贵州省人工耳蜗植入患儿的常见耳聋基因突变位点分析

目的分析贵州省85例人工耳蜗植入患儿常见耳聋基因突变特点,初步了解其耳聋基因热点突变谱系及频率。方法采集贵州省85例平均年龄为3.31±1.67岁的人工耳蜗植入患儿的外周血,提取基因组DNA,采用基质辅助激光解吸电离飞行时间质谱技术(MALDI-TOF-MS)进行SNP基因分型检测。对GJB2,SLC26A4,GJB3 and mtDNA12srRNA4个基因(GJB2基因c.35delG、c.167delT、c.176-191del16、c.235delC、c.299-300delAT,GJB3基因c.538C>T、c.547G>A、SLC26A4基因c.281C>T、c.589G>A、C.919-2A>G、c.1174A>T、c.1226G>A、c.1229C>T、IVS15+5G>A、c.1975G>C、c.2027T>A、c.2162C>T、c.2168A>G,线粒体12SrRNA基因1555A>G、1494C>T)的20个位点进行检测。结果 85例人工耳蜗植入患儿中,共有25例(29.41%)患儿携带不同的常见致聋基因,1例携带GJB2、SLC26A4双基因突变。其中GJB2基因突变15例(17.65%)(含前述1例双基因突变者),其中纯合突变9例(10.59%),复合杂合突变3例(3.53%),单杂合突变2例(2.35%);SLC26A4基因突变9例(10.59%)(含前述1例双基因突变者),其中纯合突变2例(2.35%),单杂合突变6例(7.06%);DNA12SrRNA基因突变2例(2.35%),m.1555A>G同质突变1例(1.18%),m.1494C>T均质突变1例(1.18%);GJB3检出率为0。汉族与少数民族的突变检出率分别为36.73%、19.44%。结论人工耳蜗植入患儿中很多是遗传因素造成的,贵州省人工耳耳蜗植入患儿以GJB2基因和SLC26A4基因为最主要的致病基因,其中c.235delC突变为最常见突变位点,其次为C.919-2A>G突变。汉族患者基因突变检出率较少数民族患者高。     

43例人工耳蜗植入患者基因检测及术后康复效果分析

目的总结川南地区43例人工耳蜗植入患者的基因突变类型,分析其人工耳蜗术后康复效果,了解两者的相关性。方法对43例耳聋患者行GJB2、SLC26A4、mtDNA 12S rRNA基因检测,有基因位点发生致病突变者为耳聋基因检测阳性,归为A组;其余为基因检测阴性,归为B组。两组患者均行单侧人工耳蜗植入术,于术前、术后3、6、12个月行听觉行为分级（categories of auditory performance,CAP）、言语可懂度分级（speech intelligibility rating,SIR）评估。结果43例患者中基因位点发生致病突变者14例（A组）;耳聋基因筛查阴性29例（B组）。A组中9例患者GJB2检测阳性,6例患者SLC26A4检测阳性,其中1例患者GJB2、SLC26A4检测结果均为阳性,两组患者术后1年内不同时间点 CAP 和SIR 评分均较术前明显提高,且评分随着术后时间的延长逐渐提高(P<0.05),但两组患者术前及术后不同时间点CAP和SIR评分比较均无差异(P>0.05)。结论43例患者中常见致病耳聋基因为GJB2、SLC26A4,人工耳蜗植入术能有效提高患者听力及言语能力,但耳聋基因突变与人工耳蜗植入术后康复效果无明显相关性。     

人工耳蜗植入患者常见聋病相关基因突变与内耳畸形的相关性分析

目的通过对250例接受人工耳蜗植入手术的患者进行常见聋病相关基因突变检测,分析人工耳蜗植入的感音神经性听力损失群体中常见致聋基因的流行情况及突变频率,探讨基因突变与内耳畸形的关系,研究开展遗传咨询和人工耳蜗植入术前评估的科学途径。方法收集在我院接受工耳蜗植入手术的250例患者的临床资料,签订知情同意书后采全血,提取外周血基因组DNA,设计特异性扩增引物后利用多重PCR技术扩增目的片段进行纯化,采用华大基因公司定制的基因片段捕获芯片进行22个聋病相关基因共159个突变位点筛查。总结人工耳蜗植入群体基因突变的分布规律及突变频率,探讨基因突变与内耳畸形的相关性。结果所有250例患者中有77例患者检出基因突变,突变频率为30.80%(77/250)。其中SLC26A4基因突变频率为13.60%(34/250),占所有突变阳性患者的44.16%(34/77),共检出13种序列改变,其中23例患者检出c.919-2A>G突变,占SLC26A4基因突变患者的67.65%(23/34),等位基因频率为5.2%,是该基因突变检出率最高的突变形式。有33例患者检出GJB2基因突变,突变频率为13.20%(33/250),占所有突变阳性患者的42.86%(33/77),共检测到GJB2基因7种致病突变,其中GJB2双等位基因突变23例,突变频率为9.2%(23/250),有20例患者检测到c.235delC突变,有18例患者检测到c.299-300delAT突变,等位基因频率分别为5.4%和3.8%。250例患者中6例检出mtDNA 12SrRNA突变,突变频率为2.4%(6/250)。2例患者检出GJB3基因突变,突变频率为0.8%(2/250)。分析表明大前庭水管综合征(Large vestibular aqueduct syndrome, LVAS)与内耳结构正常的SLC26A4基因突变携带率存在统计学差异(P<0.001),LVAS伴不完全分隔Ⅱ型(Incomplete partition typeⅡ,IP-Ⅱ)与内耳结构正常的SLC26A4基因突变携带率存在统计学差异(P<0.001),而LVAS与LVAS伴IP-Ⅱ的SLC26A4基因突变结果的差异没有统计学意义(P=0.059)。GJB2基因突变患者合并内耳畸形的比例较低。结论 SLC26A4基因突变和GJB2基因突变在遗传性耳聋人群中有较高的发生频率。c.919-2A>G突变和c.235delC突变分别是人工耳蜗植入群体中SLC26A4基因突变和GJB2基因突变的常见形式。SLC26A4基因突变是LVAS发生的主要分子病因。LVAS及LVAS伴IP-Ⅱ与SLC26A4基因突变有明确的相关性,单纯IP-Ⅱ与SLC26A4基因突变可能无关。GJB2基因突变与多数内耳畸形无关。开展常见聋病基因的突变诊断有助于人工耳蜗植入的术前评估。     

GJB2基因突变致聋患儿人工耳蜗植入效果分析

目的 比较GJB2基因突变致聋患儿与非GJB2基因突变且内耳结构正常聋儿人工耳蜗植入术后的听觉言语康复效果.方法 对37例经C下及MRI检查排除内耳畸形的聋儿术前行GJB2基因检查,根据结果 分成A组(GJB2基因突变10例)和B组(非GJB2基因突变27例),术后随访0.5～2年,进行术后的听阈、言语识别率及言语能力评估.结果 37例聋儿人工耳蜗植入手术全部成功,均建立了主观听性反应.A组的声场听阈水平平均为34.41±6.12 dB HL.言语识别率平均为76%; B组的声场听阈水平平均为36.23±4.16 dB HL.言语识别率平均为79%,两组均达到平均言语康复级别二级;两组听觉及言语能力测试结果 均无统计学意义(P>0.05).结论 人工耳蜗患者中GJB2基因突变率高,可能是内耳结构正常的人工耳蜗植入人群耳聋的主要致聋原因;GJB2基因突变致聋患儿与非GJB2基因突变且内耳结构正常聋儿人工耳蜗植入术后效果基本一致.人工耳蜗植入可作为GJB2基因突变致聋患儿的有效治疗手段.     

安徽地区299例人工耳蜗植入患者常见耳聋基因检测分析CSCD

目的初步筛查安徽地区299例人工耳蜗植入(cochlear implant,CI)患者中耳聋基因热点突变,初步了解该地区CI患者中耳聋基因热点突变谱系及发生频率。方法我们收集299例CI患者常见耳聋基因突变的临床资料和病历,利用基因芯片检测4种常见耳聋基因的9个突变位点:GJB2(c.35delG、c.176del16、c.235delC、c.299delAT),GJB3(c.538C>T),SLC26A4(c.2168A>G、c.IVS7-2A>G)和mtDNA 12S rRNA(c.1494C>T、c.1555A>G)。结果(1)299例CI患者中,148例(49.50%)携带不同的常见耳聋基因突变,其中GJB2突变96例(64.86%),SLC26A4突变51例(34.46%),GJB3基因突变2例(1.35%),mtDNA 12S rRNA突变6例(4.05%);(2)在50例(16.72%)前庭导水管扩大(EVA)患者中,32例(64.00%)检测出基因突变,其中20例(62.50%)存在单杂合突变;且17例(34.00%)听性脑干反应(ABR)测试过程中伴有声诱发短潜伏期反应的患者中,11例也存在基因突变。结论GJB2和SLC26A4是安徽地区CI患者最重要的致病基因,其中,c.235delC突变是最常见的突变,其次是c.IVS7-2A>G突变。对于许多伴有EVA的CI患者,4个常见耳聋基因的9个突变位点并非全部为纯合或双杂合。EVA的诊断包括基因检测、听力学、影像学和许多其他结合使用的诊断方法。     

GJB2相关聋儿人工耳蜗术后有意义听觉整合量表评估

目的探讨GJB2基因突变致聋患儿人工耳蜗植入效果。方法对114例资料完整的2～6岁的人工耳蜗植入患者进行GJB2基因检查,根据年龄和GJB2测序结果分成2～4岁GJB2相关聋儿组和非GJB2相关聋儿组;4～6岁GJB2相关聋儿组和非GJB2相关聋儿组。术后1年,使用有意义听觉整合量表（Meaningful Auditory Integration Scale,MAIS）进行听觉康复效果问卷评估。结果114例聋儿人工耳蜗植入手术全部成功,均建立了主观听性反应。术后1年,28例2～4岁GJB2相关聋儿组的MAIS评分为25～37分,平均（34.0±2.7）分;50例2～4岁非GJB2相关聋儿组的MAIS评分为18～38分,平均（31.6±4.0）分;两组比较差异具有统计学意义（Ｐ＜0.05）。13例4～6岁GJB2相关聋儿组的MAIS评分为22～36分,平均（31.5±4.4）分;23例4～6岁非GJB2相关聋儿组的MAIS评分为25～37分,平均（31.7±3.1）分;两组比较差异无统计学意义（Ｐ＞0.05）。结论人工耳蜗患者中GJB2基因突变率高;GJB2基因突变致聋患儿的人工耳蜗植入效果稍好于非GJB2基因突变致聋患儿的人工耳蜗效果,或者他们的人工耳蜗植入效果基本一致;人工耳蜗植入可作为GJB2基因突变致聋患儿的有效治疗手段。     

339例非综合征型耳聋患者致病基因突变分析

目的通过分析东北地区339例非综合征型耳聋患者的常见耳聋基因序列,初步了解其耳聋热点基因突变特点及频率,为临床耳聋的预防及治疗提供参考。方法收集东北地区在中国医科大学附属盛京医院就诊的非综合征型耳聋患者339例,采集外周血并从中提取DNA,应用DNA测序法对中国人群中常见的4个致聋基因GJB2,GJB3,SLC26A4及线粒体12srRNA进行检测。其中GJB2,GJB3基因采用全基因组测序;SLC26A4,及线粒体12srRNA基因则采用对其常见的热点突变位点进行检测。结果 339例患者中,共检测出基因突变患者114例,检出率为33.63%(114/339),其中66例GJB2基因突变(19.47%, 66/339);7例GJB3基因突变(2.06%,7/339);39例SLC26A4基因突变(11.50%,39/339);4例12srRNA基因突变(1.18%, 4/339);其中2例为复合基因突变。114例耳聋基因突变患者中有62例单杂合突变为携带单个致病基因的耳聋患者;52例为由基因突变致聋的患者,其中30例纯合突变,6例单杂合突变和16例复合突变。结论 GBJ2和SLC26A4基因为东北地区非综合征性耳聋患者中的最为常见致病基因。c.235delC为GJB2基因突变主要形式,c.919A>G为SLC26A4基因突变主要形式。c.580G>A为GJB3基因突变主要形式,1555A>G为12srRNA基因突变主要形式。     

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.     

86例非综合征型耳聋患者耳聋基因芯片检测结果分析

目的探讨遗传性耳聋基因芯片用于非综合征型耳聋患者检测的临床意义。方法采用遗传性聋基因芯片试剂盒对86例非综合征型耳聋患者基因组DNA的GJB2、SLC26A4、GJB3和mtDNA12s rRNA四个耳聋相关基因的9个致聋突变位点进行检测;对所有患者进行颞骨高分辨率CT（HRCT）、头颅MRI、内听道扫描,耳蜗水成像。结果在86例非综合征型耳聋患者中携带所检测热点耳聋相关基因突变者占51.16%;其中GJB2基因突变携带者24例(27.91%,24/86),GJB3基因突变携带者2例,SLC26A4基因突变携带者19例,颞骨CT均显示前庭水管扩大,而且均伴有耳蜗发育畸形,表现为蜗顶发育不全;mtDNA12s rRNA基因突变0例,考虑与样本量少有关。结论遗传性聋基因芯片试剂盒可以考虑作为新疆地区耳聋患者的快速诊断方法,但基因测序法应作为必要补充。大前庭水管综合征患者的SLC26A4基因检测结果与其颞骨影像学检查结果吻合。     

贵州省常见致聋基因突变患儿人工耳蜗植入术后康复效果评估

目的对不同致聋基因突变患儿人工耳蜗植入后1年的听力言语康复效果进行评估,为人工耳蜗手术前预估术后康复效果提供参考。方法对常见的遗传性聋基因突变热点进行检测,对检测结果为杂合突变的人工耳蜗植入者进行相关基因全序列分析。根据基因结果,80例患儿分为4组,SLC26A4基因突变组、GJB2基因突变组、线粒体基因突变组,对照组为未发现SLC26A4、GJB2、线粒体基因突变患儿,使用声场扬声器测试人工耳蜗植入后助听听阈,采用人工耳蜗植入术后效果评估体系对患儿术后听觉言语能力进行评估,比较4组患儿CI植入术后1年康复效果的差异。结果 CI植入术后1年所有人工耳蜗患儿听觉言语能力较术前明显提高,各组患儿术前术后的听觉言语得分差异显著。GJB2基因突变组的患儿术后1年IT-MAIS、CAP分级和SIR分级得分高于对照组,其差异有统计学意义,声场助听听阈及言语年龄和SLC26A4基因突变组及对照组相比略有优势,但无统计学意义;SLC26A4基因突变组术后1年统计学分析显示各项评估结果略高于对照组,不及GJB2基因突变组,但差异无统计学意义;线粒体12S rRNA基因突变组术后1年仅2例各项得分接近对照组平均水平。结论不同致聋基因突变的患儿CI植入术后听觉言语能力均有改善,GJB2基因突变组人工耳蜗植入后1年效果较好,SLC26A4基因突变组效果优势有待长期观察进一步证实。     

Ethnicity and mutations in GJB2 (connexin 26) and GJB6 (connexin 30) in a multi-cultural Canadian paediatric Cochlear Implant Program

OBJECTIVE: To determine the relationship between ethnicity and mutations in the GJB2 and GJB6 genes in multi-cultural patients enrolled in a Canadian paediatric Cochlear Implant Program. METHODS: Blood was analyzed from 65 paediatric cochlear implant users by direct sequencing of the coding region and intron/exon boundaries of the GBJ2 gene. Individuals heterozygous for one mutation in GJB2 or in whom mutations in GJB2 were not detected were analyzed for the common 342 kb deletion mutation D13S1830 in the GJB6 gene. Information regarding ethnicity of patients' families was obtained from patient records and/or interview. RESULTS: GJB2 mutations were found in 36.9% of paediatric cochlear implant users tested. Nine different GJB2 mutations were identified among individuals from 14 different countries of origin. Seventy-eight percent of all identified pathogenic GJB2 mutations were 35delG. Biallelic GJB2 mutations were found in 16 cochlear implant users (66.7% of GJB2 mutations). Three novel GJB2 sequence changes were identified: (1) a missense mutation T107C (L36P) in an individual of African decent; (2) a missense mutation G475T (D159Y) in an individual of Caribbean decent; (3) a regulatory region change 1-34C to T in an individual of African decent. GJB6-D13S1830 mutations were not found in any of the patients tested. Individuals of African, Caribbean and East Indian decent had different GJB2 mutations than the remainder of individuals tested. Patients of Asian, Italian, Spanish, Polish and Armenian decent were not found to carry mutations in GJB2 or the common GJB6-D13S1830 mutation. CONCLUSIONS: This study represents the largest number of biallelic GJB2 mutations isolated in a group of paediatric cochlear implant users to date. Numerous and diverse GJB2 mutations were found in this multi-cultural group of children. Even though GJB2 mutations have been widely reported in the literature, this discussion represents the first report of GJB2 mutations in a multi-ethnic population (Canadian), as compared with previous studies that investigated fairly homogeneous populations. The diversity of GJB2 mutations identified reinforces the importance of testing for changes in GJB2 by direct sequencing of the entire coding region rather than testing only for common mutations.     

Cochlear implantation for children with GJB2-related deafness

OBJECTIVES/HYPOTHESIS: Mutations in GJB2 are a common cause of congenital sensorineural hearing loss. Many children with these mutations receive cochlear implants for auditory habilitation. The purpose of the study was to compare the speech perception performance of cochlear implant patients with GJB2-related deafness to patients without GJB2-related deafness. STUDY DESIGN: Retrospective case review. METHODS: Pediatric cochlear implant recipients who have been tested for GJB2 mutation underwent chart review. All patients received cochlear implantation at a tertiary referral center, followed by outpatient auditory habilitation. Charts were reviewed for cause and duration of deafness, age at time of cochlear implantation, intraoperative and postoperative complications, duration of use, and current age. Results of standard tests of speech perception administered as a part of the patients' auditory habilitation were reviewed. RESULTS: Twenty patients with GJB2 mutations were compared with 27 patients without GJB2 mutations. There was no statistical difference between patients with and without GJB2-related congenital sensorineural hearing loss with regard to open-set and closed-set speech recognition performance at 12, 24, and 36 months after cochlear implantation. Surgical complications were uncommon. CONCLUSION: Pediatric patients with congenital sensorineural hearing loss without other comorbid conditions (eg, developmental delay, inner ear malformations) perform well when they receive cochlear implantation and auditory habilitation. The presence or absence of GJB2 mutation does not appear to impact speech recognition performance at 12, 24, and 36 months after implantation.     

Identification of mutations in members of the connexin gene family as a cause of nonsyndromic deafness in Taiwan

Connexins (Cx), a large family of membrane proteins, are key components of gap junction channels. These channels are critical intercellular pathways through which ions or small molecules are passed, regulating a variety of physiological and developmental processes. One of these processes is hearing. In the current study, a genetic survey was made on 380 Taiwanese individuals, 260 with nonsyndromic deafness and 120 with normal hearing. All the 380 Taiwanese were screened for the presence of mutations in 8 genes of the Cx gene family. These genes included Cx26 (GJB2), Cx29 (GJE1), Cx30 (GJB6), Cx30.3 (GJB4), Cx31 (GJB3), Cx32 (GJB1), Cx43 (GJA1) and pseudogene [rho] of Cx43 (rho GJA1). Mutations were identified in 7 out of the 8 screened genes of the Cx family from 62 of the 260 deaf subjects (23.85%). Of the 17 mutations observed in the Cx gene family, 11 were novel mutations. Fourteen polymorphisms that were not associated with hearing loss were identified in the Cx gene family. The first 2 most frequently occurring mutations were found in the Cx26 (28/62; 45.16%) and the rho Cx43 (17/62; 27.42%), respectively. Nine cases of mutations were found in the Cx30.3 (9/62; 14.52%). In the Cx30, 1 novel mutation was identified in 1 case (1/62; 1.61%). Two patients with mutations of each of Cx29 and Cx43 were found (2/62; 3.23%). One novel mutation of Cx31 was identified in 3 patients with nonsyndromic deafness (3/62; 4.84%). The Cx32 was the only gene without detecting any mutation or polymorphism.Our study provides information for understanding the importance of genetic factors in nonsyndromic deafness of the Taiwanese and may be of use in the improvement of genetic diagnosis of hearing loss in Taiwan.     

Mutation analysis of the Cx26, Cx30, and Cx31 genes in autosomal recessive nonsyndromic hearing impairment

Conclusion. Biallelic Cx26 mutations are the most common cause of autosomal recessive nonsyndromic hearing impairment (ARNHI) in Switzerland. Mutations in Cx30 and 31, digenic mutations as well as large deletions/duplications, are unlikely to be a major cause of hearing loss in Swiss patients with ARNHI. Multiplex ligation-dependent probe amplification (MLPA) is a highly accurate screening method for detection of c.del(GJB6-D13S1830). Objectives. The intent of this study was to investigate the prevalence of the point and digenic mutations including large deletions and duplications in the Cx26, 30, and 31 genes in a Swiss patient cohort with ARNHI and cochlear implant. Patients and methods. The coding regions of Cx26, 30, and 31 were sequenced in 32 patients. Large deletions/duplications were assessed by MLPA. Results. In one patient digenic heterozygous mutations involving Cx26 (c.35delG) and Cx30 (c.del(GJB6-D13S1830)) were identified. Biallelic Cx26 mutations were detected in 31%. One putative mutation (c.94C>T) was found in Cx31. MLPA analysis did not reveal any additional deletion or duplication in all three Cx genes, except for the heterozygous c.del(GJB6-D13S1830) deletion.     

Cx26 gene mutations in idiopathic progressive hearing loss

OBJECTIVE: The present study evaluated the frequency and type of mutations throughout the entire GJB2 region in a population of 39 patients affected with sporadic progressive "idiopathic" hearing loss. MATERIAL: A large series of patients suffering from progressive hearing loss underwent a systematic screening program to identify the etiology of the hearing loss. Of these patients, 39 presented with sporadic idiopathic progressive hearing loss and were included in this study. METHOD: We performed molecular analysis of GJB2 in each patient sequencing the genomic deoxyribonucleic acid (DNA) in both directions for detection of GJB2 mutations. Furthermore, in all patients bearing a Cx26 mutation, a search was also conducted for mutations or deletions of GJB6 (Cx30 gene) and for the A1555G mutation of the mitochondrial DNA. A control group was also considered to evaluate the frequency of Cx26 mutations in the normal population. RESULTS: A Cx26 gene mutation was detected in nine cases. One subject was found to bear a homozygous genotype for the 35delG mutation, another subject was compound heterozygous for 35delG and E47X, and the remaining patients showed heterozygous genotypes (35delG, L90P, R127H, M34T, V153I, V37I). No mutation or delection of the Cx30 gene was observed in these nine patients, and none of them presented with the A1555G mutation in the mitochondrial DNA. In the control group (40 individuals), a Cx26 mutation was detected in two cases (5%). CONCLUSIONS: About 23% of our patients (nine subjects) presented with mutations in GJB2, and 18% (seven subjects) were heterozygous. However, most of the described mutations are recessive, so a monogenic model of inheritance cannot explain the deafness phenotype. On the basis of these findings, we can speculate that the heterozygote Cx26 genotype could be a cause of progressive hearing loss, probably in association with mutations in other alleles. Thus, we recommend carefully following all hearing-impaired subjects with GJB2 mutations, even if they present with only mild hearing loss, because the hearing deficit could worsen. Furthermore, molecular analysis of the Cx26 gene should also be performed in adult patients affected with idiopathic progressive hearing loss.     

Autosomal recessive and sporadic deafness in Morocco: high frequency of the 35delG GJB2 mutation and absence of the 342-kb GJB6 variant

Deafness is a heterogeneous disorder showing different pattern of inheritance and involving a multitude of different genes. Mutations in the gene, GJB2 Gap junction type 1), encoding the gap junction protein connexin-26 on chromosome 13q11 may be responsible for up 50% of autosomal recessive nonsyndromic hearing loss cases (ARNSHL), and for 15–30% of sporadic cases. However, a large proportion (10–42%) of patients with GJB2 has only one GJB2 mutant allele. Recent reports have suggested that a 342-kb deletion truncating the GJB6 gene (encoding connexin-30), was associated with ARNSHL through either homozygous deletion of Cx30, or digenic inheritance of a Cx30 deletion and a Cx26 mutation in trans. Because mutations in Connexin-26 (Cx26) play an important role in ARNSHL and that distribution pattern of GJB2 variants differs considerably among ethnic groups, our objective was to find out the significance of Cx26 mutations in Moroccan families who had hereditary and sporadic deafness. One hundred and sixteen families with congenital deafness (including 38 multiplex families, and 78 families with sporadic cases) were included. Results show that the prevalence of the 35delG mutation is 31.58% in the family cases and 20.51% in the sporadic cases. Further screening for other GJB2 variants demonstrated the absence of other mutations; none of these families had mutations in exon 1 of GJB2 or the 342-kb deletion of GJB6. Thus, screening of the 35delG in the GJB2 gene should facilitate routinely used diagnostic for genetic counselling in Morocco.     

Connexin-associated deafness and speech perception outcome of cochlear implantation

OBJECTIVE: To compare performance after cochlear implantation in children with mutations in connexin (Cx) 26 (GJB2) or Cx30 (GJB6) and children with deafness of unknown etiology. DESIGN: Genetic analysis and speech perception evaluation was performed in the children with and without Cx mutations who had undergone cochlear implantation. Speech perception performance was retrospectively analyzed 6, 12, 24, 36, and 48 months after implantation. Test material was selected according to the child's age and cognitive and language abilities. SETTING: The study took place at speech and hearing and genetic centers of a hospital in the central part of Israel and the genetics departments of 3 additional centrally located hospitals. PATIENTS: A total of 30 children who had undergone cochlear implantation were selected for the study, with control patients matched according to age at implantation, duration of implant use, and mode of communication. There was no evidence for additional disabilities or handicaps in either group. MAIN OUTCOME MEASURES: Speech perception measurements included a questionnaire, as well as closed and open-set tests. RESULTS: Overall, the 2 groups showed significant improvement in speech perception results after implantation. Four years after implantation, both groups achieved mean open-set speech perception scores of approximately 60%, 75%, and 90% for monosyllabic, 2 syllables, and words in sentences tests, respectively. CONCLUSIONS: There were no apparent differences in speech perception performance after implantation between the children with Cx mutations and children with deafness of unknown etiology. These data have important implications as a prognostic indicator when counseling candidates for cochlear implantation.     

The effect of GJB2 allele variants on performance after cochlear implantation

OBJECTIVES/HYPOTHESIS: It has been hypothesized that etiology of hearing loss may serve as an independent variable in performance after cochlear implantation. To test this hypothesis, the authors identified pediatric cochlear implant recipients with gap junction protein beta2 (GJB2)-related deafness. The study examines performance outcomes associated with GJB2 deafness-causing allele variants. STUDY DESIGN: Pediatric cochlear implant patients were screened for GJB2 allele variants; statistical comparisons were made with prospectively obtained performance measures. METHODS: From 181 children who participated in a nationwide cochlear implant research program, 122 children were identified with congenital nonsyndromic sensorineural hearing loss and invited to participate. Screening for GJB2 allele variants was completed for 55 children. The children were homogeneous with respect to age (8 or 9 y) and age at implant (before age 5 y). All patients have previously undergone a prospective regimented battery of performance measures. RESULTS: Performance measures were compared between 22 children with and 33 children without mutations to determine whether GJB2 status was a significant predictor of cochlear implant outcomes. Reading and cognitive outcomes were significantly dependent on connexin status. The group of children who tested positive for GJB2-related deafness scored significantly higher on a nonverbal cognitive measure, Block Design, and on a measure of reading comprehension. CONCLUSION: The isolated insult to the cochlea created by GJB2 allele variants allows for preservation of central cognitive function. Better reading performance is seen in children with GJB2-related deafness.     

GJB2及SLC26A4基因突变患儿耳蜗植入效果分析

目的探讨GJB2及SLC26A4基因突变的患儿人工耳蜗植入(cochlear implantation,CI)术后的效果。方法根据耳聋基因检测结果,将40名单侧CI患儿分成3组:GJB2组包括15名GJB2基因突变患儿,SLC26A4组包括8名SLC26A4基因突变患儿,对照组组包括17名未发现GJB2、SLC26A4及线粒体基因突变患儿。术后效果采用听觉意义整合量表(Meaningful Auditory Integration Scale,MAIS)、听觉行为分级标准(Categories of Auditory Performance,CAP)、规范学语时期出现时间、言语可懂度分级标准(Speech Intelligibility Rating,SIR)进行评估,比较3组术后1年效果差异的统计学意义。结果 GJB2基因突变组在MAIS及CAP两项评估中均明显优于其他两组,其差异有统计学意义。GJB2组的规范学语出现时间及SIR相较于另外两组也具有一定优势,但差异无统计学意义。SLC26A4组略优于非基因突变组,尽管统计学分析显示各项评估结果无显著差异。结论因病变部位在耳蜗,GJB2相关性耳聋患儿人工耳蜗植入术后效果较好,SLC26A4相关性耳聋术后是否存在优势有待进一步证实。     

间隙连接蛋白基因与遗传性聋的相关性研究

OBJECTIVE: To study the relation between hereditary nonsyndromic hearing impairment (NSHI) in Chinese and mutation in Connexin 31 (Cx31) gene and to explore the pathogenic mechanism. METHODS: Forty-seven pedigrees with hereditary NSHI, 38 Children with sporadic NSHI and cases of control were collected in present studies. The coding sequence of Cx31 gene was amplified by polymerase chain reaction (PCR), screened by denaturing high-performance liquid chromatography (DHPLC) and confirmed by direct sequencing. RESULTS: The mutation rate of heterozygous mutation C --> T at position 798 of Cx31 cDNA in patient group and in control were 14.1% (12/85) and 1% (1/100) respectively. Significant difference was found between the two group (P < 0.01). Heterozygous mutation G --> A at position 580 of GJB3 cDNA, which results in a missense mutation (A194T), was found in two members of one pedigree with autosomal dominant NSHI. The mutation was not found in numbers with normal hearing of this pedigree and controls. Heterozygous mutation G --> A at position 250 of Cx31 cDNA was found in one child with sporadic congenital NSHI. In our previous studies, Cx26 gene mutations have been screened among the patient with hereditary NSHI and sporadic NSHI and the control of our test, and two Cx26 gene mutations were found in two pedigrees. But the two NSHI pedigrees which were confirmed to have Cx26 gene mutation were not found to have Cx31 mutation. The patient and the control which were confirmed to have Cx31 gene mutations were not found to have Cx26 mutations. CONCLUSIONS: Cx31 gene was associated with nonsyndromic hearing impairment There was no cross and cooperative effect between Cx26 gene and Cx31 gene.