常染色体显性先天性白内障大家系致病基因定位的初步研究

目的:报道1个涉及5代17例患者的常染色体显性先天性白内障(ADCC)大家系,并进行致病基因的定位. 方法:对家系中8例患者进行眼科检查后明确临床表型,并提取所有血样的基因组DNA.首先对已报道的中国ADCC家系致病位点(9个基因的16个突变位点)进行DNA测序,然后根据已报道的17个ADCC候选基因和13个染色体区域,选取27个微卫星分子标记,应用LINKAGE软件进行连锁分析. 结果:8例患者均为先天性核性白内障.直接DNA测序未发现有已报道的中国家系基因突变.所选取的27个微卫星分子标记与该家系致病基因均不连锁. 结论:该ADCC家系致病基因不在已报道的17个ADCC候选基因和13个染色体区域,该家系中可能存在一个新的ADCC致病基因.     

常染色体显性遗传性先天性白内障一家系致病基因的初步定位

目的 初步定位常染色体显性遗传性先天性白内障(ADCC)一家系的致病基因。方法 收集ADCC一家系资料，在已知先天性白内障致病基因和位点附近，选择合适的短串联重复序列多态性标记(STRP)，对ADCC一家系进行连锁分析，使用Mlink软件采用对数优势记分法(LOD)计算LOD值。结果 在STRP中，D17S805、D17S1294及D17S1293与致病基因位点连锁的最大IDD值分别为2．03、2．49及2．22(重组率θ=0)。结论 该ADCC家系的致病基因初步定位在第17对染色体上；CRYBA1基因为候选基因。     

常染色体显性遗传性先天性白内障一家系

<正>先天性白内障在临床上并不少见,但常染色体显性遗传性先天性白内障,近年来报道较少,现将本院眼科门诊调查的一家系报告如下。     

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.     

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(de1450A)，CRYBA1(EX3-4 DEL)，CRYBB2(GLN155TER)，CRYGC(THR5PRO，5-BP DUP at NT226)，CRYGD(ARG14CYS，PR023THR，ARG58HIS，ARG36SER)，GJA3(ASN63SER，PR0187LEU)，GJA8(GLU48LYS，PR088SER)，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。     

基因扫描微卫星DNA进行常染色体显性遗传性多囊肾病囊肿前诊断

目的；利用与多囊肾病PKD1基因紧密连锁的微卫星DNA，通过家系连锁分析，进行了常染色体显性遗传性多囊肾病（ADPKD）的囊肿前诊断，为临床分子诊断奠定基础。方法：采用PCR－基因扫描的方法，对4个ADPKD家系共39人进行了连锁分析。结果：通过连锁分析，发现4个家系中1名16岁个体为PKD1突变携带者，处于囊肿发生前期。结论：基因扫描微卫星DNA是一种快速，准确的基因分型方法，可用于ADPKD的囊肿前诊断。     

一常染色体显性遗传寻常型鱼鳞病家系致病基因的定位

目的 研究一常染色体显性遗传寻常型鱼鳞病家系的致病基因。方法 采用基因组扫描方法,利用1号染色体上的微卫星标记对该家系进行连锁分析,然后对候选基因FLG的部分编码区及外显子与内含子交界处进行突变检测。结果 在D1S2696得到最大两点连锁LOD值3．46（0=0）,单体型分析将疾病基因定位在D1S2726-D1S305之间约15cM范围内;在FLG基因的外显子非重复序列及部分重复序列未发现与疾病相关的突变。结论 该寻常型鱼鳞病家系的致病基因位于D1S2696附近,其致病基因可能是除FLG以外的其他基因。     

一个先天性甲状腺功能亢进症家系的排除性定位分析

目的 对一个常染色体显性遗传的先天性甲状腺功能亢进症家系,进行与已知致病基因TSHR和THRB的连锁分析以确定此家系致病基因是否为这2个已知基因.方法 选择3个与TSHR和THRB紧密连锁的微卫星标记物D14S74、D3S2338和D3S1266,进行微卫星标记的基因连锁分析,采用Genemapper 3.5软件分析数据. 结果 3个微卫星标记物的LOD值均小于1,显示该家系致病基因与这3个位点均不连锁,提示该家系可能存在新致病基因. 结论 常染色体显性遗传类型的先天性甲状腺功能亢进症可能有新致病基因.     

常染色体隐性遗传性共济失调家系临床及致病基因定位研究

目的：探讨常染色体隐性遗传性共济失调家系的临床特征并排除已知的致病基因。方法：对可追溯5代32人，具有一级表兄妹婚配共济失调的W家系进行详细的神经系统临床和辅助检查，通过OMIM数据库查询及表型鉴别和连锁分析验证方法排除已知致病基因。结果：W家系临床表现为常染色体隐性遗传性共济失调，通过2种方法排除了已知基因致病可能。结论：W家系发病为未知致病基因的突变引起，本项研究为定位克隆新的致病基因奠定了基础。     

常染色体显性视网膜色素变性家系基因定位

目的探讨一常染色体显性视网膜色素变性（autosomal dominant retinitis pigmentosa,adRP）家系致病基因与盘膜边缘蛋白/视网膜变性慢基因（eripherin/retinal degeneration slow,RDS）、视杆外节盘膜蛋白1基因（retinal outer segment membraneprotein 1,ROM1）、视锥杆细胞同源盒基因（cone-rod homeobox gene,CRX）、神经视网膜亮氨酸拉链基因（neural retinalleucine zipper,NRL）、鸟甘酸环化酶激活1B基因（guanylate cyclase activator 1B,GUCA1B）、肌动蛋白同源2基因（fascinhomolog 2,FSCN2）和拓扑异构酶结合1基因（topoisomerase I binding,TOPORS）多发突变位点的关系。方法采集一个连续4代发病的RP家系14个成员外周血4~5 ml,提取基因组DNA,采用聚合酶链反应（plymerase chain reaction,PCR）对常见的7个adRP候选基因的17个外显子多发突变位点进行扩增,PCR产物纯化后直接测序,测序结果与美国国立生物技术信息中心（National Center for Biotechnology Information,NCBI）数据库中公布的核酸标准序列进行比对分析。结果该家系视网膜色素变性为常染色体显性遗传,家系成员在RDS、ROM1、CRX、NRL、GUCA1B、FSCN2和TOPORS基因中未发现致病突变,仅在RDS基因第1外显子和第3外显子编码区发现5处单核苷酸改变。结论 RDS、ROM1、CRX、NRL、GUCA1B、FSCN2和TOPORS不是本研究家系的致病基因,RDS基因外显子中的5处单核苷酸的改变为单核苷酸多态性（single nucleotide polymorphism,SNP）。     

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.     

Targeted Genes Sequencing Identified a Novel 15 bp Deletion on GJA8 in a Chinese Family with Autosomal Dominant Congenital Cataracts

Background:

Congenital cataract (CC) is the leading cause of visual impairment or blindness in children worldwide. Because of highly genetic and clinical heterogeneity, a molecular diagnosis of the lens disease remains a challenge.

Methods:

In this study, we tested a three-generation Chinese family with autosomal dominant CCs by targeted sequencing of 45 CC genes on next generation sequencing and evaluated the pathogenicity of the detected mutation by protein structure, pedigree validation, and molecular dynamics (MD) simulation.

Results:

A novel 15 bp deletion on GJA8 (c.426_440delGCTGGAGGGGACCCT or p. 143_147delLEGTL) was detected in the family. The deletion, concerned with an in-frame deletion of 5 amino acid residues in a highly evolutionarily conserved region within the cytoplasmic loop domain of the gap junction channel protein connexin 50 (Cx50), was in full cosegregation with the cataract phenotypes in the family but not found in 1100 control exomes. MD simulation revealed that the introduction of the deletion destabilized the Cx50 gap junction channel, indicating the deletion as a dominant-negative mutation.

Conclusions:

The above results support the pathogenic role of the 15 bp deletion on GJA8 in the Chinese family and demonstrate targeted genes sequencing as a resolution to molecular diagnosis of CCs.     

Autosomal dominant coralliform cataract related to a missense mutation of the γD-crystallin gene

Background Congenital cataract is a sight-threatening disease that affects about 1 -6 cases per 10 000 live births and causes 10% -30% of all blindness in children. About 25% of all cases are due to genetic defects. We identified autosomal dominant congenital coralliform cataracts-related genetic defect in a four-generation Chinese family.Methods Complete ophthalmological examinations were performed prior to lens extraction. Lens samples were then studied by electron microscopy. Genomic DNA from family members were examined using whole-genomic linkage analysis, with two-point logarithm of odds (LOD) scores calculated using the Linkage program package (version 5. 1 ). Mutation analysis of candidate genes was performed by direct sequencing. Finally, a three-dimensional protein model was predicted using Swiss-Model (version 2.0).Results Eleven of the 23 examined individuals had congenital cataracts. Ultrastructure studies revealed crystal deposits in the lens, and granules extensively dispersed in transformed lens fiber cells. The maximum two-point LOD score, 3. 5 at θ = 0. 1, was obtained for the marker D2S,325.Mutation analysis of the γ-crystallin (CRYG) gene cluster identified a mutation (P23T) in exon 2 of γD-crystallin (CRYGD). Protein structure modeling demonstrated that the P23T mutation caused a subtle change on the surface of the γD protein.Conclusions The results suggest that the coralliform cataract phenotype is due to a mutated CRYGD gene, and that this sequence change is identical to one reported by Santhiya to be related to another distinct clinical condition, lamellar cataract. This study provides evidence that this same genetic defect may be associated with a different phenotype. This is the first report identifying the genetic defect associated with an autosomal dominant congenital coralliform cataract.     

右心旁路手术治疗复杂先天性心脏病

目的总结右心旁路手术治疗复杂先天性心脏病的临床经验。方法2004年10月至2008年1月，采用右心旁路手术治疗复杂先天性心脏病共24例（病种包括三尖瓣闭锁、单心室等，其中心脏位置异常8例）。19例行双向格林术，5例行全腔静脉-肺动脉吻合术。24中16例在非体外循环下实施，2例双向格林术术后再次手术。结果全组手术死亡1例（4．2％），乳糜胸及低氧血症各1例。结论①右心旁路手术治疗复杂先天性心脏病分期手术效果好，但手术难度增加；②全腔静脉-肺动脉吻合术，外管道与右心房开窗效果较好；③技术达标后可尝试非体外下手术，但体外循环必须有良好的应急能力。