非综合性耳聋GLB2与SLC26A4双基因突变分析

报告1例基因遗传检查为GLB235delc杂合同时伴SLC26A41VS7-2A〉G杂合2168A〉G位点杂合突变的耳聋患者。重度耳聋,根据临床床和细胞学研究估计该基因型可能不存在多基因的加性效应。     

变性高效液相色谱法分析非综合征型耳聋人群SLC26A4基因突变

目的 研究非综合征型耳聋(nonsyndromic hearing loss,NSHL)患者SLC26A4基因的突变情况,为临床上NSHL患者基因诊断提供指导.方法 PCR分别扩增SLC26A4基因的21个外显子及其侧翼序列,所得目的 片段用变性高效液相色谱(denaturing high-performance liquid chromatorgraphy,DHPLC)进行突变筛查,有异常峰形的样本进行DNA测序.结果 在所选30例无血缘关系且GJB2基因检测未发现突变的NSHL患者中,共检测出10种SLC26A4基因变异,其中包括7种已知突变,2种未见报道的新突变(F572L和D87Y),及一种已知多态(Ivs11+47T＞C),其中Ivs7-2A＞G是最常见的突变,约占总突变的40%.结论 SLC26A4基因为仅次于GJB2的导致NSHL的相关基因,在(GJB2基因检测未发现突变的NSHL人群中SLC26A4基因的检出率达到23.3%,其中Ivs7-2A＞G是其最常见的突变.     

感音神经性耳聋患者大前庭导水管综合征相关SLC26A4基因IVS7-2A＞G的全序列分析

目的 对携带SLC26A4基因IVS7-2A＞G单杂合突变感音神经性耳聋患者进行 SLC26A4基因的全序列检测,以期发现除IVS7-2A＞G以外的其他突变.方法 应用直接测序法对80例携带IVS7-2A＞G单杂合突变的感音神经性耳聋患者进行SLC26A4基因进行全序列测序.结果 80例患者中47例发现另1个突变位点,其余33例未发现复合杂合突变,IVS7-2A＞G单杂合突变找到另外1个突变的比例为58.8%(47/80).发现了 3个新的突变,分别是5+2T＞A、14-2A＞G和1825del G,最为常见的5种突变为H723R(20%)、T410M(5%)、15+5G＞A(5%)、L676Q(5%)、N392Y(3.75%).第17外显子是突变发生种类最多的外显子.结论 SLC26A4基因IVS7-2A＞G单杂合突变者应该进行其他突变的筛查,SLC26A4基因复合突变可以解释部分的耳聋原因.     

山西耳聋四家系分子病因学分析

目的应用分子生物学方法对耳聋四家系14例标本就耳聋热点突变基因进行筛查,分析四家系的耳聋病因。方法结合临床症状运用基因芯片、酶切和测序的方法对四家系耳聋的致病原因进行分析。结果芯片检测和测序显示:家系1患者IVA7-2A>G杂合突变来自母亲,c.C1229T突变来自父亲;家系2患者c.G79A(p.V27I)和c.A341G(p.R114G)来自母亲,GJB2 c.T70A(p.W24R)为体细胞突变;家系3患者c.G79A(p.V27I)和c.A341G(p.R114G)双杂合突变均来自父亲;家系4患者GJB2 235delC纯合缺失来自父母双方,c.G79A(p.V27I)和c.G232A(p.A78Y)杂合突变均来自母亲。结论本研究通过分子生物学的手段从基因的角度阐述了四家系的病因,为患者以后的优生优育及完善耳聋基因突变数据库奠定了基础。     

一个非综合征型耳聋家系的分子病因学分析

目的分析一非综合征型耳聋家系的分子病因,为患病家系遗传咨询和产前诊断提供依据。方法采用聚合酶链反应(polymerase chain reaction,PCR)和Sanger测序法对4名耳聋患者进行GJB2和SLC26A4基因编码区及侧翼序列测序。结果先证者GJB2基因序列测定为野生型,检出SLC26A4基因c.240delC和c.2168A>G复合杂合突变。先证者父亲检出SLC26A4基因c.240delC杂合突变,先证者母亲检出SLC26A4基因c.563T>C、c.1746delG和c.2168A>G三个杂合突变,先证者妹妹检出SLC26A4基因c.240delC、c.563T>C和c.1746delG三个杂合突变。其中,SLC26A4c.240delC为未见报道的新发框移突变,其余三个突变均为文献已报道的致病突变。结论该家系先证者、先证者母亲及先证者妹妹均为SLC26A4基因复合杂合突变导致的非综合征型耳聋,先证者父亲仅检出单杂合突变。明确基因突变有助于该家系进行遗传咨询和婚育指导,避免聋儿出生。     

携带 GJB2或 SLC26A4基因单杂合变异新生儿的Sanger测序分析

目的明确长沙地区GJB2或SLC26A4基因单杂合变异新生儿携带其他变异位点的情况, 探究该地区耳聋基因的变异谱。方法应用Sanger测序技术对462例携带GJB2和(或)SLC26A4基因单杂合变异的新生儿进行耳聋相关基因的外显子测序, 结合数据库和文献检索, 综合分析变异位点的致病性。结果在305例GJB2杂合变异者中, 有143人(46.49%)携带其他变异位点, 其中29人(9.51%)携带c.109G>A可能致病变异, 1人(6.48%)携带c.551G>A致病变异。在153例SLC26A4杂合变异者中, 2人(1.31%)携带c.281C>T变异, 1人(0.65%)携带c.1547₁548ins致病变异。在4例同时携带GJB2和SLC26A4变异的新生儿中, 2人分别携带c.109G>A和c.844T>C(临床意义不明)变异。结论长沙地区携带GJB2和SLC26A4单杂合变异的新生儿中, 其他变异位点的携带率较高, 应用Sanger测序技术对耳聋基因杂合变异进行检测, 能够有效提高耳聋高风险新生儿的检出率, 丰富耳聋基因...     

耳聋基因与新生儿听力的同步筛查结果比较

目的了解听力筛查与耳聋基因检测结果的不同意义,为新生儿大规模耳聋基因筛查的可行性和有效性提供理论依据。方法 2013年4月至2013年3月于绍兴市妇幼保健院出生的新生儿,其中有4063名新生儿接受了听力和耳聋基因的同步筛查,并对其结果进行对照和比较。结果 4063例新生儿中840例未通过听力筛查,231例携带耳聋基因。耳聋基因阳性231例中,152例听力筛查通过,听力筛查与耳聋基因阳性率有统计学差异。结论部分迟发型耳聋的儿童可通过新生儿耳聋基因筛查有效地进行基因预警,对新生儿进行听力及基因联合筛查具有临床可行性。     

Connexin26基因与常染色体隐性非综合征性耳聋

已知所有的常染色体隐性非综合征性耳聋(ARNSHL)基因可致重度或极重度学语前耳聋，目前已有32个ARN—SHL基因，通过对单一的有血缘关系的家系分析而定位。其中编码缝隙连接蛋白26的Connexin26(Cx26)基因突变与ARN—SHL关系最为密切。同时Cx26基因突变也是DFNA3／DFNBl的遗传基础。有关Cx26基因突变及其产生异常缝隙连接蛋白在听觉功能中的作用尚不清楚，本文综合目前对Cx26基因的突变及其产生缝隙连接蛋白在遗传性耳聋中的发病机制中的研究资料作一简要论述。     

一个X-连锁视网膜色素变性中国家系的RPGR基因的新突变

目的 对中国人X-连锁视网膜色素变性一家系进行分子遗传学检测，报告RPGR基因突变。方法 首先对该家系X染色体进行致病基因的连锁分析，然后用单链构象多态性技术和直接DNA测序方法进行基因突变分析。结果 连锁分析在多态性微卫星遗传标记DXSS012和DXS8025产生正的Lod值分别为2．41（Zmax=2．40，θ=0）和1．26。进一步单倍型分析确定该家系致病基因位于Xp21．1，与RP3连锁。用RPGR基因突变分析，在外显子ORF15＋483－484发现GA缺失，引起阅读框架的改变，该基因缺失突变在家系中共分离。结论 报告了中国人X-连锁视网膜色素变性RPGR基因外显子ORF15＋483-484的GA缺失突变，丰富了中国人RPGR基闪突变谱，为今后研究X-连锁视网膜色素变性的基因奠定基础。     

SLC26A3基因复合杂合突变致产前胎儿肠管扩张1例并文献复习

目的 探究SLC26A3基因突变致产前胎儿肠管扩张的临床特点及发病机制.方法 回顾性分析1例产前超声诊断胎儿肠管扩张的临床资料并对SLC26A3基因突变进行文献复习.结果 1名孕妇在妊娠31周时经产前超声检查发现羊水过多、胎儿肠管弥漫性扩张,遗传学基因检测发现胎儿染色体核型未见异常,全外显子组高通量测序检测结果示受检者...     

连接蛋白基因一个新致聋突变体p.Y155X及功能分析

目的 观察连接蛋白(connexin 26,CX26)基因的一个新致聋突变c.465T→A,P.Y155X,在体外表达细胞功能的改变,以探讨其致聋的可能机理.方法 常染色体隐性遗传耳聋家系的先证者外周血抽提DNA,DNA直接测序法分析CX26基因突变.将在该家系发现的突变c.465T→A,P.Y155X和野生型CX26(wtCX26)定向克隆到pEGFP-N1质粒,构建CX26 p.Y155X-EGFP及wtCX26-EGFP融合蛋白表达载体,转染HeLa细胞,Western印迹分析蛋白的表达,共聚焦显微镜观察突变蛋白和野生型CX26在HeLa细胞的定位及有无间隙连接斑形成,染料转移实验分析间隙连接的功能.结果 在该耳聋家系发现CX26基因一个新的致聋突变:c.465T→A,P.Y155X.CX26 P.Y155X突变体在HeLa细胞表达的突变蛋白的分子量小于野生型蛋白分子量;突变蛋白在细胞质表达,不能分布到细胞膜和形成间隙连接,无染料转移.野生型表达于细胞膜并形成间隙连接斑,能转移染料.结论 CX26 P.Y155X突变体在翻译后不能从细胞内转运到细胞膜,不能形成间隙连接通道.CX26基因c.465T→A,P.Y155X导致常染色体隐性遗传性聋.     

Molecular analysis of hearing loss associated with enlarged vestibular aqueduct in the mainland Chinese: a unique SLC26A4 mutation spectrum

It has been shown that mutations in the SLC26A4 gene are involved in syndromic deafness characterized by congenital sensorineural hearing impairment and goitre (Pendred's syndrome), as well as in congenital isolated deafness (DFNB4), both of which are associated with enlarged vestibular aqueduct (EVA). The prevalence of SLC26A4 mutations in Pendred's syndrome is clearly established in many ethnic groups, but the data from Mainland Chinese patients with deafness and EVA remain poor. In this report, 15 patients from 13 unrelated Chinese families with deafness and EVA were analyzed for SLC26A4 using direct sequencing. A total of 15 pathogenic mutations were observed in 11 unrelated families, 4 of which were novel. One mutation, IVS7-2A>G, was most common, accounting for 22.3% (5/22) of all the mutant alleles, and H723R was infrequent. To date, a total of 23 mutations have been reported among the Chinese, 13 of which were unique. In conclusion, EVA could be a radiological marker for SLC26A4 analysis among Mainland Chinese hearing-loss patients, and the SLC26A4 mutation spectrum in the Chinese was different from other reported populations.     

Screening of SLC26A4 (PDS) gene in Pendred's syndrome: a large spectrum of mutations in France and phenotypic heterogeneity

Sensorineural hearing defect and goiter are common features of Pendred's syndrome. The clinical diagnosis of Pendred's syndrome remains difficult because of the lack of sensitivity and specificity of the thyroid signs. The identification of PDS as the causative gene allowed molecular screening and enabled a re-evaluation of the syndrome to identify potential diagnostic characteristics. This report presents the clinical and genotypic findings of 30 French families, for whom a diagnosis of Pendred's syndrome had been made. Twenty-seven families had at least one mutated allele. Twenty-eight different mutations were identified, 11 of which had never been previously reported. The main clinical characteristics were: early hearing loss, fluctuation in terms of during deafness evolution, and the presence of an enlarged vestibular aqueduct.     

Identification of five new mutations of PDS/SLC26A4 in Mediterranean families with hearing impairment

Pendred syndrome is an autosomal‐recessive disorder characterized by congenital sensorineural hearing loss combined with goiter. This disorder may account for up to 10% of cases of hereditary deafness. The disease gene (PDS/SLC26A4) has been mapped to chromosome 7q22‐q31 and encodes a chloride‐iodide transport protein. Mutations in this gene are also a cause of non‐syndromic autosomal recessive hearing impairment (DFNB4). We have analyzed the PDS/SLC26A4 gene in Spanish and Italian families and we have detected five new mutations (X871M, T132I, IVS1‐2A>G, Y556H and 406del5). © 2001 Wiley‐Liss, Inc.     

Allele specific oligonucleotide analysis of the common deafness mutation 35delG in the connexin 26 (GJB2) gene

Despite the large number of genes that are expected to be involved in non-syndromal, recessive deafness, only a few have been cloned. One of these genes is GJB2, which encodes connexin 26. A frameshift mutation in this gene has been reported to be common in several populations and a carrier frequency of about 1 in 30 people has been detected in Italy and Spain. Mutation 35delG is difficult to detect because it lies within a stretch of six guanines flanked by thymines, so the deletion of one G does not create or destroy a restriction site and mutagenesis primers are not useful for this mutation. We have generated an allele specific oligonucleotide method that uses 12-mer oligonucleotides and easily discriminates between the normal and 35delG alleles. The method should permit a rapid analysis of this mutation in congenital cases (recessive or sporadic), including diagnosis and carrier detection of 35delG in the population.     

Association of SLC26A4 muations with clinical features and thyroid function in deaf infants with enlarged vestibular aqueduct

Pendred syndrome and non-syndromic recessive deafness associated with enlarged vestibular aqueduct (NSRD with EVA) are caused by mutations in the SLC26A4 (PDS) gene. Unlike NSRD with EVA, Pendred syndrome is characterized by goiter, which may be present after early adulthood. However, the clinical diagnosis of these two disorders is difficult in deaf children. Expression of the SLC26A4 gene may be responsible for iodide transport in the thyroid as well as for formation and function of the inner ear. Here, we analyzed the SLC26A4 gene and performed thyroid function tests (FT3, FT4, TSH, and Thyroglobulin) on six congenitally deaf infants (mean age 2.7 years) with EVA. Mutation of the SLC26A4 gene was identified in five patients: four were compound heterozygous (H723R/919−2A>G, H723R/IVS15+5G>A, H723R/R581S, IVS7-2A>G/IVS8+1G>A), the fifth had a frameshift mutation (322delC). All the patients demonstrated an elevation of serum thyroglobulin level. FT3 level was elevated in four of the five patients. The patient who did not have a detectable gene mutation showed normal thyroid function. We conclude that the mutations in the SLC26A4 gene identified here are highly associated with high serum thyroglobulin levels in congenital and deafness infants. These mutations may be of value for the diagnosis of Pendred syndrome and NSRD with EVA.     

W44C mutation in the connexin 26 gene associated with dominant non-syndromic deafness

Although more than 50% of recessive non-syndromic deafness is attributed to mutations in the connexin 26 (Cx26) gene, only a few reported families have shown dominant transmission of the trait. The W44C mutation was originally reported in two families from the same geographic region of France, which exhibited dominant non-syndromic hearing loss. In this report, we describe a third family with early-onset severe-to-profound non-syndromic hearing loss segregating with the W44C mutation. Our observation places W44C among recurrent mutations in the Cx26 gene and emphasizes the importance of screening for this as well as other Cx26 mutations in autosomal dominant families.     

A distinct spectrum of SLC26A4 mutations in patients with enlarged vestibular aqueduct in China

There is a worldwide interest in studying SLC26A4 mutations that are responsible for enlarged vestibular aqueduct (EVA) in different ethnic background and populations. The spectrum of SLC26A4 mutations in Chinese population is yet to be fully characterized. In this study, all the 21 exons of SLC26A4 were screened in 107 Chinese patients with hearing loss associated with EVA or both EVA and Mondini dysplasia (MD), taken from six multiplex and 95 simplex families. The two types of control populations consisted of 84 normal-hearing subjects and 46 sensorineural hearing loss subjects without inner ear malformations. Biallelic mutations were found in 12 patients from multiplex families and 84 patients (88.4%) from the simplex families. In addition, monoallelic variant was detected in nine patients in the remaining 11 simplex families. Overall, up to 97.9% patients were found having at least one possible pathogenic variant in SLC26A4 , with most having biallelic variants consistent with recessive inheritance of this disorder. A total of 40 mutations including 25 novel mutations were identified in the Chinese patients but were not detected in all the controls except for one normal subject. For the Chinese mutation spectrum of SLC26A4 gene, IVS7-2A>G mutation was the most common form accounting for 57.63% (102/177) of all the mutant alleles.