A COMPLETE SCREEN FOR MUTATIONS OF THE RHODOPSIN GENE IN A PANEL OF CHINESE PATIENTS WITH AUTOSOMAL DOMINANT RETINITIS PIGMENTOSA

Objective To evaluate the prevalence of rhodopsin (RHO) mutations and the genotype-phenotype relationships in Chinese patients with autosomal dominant retinitis pigmentosa (ADRP) by conformation sensitive gel electrophoresis (CSGE) and direct DNA sequencing. Methods We have screened the five coding exons and splice sites of RHO gene in 27 probands who had no relativity from Chinese ADRP families and 100 normal controls to identify disease-associated mutations, using CSGE and direct DNA sequencing. Family members of some probands with disease-associated mutations were also genotyped to determine whether the RHO mutations segregated with retinitis pigmentosa (RP) in their families. Two RHO mutations, Pro347Leu and Pro327 (l-bp del), were identified separately in two families, thus the frequency of RHO mutations among this set of Chinese ADRP families is about 7.4% (2/27). Pro347Leu mutation was found in one ADRP proband as well as three her children who also had RP. She had relatively early onset at about 17 years.The only one child without this mutation had no symptom or sign of RP at age of 34. Pro327 (l-bp del) was identified in a late-onset ADRP patient, who appeared night blindness around 30 years old and in her fifties electroretinogram (ERG) has been fiat in both scotopic and photopic phases. Family analysis showed that this mutation also existed in her younger daughter and her elder sister, both of them also had RP. Three other family members were genotypically and phenotypically normal. Neither of the two mutations was detected in 100 normal controls. Conclusions The frequency of RHO mutations in Chinese patients was lower than that in Europe and North America.The phenotype of the patients with Pro347Leu corresponded to type 1 ADRP, with severe rod degeneration and some cone preservation later, while the phenotype of the patients carrying Pro327 (l-bp del) corresponded to type 2 ADRP, with a concomitant loss of rod and cone visual function. CSGE was found to be a sensitive, simple, and practical method for the screening of a large number of samples under highly reproducible conditions, and could be utilized in routine molecular diagnostic laboratories.     

良性家族性婴儿惊厥基因定位

目的：对5个中国良性家族性婴儿惊厥(benign familial infantile convulsion,BFIC)家系进行基因定位研究。方法：选择D19S245、D19S250、D16S3131、D16S3133、D2S399、D2S2330等6个STR作为DNA标记,应用聚合酶链反应(PCR),变性聚丙烯酰胺凝胶电泳(PAGE)和银染技术,采用LINKAGE软件包中的MLINK程序进行连锁分析。结果：在常染色体显性(AD)模式下,在标记位点D19S250处,家系2、3、5在重组率为0．000,外显率为90％时,获得最大两点对数优势计分值(log odds score,LOD)总和为2．151;在标记位点D16S3131处,家系2、5在重组率为0．085,外显率为70％、60％时,获得最大两点LOD值总和分别为1．056、1．155;在重组率为0．080,外显率为50％时,获得最大两点LOD值总和为1．227。提示这2个位点与BFIC疾病基因可能存在连锁关系。在其他位点处未获得提示连锁关系的信息。结论：部分BFIC家系的致病基因可能与D19S250或D16S3131存在连锁关系。     

A novel candidate locus on chromosome 11p14.1-p11.2 for autosomal dominant hereditary spastic paraplegia

Background Hereditary spastic paraplegia （HSP） is a group of inherited neurodegenerative disorders with the shared characteristics of slowly progressive spasticity and weakness of the lower limbs. Thirteen loci for autosomal dominant HSP have been mapped. Methods A Chinese family with HSP was found in the Shandong province and Inner Mongolia Autonomous Region of China and genomic DNA of all 19 family members was isolated. After exclusion of known autosomal dominant loci, a genome wide scan and linkage analysis were performed. Results The known autosomal dominant loci of SPG3A, SPG4, SPG6, SPG8, SPG9, SPG10, SPG12, SPG13, SPG17, SPG19, SPG29, SPG31 and SPG33 were excluded by linkage analysis. The results of a genome wide scan demonstrated candidate linkage to a locus on chromosome 11 p14.1-p11.2, over an 18.88 cM interval between markers D11 S1324 and D11 S1933. A maximal, two point LOD score of 2.36 for marker D11S935 at a recombination fraction （e） of 0 and a multipoint LOD score of 2.36 for markers D11S1776, D11S1751, D11S1392, D11S4203, D11S935, D11S4083, and D11S4148 at θ=0, suggest linkage to this locus. Conclusion The HSP neuropathy in this family may represent a novel genetic entity, which will facilitate discovery of this causative gene.     

A missense mutation S228P in the CRYBB1 gene causes autosomal dominant congenital cataract

Background Congenital cataract is a highly heterogeneous disorder at both the genetic and phenotypic levels. This study was conducted to identify disease locus for autosomal dominant congenital cataracts in a four generation Chinese family. Methods Family history and clinical data were recorded. All the members were genotyped with microsatellite markers which are close to the known genetic loci for autosomal congenital cataracts. Two-point Lod scores were obtained using the MLINK of the LINKAGE program package （vet 5.1）. Candidate genes were amplified by polymerase chain reaction （PCR） and direct cycle sequencing. Results The maximum Lod score of Zmax=2.11 was obtained with three microsatellite markers D22S258, D22S315, and D22S1163 at recombination fraction θ= 0. Haplotype analysis showed that the disease gene was localized to a 18.5 Mbp region on chromosome 22 flanked by markers D22S1174 and D22S270, spanning the β-crystallin gene cluster. A c.752T→C mutation in exon 6 of CRYBB1 gene, which resulted in a heterozygous S228P mutation in predicted protein, was found to cosegregate with cataract in the family. Conclusions This study identified a novel mutation in CRYBB1 gene in a Chinese family with autosomal dominant congenital cataract. These results provide strong evidence that CRYBB1 is a pathogenic gene for congenital cataract.     

一个疑似X连锁型视网膜色素变性家系的遗传连锁分析的研究

目的对一个疑似X连锁型视网膜色素变性(X-linked retinitis pigmentosa,XLRP)家系进行分析,确定其致病基因的所在位点。方法选取已知XLRP候选基因附近的微卫星位标,用多点参数分析方法计算其最大优势对数值(LOD score),并通过对家系成员单倍型分析,确定该家系致病基因所在的染色体位置。结果位于X染色体长臂的微卫星标记DXS8043与该例遗传家系间最大LOD值小于-2,其他位于X染色体短臂的11个微卫星标记与该例遗传家系LOD值保持在0.5上下,无明显的高值。单倍型结果表明该家系中2例患者兄弟(Ⅲ1、Ⅲ6)和他们的携带者母亲(Ⅱ2)在DXS8051与DXS1214之间拥有在正常成员中不存在的基因型,表明该基因型与疾病共分离,进一步确定了他们X性连锁遗传模式,并且可将致病基因初步定位于DXS8051与DXS1214之间的RP23和RP6基因。结论可以排除该例家系的致病位点与X染色体长臂上的RP24基因的连锁,高度怀疑连锁位点存在于X染色体的短臂的RP23和RP6基因,需另增加位标的信息量,以进一步缩小致病基因所在的具体范围。     

视紫红质和Peripherin/RDS基因在视网膜色素变性家系中的突变检测

目的 对一常染色体显性视网膜色素变性(autosomal dominant retinitis pigmentosa,adRP) 家系进行视紫红质基因(rhodopsin,RHO)、盘膜边缘蛋白/ 视网膜变性慢基因(Peripherin/retinal degeneration slow,Peripherin/RDS)、视杆外节盘膜蛋白1 基因(retinal outer segment membrane protein 1,ROM1)、神经视网膜亮氨酸拉链基因(neural retinal leucine zipper,NRL) 和视锥杆细胞同源盒基(cone-rod homeobox-containing gene,CRX) 基因的突变检测.方法 采集一连续3 代发病的adRP 家系28 名成员外周血,提取基因组DNA,采用聚合酶链反应(polymerase chain reaction,PCR) 和直接测序技术,对RHO、Peripherin/RDS、ROM1、NRL 和CRX 基因进行检测,结果与标准核酸序列进行比对和分析.结果 该家系成员在RHO、Peripherin/RDS、ROM1、NRL 和CRX 基因中未发现致病突变,但是在Peripherin/RDS 基因第1 外显子和第3 外显子编码区发现4 处单核苷酸改变.结论 该家系在RHO、Peripherin/RDS、ROM1、NRL 和CRX 基因中未检测到致病突变,Peripherin/RDS 基因外显子中4 处单核苷酸改变属于单核苷酸多态性(single nucleotide polymorphisms,SNPs).     

Familial Wolff-Parkinson-White syndrome is linked to the locion chromosome 7q3

Objective Wolff-Parkinson-White syndrome (WPW) is considered to be an autosomal dominanthereditary disease, but the gene is not identified. The objective of this study was to localize the genetic loci of Wolff-Parkinson-White syndrome. Methods Linkage analysis between the disease of Wolff-Parkinson-White syndrome and 3 STR (short tandem repeats) markers on 7q3 (D7S505, D7S688, and D7S483) was tested in 3 kindreds of the Wolff-Parkinson-White syndrome (101 numbers in total) by genotyping. Results Wolff-Parkinson-White syndrome was linked to the loci above. The maximum two-point Lod score detected at D7S505 was 6. 4 at a recombination fraction (θ) of 0. 1; the Lod score of D7S688, D7S483 was 5. 3 vs 2. 5. Conclusion The gene of Wolff-Parkinson-White syndrome is located at 7q3.     

应用微卫星多态位点对X连锁型视网膜色素变性疾病进行遗传连锁分析的研究

目的应用遗传连锁分析方法对X连锁型视网膜色素变性家系进行分析，确定其致病基因的所在位点。方法在2个目前常见的X-连锁遗传位点——RP2和RP3处分别选取具有高信息量的微卫星位标，对2例疑似X连锁型视网膜色素变性家系进行遗传连锁分析。通过对家系成员的单倍型分析，并使用两点法计算其最大优势时数（LOD Score）值，确定致病基因所在的染色体位置。结果微卫星标记DXS993与2例遗传家系表型间最大LOD值分别为：〈-2和0．8；DXS 1068在2例遗传家系LOD值分别为0．4和0．8。结论RP2基因可能不是XY家系的致病性基因；在ZLK家系，怀疑疾病位点与RP2或RP3基因连锁。用遗传连锁分析方法确定致病基因所在染色体的范围起到重要的作用。     

良性家族性婴儿惊厥疾病基因与染色体8q24的连锁分析

目的 :对 5例中国良性家族性婴儿惊厥 ( BFIC)家系进行基因定位研究。方法 :选择 D8S50 2 、D8S537等 STR作为 DNA标记 ,应用聚合酶链反应 ( PCR) ,变性聚丙烯酰胺凝胶电泳 ( PAGE)和银染技术 ,采用 LINKAGE软件包中的 MLINK程序进行连锁分析。结果 :在常染色体显性 ( AD)模式下 ,在标记位点 D8S50 2 处 ,5个家系在重组率为 0 .0 5 0 ,外显率为 70 %时 ,获得两点对数优势计分 ( LOD)值总和为 0 .337;在标记位点 D8S537处 ,5个家系在外显率为 70 % ,重组率从 0 .0 0 0到 0 .40 0之间 ,获得两点 L OD值总和均为负值。结论 :不能认为位点D8S50 2 和 D8S537与 BFIC疾病基因存在连锁关系     

Clinical evidences in concurrence of retinitis pigmentosa and glaucoma

Objective To provide clinical evidences for concurrence of retinitis pigmentosa and glaucoma in two children of a Chinese family. Design Case series. Participants 2 cases with varying degrees of retinitis pigmentosa and glaucoma in a two-child Chinese family. Methods Complete ophthalmic examinations of the two present cases are conducted. The interesting concurrence of retinitis pigmentosa and glaucoma is reviewed and discussed. Main Outcome Measures The clinical findings including general ocular examinations, visual fields, ultrasound biomicroscopy, B ultrasonography, flourescein angiography, optical coherence tomography and electrophysiologic tests. Results In the present two-child Chinese family without positive history, the older sister presented with bilateral sector retinitis pigmentosa and coexisting chronic angle-closure glaucoma, and the brother with bilateral whole retinitis pigmentosa but without coexisting glaucoma. Conclusions Clinical evidences in concurrence of variants of retinitis pigmentosa and glaucoma because of possible different gene mutations from the same genetic background represent a rare situation, which may provide clues for future researches in molecular pathogenesis of these rare diseases.     

应用遗传连锁分析法对伴传导功能障碍的扩张型心肌病家系致病基因的定位

目的: 对一个常染色体显性遗传扩张型心肌病(familial dilated cardiomyopathy,FDCM)家系进行基因定位。方法: 收集FDCM 家系, 对该家系成员进行详细心血管内科检查确诊为扩张型心肌病,且伴发有传导功能障碍;采集外周血3～5 mL,并抽提基因组DNA;选取与该表型相关的已定位区间CMD1A(1q21.2-q21.3),CMD1H(2q14-q22), CMD1E(3p22-p25)和CMD1F(6q22-23)内的共计18个微卫星DNA标记,在该家系中进行排除性定位分析;最后,进行全基因组扫描及连锁分析。结果：①已定位区间的18个微卫星DNA标记位点的LOD值均<-2,证实该家系与已知DCM位点不连锁;②全基因组扫描及两点连锁分析结果显示,该家系致病基因位点与遗传标记D3S1614(3q26)连锁, 在θ= 0时得到最大LOD值2.68。结论: 该家系与已知的4个DCM位点均不连锁,其致病基因位于D3S1614（3q26）附近的一个新位点。     

两例疑为X连锁型视网膜色素变性家系的单倍型分析研究

目的应用遗传连锁分析方法对X连锁型视网膜色素变性家系进行分析,定位其致病基因的所在位点.方法选取已知X连锁视网膜色素变性候选基因附近的短串联重复序列多态性标记(short tandem repeat polymorphism, STRP),即在RP2、RP3、RP6、RP23和RP24处分别选取具有高信息量的微卫星位标,对2例疑似为X连锁型视网膜色素变性家系进行遗传连锁分析;通过对家系成员的单倍型分析,并进行两点法连锁分析,确定其致病基因所在染色体的大致位置.结果 2例家系在DXS 993处得到的最大LOD值分别为:1.18和1.03;在DXS 1068处得到的最大 LOD值分别为:0.58和-2.69;在DXS 1214处得到的最大LOD值分别为:-2.33和-2.45;在DXS 8051处得到的最大LOD值分别为:-2.34和-2.51;在DXS 8043处得到的最大LOD值分别为:-2.23和-2.62.结论 ZCF家系的致病基因,可能不在RP3、RP6、RP23或RP24位点;而对于FYJ家系,我们则怀疑致病基因位于RP2位点,但也不排除与RP3连锁;用遗传连锁分析方法对确定致病基因所在染色体的范围起到重要的作用.     

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）。     

Two novel mutations of the retinitis pigmentosa GTPase regulator gene in two Chinese families with X-linked retinitis pigmentosa

目的：检测引起两个中国家系产生X连锁视网膜色素变性的RPGR基因突变。方法：以人类基因组DNA为模板,用位于内含子的引物扩增出RPGR基因外显子1-19的PCR片段。PCR产物经SSCP分析后直接进行测序。通过比较病人和正常人相应的DNA顺序,检出基因突变位点。结果：在两个家系检测到两个新突变c1536delC和E332X,它们分别位于RPGR基因的第12和第9外显子（这是两个外显子首次发现的突变）。两突变均可导致翻译提前终止,产生不具备正常功能的截短蛋白。结论：两个突变是相应空系产生视网膜色素变性的遗传学基础,所得结果有助于分析RPGR蛋白功能。     

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。     

肝豆状核变性基因连锁图谱的研究

为寻找适于中国人Ｗｉｌｓｏｎ氏病（ＷＤ）基因连锁分析的遗传标记及制定ＷＤ基因所在区域的遗传图谱，我们应用Ｄ１３ｑ１４－２１区域４个ＤＮＡ标记对７５名无亲缘关系个体及９个ＷＤ家系成品进行连锁分析。结果发现４个ＤＮＡ标记中３个标记等位片段与白种人相同而杂合率相异，其中２个ＤＮＡ标记Ｄ１３Ｓ３１，Ｐ１２３Ｍ１．８与ＷＤ基因存在紧密连锁关系。其遗传顺序为：着丝点－Ｒｂ－Ｄ１３Ｓ３１－ＷＮＤ。     

一个常染色体显性视网膜色素变性家系表型分析和RHO基因突变检测

目的分析一常染色体显性视网膜色素变性(autosomal dominant retinitis pigmentosa,adRP)家系的临床表型,确定该家系与视紫红质(rhodopsin,RHO)基因的关系。方法依据RP诊断标准及患者临床表型,确定一连续4代发病的adRP家系遗传的特点;采集家系中13位成员外周血8-10ml,提取基因组DNA;聚合酶链反应(polymerase chain reaction,PCR)扩增RHO基因的第1-5外显子基因片段,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 forBiotechnology Information,NCBI)数据库上公布的核酸标准序列进行比对分析。结果该家系临床特点为所有患者均于10岁左右出现夜盲,1例22岁出现视野损害,2例40岁左右出现视野损害,并且于50岁左右双眼相继发生急性闭角型青光眼和并发性白内障。该家系5例患者在RHO基因外显子、上下游非编码序列以及内含子及外显子拼接部中均未发现碱基改变。结论本研究家系患者存在遗传异质性和表型异质性,RHO基因不是该家系的致病基因。     

Linkage analysis of five Chinese families with arrhythmogenic right ventricular cardiomyopathy using microsatellite genetic markers

Objective To explore the linkage relationship between specific genetic markers and arrhythmogenic right ventricular cardiomyopathy (ARVC) in Chinese pedigrees. Methods The microsatellite genetic markers D2S152, D14S252, and D10S1664 were studied for their linkages to ARVC in five Chinese ARVC pedigrees and a normal population of 121 Chinese individuals. Genomic DNA of the pedigrees and normal population was amplified using PCR techniques. Denaturing polyacrylamide sequencing gel (4%) electrophoresis was used to detect microsatellite repeat polymorphisms. Gels were silver-stained. A classical linkage analysis program was used assuming models of autosomal dominance and recession. Results The logarithm of the odds (LOD) scores of D2S152 with ARVC in LW, WD, DS, LC and TY pedigrees were 2.174, －0.589, －∞, － （indicating that linkage is not supported in this mode）, and －∞ respectively in autosomal dominant model （recombination fraction=0.000 respectively）and were －∞, －∞, －∞, －∞, and 0.182 respectively in the autosomal recessive model. The LOD scores of D14S252 with ARVC in LW, WD, DS, LC and TY pedigrees were －, －, －∞, －, and 0 respectively in autosomal dominant model, and were －∞, －0.812, －∞, －∞, and 0.087 respectively in autosomal recessive model. The LOD scores of D2S152 with ARVC in LW, WD, DS, LC and TY pedigrees were －, －0.539, －, and 0.602 respectively in autosomal dominant model and were －, －∞, －∞, －∞, and －∞ respectively in autosomal recessive model. Conclusions The LOD score for D2S152 in the LW pedigree was 2.174, indicating that the chance of linkage is about 150∶1. This suggests that there is a possible ARVC-related gene near this marker. There were no clear linkage relationships between ARVC and D10S1664 and D14S252 in this family, and no linkages between ARVC and any of the three genetic markers in the other four families. These results also suggest that there is genetic heterogeneity in LW and in the other pedigrees.     

Genetic heterogeneity for familial hypertrophic cardiomyopathy in Chinese: analysis of six Chinese kindreds

OBJECTIVE: Familial hypertrophic cardiomyopathy (FHCM) is a primary myocardial disease characterized by unexplained ventricular hypertrophy. The application of the techniques of reverse genetics has identified at least five chromosomal loci as the major causes for FHCM in diverse ethnic populations, suggesting substantial genetic heterogeneity for FHCM. Recently, the defective gene loci of two Chinese families with FHCM have been mapped to chromosome 11 and 14q1, respectively. For further understanding of the molecular basis of FHCM in Chinese, we analyzed the linkage between four other Chinese kindreds and DNA markers from chromosome 14q1. METHODS: Six unrelated Chinese families with FHCM, including two previously reported, were studied. Totally 90 family members were included for analysis. DNA from 80 individuals was extracted and polymerase chain reactions were performed using the primers designed according to the sequences derived from the alpha and beta myosin heavy chain gene. Totally four polymorphisms were studied, including three polymorphic microsatellite sequences and one single strand conformation polymorphism. Genetic linkage analysis were performed using the Linkage program. RESULTS: In the six studied families, 39 of the 90 family members were found to be affected diagnosed either by echocardiography or by clinical evaluation. The pattern of inheritance in all six studied families was most consistent with an autosomal dominant trait with a high degree of penetrance. Genetic linkage analysis using polymorphisms on the alpha and beta MHC genes showed a combined maximal lod score of 6.2 for trinucleotide repeat polymorphism AMHC-I 15 at theta = 0.00 for three studied families without recombination. Exclusion of linkage to the chromosome 14q1 location was noted in two of three other families with the maximal lod score of -2 or less. CONCLUSIONS: These results provide further evidence that FHCM in Chinese is genetically heterogeneous. Chromosome 14q1 locus, probably the beta myosin heavy chain gene, is important as the molecular basis for FHCM in Chinese.