综合征性感音神经性耳聋患者进行线粒体DNA 12SrDNA A1555G点突变检测和G朋12基因突变检测。结果 8例（5．19％）存在线粒体DNA 12SrDNA A1555G点突变；11例（7．14％）存在GJB2 235delC纯合突变；13例（8．44％）存在GJB2 235delC杂合突变。在分子水平能够明确诊断者占20．77％。结论 安阳地区耳聋患者存在较高的遗传性耳聋发生率。特别是线粒体DNA A1555G突变发生率高于全国平均水平，通过聋病分子诊断，可达到防聋、指导聋儿康复及评估耳聋预后等积极效果。     

武汉地区非综合征性聋分子病因学分析--GJB2 235delC突变和线粒体DNA 12SrRNA A1555G突变筛查报告

目的 分析武汉地区非综合征性耳聋（nonsyndromic hearing impairment，NSHI）患儿GJB2 235delC突变率和线粒体DNA A1555G突变率。方法 收集武汉市艺萌听力康复中心的94例耳聋患儿血样，非综合征性耳聋患儿88例，提取DNA后经聚合酶链反应（PCR）分别扩增GJB2基因编码区及线粒体DNA，ApaI酶切分析GJB2 235位点的C缺失突变，Prev—DAF药物性耳聋基因诊断试剂盒分析线粒体1555位点的A—G突变，对GJB2 235ddC及线粒体DNA A1555G的突变率进行统计分析。结果 88例患儿中9例（10．23％）为GJB2 235delC纯合突变，7例（7．96％）为GJB2 235delC杂合突变；2例（2．27％）存在线粒体DNA A1555G点突变。在分子水平能够明确诊断者占20．46％。结论 武汉地区耳聋患者存在较高的遗传性耳聋发生率，应用基因诊断技术可以在耳聋患者病因调查中进行快速诊断筛查，达到防止再生育聋儿、指导聋儿康复等积极效果。     

柳州市盲聋学校非综合征性聋分子病因学分析--GJB2 235delC突变和线粒体DNA 12SrRNA A1555G突变筛查报告

目的 分析GJB2 235delC突变和线粒体DNA 12SrRNA A1555G突变在广西壮族自治区柳州地区非综合征性耳聋（nonsyndromic hearing impairment，NSHI）患儿中的作用。方法 收集广西壮族自治区柳州聋哑学校的88例非综合征性耳聋患儿的血样，提取DNA后经聚合酶链反应（PCR）分别扩增GJB2基因编码区及线粒体DNA，ApaI酶切分析GJB2 235位点的C缺失突变、Prey—DAF药物性耳聋基因诊断试剂盒分析线粒体1555位点的A—G突变，对GJB2 235delC及线粒体DNA 12SrRNA A1555G的突变率进行统计分析。结果 88例患儿中1例（1．14％）为GJB2 235delC纯合突变；5例（5．68％）为GJB2 235delC杂合突变；4例（4．55％）存在线粒体DNA 12SrRNA A1555G点突变，其中1例同时伴有GJB2 235delC杂合突变。在分子水平能够明确诊断者占11．37％。结论 柳州地区耳聋患者常染色体隐性遗传性耳聋发生率较全国平均水平低，线粒体DNA 12SrRNA A1555G突变发生率偏高。应用基因诊断技术可以在地区性耳聋病因调查中进行快速筛查、诊断，可达到防止聋儿再生、指导聋儿康复等积极效果。     

中国西北地区线粒体DNA12SrRNAA1555G和GJB2基因突变

目的研究mtDNA 12SrRNA A1555G突变和GJB2突变在西北地区非综合征型感音神经性聋患者中的流行情况,探讨GJB2基因与mtDNA A1555G点突变的关系。方法收集本地区221例非综合征感音神经性聋患者的基因组DNA,多聚酶链反应扩增线粒体DNA和GJB2基因目的片断,Alw26Ⅰ限制性内切酶检测A1555G点突变,对酶切阳性病例和全部的GJB2基因的PCR产物进行DNA测序。结果21例患者检出mtDNA 12SrRNA A1555G突变;发现GJB2基因11种序列改变,有44例患者检出GJB2致病突变,235delC占携带致病突变患者的54．54％：在21例A1555G突变患者中,11例为GJB2基因多态改变,9例未检出GJB2基因序列改变,1例为109G→A（V371）突变。结论mDNA 12SrRNA A1555G在这一地区人群中有较高的发生频率．235delC是本地区GJB2基因突变的主要形式,GJB2基因突变不是mtDNA A1555G突变致聋的主要修饰因素。     

赤峰市特教学校重度感音性聋分子病因学分析--GJB2 235delC突变和线粒体DNA 12SrRNA A1555G突变筛查报告

目的 调查内蒙古赤峰市聋哑学校重度感音性耳聋病因学情况。方法 对赤峰市聋哑学校140名学生进行耳聋病因问卷调查、纯音听阈测试。所有受检学生均采集外周血并提取DNA．进行线粒体DNA 12SrRNA A1555G点突变检测、GJB2基因突变检测。结果 1例（0．71％）存在线粒体DNA A1555G点突变；16例（11．43％）存在GJB2 235delC纯合突变，19例（13．57％）存在GJB2 235delC杂合突变。结论 赤峰市耳聋患者存在较高的遗传性耳聋发生率，并呈现明显的地域特点。通过聋病分子诊断，可达到防聋、指导聋儿康复及评估耳聋预后等积极效果。     

非综合征型聋患者GJB2 235delC及线粒体DNA A1555G突变分析

目的 对非综合征型聋患者进行聋病分子病因学分析。方法 对北京第三聋哑学校学生进行耳聋病因问卷调查、纯音测听检查，应用PCR扩增及限制酶切方法对158名非综合征型感音神经性聋患者进行GJ-B2和线粒体DNA12SrRNAA1555G基因突变的检测。结果 在158例感音神经性聋患者中，5例（3．16％）存在线粒体DNA12SrRNAA1555G点突变，其中2例有明确的氨基糖甙类抗生素用药史；24例（15．18％）存在GJB2235delC纯合性突变；12例（7．59％）存在GJB2 235delC杂合性突变。在基因水平明确诊断或强烈提示遗传性聋者占25．93％。结论 对GJ-B2 235delC突变和线粒体DNA12SrRNAA1555G突变的基因筛查可以明确或提示部分非综合征型聋的病因，对防聋、指导聋儿家庭婚育及评估人工耳蜗手术预后起到重要作用。     

运城市聋哑学校重度感音性聋分子病因学分析--GJB2 235delC突变和线粒体DNA 12SrRNA A1555G突变筛查报告

目的 调查山西省运城地区重度感音性耳聋病因学情况。方法 对运城市聋哑学校142名学生进行耳聋病因问卷调查、纯音听阈测试，对其中139名非综合征性感音神经性耳聋患者进行线粒体DNA 12SrRNA A1555G点突变检测和GJB2基因突变检测。结果 7例（5．04％）存在线粒体DNA A1555G点突变，8例（5．76％）存在-GJB2 235delC纯合突变，14例（10．07％）存在 -GJB2 235delC杂合突变，在分子水平能够明确诊断者占20．87％。结论 运城地区耳聋患者存在较高的遗传性耳聋发生率，特别是线粒体DNA 12SrRNA A1555G突变发生率高于全国平均水平，通过聋病分子诊断，可达到防聋、指导聋儿康复及评估耳聋预后等积极效果。     

GJB2 gene mutations in newborns with non-syndromic hearing impairment in Northern China

Mutations in GJB2 account for the majority of recessive forms of prelingual hearing loss. However, in most previous studies it was not possible to distinguish between congenital (present at birth) and non-congenital prelingual hearing loss. In the present study, the frequency of GJB2 alleles in 20 newborns with bilateral severe-to-profound non-syndromic hearing impairment (NSHI) who were found at birth through newborn hearing screening and clinical examination is reported. PCR was used to amplify the coding region of GJB2 gene followed by sequencing analyses. Fifty volunteers with normal hearing were included as controls. Results showed that three cases were 235delC/235delC homozygotes; one was 235delC/605ins46 compound heterozygotes, 605ins46 mutation was a novel mutation reported in the Chinese population; another was 235delC/299-300delAT compound heterozygotes. 25% (5/20) of the deafness in newborns studied was caused by GJB2 gene mutations. The frequency of 235delC allele carrier in patients and in control group was 22.5% and 1%, respectively. One case was identified as being a 235delC heterozygote without other mutations detected. Besides, multiple polymorphisms such as V27I, V37I, E114G, T123N were also detected. In conclusion, GJB2 analysis is an important test that identifies a major cause of newborns with bilateral severe-to-profound NSHI screened by universal newborn hearing screening in Northern China. The most common pathologic mutation of GJB2 in studied cases was 235delC. Molecular analysis and genetic counseling will be extremely important for congenital deafness present at birth.     

Molecular analysis of the GJB2, GJB6 and SLC26A4 genes in Korean deafness patients

OBJECTIVES: Mutations in the GJB2, GJB6 and SLC26A4 genes are a frequent cause of hearing loss in a number of populations. However, little is known about the genetic causes of hearing loss in the Korean population. METHODS: We sequenced the GJB2 and GJB6 genes to examine the role of mutations in these genes in 22 hearing loss patients. We also sequenced the SLC26A4 gene in seven patients with inner ear malformations, including enlarged vestibular aqueduct (EVA) revealed by computer tomography. RESULTS: Coding sequence mutations in GJB2 were identified in 13.6% of the patients screened. Two different mutations, 235delC and T86R were found in three unrelated patients. The 235delC was the most prevalent mutation with an allele frequency of 6.9% in our patient group. No mutations, including 342-kb deletion, were found in GJB6 gene. Three different variants of SLC26A4 were identified in the EVA patients, including one novel mutation. Four EVA patients carried two mutant alleles of SLC26A4, and at least one allele in all patients was the H723R mutation, which accounted for 75% of all mutant alleles. CONCLUSIONS: Our results suggest that GJB2 and SLC26A4 mutations together make up a major cause of congenital hearing loss in the Korean population. Further studies may be able to identify other common variants that account for a significant fraction of hearing loss in the Korean population.     

GJB2235delC单杂合突变携带者的纯音测听评估

目的 分析GJB2突变致聋患者父母(GJB2 235delC单杂合突变携带者)的听力变化特点.方法 32例30～60岁经直接测序法证实为GJR2基因235delC单杂合突变的携带者作为研究对象,选择32例年龄和性别相匹配的无GJB2基因突变的健康人作为对照组.两组均进行纯音测听,比较不同年龄段各频率纯音听阈的差异.结果 与对照组相比,突变基因携带者各年龄段4000及8000 Hz高频听力均下降,且从40～49岁年龄段开始1000及2000 Hz中频听力也开始出现减退,差异具有统计学意义(P值均＜0.05);随着年龄的增加,听力损失有逐渐加重的趋势.结论 GJB2235delC致聋等位基因携带者可能是耳聋的危险群体,不仅存在高频听力损失,40岁以后即可能出现中频听力下降.

Abstract：

Objective To analyze GJB2 235delC monoallelic mutation carrier individuals and test the possible presence and incidence of audiometric abnormalities among 30 - 60 years old carriers of the 235delC mutations.Methods A total of 32 unrelated subjects with nonsyndromic hearing loss were screened for the 235delC mutation.Tonal audiometric analysis was performed on the 235delC mutation carrier group and on a non-carrier control group.Results Audiometric evaluations in the control group showed the presence of thresholds within normal limits at all frequencies,while carriers of the 235delC mutation presented with decreasd hearing at 1000 Hz and 2000 Hz (age 40-49 years and 50-59 years) ,and 4000 and 8000 Hz( age 30-59 years) ,P ＜ 0.05.The hearing loss of carriers gradually increased with age.Conclusions GJB2 235delC heterozygous carriers may be a risk group for high-frequency hearing loss.Hearing thresholds may deteriorate in the intermediate frequencies over the age of 40.     

screening of gjb2 mutations in chinese population

The GJB2 gene(connexin 26) has been shown to be responsible for DFNB1 and DFNA3. We screened the GJB2 gene in 488 patients with prelingual deafness(Group 1), 124 with postlingual deafness(Group 2), and 117 normal hearing subjects(Group 3). We found that, in Group 1, 65 patients(13.32%) were homozygotes or compound heterozygotes and 51 patients (10.45%) carried a single pathogenic mutation. The 235delC mutation was the most frequent mutation, accounting for 73.22% of the known pathogenic alleles in Group 1. No homozygotes or compound heterozygotes were detected in Group 2 or Group 3. Some postlingual deaf patients (2.42%) and normal hearing subjects(4.27%) were 235delC carriers. Our preliminary data indicate that 235delC, the most frequent mutation identified in this study, is a major cause for prelingual deafness.     

散发性耳聋GJB2基因突变分析

目的 通过分析内蒙古鄂尔多斯和呼和浩特地区散发性耳聋患者GJB2 235delC点突变,以探讨散发性耳聋患者的分子病因学。方法 对131例(汉族92例,蒙古族39例) 散发性耳聋患者进行耳聋病因学问卷调查、纯音听阈及声导抗测试。聚合酶链反应(polymerase chain reaction PCR)扩增目的片段并用限制性内切酶对其进行GJB2 235delC基因突变检测,对酶切检测结果呈阳性的样本用直接测序法进行验证。对50例健康中国人和100例健康加拿大白种人行限制性内切酶GJB2 235delC点突变检测,作为阴性对照。结果 131例散发性耳聋患者全部为感音神经性聋。在该群体中4例(汉族3例,蒙古族1例)存在GJB2 235delC纯合性突变;3例(汉族2例,蒙古族1例)存在GJB2 235delC杂合性突变。50例健康中国人对照组中检测出1例GJB2 235delC点突变携带者,100例健康加拿大白种人中未检测到GJB2 235delC点突变。结论 GJB2 235delC点突变是中国人散发性感音神经性耳聋的分子病因学之一。内蒙古地区汉族、蒙古族GJB2 235delC突变频率无明显差异,对GJB2 235delC点突变的基因筛查可以明确一些散发性耳聋患者的病因,从而对基因突变引起的散发性耳聋的早期诊断、遗传咨询及防聋治聋起到重要作用。     

南通地区遗传性耳聋资源收集及病因学分析

目的 调查江苏南通地区遗传性耳聋病因流行病学情况。方法 调查南通各市县五个聋哑学校202名学生，利用聚合酶链反应一限制性片断长度多态性（PCR—RFLP）方法和Prev—DAF药物性耳聋基因诊断试剂盒筛查患者GJB2 235delC突变和线粒体DNA 12SrRNA A1555G突变。结果 195例非综合征耳聋患儿中31例（15．9％）为GJB2 235delC纯合突变，21例（10.8％）为GJB2 235delC杂合突变，5例（2．6％）存在线粒体DNA 12SrRNA A1555G点突变，在分子水平能够明确诊断者占2913％。结论 南通地区遗传性耳聋发病率较高，尤其是GJB2 235delC突变，突变率（26％）明显高于全国平均水平（18％）。此结果突出了本地区耳聋基因诊断的重要作用，利用耳聋基因检测技术，在人群中（包括重点人群和普通人群）进行生育前耳聋基因筛查，是达到减少聋儿出生的重要途径。     

非综合征型感音神经性聋儿GJB2基因突变分析

目的 对散发聋病患儿进行GJB2基因突变检测,探究其在遗传性聋临床工作中的意义.方法 收集门诊139例散发非综合征型感音神经性聋患儿及150例听力正常个体的外周血DNA样本共289例,采用聚合酶链反应分析方法扩增GJB2基因片断进行序列分析.结果 139例病患组中发现GJB2基因突变31例,占22.30%.其中235d...     

The clinical features of patients with the homozygous 235delC and the compound-heterozygous Y136X/G45E of the GJB2 mutations (Connexin 26) in cochlear implant recipients

Objective

This study aimed to investigate the prevalence of GJB2 gene for the 235delC mutations, the clinical features and the outcomes of patients who had undergone cochlear implantation.

Methods

We have sequenced the coding region of GJB2 gene for 135 patients with sensorineural deaf from September 2000 to May 2009. Of the 135 patients, the patients with the homozygous 235delC and the compound-heterozygous Y136X/G45E were detected and were investigated clinically.

Results

The GJB2 gene for the 235delC mutations was found in 39 alleles of 270 alleles (14.4%), especially for the homozygous of 235delC was detected in 26 alleles (9.6%), the single heterozygous of 235delC was 1 allele (0.4%), the compound heterozygous of 235delC was found in 12 alleles (4.4%). Of 16 subjects (29 alleles) with the homozygous 235delC and the compound-heterozygous Y136X/G45E, 2 subjects (4 alleles) were found to have complications. All of the subjects were found to show severe hearing loss and some of them have indicated progressive hearing loss. However, they showed better performance regarding the thresholds after implantation. The subjects with complications, although, suggested poorer performance in the auditory speech performance.

Conclusion

The findings of poorer outcomes might depend on complications and brain functions. In addition, considering the blood test parameters, an independent elevated LDH and ChE at diagnosis were found to be associated with hereditary enzyme's metabolic disease. Therefore, the value of LDH measurements in patients might be a helpful predictive parameter in hereditary diseases.     

52例听力损失儿童及其父母耳聋基因芯片筛查结果分析

目的：对非综合征性先天性重度及以上感音神经性听力损失儿童及其父母进行耳聋相关基因检测,探讨耳聋基因芯片筛查在临床中应用的有效性和可行性。方法选择来自医院听力检测中心的47个听障儿童家庭,包括52例非综合征性先天性感音神经性听力损失患儿及其父母,应用遗传学耳聋基因芯片对47个家庭进行GJB2、GJB3、SLC26A4、线粒体12S rRNA4个常见耳聋基因9个检测位点的基因检测。结果146例受检者中,17个家庭的43例筛查结果阳性,其中16例听力损失患儿筛查阳性,筛查阳性率为30.8%。GJB2基因235delC位点纯合突变8例,GJB2基因235delC位点杂合突变20例,GJB2基因235delC位点和SLC26A4基因IVS7-2A〉G位点杂合突变1例,SLC26A4基因IVS7-2A〉G位点纯合突变2例,SLC26A4基因IVS7-2A〉G位点杂合突变10例,SLC26A4基因2168A〉G位点杂合突变2例。结论应用耳聋基因芯片检测技术能快速、高效地检测非综合征性耳聋患者的遗传性致病基因,适用于大规模群体耳聋基因的筛查,有助于临床医生从病因学角度辅助耳聋诊断,引入正确的康复干预措施,并为具有聋病易感基因的听力损失儿童家庭提供针对性的遗传咨询指导。     

湖南地区汉族非综合征型耳聋相关基因检测及热点突变分析

目的研究湖南地区汉族非综合征型耳聋（NSHL）患者中GJB2、SLC26A4基因的突变频率和突变热点,了解线粒体DNA（mtDNA）12SrRNA A1555G突变的频率。方法收集湖南地区汉族NSHL患者共139例,抽取外周静脉血并提取DNA;分别采用直接测序、变性高效液相色谱法（denaturing high performance liquid chromatography,DHPLC）和聚合酶联-限制性片段变态（polymerase chain reaction restriction fragment length polymorphism,PCR RFLP）技术对患者进行GJB2、SLC26A4基因和mtDNA 12SrRNA A1555G突变的检测;对SLC26A4基因突变者进行回访并行高分辨颞骨CT检查。结果61例（43.9%）NSHL患者至少携带一种常见耳聋相关基因突变,GJB2、SLC26A4和线粒体DNA 12SrRNA A1555G突变的检出率分别为23%、18.7%和3.6%;共发现6种GJB2和13种SLC26A4基因已报道致病性突变,235delC和IVS7-2A〉G分别是GJB2和SLC26A4基因最常见的突变类型,分别占这两个基因突变等位基因的87.5%和46.5%;与SLC26A4基因突变有关的EVAS的发生率为14.4%,低于该地区GJB2基因相关性耳聋的发生率17.3%。结论湖南地区汉族NSHL中43.9%的患者携带常见耳聋基因突变,反映湖南地区遗传性耳聋高发的现象。GJB2基因突变是该地区NSHL最常见的原因,其次为SLC26A4基因。235delC、IVS7-2A〉G和A1555G突变分别是GJB2、SLC26A4和线粒体DNA基因的热点突变,占所有突变的71.2%。通过筛查,为其中35.3%的患者明确了分子病因。为该地区进一步开展遗传咨询、基因诊断和产前诊断提供了重要的依据,并为临床用药提供指导。     

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。