中国Y连锁遗传性聋DFNY1家系POU3F4基因突变的检测

目的:进行Y连锁遗传性聋(Y-linked hereditary hearing impairment)家系的候选基因——POU3F4基因的突变分析。方法: 在POU3F4基因的全部编码序列设计5对引物进行聚合酶链反应 (polymerase chain reaction,PCR)扩增反应。应用PCR-单链构像多态性(single-strand conformation polymorphism SSCP)方法对DFNY1 家系中的43名成员进行突变检测及鉴定。结果:POU3F4基因的5 对引物均有较好的扩增效果,PCR-SSCP的多态性分析显示所有家系成员在POU3F4基因中均未检测到多态及突变。结论:本研究通过对一个位于X染色体与Y染色体存在同源交换区域的耳聋基因POU3F4 基因的检测排除了该基因易位到Y染色体导致DFNY1家系耳聋的可能性,说明中国Y连锁遗传性聋家系的致病基因更多可能是位于Y染色体上的基因突变所致。图2表1参10     

一个遗传性耳聋大家系的基因突变检测

目的 :探讨中国人遗传性耳聋基因的突变热点和明确我们最近收集到的一个遗传性耳聋家系是否为已克隆的耳聋基因的突变所致。方法 :该家系 5代共 4 7人 ,其中耳聋患者 1 8人 ,从家系图分析 ,符合常染色体显性遗传 ;所有患者均为语后聋 ,从 1 6 3 0岁起病 ,为双耳对称性、进行性、高频听力下降为主的感觉神经性聋 ,不伴其它器官系统的异常 ;采用PCR 直接测序法在该家系中进行HDIA1、GJB3、GJB2、DFNA5、а tectorin(可导致DFNA8和DFNA1 2两型遗传性耳聋 )、MYO7A、POU4F3等 7个常染色体显性耳聋基因的突变检测。结果 :发现CX2 6基因有 2种核苷酸改变即A3 4 1G和GC2 5 7 2 5 8CG ;POU4F3基因有 1种核苷酸改变即T90C。分析后发现 ,上述核苷酸改变均不是该家系耳聋的致病性突变。其余 5个基因未发现突变。结论 :该常染色体显性耳聋家系由目前已克隆基因突变所致的可能性较小 ,笔者目前正在进行的全基因组扫描和连锁分析极有可能定位一个新的耳聋基因位点     

KCNN4及KPTN基因在中国DFNA4型耳聋中的突变检测

目的应用位置候选基因法了解中国DFNA4型耳聋家系定位区域内的两个基因KCNN4、KPTN与该家系耳聋表型的相关性。方法对一个6代相传、全基因组扫描连锁分析定位于DFNA4座位的常染色体显性遗传性耳聋中国家系成员,针对候选基因KCNN4、KPTN的全部编码序列设计引物,应用PCR扩增反应、产物纯化后直接测序的方法进行突变或多态性位点的检测与鉴定。结果两种基因的各对引物均有较好的扩增效果,直接测序结果与标准序列比对分析显示在KCNN4基因的所有编码区未检测到突变;在KPTN基因外显子10的编码区鉴定出一处同义突变（2154G／A,P302P）,该突变不与家系的耳聋表型共分离,为已报道的单核苷酸多态性（SNP）位点（rs2293424）。结论该中国DFNA4家系的耳聋表型不是由其定位区域内的KCNN4、KPTN基因编码区的突变所导致,但这两个基因仍是极好的耳聋候选基因,其与遗传性耳聋的相关性有待进一步研究。     

一个遗传性聋伴前庭功能障碍家系的表型研究与相关基因探讨

目的分析一个遗传性聋伴前庭功能障碍家系的表型特征,并探讨该家系的相关致病基因。方法对门诊发现的1例渐进性聋伴眩晕患者进行家系调查、病史资料采集、常规检查、听力学及前庭功能检查。听力学检查包括纯音测听、声导抗,前庭功能检查为冷热水试验。采集家系成员外周血DNA,采用聚合酶链反应(poly-merase chain reaction,PCR)扩增-直接测序法对POU3F4基因和COCH基因进行全部编码序列突变检测。结果该家系共4代28人,现存3代26人,主诉听力障碍者4人,耳聋患者均为正常女性后代中的男性,表现出隔代交叉遗传特征。耳聋患者出生时听力正常,6~10岁出现听力减退,并同时出现眩晕,走路不稳感。其中2人听力快速恶化,言语能力差,纯音测听为双耳对称的重度-极重度感音神经性听力损失,另外2人表现为高频下降型听力曲线。4名耳聋患者前庭功能低下或丧失。家系成员基因测序结果显示在POU3F4基因和COCH基因中均未检测到突变。结论本研究家系为非综合征型聋并前庭功能异常的家系,符合X-连锁隐性遗传特征规律,遗传方式最终确定有赖于进一步的分子遗传学研究。该家系患者高度一致的表型特征提示为单一基因致病,但筛查目前与这一表型相关的POU3F4基因和COCH基因未发现突变,可能存在其他与这一表型相关的基因。     

POU3F4基因与X连锁的遗传性聋

POU3F4基因是X染色体上唯一已克隆的非综合征型耳聋相关基因,该基因突变导致的遗传性聋具有显著的遗传学特点和特异的颞骨影像学改变.本文对POU3F4基因及其突变引起的耳聋做简要综述.     

先天性内耳畸形家系致病基因的定位克隆

目的应用分子遗传学的方法揭示一个X-连锁遗传先天性内耳畸形家系的分子病理机制。方法利用X染色体上的微卫星标记进行基因组扫描,通过连锁分析的方法进行致病基因的定位;在定位区域内选取候选基因进行突变筛查。结果①家系所有患者成员均为男性,表型特征为先天性极重度耳聋,颞骨CT扫描发现内耳道扩大,其基底部骨质缺损,蜗轴发育不全,遗传特点符合X-连锁遗传模式;②通过连锁分析在DXS990处得出的最大LOD值为3．27(θ=0．0),将该家系定位在Xq13．1-23之间的区域内;③对定位区域内的基因进行分析后将POU3F4基因作为候选基因对家系成员进行突变检测,发现了与家系中患者成员内耳畸形表型共分离的POU3F4基因新的突变形式(925T→C),该突变位于POU同源结构域中的保守位点,导致编码蛋白氨基酸第309位的丝氨酸突变成脯氨酸(Ser309Pro),110例正常对照者中没有发现同样的突变。结论POU3F4基因一种新的突变形式是导致中国先天性内耳畸形家系中患者的分子病理机制。     

耳聋基因芯片检测技术

临床上一般先依照临床表现对遗传性聋患者进行分类,然后确定与各类遗传性聋可能相关的致病基因,再根据这些基因的突变频率确定检测顺序,针对不同的基因结构采用不同的突变检测方法,最后对有突变家系的其他成员进行突变检测以最后确诊。目前常用的耳聋基因检测技术包括基因测序、PCR产物限制性片段长度多态性分析(PCR-RFLP)、PCR产物单链构象多态性(PCR-SSCP)、     

非综合征性耳聋患者连接蛋白26基因突变的研究

目的　探讨中国人非综合征性耳聋患者连接蛋白 2 6 (connexin 2 6 ,Cx2 6 )基因突变频率和特性。方法　收集中国散发先天性聋哑儿童 16例 ,常染色体隐性遗传性聋 39例 (39个家系 ) ,10岁前开始听力下降的常染色体显性遗传性聋 30例 (30个家系 )和健康对照组 10 0例。聚合酶链反应 单链构象多态 (singlestrandconformationalpolymorphismanalysisofpolymerasechainreaction ,PCR SSCP)分析初筛可疑突变者 ,SSCP分析发现异常构象带后再行DNA测序。结果　健康对照组中 15例发现 5种多态性改变 ,耳聋患者中 10例发现 6种多态性改变。散发先天性聋哑和常染色体隐性遗传非综合征性耳聋中未发现致病突变。 1个常染色体显性遗传性聋家系发现所有患者 (3例 )Cx2 6基因的编码区2 99 30 0位碱基AT杂合性缺失 ,导致移码突变 ,翻译的蛋白质截短 ,该家系听力正常者无此突变。结论　蒙古人种中常染色体隐性遗传性非综合征性耳聋的Cx2 6基因突变率可能低于其他人种。Cx2 6基因编码区 2 99 30 0位碱基AT杂合性缺失可致常染色体显性遗传性聋DFNA3型     

遗传性耳聋资源收集保存及基因定位克隆

目的建立聋病遗传资源收集网络,着重收集具有中国特色的聋病遗传资源,进行聋病基因定位克隆及相关的分子流行病学研究。方法通过遗传资源收集网络进行聋病遗传资源的收集,建立资源库进行遗传资源的表型鉴定和分析。应用微卫星标记的连锁分析及候选基因法进行家系的基因定位克隆和分子流行病学研究。结果共收集到含有多种耳聋表型的大小家系2071个,其中涵盖了单基因病孟德尔遗传的全部遗传方式:包括X-连锁遗传家系2个,Y-连锁遗传家系1个(命名为DFNY1基因座)、常染色体显性遗传性耳聋大家系12个(完成了基因定位5个)、常染色体隐性遗传性耳聋核心家系619个以及线粒体突变母系遗传性耳聋家系76个;大前庭水管综合征163例;听神经病108例;不明原因感音神经性耳聋478例;西北地区聋哑学校聋哑患者612例。对1489例散发患者进行了线粒体基因12S rRNA 1555G,缝隙连接蛋白基因(GJB2,GJB3和GJB6)以及SLC26A4基因的突变筛查与分析。其中西北地区612例聋哑人群中发现27．92％患者分别存在三个基因的突变,mtDNAA1555G平均阳性率为9．15％,GJB2为9．97％,SLC26A4为8．8％。结论遗传性听力损失是非常常见的耳聋疾病,其发病率超出原有的预测。基于大家系的基因定位研究有望发现新的基因座位及新的基因突变。分子流行病学研究发现遗传因素在先天性聋和学语后听力损失中的作用强于环境因素,并发现中国人群具有耳聋基因的高发病率和特异的突变图谱。     

connexin26基因突变与国人遗传性无综合性耳聋相关性分析

目的 分析国人遗传性无综合征耳聋与缝隙连接蛋白26（connexin26,Cx26）基因突变相关性,从分子水平探讨该病的发病机理。方法 收集国人35个无综合征耳鼻聋家系中138名成员,99例散发的无综合征耳 聋患者以及100份健康对照个体的外周血DNA样本共337份;采用聚合酶链反应－单链构像多态性（polymerase chain reaction-single stand conformational polymorphism,PCR-SSCP)分析方法,初筛受试者Cx26基因部分编码区的突变,发现异常电泳带的PCR产物直接序列分析。结果 PCR－SSCP检出2个家系5例耳聋成员异常泳带的样本。2个常染色体遗传性耳聋家系发现所有5例患者Cx-26基因的编码区233－235位碱基C纯合性缺失,导致移码突变,这2个家系听力正常者为杂合性突变或无此突变。结论 国人遗传性无综合征耳聋患者的Cx26基因突变热点可能与其他人种不同。Cx26基因编码区233－235位碱基C纯合性缺失可致常染色体隐性遗传性聋,是国人遗传性无综合征耳聋的致病因素之一。     

The genetic load for hereditary hearing impairment in Chinese population and its clinical implication

Objective To understand the genetic load in the Chinese population for improvement in diagnosis, prevention and rehabilitation of deafness. Methods DNA samples, immortalized cell lines as well as detailed clinical and audiometric data were collected through a national genetic resources collecting network. Two conventional genetic approaches were used in the studies. Linkage analysis in X chromosome and autosomes with microsatellite markers were performed in large families for gene mapping and positional cloning of novel genes. Candidate gene approach was used for screening the mtDNA 12SrRNA, GJB2 and SLC26A4 mutations in population-based samples. Results A total of 2,572 Chinese hearing loss families or sporadic cases were characterized in the reported studies, including seven X-linked, one Y-linked, 28 large and multiplex autosomal dominant heating loss families, 607 simplex autosomal recessive hereditary hearing loss families, 100 mitochondrial inheritance families, 147 GJB2 induced heating loss cases, 230 cases with enlarged vestibular aqueduct(EVA) syndrome, 169 sporadic cases with auditory neuropathy, and 1,283 sporadic sensorineural hearing loss cases. Through linkage analysis or sequence analysis, two X-linked families were found transmitting two novel mutations in the POU3F4 gene, while another X-linked family was mapped onto a novel locus, nominated as A UNX1 (auditory neuropathy, X-linked locus 1). The only Y-linked family was mapped onto the DFNY1 locus(Y-linked locus 1, DFNY1). Eight of the 28 autosomal dominant families were linked to various autosomal loci. In population genetics studies, 2,567 familial cases and sporadic patients were subjected to mutation screening for three common hearing loss genes: mtDNA 12S rRNA 1555G, GJB2 and SLC26A4. The auditory neuropathy cases in our samples were screened for OTOF gene mutations. Conclusions These data show that the Chinese population has a genetic load on hereditary heating loss. Establishing personalized surveillance and prevention models for hearing loss based on genetic research will provide the opportunity to decrease the prevalence of deafness in the Chinese population.     

A new mutation in the POU3F4 gene in a japanese family with x-linked mixed deafness (DFN3)

Objective: The molecular defect in patients with X-linked mixed deafness showing a perilymphatic gusher at stapedectomy (DFN3) has been attributed to mutations in the POU3F4 gene. This study aimed to clarify an allelic variant of this gene. Study Design: This was a genetic study of a single Japanese family with DFN3. Methods: Products of a polymerase chain reaction (PCR) were subjected to single-strand conformation polymorphism (SSCP) analysis. Direct sequencing of PCR products from patients and carriers showing SSCP variants was performed using the fluorescent dideoxy termination method and a sequencer. Results: Sequencing of the PCR product revealed a 6-base deletion (TTCAAA) at nucleotides 601 to 606, resulting in a two-amino-acid deletion in the POU3F4 protein, (phenylalanine and lysine at amino acid residues 201 and 202). The deletion was adjacent to the site of a nonsense mutation previously described. Conclusion: Microdeletions at a previously undescribed location account for some clinically important POU3F4 mutations. Laryngoscope, 108:1544–1547, 1998     

Deletion of and novel missense mutation in POU3F4 in 2 families segregating X-linked nonsyndromic deafness

OBJECTIVE: To analyze the physical manifestations and genetic features of 2 families segregating X-linked deafness, which is most commonly reported to be caused by mutations of the POU domain gene POU3F4 at the DFN3 locus. DESIGN: Computed tomographic study of the temporal bone in probands from each family, followed by mutation screening and deletion mapping of POU3F4 in family members. SETTING: Two midwestern genetics clinics. PARTICIPANTS: Two families with X-linked deafness. MAIN OUTCOME MEASURES: Anomalies of the inner ear in the probands; results of gene mapping and severity and effects of hearing loss in the family members. RESULTS: In the first family, a large deletion was identified that includes POU3F4 and extends upstream approximately 530 kilobases; in the second family, a novel serine-to-leucine (S228L) amino acid mutation was identified in the POU-specific domain of POU3F4. Both the deletion and the missense mutation segregate with the clinical phenotype and are causally related to the deafness in these families. CONCLUSIONS: Deafness related to the POU3F4 gene is associated with dilation of the internal auditory canal and a spectrum of other temporal bone anomalies that range in severity from mild to severe dysplasia of the cochlea and semicircular canals. The consequence of these anomalies is a congenital mixed hearing loss, the sensorineural component of which progresses over time. Affected males can also present with vestibular dysfunction that is associated with delayed developmental motor milestones. Intrafamilial variability occurs.     

KCNQ4基因突变对常染色体显性遗传性聋家系的影响

目的 应用选基因法了解KCNQ4基因对中国耳聋家系的影响，检测其突变形式。方法 在一个6代相传的常染色体显性遗传性家系中，应用聚合酶链反应－单链构像多态性（polymerase chain reaction-single strand conformation polymorphism,PCR-SSCP)及克隆测序方法对KCNQ4基因的全部编码序列的PCR产物进行突变位点及多态序列检测。结果 在该家系中，对36位家系成员进行了KCNQ4基因的编码序列的检测，发现KCNQ4基因外显子2的分子多态现象，经测序分析证明这种多态是由于内含子中47个碱基复制数的差异所造成的。结论 本实验证明KCNQ4基因外显子2的编码区附近存在一个新的分子多态标记，这种分子多态表现出不同的基因型。通过对这些基因型与耳聋表型的相关分析发现，随着内含子复制数的增加，耳聋表现度明显增加。提示KCNQ4基因外显子2与外显子3之间内含子复制数的变化可能是这个家系出现耳聋的一种特征性分子标记。     

KCNQ4基因突变对常染色体显性遗传性聋家系的影响

目的应用候选基因法了解KCNQ4基因对中国耳聋家系的影响,检测其突变形式. 方法在一个6代相传的常染色体显性遗传性聋家系中,应用聚合酶链反应-单链构像多态性(polymerase chain reaction-single strand conformat io n polymorphism,PCR-SSCP)及克隆测序方法对KCNQ4基因的全部编码序列的PCR产物进行突变位点及多态序列检测. 结果在该家系中,对36位家系成员进行了KCNQ4基因的编码序列的检测,发现KCNQ4基因外显子2的分子多态现象,经测序分析证明这种多态是由于内含子中47 个碱基复制数的差异所造成的. 结论本实验证明KCNQ4基因外显子2的编码区附近存在一个新的分子多态标记,这种分子多态表现出不同的基因型.通过对这些基因型与耳聋表型的相关分析发现,随着内含子复制数的增加,耳聋表现度明显增加.提示KCNQ4基因外显子2与外显子3之间内含子复制数的变化可能是这个家系出现耳聋的一种特征性分子标记.     

MYO1F as a candidate gene for nonsyndromic deafness, DFNB15

BACKGROUND: Earlier studies have mapped the autosomal recessive nonsyndromic deafness locus, DFNB15, to chromosomes 3q21.3-q25.2 and 19p13.3-13.1, identifying one of these chromosomal regions (or possibly both) as the site of a deafness-causing gene. Mutations in unconventional myosins cause deafness in mice and humans. One unconventional myosin, myosin 1F (MYO1F), is expressed in the cochlea and maps to chromosome 19p13.3-13.2. OBJECTIVE: To evaluate MYO1F as a candidate gene for deafness at the DFNB15 locus by determining its genomic structure and screening each exon for deafness-causing mutations to identify possible allele variants of MYO1F segregating in the DFNB15 family. METHODS: We used radiation hybrid mapping to localize MYO1F on chromosome arm 19p. We next determined its genomic structure using multiple long-range polymerase chain reaction experiments. Using these data, we completed mutation screening using single-stranded conformational polymorphism analysis and direct sequencing of affected and nonaffected persons in the original DFNB15 family. RESULTS: Radiation hybrid mapping placed MYO1F in the DFNB15 interval, establishing it as a positional candidate gene. Its genomic structure consists of 24 coding exons. No mutations or genomic rearrangements were found in the original DFNB15 family, making it unlikely that MYO1F is the disease-causing gene in this kindred. CONCLUSIONS: Although we did not find MYO1F allele variants in one family with autosomal recessive nonsyndromic hearing loss, the gene remains an excellent candidate for hereditary hearing impairment. Given its wide tissue expression, MYO1F might cause syndromic deafness.     

The DFNA2 locus for hearing impairment: two genes regulating K+ ion recycling in the inner ear

DFNA2 is a locus for autosomal dominant non-syndromal hearing impairment (ADNSHI) located on chromosome 1p34 and six linked families have been identified. An audiometric study of these families showed that despite small differences in the phenotype all families suffer from progressive hearing impairment starting in the high frequencies. A detailed genetic analysis revealed that this deafness locus contains more than one gene responsible for hearing impairment. Thus far, two genes on chromosome 1p34 have been implicated in ADNSHI. The first, connexin 31 (GJB3), is a member of the connexin gene family. Connexins form gap junctions. These are connections between neighbouring cells that allow transport of small molecules. GJB3 mutations were found in two small Chinese families with ADNSHI. The second is KCNQ4, a voltage-gated K+ channel. Mutations in KCNQ4 were first found in a small French family, later in five of the six linked DFNA2 families. No GJB3 or KCNQ4 mutations were detected in patients of an extended Indonesian DFNA2 family. Two pathways have been proposed for the recycling of K+ from the hair cells back to the endolymph. These pathways involve the use of gap junctions, K+ pumps and K+ channels. The expression of GJB3 and KCNQ4 in the inner ear and their functions suggest that both DFNA2 genes may play a role in K+ homeostasis.