语前非综合征性耳聋与Connexin26基因突变的研究进展

学语前非综合征性耳聋致病基因的研究近年来取得了一些进展.编码缝隙连接蛋白26的Connexin26(Cx26)基因突变是学语前非综合征耳聋的分子遗传基础.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十分清楚.Cx26基因突变致聋具有种族特异性.国人的Cx26基因突变热点尚处于探索阶段.应用单链核甘酸多态性分析(SSCP)及基因测序寻找具有致病意义的基因突变,探讨其可能的发病机制为基因诊断,预防及治疗提供了新的理论依据.     

非综合征型遗传性耳聋基因及分子诊断研究进展

耳聋是严重影响人类生存质量的致残性疾病,先天性耳聋多由遗传因素导致。遗传性耳聋包括综合征型耳聋和非综合征型耳聋,其中非综合征型耳聋约占70%,分子诊断技术是目前检测遗传性耳聋的主要方法。本文对我国非综合征型遗传性耳聋致病基因及耳聋的分子诊断技术进行简述。     

遗传性非综合征型耳聋患者GJB2基因编码序列分析

目的 对6个遗传性非综合征型耳聋家系成员的GJB2基因编码序列进行分析,寻找耳聋患者的致病基因突变,探讨GJB2基因突变致病的遗传模式.方法 提取患者及家系成员的外周血基因组DNA,扩增GJB2基因的编码序列,然后对扩增产物进行DNA测序,对出现重叠峰形的扩增产物进行TA克隆后再测序,确定基因突变是否存在于同一拷贝.结果 6个遗传性非综合征型耳聋家系中,4个家系是GJB2基因突变所致.患者的GJB2基因突变包括235delC、299-300delAT、79G→A+341A→G和109G→A.非致聋突变79G→A与341A→G组合具有致聋效应,109G→A和235delC的杂合突变可能也有致聋效应.结论 GJB2基因突变致聋具有明显异质性,非致聋突变并非完全不致聋,环境因素或其它基因可能参与GJB2基因突变所致耳聋.     

河北邢台地区非综合征型耳聋患者GJB2、GJB3基因突变分析

目的通过检测邢台市聋哑学校非综合征性耳聋(non-syndromic hearing loss,NSHL)患者常见耳聋相关基因GJB2、GJB3的突变情况,初步掌握本地区NSHL常见基因的分布及突变特点,明确本地区病因以制定个性化的基因诊断策略,为耳聋基因筛查、临床分子诊断提供切实的理论依据。方法采集入选对象EDTA-K2抗凝的静脉全血,分离血浆和血细胞;抽提外周血细胞基因组DNA,采用聚合酶链反应(polymerase chain reaction,PCR)扩增GJB2、GJB3,并应用琼脂糖凝胶电泳成像系统进行鉴定;采用直接测序法GJB2基因的2个基因片段、GJB3基因的整个编码区进行检测;应用Mutation surveyor软件对所有基因的测序结果进行比对分析。结果被检测的110例邢台市特教学校耳聋学生均被诊断为重度以上双侧耳聋且均为非综合征型耳聋,其中携带GJB2基因235delC纯合突变的11例(占10%),携带GJB2基因复合杂合突变的11例(占10%);3例患者携带2个未分类的GJB3的突变基因。结论邢台地区为遗传性NSHL耳聋的高发区,最常见致聋基因为GJB2基因突变,应将GJB2、GJB3基因作为邢台地区临床常规筛查项目,同时为进一步开展遗传咨询、产前诊断以及基因诊断提供了重要的理论依据。     

一个常染色体显性遗传非综合征性耳聋家系的HBSY-012家系基因检测及遗传学特征分析

目的 研究常染色体显性遗传非综合征性耳聋家系的HBSY-012家系致病基因的突变位点，分析基因型与异常表型的关系。方法 采集一个常染色体显性遗传性非综合征型耳聋HBSY-012家系患者的临床资料，分析耳聋表型、遗传方式，并绘制家系图。提取家系成员外周血DNA，利用耳聋相关基因靶向测序，对家系成员进行全基因组外显子测序，寻找致病基因，采用Sanger测序技术验证突变位点。结果 HBSY-012家系现存四代共19人，9人诊断为感音神经性聋，耳聋表型特点为语后聋，发病早期呈现高频感音神经性耳聋，双耳对称，随着疾病进展出现渐进性听力下降，且快速下降，并转变成全频受累的极重度感音神经性耳聋。该家系的9例患者均在5～7岁开始出现听力下降，患者中年龄最大68岁，最小10岁。HBSY-012家系系谱分析该家系符合常染色体显性遗传特征。遗传性耳聋基因筛查检测显示EVI5基因NM＿005665:c.2399C>T变异、ANKMY2基因NM＿020319:c.822＿826del变异以及CCDC50基因c.363C>T(p.Leu121Phe)杂合突变，其中CCDC50基因c.363C>T...     

220例女性听障患者耳聋致病基因突变分析及遗传咨询

目的了解威海本地区女性听障患者耳聋基因突变位点分布特点,根据基因检测结果提供必要的遗传咨询和产前诊断服务,以降低本地区遗传性耳聋出生缺陷率。方法采用遗传性耳聋基因芯片和基因测序技术,对威海地区220例女性听障患者进行4个常见致聋基因(GJB2、SLC26A4、GJB3和线粒体12srRNA)的突变位点分析;为遗传性耳聋患者提供相应遗传咨询;对已婚配且有生育意愿的患者丈夫进行相应基因测序;对在同一个基因上发生致病突变的夫妇,在知情同意的情况下提供产前诊断服务。结果 220例样本中101例为突变型(45.9%)。GJB2基因突变率为19.5%;SLC26A4基因突变率为20.9%;GJB3基因突变率为0.7%;线粒体12srRNA突变率为4.5%。3个家庭因夫妇同时携带相同致聋基因的突变行产前诊断,结果显示2个家庭因胎儿为致聋基因的纯合突变或复合杂合突变,在知情同意的情况下选择终止妊娠,1个家庭胎儿为致病基因携带者选择继续妊娠。结论耳聋基因检测结合遗传咨询和产前诊断是降低耳聋出生缺陷率的有效手段。     

一个常染色体显性非综合征型耳聋DFNA15家系的基因检测

目的:探究一个常染色体显性非综合征型语后聋家系的致病基因变异类型,明确可能的遗传学病因。方法:应用高通量测序方法对先证者进行415个遗传性耳聋相关基因的序列检测,应用Sanger测序法对高通量测序结果进行验证并对家系成员进行基因变异位点检测。结果:先证者基因组DNA中检测到一个与非综合征型常染色体显性耳聋15(auto...     

四例非综合征型白化病家系的产前基因检测

目的探讨非综合征型白化病产前基因诊断的临床价值和意义。方法本研究应用Sanger测序法分别对四个非综合征型白化病家系进行常见致病基因检测。结果家系1患者在OCA2基因发现致病突变位点c.1441AG和c.727CT,胎儿与患者检测结果一致。家系2患者在SLC45A2基因存在c.478GC纯合突变,胎儿发现该位点杂合突变,为携带者。家系3患者在TYR基因存在致病突变位点c.655GA和c.929ins C,胎儿发现c.655GA杂合突变,为携带者。家系4患者在TYR基因上存在突变位点c.346CT和c.929ins C,但胎儿在TYR基因上未见异常。结论明确患者的致病基因可明显缩短胎儿产前基因诊断的时间,为白化病家庭提供积极且准确的优生指导。     

遗传性耳聋检测及风险分析

遗传性耳聋由遗传缺陷引起,与基因异常及相关的综合症关系密切,属临床常见疾病。鉴于目前绝大多数的遗传性耳聋无有效治疗手段,遗传咨询的意义显得尤为重要,其核心问题为遗传风险的估算。简要介绍了遗传性耳聋的分类以及利用致病基因特点和家系信息进行概率分析的方法。     

盖膜基因与耳聋

盖膜是耳蜗的 Corti器表面的细胞外基质成分 ,在早期的耳聋研究中它是一个被忽略的因素 ,但是许多的研究发现盖膜的组成成分盖膜蛋白、 型胶原、 型胶原、Otogelin糖蛋白与综合征型耳聋和非综合征型耳聋都有关系。本文就盖膜基因的克隆、结构、功能、表达和致病情况作一综述     

A proposal for comprehensive newborn hearing screening to improve identification of deaf and hard-of-hearing children

Early intervention for newborns who are deaf or hard-of-hearing leads to improved language, communication, and social–emotional outcomes. Universal physiologic newborn hearing screening has been widely implemented across the United States with the goal of identifying newborns who are deaf or hard-of-hearing, thereby reducing time to diagnosis and intervention. The current physiologic newborn hearing screen is generally successful in accomplishing its goals but improvements could be made. In the past ten years, genetic testing has emerged as the most important etiological diagnostic test for evaluation of children with deafness and congenital cytomegalovirus has been recognized as a major cause of childhood deafness that may be treatable. A comprehensive newborn hearing screen that includes physiologic, genetic, and cytomegalovirus testing would have multiple benefits, including (1) identifying newborns with deafness missed by the current physiologic screen, (2) providing etiologic information, and (3) possibly decreasing the number of children lost to follow up. We present a framework for integrating limited genetic testing and cytomegalovirus screening into the current physiologic newborn hearing screening. We identify needed areas of research and include an overview of genome sequencing, which we believe will become available over the next decade as a complement to universal physiologic newborn hearing screening.     

Clinical phenotype and mutations in connexin 26 (DFNB1/GJB2), the most common cause of childhood hearing loss

Mutations in the gene for connexin 26, GJB2, are the most common cause of hearing loss in American and European populations, with a carrier rate of about 3%-a rate similar to that for cystic fibrosis. A single mutation, 35delG, is responsible for most of this autosomal recessive hearing loss, DFNB1. A broad spectrum of mutations in GJB2 has been found to be associated with hearing loss, including another deletion mutation, 167delT, which has a carrier rate of about 4% in the Ashkenazi Jewish population. Mutations in GJB2 have also been found to be associated with dominant nonsyndromic hearing loss, DFNA3. Clinical studies have shown that the recessive hearing loss can vary from mild to profound, even within the same sibship. This type of hearing loss is nonsyndromic and is accompanied by normal vision, vestibular responses, and no malformations of the inner ear detectable by computed tomography scanning. Progressive and asymmetrical hearing loss has been noted in some cases, but it accounts for fewer than one-third of the cases of this type of hearing loss. The discovery of mutations in GJB2 that cause hearing loss has profound implications in the early diagnosis of hearing loss in general. The relative ease of diagnosis by genetic testing of Cx26 permits early identification of children with GJB2/DFNB1 hearing loss. This testing, coupled with hearing loss diagnosed by infant auditory brainstem response audiometry, will ensure that hearing-impaired children and their parents receive proper medical, audiologic, genetic, and educational counseling. Am. J. Med. Genet. (Semin. Med. Genet.) 89:130-136, 1999.     

Attitudes of deaf individuals towards genetic testing

Recent advances have made molecular genetic testing for several forms of deafness more widely available. Previous studies have examined the attitudes of the deaf towards genetic testing, including prenatal diagnosis. This study examines the attitudes of deaf college students towards universal newborn hearing screening, including molecular testing for specific forms of deafness, as well as the utilization of genetic test results for mate selection. We found that there may be differences in the attitudes of deaf individuals who associate closely with the deaf community (DC), and those who have equal involvement with both the deaf and hearing communities (EIC). The majority perceived newborn hearing screening for deafness to be helpful. However, more members of the EIC than the DC groups support newborn testing for genes for deafness. While there was reported interest in using genetic testing for partner selection, most participants reported they would not be interested in selecting a partner to have children with a specific hearing status. The results of this study point out important differences that genetic professionals should be aware of when counseling deaf individuals.     

Frequency of Usher syndrome in two pediatric populations: Implications for genetic screening of deaf and hard of hearing children

PurposeUsher syndrome is a major cause of genetic deafness and blindness. The hearing loss is usually congenital and the retinitis pigmentosa is progressive and first noticed in early childhood to the middle teenage years. Its frequency may be underestimated. Newly developed molecular technologies can detect the underlying gene mutation of this disorder early in life providing estimation of its prevalence in at risk pediatric populations and laying a foundation for its incorporation as an adjunct to newborn hearing screening programs.MethodsA total of 133 children from two deaf and hard of hearing pediatric populations were genotyped first for GJB2/6 and, if negative, then for Usher syndrome. Children were scored as positive if the test revealed ≥1 pathogenic mutations in any Usher gene.ResultsFifteen children carried pathogenic mutations in one of the Usher genes; the number of deaf and hard of hearing children carrying Usher syndrome mutations was 15/133 (11.3%). The population prevalence was estimated to be 1/6000.ConclusionUsher syndrome is more prevalent than has been reported before the genome project era. Early diagnosis of Usher syndrome has important positive implications for childhood safety, educational planning, genetic counseling, and treatment. The results demonstrate that DNA testing for Usher syndrome is feasible and may be a useful addition to newborn hearing screening programs.     

Variants in CIB2 cause DFNB48 and not USH1J

The genetic, mutational and phenotypic spectrum of deafness‐causing genes shows great diversity and pleiotropy. The best examples are the group of genes, which when mutated can either cause non‐syndromic hearing loss (NSHL) or the most common dual sensory impairment, Usher syndrome (USH). Variants in the CIB2 gene have been previously reported to cause hearing loss at the DFNB48 locus and deaf‐blindness at the USH1J locus. In this study, we characterize the phenotypic spectrum in a multiethnic cohort with autosomal recessive non‐syndromic hearing loss (ARNSHL) due to variants in the CIB2 gene. Of the 6 families we ascertained, 3 segregated novel loss‐of‐function (LOF) variants, 2 families segregated missense variants (1 novel) and 1 family segregated a previously reported pathogenic variant in trans with a frameshift variant. This report is the first to show that biallelic LOF variants in CIB2 cause ARNSHL and not USH. In the era of precision medicine, providing the correct diagnosis (NSHL vs USH) is essential for patient care as it impacts potential intervention and prevention options for patients. Here, we provide evidence disqualifying CIB2 as an USH‐causing gene.     

A systematic review of the monogenic causes of Non-Syndromic Hearing Loss (NSHL) and discussion of Current Diagnosis and Treatment options

Hearing impairment is one of the most widespread inheritable sensory disorder affecting at least 1 in every 1000 born. About two-third of hereditary hearing loss (HHL) disorders are non-syndromic. To provide comprehensive update of monogenic causes of non-syndromic hearing loss (NSHL), literature search has been carried out with appropriate keywords in the following databases–PubMed, Google Scholar, Cochrane library, and Science Direct. Out of 2214 papers, 271 papers were shortlisted after applying inclusion and exclusion criterion. Data extracted from selected papers include information about gene name, identified pathogenic variants, ethnicity of the patient, age of onset, gender, title, authors' name, and year of publication. Overall, pathogenic variants in 98 different genes have been associated with NSHL. These genes have important role to play during early embryonic development in ear structure formation and hearing development. Here, we also review briefly the recent information about diagnosis and treatment approaches. Understanding pathogenic genetic variants are helpful in the management of affected and may offer targeted therapies in future.     

Prader-Willi综合征的临床实践指南

Prader-Willi综合征(Prader-Willi syndrome,PWS)是首个被阐明的以基因组印记异常为致病机理的多系统遗传病。PWS的临床表现因年龄而异。胎儿期表现为胎动少;新生儿期主要表现为肌张力低下、哭声弱、吸吮无力、喂养困难等;婴幼儿期表现为生长发育及语言运动发育迟缓;儿童期表现为矮胖、小手足和认知功能障碍等;青春期以身高明显不足、肥胖、性腺发育不良、异常行为、学习困难等为主要特征。患者因饮食过度导致的病态肥胖是影响预后的主要因素。早期诊断、早期干预,对于改善其生活质量、预防严重的并发症和延长寿命具有重要的意义。本指南主要介绍PWS的临床症状、疾病发展过程、发病机制、分子诊断以及遗传咨询等内容,为临床医师对该病进行早期识别、合理干预和遗传咨询提供参考。     

Spectrum and frequencies of non GJB2 gene mutations in Czech patients with early non-syndromic hearing loss detected by gene panel NGS and whole-exome sequencing

Non-syndromic autosomal recessive hearing loss is an extremely heterogeneous disease caused by mutations in more than 80 genes. We examined Czech patients with early/prelingual non-syndromic, presumably genetic hearing loss (NSHL) without known cause after GJB2 gene testing. Four hundred and twenty-one unrelated patients were examined for STRC gene deletions with quantitative comparative fluorescent PCR (QCF PCR), 197 unrelated patients with next-generation sequencing by custom-designed NSHL gene panels and 19 patients with whole-exome sequencing (WES). Combining all methods, we discovered the cause of the disease in 54 patients. The most frequent type of NSHL was DFNB16 (STRC), which was detected in 22 patients, almost half of the clarified patients. Other biallelic pathogenic mutations were detected in the genes: MYO15A, LOXHD1, TMPRSS3 (each gene was responsible for five clarified patients, CDH23 (four clarified patients), OTOG and OTOF (each gene was responsible for two clarified patients). Other genes (AIFM1, CABP2, DIAPH1, PTPRQ, RDX, SLC26A4, TBC1D24, TECTA, TMC1) that explained the cause of hearing impairment were further detected in only one patient for each gene. STRC gene mutations, mainly deletions remain the most frequent NSHL cause after mutations in the GJB2.     

Comprehensive genetic testing with ethnic‐specific filtering by allele frequency in a Japanese hearing‐loss population

Recent advances in targeted genomic enrichment with massively parallel sequencing (TGE+MPS) have made comprehensive genetic testing for non‐syndromic hearing loss (NSHL) possible. After excluding NSHL subjects with causative mutations in GJB2 and the MT‐RNR1 (1555A>G) variant by Sanger sequencing, we completed TGE+MPS on 194 probands with presumed NSHL identified across Japan. We used both publicly available minor allele frequency (MAF) datasets and ethnic‐specific MAF filtering against an in‐house database of 200 normal‐hearing Japanese controls. Ethnic‐specific MAF filtering allowed us to re‐categorize as common 203 variants otherwise annotated as rare or novel in non‐Japanese ethnicities. This step minimizes false‐positive results and improves the annotation of identified variants. Causative variants were identified in 27% of probands with solve rates of 35%, 35% and 19% for dominant, recessive and sporadic NSHL, respectively. Mutations in MYO15A and CDH23 follow GJB2 as the frequent causes of recessive NSHL; copy number variations in STRC are a major cause of mild‐to‐moderate NSHL. Ethnic‐specific filtering by allele frequency is essential to optimize the interpretation of genetic data.     

Morphological and genetic causes of fetal cardiomyopathies

Cardiomyopathies are diseases of the heart muscle with variable clinical expressivity. Most of forms are inherited as dominant trait, and with incomplete penetrance until adulthood. Severe forms of cardiomyopathies were observed during the antenatal period with a pejorative issue leading to fetal death or medical interruption of pregnancy. Variable phenotypes and genetic heterogeneity make etiologic diagnosis difficult. We report 11 families (16 cases) whose unborn, newborn or infant with early onset cardiomyopathies. Detailed morphological and histological examinations of hearts were implemented, as well as genetic analysis on a cardiac targeted NGS panel. This strategy allowed the identification of the genetic cause of the cardiomyopathy in 8/11 families. Compound heterozygous mutations in dominant adulthood cardiomyopathy genes were found in two, pathogenic variants in co-dominant genes in one, de novo mutations in 5 including a germline mosaicism in one family. Parental testing was systematically performed to detect mutation carriers, and to manage cardiological surveillance and propose a genetic counseling. This study highlights the great diagnostic value of the genetic testing of severe antenatal cardiomyopathy both for genetic counseling and to detect presymptomatic parents at higher risk of developing cardiomyopathy.