GJB2基因突变导致非综合征性耳聋的特点及JL055小家系

目的利用JL055小家系分析GJB2基因突变导致非综合征性耳聋（non-syndromic hearing impairment，NSHI）的特点，为遗传咨询和产前诊断提供理论基础。方法对来自吉林聋哑学校的先证者JL055及其部分家属的血样，进行GJB2基因聚合酶链反应（polymerase chain reaction，PCR）扩增产物测序，检测GJB2基因的序列改变，对测序结果进行临床分析。结果JL055的基因型为35delG／299-300delAT，两个等位基因分别来自父系和母系。结论JL055家系的测序结果为遗传咨询和产前诊断提供了理论基础。     

新疆哈萨克族非综合征型聋GJB2基因突变的研究分析

目的：研究新疆哈萨克族非综合征型聋患者GJB2基因突变的情况。方法：调查对象为来自新疆地区的193例哈萨克族患者,采用直接测序法对非综合征型聋患者97例和健康对照96例进行GJB2基因突变的检测。结果：在编码区耳聋组共发现8种碱基改变：其中35delG纯和12例,79G〉A纯合5例,79G〉A杂合8例,79G〉A与608T〉C复合杂合1例,79G〉A与341A〉G复合杂合5例,235delC杂合4例,341A〉G杂合2例,439T〉G杂合1例,457G〉A杂合1例,521G〉A纯合2例。对照组发现4种已明确的常见多态性碱基改变。结论：本研究提示新疆哈萨克族非综合征型聋患者GJB2基因突变具有种族和地域性特点,该地区哈萨克族耳聋人群中GJB2有较高携带率,在本研究中35 delG为其常见突变方式。     

Absence of GJB6 mutations in Indian patients with non-syndromic hearing loss

Objective

Hearing loss is the most frequent sensory defect in human being. Genetic factors account for at least half of all cases of profound congenital deafness. The 13q11-q12 region contains the GJB2 and GJB6 genes, which code connexin 26 (CX26) and connexin 30 (CX30) proteins, respectively. Mutations in the gene GJB2, encoding the gap junction protein connexin 26, are considered to be responsible for up to 50% of familial cases of autosomal recessive non-syndromic hearing loss and for up to 15-30% of the sporadic cases. It has also been reported that mutations in the GJB6 gene contribute to autosomal recessive and autosomal dominant hearing defects in many populations. The 342-kb deletion [del(GJB6-D13S1830)] of the Cx30 gene is the second most common connexin mutation after the CX26 mutations in some NSHL populations. The aim of this study was to screen GJB6 gene mutations in Asian Indian patients with autosomal non-syndromic hearing loss.

Methods

We screened 203 non-syndromic hearing loss patients, who were negative for homozygous mutations in GJB2 gene, for GJB6-D13S1830 deletion and mutations in coding regions of GJB6 using polymerase chain reaction, denaturing high performance liquid chromatography and direct sequencing.

Results

No deleterious mutation in GJB6 gene was detected in our study cohort.

Conclusion

The present data demonstrated that mutations in the GJB6 gene are unlikely to be a major cause of non-syndromic deafness in Asian Indians.     

Prevalence of GJB6 mutations in Chinese patients with non-syndromic hearing loss

Objective

To investigate the distribution of GJB6 mutations in Central Chinese population with non-syndromic hearing loss.

Method

Totally 655 hearing impaired patients in Hubei province of China were screened for del(GJB6-D13S1830) deletions by using multiplex PCR and sequencing of GJB6 whole coding region.

Result

The del(GJB6-D13S1830) and other mutations in GJB6 gene were not observed in our study cohort.

Conclusion

The results suggest that GJB6 mutations is not a common cause among Central Chinese population and screening for the mutations of GJB6 can be ranked as unconventional deaf gene test for this population.     

中国西北地区耳聋家系中GJB2基因突变频率分析

目的 分析在中国西北地区耳聋家系人群与散发人群之间GJB2基因突变频率的差异性,探讨GJB2基因突变在西北地区耳聋家系人群中的发生频率及其特点.方法 收集中国西北地区29个家系的87例耳聋患者、散发非综合征型感音神经性耳聋患者169例及听力正常人117例血样,提取外周血DNA后,进行聚合酶链反应扩增GJB2基因编码区,将扩增产物进行直接测序.运用DNAStar5.0软件进行测序结果分析,对各组CJB2基因突变频率进行统计学分析.结果 87例家系耳聋患者中存在GJB2致病突变2S例,占32.18%;169例散发耳聋患者中GJB2基因致病突变24例.占14.20%;117例正常对照人群发现GJB2基因突变携带者5例,占4.27%.结论 GJB2基因突变在中国西北地区家系耳聋患者与散发耳聋人群的发生频率存在统计学差异(X2=11.474,P<0.05),对存在CJB2基因突变的耳聋患者进一步对其家系成员重点进行该基因的突变筛查具有重要意义.     

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...     

中国散发耳聋患者GJB6基因的突变筛查

目的研究中国散发耳聋患者与缝隙连接蛋白beta-6基因(gap junction protein beta 6 gene,GJB6)突变的相关性。方法分别设计扩增GJB6基因编码区和大片缺失后产物的引物各1对,应用PCR产物直接测序方法对各种感音神经性耳聋患者214例、正常听力者86例进行GJB6基因的突变检测及鉴定。结果没有发现在欧美耳聋人群中常见的GJB6大片段缺失,在214例患者中仅发现GJB6基因一种杂合错义突变,为一个新的突变形式233(C→A),进一步的各物种多种连接蛋白氨基酸序列进化分析证实该突变位点位于C×30高度保守的第二跨膜区。86例正常对照组中未发现同样突变。结论通过研究发现GJB6突变不是中国散发耳聋患者中的常见致病因素,为下一步开展耳聋相关基因和临床基因诊断研究打下了基础。     

新疆维吾尔族非综合征性遗传性聋GJB2基因突变的研究

目的:研究新疆维吾尔族非综合征性遗传性聋患者GJB2基因突变的情况.方法:采用直接测序法对新疆维吾尔族非综合征性遗传性聋患者43例和健康对照46例进行GJB2基因突变的检测.结果:在编码区耳聋组共发现6种碱基改变:380G>A、109G>A、235 delC、233delC、71G>A及35 delG,其中235 delC杂合突变1例,233 delC纯合突变2例,35 delG杂合突变2例;对照组发现6种碱基改变,其中5种为已明确的常见多态性改变.结论:新疆维吾尔族非综合征性遗传性聋患者GJB2基因突变检出率较低,具有种族和地域性特点.     

Association of GJB2 gene mutation with cochlear implant performance in genetic non-syndromic hearing loss

Objective

To analyze the association of GJB2 gene mutations with cochlear implant performance in children.

Methods

Sixty-five consecutive children who underwent cochlear implantation due to congenital profound senseurineural hearing between 2006 and 2008 were included in the study. In children, GJB2 gene mutation analysis was performed. Their auditory performance was assessed using MAIS, MUSS and LittlEARS tests.

Results

Twenty-two of sixty-five patients GJB2 mutations, and 35delG was the most frequent mutation. No significant difference was found between the auditory performance of mutation positive and negative children after one year follow up (p > 0.05).

Conclusion

GJB2 gene mutations do not impact on the outcome of cochlear implantation.     

Compound heterozygous GJB2 mutations associated to a consanguineous Han family with autosomal recessive non-syndromic hearing loss

Conclusion: This study demonstrates that the gap junction protein beta-2 gene (GJB2) p.R32C and p.L79Cfs*3 variants are associated to a consanguineous family with autosomal recessive non-syndromic hearing loss (ARNSHL). The p.R32C variant is found for the first time in the NSHL patients of Han Chinese origin. The finding sheds new light on the accurate genetic diagnosis and counseling for the family. Objective: ARNSHL is a highly heterogeneous genetic disease. ARNSHL usually displays non-progressive congenital or pre-lingual deafness. In this study, the aim is to detect the disease-causing mutation(s) in a Han family with ARNSHL. Methods: A consanguineous Han family with ARNSHL was enrolled. Two hundred ethnicity-matched unrelated subjects without any hearing impairments were used as normal controls. Exome sequencing and Sanger sequencing were applied to identify the causative mutation in the ARNSHL family. Results: Compound heterozygous variants c.94C?>?T (p.R32C) and c.235delC (p.L79Cfs*3) in the GJB2 gene were identified in the two patients of the ARNSHL family, and the heterozygous GJB2 c.94C?>?T and c.235delC variants were identified in his unaffected father and mother, respectively. The two variants in the GJB2 gene were absent in the 200 unrelated controls.     

GJB2 (connexin 26) gene mutations in Moroccan patients with autosomal recessive non-syndromic hearing loss and carrier frequency of the common GJB2-35delG mutation

OBJECTIVE: Mutations in the connexin 26 gene (GJB2), which encodes a gap-junction protein expressed in the inner ear, have been shown to be responsible for a major part of autosomal recessive non-syndromic hearing loss in Caucasians. The aim of our study was to determine the prevalence and spectrum of GJB2 mutations, including the (GJB6-D13S1830) deletion, in Moroccan patients and estimate the carrier frequency of the 35delG mutation in the general population. METHODS: Genomic DNA was isolated from 81 unrelated Moroccan familial cases with moderate to profound autosomal recessive non-syndromic hearing loss and 113 Moroccan control individuals. Molecular studies were performed using PCR-Mediated Site Directed Mutagenesis assay, PCR and direct sequencing to screen for GJB2, 35delG and del(GJB6-D13S1830) mutations. RESULTS: GJB2 mutations were found in 43.20% of the deaf patients. Among these patients 35.80% were 35delG/35delG homozygous, 2.47% were 35delG/wt heterozygous, 3.70% were V37I/wt heterozygous, and 1 patient was E47X/35delG compound heterozygous. None of the patients with one or no GJB2 mutation displayed the common (GJB6-D13S1830) deletion. We found also that the carrier frequency of GJB2-35delG in the normal Moroccan population is 2.65%. CONCLUSIONS: These findings indicate that the GJB2-35delG mutation is the major cause of autosomal recessive non-syndromic hearing loss in Moroccan population. Two other mutations were also detected (V37I and E47X), in agreement with similar studies in other populations showing heterogeneity in the frequencies and types of mutation in connexin 26 gene.     

High incidence of GJB2 mutations during screening of newborns for hearing loss in Austria

OBJECTIVES: The aim of the present study was to evaluate gap junction protein beta2 (GJB2) genetic testing within a national neonate screening program for hearing loss (HL) in a European population. DESIGN: Neonatal cases of nonsyndromic HL (N = 21) were identified by postpartal otoacoustic emissions (OAE) and brain stem electric response audiometry (BERA) analysis. GJB2 testing was performed by direct sequencing. RESULTS: Mutations in GJB2 were found in 15 of 21 children (71.4%) identified by neonatal audiological screening. The 35delG mutation in GJB2 was found homozygous in 10 cases (47.6%) and also as a clear cause of HL as the heterozygous alterations 35delG/del311-324 and 35delG/L90P. In a single case, L90P/R143Q was also identified as a cause of HL. In 3 HL cases that were not identifiable during initial OAE testing, homozygous 35delG and 35delG/R184P defined the genetic basis for HL in 2 cases, whereas one case had wild-type GJB2. CONCLUSIONS: Our findings of the high mutation rate in the Austrian population, especially in neonates identified during the newborn screening program, confirm the importance of screening for mutations in GJB2.     

4个非综合征耳聋家系中检出线粒体COI和COII基因的新变异

目的报道4个疑有母系遗传特征的中国非综合征耳聋家系的线粒体分子遗传学特征。方法应用限制性内切酶酶切和直接测序技术对先证者的线粒体基因序列进行分析,同时收集患者的相关临床资料。结果在2个非综合征耳聋家系的先证者中发现线粒体COⅠ和COⅡ基因上两个新变异形式(7250A>G和7774G>A)均为沉默突变(Thr→Thr和Thr→Thr),而位于COⅠ基因上的7196C>A(Leu→Leu)、7319T>C(Ile→Ile)和COⅡ基因上的7660A>G(Asp→Asp)为国外及汉族群体中已报道的3个多态性位点,其中COⅠ基因两个多态性位点为首次在畲族耳聋遗传家系中报道。这些突变或多态没有产生错义氨基酸,可能通过基因调控机制使tRNA代谢或线粒体功能产生缺陷,或者对氨基糖甙类药物易感而致聋。同时,在家系中未发现GJB2、MTO1基因及其他线粒体基因突变。结论 mtDNA7250A>G和7774G>A为汉族耳聋家系中新发现的线粒体基因突变形式,而mtDNA7196C>A和7319T>C是首次在畲族耳聋遗传家系中报道。     

GJB2 mutations in the Swiss hearing impaired

OBJECTIVE: Mutations in the GJB2 gene encoding connexin 26 (Cx26) protein are a major cause for nonsyndromic autosomal recessive and sporadic deafness. However, its contribution to hearing impairment in Switzerland remains undefined. To determine the frequency and type of GJB2 mutations in the Swiss hearing-impaired population diagnosed under the age of 2 yr and at 2 yr and older and to assess the effectiveness of denaturing high-performance liquid chromatography (DHPLC) in screening for mutation in GJB2. METHODS: Thirty-four patients with hearing impairment underwent mutation screening of the single coding exon of GJB2 with DHPLC followed by bidirectional sequencing to identify sequence alterations. RESULTS: GJB2 mutations were more common in children diagnosed with hearing impairment under the age of 2 yr compared to the group 2 yr and older. In patients under age 2 yr, 9 of 20 (45%) harbored 13 GJB2 mutations including a common 313del14nt mutation; four of these patients were homozygous or compound heterozygous for GJB2 mutations. In contrast, 2 of 14 patients in the 2 yr and older group (14%) had a single mutation in GJB2. The 35delG mutation was exclusively found in 5 patients under the age of 2 yr. DHPLC for mutation screening was 100% sensitive and 83% specific for detecting sequence alterations in GJB2. CONCLUSIONS: In Switzerland, GJB2 mutations are a major cause of nonsyndromic hearing impairment in children under the age of 2. Similar to other populations, GJB2 mutations are uncommon in the affected Swiss patients identified after 2 yr. Although 35delG mutation is common in the hearing-impaired children under the age of 2, it was absent in patients diagnosed with hearing impairment after the age of 2. DHPLC is a highly sensitive tool for detection of GJB2 mutations.     

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。