原发性先天性青光眼CYP1B1基因变异初步研究

目的了解CYP1B1基因变异在中国原发性先天性青光眼(PCG)患者发病中的作用。方法收集来自不同地区的16例PCG患者,对其CYP1B1基因编码外显子进行直接测序,对照组进行单核苷酸多态性分析。结果在1例PCG患者中发现了一种变异,为8006G>A(R390H)。它是位于外显子III的错义突变。还发现了五种单核苷酸多态性,分别为3793T>G,R48G,A119S,A330S,V432L。结论CYP1B1基因是导致中国人PCG患者的致病基因,但也有其他变异可能和PCG变异有关。     

湖北地区汉族原发性先天性青光眼患儿CYP1B1基因突变分析

目的研究湖北地区汉族原发性先天性青光眼(primary congenital glaucoma,PCG)患儿CYP1B1基因的突变情况。方法用苯酚-氯仿法从38例原发性先天性青光眼患儿的全血细胞中提取基因组DNA。然后通过聚合酶链反应-单链构象多态性(single-strand conformation polymorphism,PCR-SSCP)银染色法检测CYP1B1基因第2、3外显子的突变情况。结果5例PCG患儿检出CYP1B1基因第3外显子异常DNA片段条带,经测序分析证实为7990C→T,未发现第2外显子存在基因突变。结论CYP1B1基因具有明显的遗传异质性。应用PCR-SSCP技术可初步筛查原发性先天性青光眼患儿CYP1B1基因突变。     

原发性先天性青光眼CYP1B1基因新变异

目的 探讨CYP1B1基因变异在湖南地区原发性先天性青光眼患者中的分布.方法 病例对照研究.收集来自湖南地区的13例原发性先天性青光眼患者的临床资料进行分析,对13例患者的CYP1B1基因编码外显子进行直接测序和聚合酶链反应-限制性内切酶技术检测.结果 13例原发性先天性青光眼患者中,有1例发现一种基因新突变(c.C319G,L107V),是位于外显子2的错义突变.100例正常人中未见L107V突变.同时发现已报道的4种单核苷酸多态位点,分别为R48G、A119S、V432L、D449D.结论 CYP1B1基因L107V突变可能是导致湖南地区原发性先天性青光眼患者的致病原因之一.     

中国人原发性先天性青光眼患者CYP1B1基因突变分析

原发性先天性青光眼(primary congenital glaucoma,PCG),是一种严重危害儿童视力的致盲性眼病,与遗传有一定关系。为探讨中国人PCG与CYP1B1基因的关系,我们对7例PCG患者的CYP1B1基因进行分析,现报告如下。1材料与方法1.1病例收集在广州市儿童医院眼科就诊的表型为PCG的患者7例,抽取静脉血5mL,EDTA抗凝。所有标本间均无任何血缘关系。1.2主要试剂和仪器DNA抽提试剂盒、dNTPs、Taq酶(美国Fermentas公司),100bp DNA Markers、EB替代品(广州威佳公司)。采用Biometra UNOⅡ型PCR仪(德国Biometra公司)。1.3基因组DNA的制备按…     

CYP1B1基因突变与原发性开角型青光眼发病关系的研究进展

原发性青光眼包括原发性开角型青光眼（POAG）、原发性闭角型青光眼（PACG）及原发性婴幼儿青光眼（PCG）.目前认为原发性青光眼的发病是遗传因素、环境因素、生活习惯等多种因素综合作用的结果,其中遗传因素,尤其是基因突变,在青光眼的发病过程中起着重要作用.自1997年发现CYP1B1基因为PCG的致病基因以来,关于CYP1B1基因突变与青光眼发病关系的研究成为青光眼遗传和基因研究的热点.随着研究的逐渐深入,许多学者认为CYP1B1基因也是POAG致病基因的候选基因.本研究对近十余年来对CYP1 B1基因的结构和功能以及CYP1B1基因突变与POAG发病及进展关系的研究进展进行总结.     

湖北地区原发性先天性青光眼患儿CYP1B1基因的新突变研究

目的探讨湖北地区汉族原发性先天性青光眼（PCG）患儿的基因突变情况并为基因诊断奠定基础。方法对47例无关个体PCG患儿及100例健康正常儿童进行基因分析。采取外周静脉血4ml,制备外周白细胞基因组DNA,参照文献所报道的引物序列,聚合酶链反应（PCR）分别扩增CYP1B1基因的第2、3外显子,琼脂糖凝胶电泳鉴定产物后,应用单链构象多态性（SSCP）、变性高效液相色谱分析（DHPLC）及DNA序列分析技术对患儿和对照组进行基因分析。结果7例PCG患儿呈现CYP1B1基因的第3外显子第385密码子的第1个碱基C→T碱基点突变,致对应的亮氨酸转变为苯丙氨酸（L385F）。这一变异在正常对照组成员中未检出,且检索国内外文献尚未见报道。结论湖北地区汉族PCG患者存在CYP1B1基因第3外显子突变,这一新突变位点位于P450蛋白的重要功能区,可能为病理性突变。在汉族PCG患者中进行CYP1B1基因突变的深入研究并寻找其他致病基因,对探讨PCG发病机制具有重要意义。     

原发性先天性青光眼的遗传学研究进展

原发性先天性青光眼作为严重威胁婴幼儿视力发育的眼病,其遗传倾向受到关注,目前GLC3A,GLC3B和GLC3C三个相关候选基因已经定位。CYP1B1是目前仅找到的先天性青光眼的致病基因,其突变和功能的研究成为热点。本文就先天性青光眼的分子遗传学研究进展及其与CYP1B1的关系作一综述。     

CYP1B1突变与眼科疾病

细胞色素P4501B1（CYP1B1）是人体重要的代谢酶，本文从生化结构、细胞定位、遗传多态等方面对P4501B1基因（CYP1B1）进行了综述，并重点讨论了该基因的突变在原发性先天性青光眼、青少年型青光眼、Peters异常等眼病中的可能致病机制。     

文摘

·青光眼·先天性青光眼病情程度与手术成功率的关系[英]/Al-Hazmi A…//Br J Ophthal mol.-2005,89(4).-449~453作者研究了原发性先天性青光眼(PCG)的病情严重程度与三种类型手术的成功率之间的关系。回顾了1982年~2002年在沙特阿拉伯利雅得的KingKhale眼科医院采用前房角切开术、小梁切开术、小梁切开(90°范围)联合小梁切除丝裂霉素C术(0·2~0·4mg/ml,2~5分钟)三种手术方式作为初次手术治疗年龄在1岁内的PCG患者的全部病例。计532例(820眼)年龄在1岁内的先天性青光眼患者进行了至少1年的随访。术后随访检查的主要内容有:眼压、角…     

CYP1B1基因与眼部发育

细胞色素P4501B1(cytochrome P450,family 1,subfamily b,polypeptide 1,CYP1B1)是细胞色素氧化酶P450家族1亚家族B的惟一成员,编码该蛋白的基因是首个被鉴定出来的婴幼儿型青光眼致病基因,其突变导致了部分先天性青光眼的发病.本文对该基因的结构、表达产物、影响眼部发育的可能机制作一综述.     

Compound heterozygous mutations in CYP1B1 gene leads to severe primary congenital glaucoma phenotype

AIM: To identify the novel mutation alleles in the CYP1B1 gene of primary congenital glaucoma (PCG) patients at Shandong Province of China, and investigate their correlation with glaucomatous features. METHODS: The DNA from the peripheral blood of 13 congenital glaucoma patients and 50 ethnically matched healthy controls from the affiliated hospital of Qingdao University were extracted. The coding region of the CYP1B1 gene was amplified by PCR and direct DNA sequencing was performed. Disease causing-variants were analyzed by comparing the sequences and the structures of wild type and mutant CYP1B1 proteins by PyMOL software. RESULTS: Two missense mutations, including A330F caused by c.988G>T&c.989C>T, and R390H caused by c.1169G>A, were identified in one of the 13 PCG patients analyzed in our study. A330F mutation was observed to be novel in the Chinese Han population, which dramatically altered the protein structure of CYP1B1 gene, including the changes in the ligand-binding pocket. Furthermore, R390H mutation caused the changes in heme-protein binding site of this gene. In addition, the clinical phenotype displayed by PCG patient with these mutations was more pronounced than other PCG patients without these mutations. Multiple surgeries and combined drug treatment were not effective in reducing the elevated intraocular pressure in this patient. CONCLUSION: A novel A330F mutation is identified in the CYP1B1 gene of Chinese PCG patient. Moreover, in combination with other mutation R390H, this PCG patient shows significant difference in the CYP1B1 protein structure, which may specifically contribute to severe glaucomatous phenotype.     

Globally, CYP1B1 mutations in primary congenital glaucoma are strongly structured by geographic and haplotype backgrounds

PURPOSE: To obtain a global perspective on the distribution and evolution of CYP1B1 mutations in primary congenital glaucoma (PCG) worldwide. METHODS: Five intragenic single-nucleotide polymorphisms in CYP1B1-R48G, A119S, V432L, D449D, and N453S-were used to generate haplotype data from 138 Indian patients with PCG and 132 ethnically matched normal controls, which were then analyzed in conjunction with data from other populations. Maximum-likelihood estimates of haplotype frequencies were estimated from the genotype data. Subsets of patients and normal control subjects were also genotyped with respect to eight short tandem repeat (STR) markers around the CYP1B1 locus (D2S305, D2S165, D2S367, D2S2259, D2S391, D2S3337, D2S23678, and D2S286), to gain evolutionary insights. RESULTS: Common mutations in CYP1B1 that are causal of PCG occurred on a uniform haplotype background among Indian patients, which is completely distinct from the modal haplotype background found among unaffected control subjects. Comparison of these data with data from other global regions reveals strong clustering of CYP1B1 mutations by geographic and haplotype backgrounds. The two distinct modal haplotypes found among Indian patients with PCG and control subjects are both ancient with ages of similar magnitudes, as indicated by large variances in the number of repeats at eight STR loci. Together with data from chimpanzee and normal control subjects from India and other global regions, it was possible to make a parsimonious reconstruction of the evolution of these haplotypes. CONCLUSIONS: The strong association of specific haplotypes with some predominant CYP1B1 mutations underlying PCG and the observed geographical clustering, probably due to founder effects, may be useful for predictive testing.     

Overview of Cytochrome P450 1B1 gene mutations in patients with primary congenital glaucoma

The objective of this study was to investigate the distribution of mutations in the Cytochrome P450 1B1 gene (CYP1B1) in patients with primary congenital glaucoma (PCG) among different populations. All identifiable original studies on CYP1B1 gene mutations of patients with PCG were reviewed. Finally, DNA mutations within the CYP1B1 gene were identified in 542 patients with PCG according to 52 scientific articles and 147 distinct mutations were found. The 3987G>A (G61E) missense mutation is a founder mutation in Middle Eastern population, responsible for 45.52% of CYP1B1 mutations. In Gypsies, missense mutation 7996G>A (E387K) seems to be a founder mutation, accounting for 79.63% of CYP1B1 mutations. It seems that there is no founder mutation in Asian or Caucasian population, but also accumulates in some spots. Mutations 7927G>A (V364M), 7990C>T (L385F) and 8006G>A (R390H) are common in Asian population. In Caucasians, 7940G>A (R368H), 8037dup10, 8006G>A (R390H), 7901del13, 4340delG, 3987G>A (G61E), 7996G>A (E387K), 4490G>A (E229K) and 8005C>T/A (R390C/S) are common mutations. The findings suggest that ethnic differences and the geographical distribution of PCG may be associated with different CYP1B1 mutation patterns. Such information may be useful in developing strategies for reliable clinical genetic testing of patients with PCG and their families.     

Genotype/Phenotype Correlation in Primary Congenital Glaucoma Patients in the Lebanese Population: A Pilot Study

Background: The incidence of primary congenital glaucoma (PCG) varies among geographic regions and ethnic groups. The frequency of PCG in Lebanon and identification of disease-causing mutations have not been studied previously.

Purpose: To investigate the role of Cytochrome P1B1 (CYP1B1) gene and Myocillin (MYOC) gene mutations in PCG in the Lebanese population and study possible genotype/phenotype correlations.

Methods: Patients with unilateral or bilateral PCG diagnosed at the American University of Beirut Medical Center and their first-degree relatives (parents and siblings) were screened for CYP1B1 and MYOC mutations. Demographic and phenotypic characteristics were recorded. Phenotypic characteristics pertaining to disease severity and outcomes were compared.

Results: Eighteen Lebanese families (66 subjects) with at least one member affected with PCG were included in this study. Mutations in the CYP1B1 gene were detected in 6 families (33%). Five previously described mutations (p.R444Q; p.E229K; p.R469W; p.G61E; p.M1T) and one new single nucleotide deletion were identified (1793delC). Patients in whom CYP1B1 mutations were detected tended to have a more severe phenotype as evidenced by earlier age at diagnosis, higher rate of bilateral disease, and higher number of glaucoma surgeries than those in whom no CYP1B1 mutations were present. MYOC gene mutations were not detected in any patients.

Conclusion: The rate of CYP1B1 mutations in Lebanese patients with PCG is lower than that reported in other Arab and Middle Eastern populations and suggests other genes are responsible for PCG in the remainder.     

Two novel variants in CYP1B1 gene: a major contributor of autosomal recessive primary congenital glaucoma with allelic heterogeneity in Pakistani patients

AIM: To find the CYP1B1 mutations associated with primary congenital glaucoma (PCG) in Pakistani consanguineous pedigrees. METHODS: After getting informed consent, 11 consanguineous pedigrees belonging to different ethnic groups were enrolled. Detailed medical history was recorded and pedigrees were drawn. The standard ophthalmological examination was done to characterize the phenotype. Genomic DNA was extracted from 10 mL whole blood and coding exons and exon intron boundaries of CYP1B1 gene were directly sequenced. Bioinformatics tools were used to model the mutant protein and predict the effect of novel variants on protein structure and function. RESULTS: Sequencing analysis revealed 5 different CYP1B1 variants in 7 families (7/11; 64%), including two novel variants. A common mutation, p.R390H was found in four families, whereas p.P437L was found once in a family. Two novel variants, a homozygous non sense variant p.L13* and a compound heterozygous variant, p.P350T along with p.V364M were segregating with PCG in two families. All the patients had the variable onset and severity of the disease. The success rate of early clinical interventions was observed dependent on mutation types and position. Two different haplotypes were associated with frequently found mutation, p.R390H. CONCLUSION: Identification of novel CYP1B1 variants reassert the genetic heterogeneity of Pakistani PCG patients. The patients with missense mutations show severe phenotypic presentations and poor vision after surgical interventions as compare to patients with null variants. This may help to better understand the role of CYP1B1 mutations in the development of PCG and its course of pathogenicity.     

LTBP2 gene analysis in the GLC3C-linked family and 94 CYP1B1-negative cases with primary congenital glaucoma

Purpose: Primary congenital glaucoma (isolated trabeculodysgensis, PCG) generally presents between birth and 3 years of age. Recently, mutations in Latent Transforming Growth Factor (TGF)-beta Binding Protein 2 (LTBP2) have been reported in several families that were diagnosed with PCG, who actually had a more complex ocular phenotype with ectopia lentis and Marfanoid features. We screened this gene for mutations in the original Turkish GLC3C-linked PCG family and in a group of CYP1B1-negative British PCG cases and their matched normal control subjects.

Methods: The 36-coding exons of the LTBP2 gene were sequenced in 94 familial or sporadic CYP1B1-negative PCG cases and 96 matched normal control subjects.

Results: No disease-causing mutations were identified in the original GLC3C-linked family. Screening of LTBP2 in 94 PCG and 96 control subjects identified three novel synonymous variations (L429L, P680P, S1031S) in 12 PCG and seven control subjects. A novel heterozygous missense mutation (R538W) was also identified in 1 of 90 PCG cases that is unlikely to be disease-causative.

Conclusions: LTBP2 mutations were not found in the Turkish GLC3C-linked PCG family or in 94 British CYP1B1-negative PCG cases. Our data suggest that LTBP2 mutations are not a significant cause for isolated trabeculodysgenesis.     

Molecular analysis of the CYP1B1 gene: identification of novel truncating mutations in patients with primary congenital glaucoma

BACKGROUND: Mutations and polymorphisms have been identified in the CYP1B1 gene; while mutations that affect the conserved core structures of cytochrome P4501B1 result in primary congenital glaucoma (PCG), mutations in other regions hold the potential to define differences in estrogen metabolism. In the present study, we analyzed the CYP1B1 gene in Mexican patients with PCG and described four novel mutations. MATERIALS AND METHODS: The sample included 12 nonrelated cases with PCG. Analysis of coding regions of the CYP1B1 gene was performed through PCR and DNA sequencing analysis from genomic DNA. RESULTS AND DISCUSSION: Molecular analysis of the CYP1B1 gene showed the following molecular defects: (1) a novel single-base pair deletion within codon 370 (1454delC) that produces a substitution of leucine instead of proline and a premature stop codon 57 amino acids after the last original amino acid; this family also harbored a novel polymorphic variant of the cytochrome P4501B1 with six single-nucleotide polymorphisms (142C-->G; 355G-->T; 729G-->C; 4326C-->G; 4360C-->G and 4379C-->T); (2) a novel single-base pair deletion within codon 277 (1176delT) that results in a premature stop codon; (3) a novel single-base pair deletion within codon 179 (880delG) that produces a substitution of arginine instead of alanine and a premature stop codon 17 amino acids downstream from the last original amino acid, and (4) a duplication (or insertion) of ten base pairs within codon 404 (1556dupATGCCACCAC) that results in a premature stop codon 26 amino acids after the last original amino acid. We also observed in 2 nonrelated patients a deletion of 13 bp (1410_1422delGAGTGCAGGCAGA) previously reported for other populations. CONCLUSION: We reported four novel mutations and a novel polymorphic variant in the CYP1B1 gene in PCG in the Mexican population; it has important implications in diagnosis and genetic counseling.     

Glaucoma-associated CYP1B1 mutations share similar haplotype backgrounds in POAG and PACG phenotypes

PURPOSE: To understand the involvement of the CYP1B1 gene in cases of primary open-angle (POAG) and primary angle-closure (PACG) glaucomas and obtain the haplotype background of these mutations. METHODS: The entire coding region of CYP1B1 was screened by resequencing in 224 unrelated cases of POAG (n = 134) and PACG (n = 90) and 200 ethnically matched normal control subjects from Indian populations. Six intragenic single nucleotide polymorphisms (SNPs) in CYP1B1 (-13T>C, R48G, A119S, V432L, D449D, and N453S) were used to generate haplotype data for the cases and controls and linkage disequilibrium (LD) and haplotype analysis were performed with Haploview software, which uses the EM (expectation-maximization) algorithm. RESULTS: The frequency of CYP1B1 mutations was higher among POAG (18.6%; 95% CI, 12.9-26.1) than PACG (11.1%; 95% CI, 6.1-19.3) cases. There was a marked allelic heterogeneity, and the Arg368His was the most prevalent mutation across both the phenotypes. The spectrum of CYP1B1 mutations was largely similar across different POAG populations. Haplotypes generated with intragenic SNPs indicated the C-C-G-G-T-A to be a risk haplotype associated with CYP1B1 mutations in POAG (P = 0.006) and PACG (P = 0.043), similar to that observed in cases of primary congenital glaucoma worldwide. CONCLUSIONS: The results demonstrate an involvement of CYP1B1 in a proportion of POAG and PACG cases that should be explored further. The similar haplotype background of these mutations is indicative of their common origin across multiple glaucoma phenotypes.