角膜营养不良家系的TGFBI基因突变研究

目的确定中国角膜营养不良患者所存在的TGFBI基因突变类型。方法对3个角膜基质营养不良家系和1个Thiel—Behnke角膜营养不良家系进行分析，其中1个家系成员是蒙古族人，另3个家系则是汉族人。利用合成的TGFBI基因13个外显子的特异性引物，应用聚合酶链反应进行扩增，并直接测序分析。结果1个颗粒状角膜营养不良家系患者中检测到R555W突变；1个Thid-Behnke角膜营养不良家系患者为R555Q突变；另外2个Avellino角膜营养不良家系患者中发现R124H突变，这3种突变均为杂合子。结论研究表明R555和R124密码子在中国人常染色体显性遗传性角膜营养不良的发病机理中起重要作用。Thiel-Behnke角膜营养不良患者为R555Q突变，在我国属首次报告。     

三个角膜营养不良家系的TGFBI基因突变

目的 筛查3个角膜营养不良家系患者TGFBI基因突变.方法 采集患者外周静脉血,提取基因组DNA,采用直接测序对TGFBI基因全部17个外显子以及外显子内含子拼接部进行序列分析.结果 3个家系中两个家系表型为格子样角膜营养不良1型(1attice corneal dystrophy type I,LCD I)和格子样角膜营养不良3A型(lattice corneal dystrophy type ⅢA,LCDⅢA),另外1个家系为Avellino角膜营养不良(avellino corneal dystrophy,ACD).在两个LCD家系中分别检出编码子R124C和H626R突变,而在ACD家系中检出R124H突变.结论 TGFBI基因是引起角膜营养不良的致病基因.R124和H626是角膜营养不良的突变热点.     

TGFBI基因相关的Thiel-Behnke角膜营养不良家系的建立者效应分析

目的 对2个Thiel-Behnke角膜营养不良的家系进行基因诊断和建立者效应分析.方法 提取家系A中15名成员(13例患者,2名健康成员)、家系B中14例成员(6例患者,8名健康成员)以及20名健康自愿者的基因组DNA,通过DNA测序检测转化生长因子β诱导基因(transforming growth factor beta induced,TGFBI/BIGH3)的突变,并对2个家系成员进行单倍型分析.结果 所有患者TGFBI基因的第12外显子发生R555Q突变,2个家系成员具有部分相同的单倍型.结论 基因检测有助于Thiel-Behnke角膜营养不良的确诊.2个患病家系可能来自于同一祖先.     

一个非典型Reis-Bückler角膜营养不良家系的TGFBI基因突变研究

目的 通过基因突变分析,确定一个非典型Reis-Bückler角膜营养不良家系突变基因型和表现型之间的关系.方法 采集家系中的4例患者及2名健康成员和100名正常对照的外周血10 mL,提取白细胞DNA,应用聚合酶链反应分别扩增TGFBI基因的第4、11、12、14外显子,并对扩增产物进行直接测序分析.结果 发现TGFBI基因第623密码子第2个碱基呈杂合性点突变G→A,导致甘氨酸突变为天冬氨酸(p.G623D),家系中健康成员和正常对照均未检测到此突变存在.结论 这一由TGFBI基因G623D突变引起的角膜营养不良为非典型的Reis-Buckler角膜营养不良,这在我国属首次报告.     

21-羟化酶缺乏症家系的基因突变研究

目的通过对3个21-羟化酶缺乏症家系的21-羟化酶基因(steroid21-hydroxylase gene,CYP21)直接测序研究,探讨家系中该基因突变类型。方法收集4例患者及其部分家系成员外周血,提取基因组DNA,PCR扩增CYP21基因后直接测序。结果CYP21基因序列分析共检测到6种突变类型。家系1中患者CYP21基因存在4种杂合突变:clusteE6、Q318X、A391T、P459H,其中前3种突变串联排列于同一条染色体上,P459H突变目前国内外尚未见报道,A391T为罕见突变;家系2中患者CYP21基因存在clusteE6、R483W两种杂合突变,其中R483W为罕见突变类型;家系3中患者第4外显子存在I172N纯合突变。结论在3个21-羟化酶缺乏症家系中共检测出6种突变类型,其中P459H为新发现的突变,A391T、R483W为罕见突变。虽然导致21-羟化酶缺乏症的突变主要是一些从假基因(CYP21P)转位到CYP21的序列,但随机突变也是21-羟化酶缺乏症的原因。     

颅内海绵状血管瘤 CCM1基因第12外显子及其5′端内含子新突变位点

目的　探讨 CCM1基因突变在中国人颅内海绵状血管瘤 ( intracranial cavernous angiomas,ICCA)发病中所起的作用。方法　收集我院神经外科 2 0 0 2年 6月～ 2 0 0 3年 2月收治并经手术病理证实的2 1例 ICCA患者及 15名正常健康对照者 ,从外周静脉血中提取 DNA,PCR法扩增 CCM1基因第 12外显子及其两侧部分内含子序列 ,应用 DNA直接测序技术对扩增产物进行检测。结果　 5例患者中检测出 3处 CCM1基因突变 ,均为首次发现。其中 ,5例患者中均存在 1172 C→ T的错义突变 ,使编码 KRIT1蛋白391位的氨基酸由丝氨酸变成苯丙氨酸。另有 1例患者存在 116 0 A→ C的错义突变 ,使编码 KRIT1蛋白387位氨基酸的谷氨酰胺变成脯氨酸。另一个突变发生在第 12外显子 5′端内含子区域 ,5例患者中有 4例第 4个碱基 C被 T取代。对照组检测结果无异常。结论　中国 ICCA患者存在 CCM1基因第 12外显子的突变 ,并与 ICCA的发病有关     

胃癌组织中PIK3CA基因热点突变筛查及临床意义

目的 检测中国人群胃癌组织中PIK3 CA基因突变频率及热点突变模式,探讨PIK3 CA基因突变的临床意义.方法 应用荧光PCR法筛查胃癌PIK3 CA基因突变阳性病例,Sanger DNA测序法检测PIK3CA基因热点突变模式;统计分析PIK3 CA基因突变与胃癌临床病理特征之间的关系.结果 400例肿瘤标本中检测出PIK3 CA基因突变率为7.5％ (30/400),突变位点主要集中在第9外显子(E542K,E545K)和第20外显子(H1047R,H1047L);且PIK3 CA基因突变与肿瘤预后相关(P＜0.05),而与肿瘤大小、组织学分级、淋巴结状态、患者年龄等因素无关.结论 中国人群胃癌组织中PIK3CA基因突变具独特的突变频率与突变模式;PIK3 CA基因突变对于胃癌预后判断及基因靶向治疗具潜在临床价值.     

127例PKU患者PAH基因第12外显子点突变及其频率研究

目的　了解中国人苯丙酮尿症 ( phenylketonuria,PKU)患者的苯丙氨酸羟化酶( phenylalanine hydroxylase,PAH)基因第 12外显子点突变种类和频率。方法　应用单链构象多态性( single strand conformation polymorphism,SSCP)、变性梯度凝胶电泳 ( denaturing gradient gelelectrophoresis,DGGE)、DNA测序分析了 12 7例 PKU患者的 PAH基因第 12外显子点突变种类及频率。结果　 DNA测序分析显示 10例患者存在 R4 13P、S4 11X、R4 0 8W、R4 0 8Q 4种杂合突变 ,其突变频率分别为 2 .76 %、0 .39%、0 .39%、0 .39% ,S4 11X突变为中国人中首次报道。 SSCP分析仅发现 2例 R4 13P杂合突变 ,DGGE分析显示 10例出现 3种类型的异常电泳带型。R4 13P突变在南北方人之间、在经典型 PKU和高苯丙氨酸血症之间的分布差异无显著性。结论　 DGGE对 PAH基因第 12外显子点突变检出率明显高于 SSCP。 DGGE结合 DNA测序是明确 PAH基因第 12外显子点突变种类和频率较好的方法。 R4 13P突变在南北方人中分布无明显差异     

一个有三例女性X-连锁肾上腺-脑白质营养不良杂合子患者家系基因突变分析

目的 对1个有3例女性杂合子患者的X-连锁肾上腺-脑白质营养不良(X-linked adrenoleukodystrophy,X-ALD)家系进行基因突变分析.方法 提取1例患者的外周血白细胞总RNA,以此为模板,采用长链逆转录-PCR技术,分4个片段扩增ABCD1基因(X-ALD疾病基因)编码序列并对其PCR产物进行直接测序.通过PCR和限制性内切酶分析患者及其家庭成员相应的基因组DNA片段,进一步确证所发现的基因突变.对突变及其对ALD蛋白结构的影响进行生物信息学分析.结果 在患者A月CD1基因第1外显子的第283位密码子发现1个新的错义突变:CAC→CGC(p.H283R),此突变使相应DNA片段的1个Msl Ⅰ酶切位点消失,其子不存在此突变.突变所改变的氨基酸残基在进化上高度保守.p.H283R突变位于ALD蛋白的跨膜结构域,可引起该分子跨膜区整体结构的改变.结论 在国内首次报道了3例杂合子女性X-ALD患者,并在其家系发现了1个新的ABCD1基因突变,即p.H283R突变.     

一个中国人裂手足伴并指趾畸形家系的表型和基因型分析

目的 确定一个中国人裂手足家系的致病性基因突变,探讨基因型-表型关系.方法 收集患者及其家庭成员的外周血,提取基因组DNA.采用PCR扩增P63基因和HOXD13基因的外显子,对PCR产物进行双向测序检测基因突变.结果 在所有患者中检测到P63基因第7外显子的杂合型956G→A突变,导致蛋白产物第280位的精氨酸被组氨酸取代(R280H).在正常家庭成员中未检测到该突变.结论 该家族中的患者以对称性裂手足伴并指趾为主要特征,由P63基因的R280H突变所致.     

Heterogeneity in granular corneal dystrophy: Identification of three causative mutations in the TGFBI (BIGH3) gene—Lessons for corneal amyloidogenesis

Six autosomal dominant corneal dystrophies are caussed by mutations in the TGFBI (BIGH3) gene on chromosome 5q31: three types of lattice corneal dystrophy (LCD), including type I and type IIIA, granular, Avellino (ACD), and Reis‐Bucklers. Initially an exact genotype‐phenotype correlation was reported. We report three families, with differing clinical features, all presenting with “granular” corneal dystrophy. We analysed the TGFBI gene by SSCP analysis and direct sequencing in order to further assess the genotype‐phenotype correlation. We describe three separate mutations in TGFBI: one novel, one initially described as causing ACD, and one previously described. The novel mutation, R124S, is at the identical position to the mutation causing LCD type I (CDL1). We review the clinical and histological phenotypes of the corneal dystrophies and hypothesize that the ability of a mutation to cause amyloid deposition depends on the location and nature of the mutation. In addition, we suggest that the classification of the granular corneal dystrophies be revised according to mutation type and that ACD should not be classified as a distinct morphological entity. Hum Mutat 14:126–132, 1999. © 1999 Wiley‐Liss, Inc.     

Corneal dystrophies in Japan

Recent advances in molecular genetics have increased our understanding of the role of genes. Four autosomal dominant corneal dystrophies (CDs); granular CD (GCD), Avellino CD (ACD), lattice CD (LCD), and Reis-Bücklers CD (RBCD) were mapped to the long arm of chromosome 5 (5q31). These four diseases were shown, in a Caucasian series, to result from different missense mutations in the TGFBI (BIGH3, keratoepithelin) gene. The same mutations were also detected in Japanese patients, from a different ethnic background. Gelatinous drop-like corneal dystrophy (GDLD), on the other hand, which was found in Japanese patients in 1914, is a rare autosomal recessive disorder characterized by corneal amyloidosis. Parents of the patients had a markedly higher frequency of consanguineous marriages than the general population. The gene responsible for GDLD, the membrane component, chromosome 1, surface marker 1 (M1S1) gene was mapped to the short arm of chromosome 1(1p). Four deleterious mutations in this gene were detected in Japanese patients. We review here additional studies on mutations of the TGFBI and M1S1 genes found in Japanese patients. In the TGFBI gene, nine different mutations were detected in Japanese patients with GCD, ACD, LCD, or RBCD. The codons R124 and R555 of the TGFBI gene were hotspots in Japanese patients, of whom many were ACD patients with the R124H mutation. New mutations responsible for LCD were detected in the TGFBI gene of patients with LCD, in addition to the P501T mutation in LCD type IIIA found earlier. These studies showed a clear genotype/phenotype correlation associated with the TGFBI gene. In the M1S1 gene, the Q118X mutation was the most common alteration, and a founder mutation in Japanese GDLD patients, as previously reported. Ninety-two percent of the mutated alleles were the Q118X. Received: March 1, 2001 / Accepted: April 21, 2001     

Allelic homogeneity in Avellino corneal dystrophy due to a founder effect

Avellino corneal dystrophy (ACD) is a common corneal dystrophy that shows allelic homogeneity, R124H mutation in the transforming growth factor beta-induced (TGFBI) gene. There are distinct phenotypes of homozygous Avellino corneal dystrophy, termed types I and II. To investigate if the difference is caused by a modifier mutation, we sequenced the entire coding region of TGFBI of two types of ACDs. The sequences obtained from each type were identical, and we could not find any nucleotide alternations. Instead, we found seven single nucleotide polymorphisms (SNPs) compared with the normal control. Primer extension analysis revealed that all 14 homozygous patients were homozygotes in each SNP, which meant that all the patients shared the same disease haplotype. Subsequent analysis of 45 heterozygous ACD patients showed strong linkage disequilibrium between disease alleles of each SNP and ACD. These results strongly suggest that the allelic homogeneity of TGFBI associated corneal dystrophies (ACD, lattice corneal dystrophy types I and III, granular corneal dystrophy and Reis–Bucklers dystrophy) might not be caused by mutation hot spots but by the founder effects.     

A subset of patients with epithelial basement membrane corneal dystrophy have mutations in TGFBI/BIGH3

Epithelial basement membrane corneal dystrophy (EBMD), also known as Cogan microcystic epithelial dystrophy or map-dot-fingerprint dystrophy, is a common bilateral epithelial dystrophy. Usually, this disease is not considered to be inherited although several families with autosomal dominant inheritance have been described. We report the analysis of two families with an autosomal dominant pattern of inheritance as well as the analysis of single affected individuals; we identified two different point mutations in the TGFBI/BIGH3 genes, genes known to be associated with other corneal dystrophies. This is the first report of a molecular mutation in individuals with EBMD and it increases the spectrum of mutations in the TGFBI/BIGH3 gene. Based on our screening, up to 10% of EBMD patients could have a mutation in this gene.     

Analysis of TGFBI gene mutation in a Chinese pedigree affected with lattice corneal dystrophyCSCD

Objective: To explore the clinical features and mutation of TGFBI gene in a Chinese pedigree affected with lattice corneal dystrophy (LCD). Methods: Genomic DNA was extracted from 35 members including 11 patients from the pedigree. The 17 exons and splicing region of introns of the TGFBI gene were amplified by PCR. The products were directly sequenced and compared with GenBank database to identify potential mutation. Bioinformatic analysis was carried out to predict the effect of mutation on proteins. Results: A heterozygous mutation (p. R124C) was found in exon 4 of the TGFBI gene in all patients from the pedigree but not among unaffected members. The mode of inheritance of corneal dystrophy in this pedigree was identified as autosomal dominant. Bioinformatics analysis predicted that the p. R124C mutation may be functionally deleterious. The phenotype of corneal dystrophy in the pedigree was determined to be LCD I type. Conclusion: The p. R124C mutation of the TGFBI gene probably underlies the pathogenesis of LCD in this Chinese pedigree. Genetic testing can facilitate proper diagnosis of this type of corneal dystrophy. © 2018 MeDitorial Ltd. All rights reserved.     

A common beta ig-h3 gene mutation (delta f540) in a large cohort of Sardinian Reis Bücklers corneal dystrophy patients. Mutations in brief no. 180. Online

Reis-Bücklers' corneal dystrophy (RBCD) is a relatively rare autosomal dominant disease originating in the Bowman's membrane, which causes severe visual impairment. Recently RBCD, together with lattice corneal dystrophy type I (LCDI), granular corneal dystrophy (CDGG1) and Avellino stromal dystrophy (ASD), all mapped on 5q31, were found to be associated to four different mutations in the beta ig-h3 gene which codify for kerato-epithelin. We identified several cases of RBCD in Sardinia. We reconstructed through genealogical search two eight generation-families, originating from the same village (Arbus), indicating a common ancestor for RBCD in Sardinia. Linkage studies on these families confirmed the association of the disease with the 5q31 region. Sequence analysis of beta ig-h3 gene revealed a trinucleotide deletion in exon 12, corresponding to the loss of F540 in the protein sequence (delta F540). Our data describe a new mutation in the beta ig-h3 gene causing RBCD. This dominant negative mutation is located in the fourth internal repeat of kerato-epithelin which is a protein domain highly conserved across species. This suggests the basic role of this domain in maintaining the proper kerato-epithelin structure which when altered can cause the typical precipitates in the RBCD cornea.     

TGFBI gene mutations in corneal dystrophies

The lattice corneal dystrophies (LCD) and granular corneal dystrophies (GCD) are autosomal dominant disorders of the corneal stroma. They are bilateral, progressive conditions characterized by the formation of opacities arising due to the deposition of insoluble material in the corneal stroma leading to visual impairment. The LCDs and GCDs are distinguished from each other and are divided into subtypes on the basis of the clinical appearance of the opacities, clinical features of the disease, and on histopathological staining properties of the deposits. The GCDs and most types of LCD arise from mutations in the transforming growth factor beta-induced (TGFBI) gene on chromosome 5q31. Over 30 mutations causing LCD and GCD have been identified so far in the TGFBI. There are two mutation hotspots corresponding to arginine residues at positions 124 and 555 of the transforming growth factor beta induced protein (TGFBIp) and they are the most frequent sites of mutation in various populations. Mutations at either of these two hotspots result in specific types of LCD or GCD. The majority of identified mutations involve residues in the fourth fasciclin-like domain of TGFBIp.