近亲结婚所致一遗传性非综合征型耳聋家系的调查

耳聋是一种最常见的人类感觉系统缺陷，在已发现的遗传性耳聋中，有70％属于非综合征型听力缺损。据估计非综合征型遗传性耳聋基因总数在100个以上，目前已经确定了近80个非综合征型遗传性耳聋的遗传位点，其中23个基因已经被成功克隆。本报道一遗传性非综合征型耳聋家系。该家系中存在2代近亲结婚，共2代13人出现聋哑症状。经遗传分析，该家系的遗传方式与常染色体显性或隐性遗传均不符合，提示此家系中的非综合征型遗传性耳聋可能为线粒体突变所致。     

一母系遗传非综合征型感音神经性耳聋线粒体基因突变分析

目的:通过对一个母系遗传非综合征型耳聋家系进行线粒体DNA(mitochondric DNA,mtDNA)12SrRNA及tRNASer(UCN)基因突变分析,mtDNA突变与遗传性耳聋相关性。方法:临床听力测试以明确诊断,收集非综合征型遗传性耳聋家系中6人的外周静脉血样本,从白细胞中提取DNA,聚合酶链反应扩增mtDNA目的片段,对扩增片段进行DNA测序,对发现的基因突变进行计算机辅助的二级结构模拟分析。结果:测序结果表明,此家系mtDNA12SrRNA基因中存在着mtDNA A1555G、G1007A、A1313G点突变,tRNASer(UCN)基因无突变。结论:在该非综合征型遗传性耳聋家系中,mtDNA12SrRNA基因区域A1555G和G1007A、A1313G突变可能共同参与了听力损害的过程。     

一个遗传性非综合征型耳聋家系的 GJB2基因突变分析

目的：对1个遗传性非综合征型耳聋家系的临床表型特征进行分析,并选取 GJB2基因进行突变检测。方法详细询问病史和临床检查后,提取患者及家系成员的外周血基因组 DNA ,PCR 扩增 GJB2基因的外显子及外显子和内含子的交界区域,然后对扩增产物进行 DNA 测序和 BLAST 比对进行突变分析。结果该家系所有患者为迟发性、渐进性、早期以高频听力下降为主的感觉神经性聋。 GJB2基因突变分析检测到6种单核苷酸多态,其中 c ．79G ＞ A （p ．Val27Ile）和 c ．341G ＞ A （p ． Glu114Gly）为已知单核苷酸多态,而位于3′‐UTR 的 g ．4159T ＞ C 、g ．5142G／T 、g ．5227G／A 、g ．5352T ／C 突变为本研究新发现。结论该家系未发现 GJB2外显子致病性突变,遗传性非综合征型耳聋存在明显的遗传异质性。     

连接蛋白与遗传性耳聋研究现状和基因治疗的研究展望

遗传性耳聋可分为综合征性耳聋（syndromic hearing impairment,SHI）和非综合征性耳聋（nonsyndromic hearing impairment,NSHI）。综合征性耳聋除听力损伤外,还有非听力方面的症状和体征,约占遗传性耳聋的30%;其余70%为非综合征性耳聋,即只有听力损害,不伴有非听力方面的症状和体征。学语前耳聋中绝大多数属于后者。人类约有15种连接蛋白,现已证实有6种与遗传性耳聋有关。迄今,对非综合征性常染色体显性遗传耳聋（ARNSHL）研究较多的基因是Connexin 26（Cx26）基因,它的高频突变与NSHI密切相关,同时Connexin 26基因突变与常染色体显性遗传性耳聋DFNA3和常染色体隐性遗传性耳聋DFNB1也有关,故称其为耳聋易感基因。本文主要从基因突变类型、器官和组织的表达,以及引起耳聋的机制和相关的治疗研究加以综述,重点探讨以Connexin 26为代表的连接蛋白与遗传性耳聋的关系。     

遗传性耳聋家系的MYO7A基因突变检测

ＭＹＯ７Ａ基因的突变可引起遗传性耳聋，既有综合征性耳聋，又有非综合征性耳聋，其中又包含隐性遗传和显性遗传性耳聋。为研究此基因突变与先天性聋哑的关系，本文通过多聚酶链式反应（ＰＣＲ）及非放射性同位素标记的单链构象多态性分析（Ｎｏｎ－ＲＩＳＳＣＰ）方法检测一隐性遗传性耳聋家系，结果发现先天性聋哑患者有ＭＹＯ７Ａ基因第九外显子突变，其父母为突变基因的携带者，证实其先天性聋哑与此位点突变相关，ＭＹＯ７Ａ基因的突变分析对遗传性耳聋的临床诊断是非常重要的。     

GJB2基因突变在遗传性非综合征性耳聋中的研究进展

遗传性耳聋可分为综合征性耳聋和非综合征性耳聋。在我国GJB2基因突变是最重要的导致遗传性耳聋的因素之一。在常染色体隐性遗传的非综合征性耳聋中,有50%的患者存在GJB2基因突变。在不同种族中GJB2基因的突变位点不同,中国人以235delC突变最常见,其次为299～300delAT、176del 16bp和35delG。目前发现GJB2基因突变不但可引起遗传性耳聋,还可引起获得性耳聋。现就GJB2基因突变致非综合征性耳聋的相关发病机制、临床表型及检测方法等最新研究进展予以综述。     

遗传性耳聋的基因研究进展

聋病是影响人类健康和造成人类残疾的常见原因,许多聋病发病过程都有遗传因素作用。遗传性耳聋包括非综合征型耳聋和综合征型耳聋。研究表明,至少50%的先天性耳聋由遗传因素导致,非综合征型耳聋占70%,约77%的非综合征型耳聋为常染色体隐性遗传,综合征型耳聋是指听力障碍只是全身多处临床症状之一的遗传综合征,因此通过耳聋基因检测可为我国40%的聋病患者明确遗传学诊断,该文就遗传性耳聋基因研究的进展予以综述。     

常染色体显性遗传性听神经病家系全外显子组测序分析

目的：在多年围绕1个常染色体显性遗传性非综合征型听神经病家系开展系统分子遗传学研究的基础上,进一步探讨该家系耳聋的致病机制,以期发现新的听神经病致病基因和突变位点。方法：对3例耳聋患者和1例配偶进行全外显子组测序,初步筛选出与家系耳聋相关的候选致病基因。采用PCR-Sanger测序法,检测上述候选基因变异是否与家系表型共分离。最后,以50例与研究家系无关的听力正常人为对照,检测候选致病突变在正常群体中的突变频率和SNPs遗传多态性。结果：全外显子测序分析得到41个候选致病基因突变;用PCR-Sanger测序法对核心家系的9名成员和2名家系外听力正常人进行验证,仅发现1个基因突变（ALOX15B 7942797 C>T）与家系耳聋表型共分离。选取50例家系外正常对照的DNA样本对ALOX15B基因进行PCR扩增和序列分析,结果显示有2例听力正常人也检测到该基因的同一变异,提示该变异为SNPs遗传多态性。结论：对核心家系成员的全外显子组测序分析和Sanger测序法验证未发现有意义的突变位点,排除了该家系耳聋由基因编码区突变及Indels致病的可能性。     

一个遗传性耳聋伴前庭功能障碍家系的分子病因学研究

目的:对1个遗传性耳聋伴前庭功能障碍家系进行遗传方式?表型特征及致病基因的分析,以研究其分子病因?方法:对门诊1例遗传性聋伴眩晕患者进行家系调查?病史收集及相应的听力学和前庭功能检查?利用目标基因捕获和大规模平行测序技术,对家系先证者进行可能致病突变筛查,包括靶向104种与遗传性听力损失相关的基因和3个microRNA分子?进一步对获得的候选突变基因进行编码区序列验证分析?结果:目标基因捕获测序结果发现先证者COCH基因第11外显子上存在c.1458C>G(p.T352S)的杂合突变?进一步对家系中所有患者和有血缘关系的正常个体进行了遗传共分离分析,发现该杂合突变在该家系中仅有Ⅰ2?Ⅱ1?Ⅱ5?Ⅱ9?Ⅱ13和Ⅳ1存在相同的杂合突变,而Ⅱ11和Ⅲ1表现为该突变的纯合子,表明该杂合突变不存在共分离现象,因此可以排除其为该家系致病突变的可能性?对先证者Ⅲ14 COCH基因全部12个外显子的序列测定结果未发现其他突变?结论:此家系为常染色体显性遗传性非综合征型耳聋伴前庭功能障碍,但初步筛查结果未发现已知耳聋相关基因,包括COCH基因的可疑致病突变?因此,该家系的分子病因可能存在一新基因的突变?     

隐性遗传性聋4家系听力学调查分析

目的 :分析无综合征性隐性遗传性耳聋 4个家系的听力学特点及遗传特征。方法 :对 4个家系进行相关资料调查和听力学检查分析。纯音测听 6 2例 ,耳聋 2 5例。对先证者 4例行双侧声导抗、ABR测试。结果 :D、G家系学语前聋 ,表现为聋哑症。E、F家系学语后聋 ,多表现为对称性、进行性听力下降。E家系耳聋始于 8岁以后 ,F家系耳聋最早始于 5岁 ,最晚始于 2 2岁。首先是高频区受损 ,以后向中、低频扩展。F家系Ⅳ5因突发性耳聋导致全聋。听力学测试支持耳蜗性感音性听力损失。 4个家系男女均有发病 ,表型正常的双亲 ,后代可有耳聋 ,耳聋患者可有正常后代。D、G家系可见隔代遗传。全身检查未见其它部位畸形。结论 :4个家系为无综合征的单基因常染色体隐性遗传性感音神经性听力损失 ,经GJB2、GJB3、GJB6、线粒体耳聋基因筛查 ,F、G家系与GJB2基因突变相连锁     

Mitochondrial DNA mutations in matrilineal nonsyndromic deafness pedigrees of southwest China]

OBJECTIVE: To identify the incidence of the 1555A-->G mutation and explore the audiological features of pedigrees with matrilineal non-syndromic deafness in Southwest of China so as to provide the theoretical evidence for establishing the method of gene diagnosis. METHODS: Six pedigrees with 102 members were evaluated audiologically and clinically. DNA was extracted from their blood samples. All subjects were screened for mitochondrial DNA 1555A-->G mutation by Alw 26I restriction endonuclease digestion. RESULTS: Seventeen maternal relatives of aminoglycoside antibiotic induced deafness (AAID) pedigree 1 and pedigree 2, carried 1555A-->G mutation. 10 maternal relatives of Non-AAID pedigree 6 also carried 1555A-->G mutation. No mutation was found among paternal relatives and pedigrees 3, 4 and 5. CONCLUSION: The same audiological features of these pedigrees are: bilateral and symmetrical progressive sensorineural hearing loss with variable age of onset. The 1555A-->G mitochondrial mutation is one of the hereditary factors for this disorder. 4 Aminoglycoside antibiotic plays an important role in developing deafness. The incidence of the 1555A-->G mutation in AAID and matrilineal non-syndromic deafness pedigrees is fairly high. Screening for mitochondrial 1555A-->G mutation may be of great clinical use fullness.     

一种筛查中国人遗传性耳聋和氨基糖苷耳毒性易感人群的分子遗传学方法

Objective: To develop a molecular screening test for genetic defects on hearing loss related genes has significant impacts on early identification of hereditary hearing loss and genetic susceptibility to aminoglycoside ototoxicity. Early identification of pre-lingual hearing loss is very important for patient‘s language development, academic achievement, and social skill. Two common mutations, the 235delC in GJB2 gene and the mutation A1555G in mitochondrial DNA, are included in the newly developed screening panel for Chinese population. Methods: A molecular genetic assay, based on fluorescent labeled multiplex PCR and automatic DNA fragment analyzing techniques, was developed to detect both mutations simultaneously. Results: This assay was able to detect both mutations from patient‘s samples, and pooled DNA tests, as well as suitable to detect mutation from the DNA extracted from dried blood spot and buccal swab. Conclusion: This assay could be a useful tool for newborn screening and carrier screening for the hereditary hearing loss for the Chinese population。     

Identification of Two Disease-causing Genes TJP2 and GJB2 in a Chinese Family with Unconditional Autosomal Dominant Nonsyndromic Hereditary Hearing Impairment

Background:

There are more than 300 genetic loci that have been found to be related to hereditary hearing impairment (HHI), including 92 causative genes for nonsyndromic hearing loss, among which 34 genes are related to autosomal dominant nonsyndromic HHI (ADNSHHI). Traditional linkage analysis and candidate gene sequencing are not effective at detecting the ADNSHHI, especially for the unconditional families that may have more than one pathogenic cause. This study identified two disease-causing genes TJP2 and GJB2 in a Chinese family with unconditional ADNSHHI.

Methods:

To decipher the genetic code of a Chinese family (family 686) with ADNSHHI, different gene screening techniques have been performed, including linkage analysis, candidate genes screening, high-throughput sequencing and Sanger sequencing. These techniques were done on samples obtained from this family over a period of 10 years.

Results:

We identified a pathogenic missense mutation, c. 2081G>A (p.G694E), in TJP2, a gene that plays a crucial role in apoptosis and age-related hearing loss (ARHL). The mutation was co-segregated in this pedigree in all, but not in the two patients who presented with different phenotypes from the other affected family members. In one of the two patients, we confirmed that the compound heterozygosity for p. Y136* and p.G45E in the GJB2 gene may account for the phenotype shown in this patient.

Conclusions:

We identified the co-occurrence of two genetic causes in family 686. The possible disease-causing missense mutation of TJP2 in family 686 presents an opportunity for further investigation into ARHL. It is necessary to combine various genes screening methods, especially for some unconventional cases.     

GJB2 (Cx26) gene mutations in Chinese patients with congenital sensorineural deafness and a report of one novel mutation

Background Mutations in GJB2 gene are a major cause of autosomal recessive congenital hearing loss and the cause in some rare cases of the autosomal dominant form. The purpose of this study was to investigate the frequency and the features of GJB2 mutations in the Chinese patients with congenital sensorineural deafness.Methods Using PCR amplifying the entire coding region of GJB2 gene and direct DNA sequencing to analyze mutations in this gene among unrelated 69 cases with autosomal recessive congenital nonsyndromic deafness and 27 cases of dominant congenital deafness and 35 sporadic cases. We also detected mutations in GJB2 in 100 control subjects with normal hearing.Results 17. 4% (12/69) of the probands in the autosomal recessive, 7. 4% (2/27) of dominant families and 5.7% ( 2/35 ) of the sporadic congenital deafness patients had deafness-causing mutations in GJB2, respectively. Nine types of the mutations in GJB2 were detected in the recessive and sporadic group. They consisted of five types of polymorphism, and four types of deafness-causing mutation with homozygous 35delG in 1 sporadic (1/35), and 235delC frameshift mutation in 1 sporadic (homozygotes) and 10 recessive patients (2 heterozygotes and 8 homozygotes), and homozygous 442G→A missense mutation and homozygous 465T→A nonsense mutation in 1 different recessive proband, respectively. The 465T→A that related to recessive deafness was a novel mutation found by this study. The homozygous (10/69, 14. 5%) and the heterozygous (2/69,2.9%) GJB2 mutation in the recessive patients (12/69, 17.4%) and the homozygotes in the sporadic patient (2/35, 5. 7%) all had congenital severe to profound sensorineural hearing loss.511G→A missense mutation and 299 -300delAT frameshift mutation were found in two autosomal dominant congenital deafness families (2/27, 7.4%). The total mutation frequency of GJB2 was 12.2% (16/131) in the Chinese patients with congenital sensorineural deafness and 235delC was the most common deafness-causing mutation. Six types of mutation-5 types of polymorphism and 1 type of heterozygous deletion (235delC) mutation were found in the 100 control subjects. The carry rate of the most frequent type of mutation 235delC was 0. 5% in the controls(1/200 alleles). 109G→A was the most frequent (15/100, 15%) and 79G→A was the second common (8/100, 8%) polymorphism in this population.Conclusions The general mutation rate of GJB2 is 12.2% (16/131) and the 235delC is the most common type of deafness-causing mutation in Chinese patients with congenital hearing loss. 465T→A nonsense mutation that is associated to autosomal recessive deafness is a novel mutation found by this screening. 511G→A and 299-300delAT mutations contribute to autosomal dominant hearing loss. The study further supports the view that the common types of mutation in GJB2 according to different ethnic background and that the mutation prevalence in the East Asian deafness population is lower than that in the white population.     

两个常染色体显性遗传先天性白内障家系突变热点筛查

[目的]对2个常染色体显性遗传先天性白内障中国家系进行基因突变热点筛查,以了解这两个家系的先天性白内障是否与文献报道的17个突变热点相关.[方法]对两个家系共20名成员(包括患者11人,非患者9人)抽取外周血提取基因组DNA,针对截至2003年1月为止国外文献报道的与常染色体显性遗传先天性白内障发病相关的10个基因上的17个突变热点,包括CRYAA(ARG116CYS),CRYAB(del450A),CRYBA1(EX3-4 DEL),CRYBB2(GLN155TER),CRYGC(THR5PRO,5-BP DUP at NT226),CRYGD(ARG14-CYS,PRO23THR,ARG58HIS,ARG36SER),GJA3(ASN63SER,PRO187LEU),GJA8(GLU48LYS,PRO88SER),BFSP2(ARG287TRP)及MIP(GLU134GLY,THR138ARG),设计引物使PCR扩增片段涵盖上述热点,对扩增产物进行序列分析,检测这11名患者在突变热点上是否有相应的序列改变.[结果]20名被检者的10个基因片段序列与GenBank发表序列相同,在17个突变热点均未发现相应基因突变.[结论]初步排除这个家系的先天性白内障与17个突变热点相关.     

Nonsense mutations in the PAX3 gene cause Waardenburg syndrome type I in two Chinese patients

Background Waardenburg syndrome type I （WS1） is an autosomal dominant disorder characterized by sensorineural hearing loss, pigmental abnormalities of the eye, hair and skin, and dystopia canthorum. The gene mainly responsible for WS1 is PAX3 which is involved in melanocytic development and survival. Mutations of PAX3 have been reported in familiar or sporadic patients with WS1 in several populations of the world except Chinese. In order to explore the genetic background of Chinese WS1 patients, a mutation screening of PAX3 gene was carried out in four WS1 pedigrees. Methods A questionnaire survey and comprehensive clinical examination were conducted in four Chinese pedigrees of WSI. Genomic DNA from each patient and their family members was extracted and exons of PAX3 were amplified by PCR. PCR fragments were ethanol-purified and sequenced in both directions on an ABl_Prism 3100 DNA sequencer with the BigDye Terminator Cycle Sequencing Ready Reaction Kit. The sequences were obtained and aligned to the wild type sequence of PAX3 with the GeneTool program. Results Two nonsense PAX3 mutations have been found in the study population. One is heterozygous for a novel nonsense mutation S209X. The other is heterozygous for a previously reported mutation in European population R223X. Both mutations create stop codons leading to truncation of the PAX3 protein. Conclusions This is the first demonstration of PAX3 mutations in Chinese WS1 patients and one of the few examples of an identical mutation of PAX3 occurred in different populations.     

6例非缺失型Duchenne型肌营养不良家系产前基因诊断

目的 :建立非缺失型Duchenne型肌营养不良家系产前基因诊断平台。方法 :用Duchenne基因非编码区(CA)n重复序列结合染色体核型分析 ,对 6个非缺失型DMD家系进行产前基因诊断。结果 :在非缺失型的家系产前诊断中 ,发现获得风险X染色体的男胎 3例 ,女胎 1例 ,余 1例女胎和 1例男胎均未携带风险X染色体。检测结果的可靠性经出生婴儿DNA分析及临床症状检测得到部分证实。结论 :胎儿性别鉴定结合基因连锁分析的方法 ,在规范的检测程序和有效的质量控制下 ,能准确地对非缺失型DMD进行产前遗传学诊断 ,是目前预防患儿出生有效的实验室检测方法。     

中国人Peutz-Jeghers综合征STK11基因突变的研究

目的 对中国人Ｐｅｕｔｚ－Ｊｅｇｈｅｒｓ（ＰＪ）综合征患者ＳＴＫ１１基因进行突变分析,确定其特征,为基因诊断奠定基础。方法 应用聚合酶链反应－单链构象多肽分析（ＰＣＲ－ＳＳＣＰ）和ＤＮＡ测序的方法,对８个中国人ＰＪＳ家系ＳＴＫ１１基因进行研究。结果 在两个家系中分别新发现一个终止突变和剪接位点突变,推测最终导致产生截短型蛋白。结论 ＳＴＫ１１基因在中国人ＰＪＳ患者中可能以点突变为主,突变发生率较国     

常染色体隐性遗传早发型帕金森病家系的DJ-1基因研究

目的：探讨DJ-1基因与中国人常染色体隐性遗传早发型帕金森病（AREP）家系的关系.方法：对3个AREP家系的6位患者和23位成员进行系统的临床检查并进行DJ-1基因PCR扩增,标本进行基因测序.结果：所有研究对象的DJ-1基因外显子均扩增成功.3个家系中6位患者的DJ-1基因所有外显子测序均未发现突变.结论：DJ-1基因突变在中国人AREP家系中发生率较低,不是常见致病因素.