携带CYP4V2基因突变的结晶样视网膜色素变性患者的表型特征

目的 分析国人结晶样视网膜色素变性（BCD）患者CYP4V2基因型及表型特征。设计 回顾性病例系列。研究对象 北京同仁医院结晶样视网膜色素变性患者138例。方法 回顾患者病历记录及眼科检查结果。先证者、直系亲属及家系患病成员采集外周静脉血,Sanger测序及实时定量荧光PCR检测先证者CYP4V2基因突变,并对致病性突变进行家系共分离验证。主要指标 最佳矫正视力、眼前节及眼底情况、CYP4V2基因突变。结果 138例BCD患者均携带CYP4V2基因双突变,突变c.802-810del17insCG、c.1091-2A>G和p.H331P是本组患者的常见突变。患者平均最佳矫正视力（LogMAR）（1.17±0.95）,平均发病年龄（29.19±9.64）岁,视力损伤程度与病程相关,不受发病年龄影响。所有患者眼底均可见细小颗粒状黄白色结晶沉积,结晶沉积范围及密度随病程而加重。结论 本研究拓展了BCD致病基因CYP4V2突变谱,BCD患者临床特征明显,结合多种影像学检查方法可有效进行诊断,致病基因突变的确定可为患者提供相应的遗传咨询帮助。（眼科, 2020, 29： 93-97）     

结晶样视网膜色素变性中与CYP4V2基因相关的致病突变

目的：使用Sanger测序法鉴定2个中国结晶样视网膜色素变性(BCD)家系中CYP4V2基因的突变位点。

方法：收集2019-01/09临床诊断为BCD患者的临床相关资料。采集患者、患者家系成员的外周血,提取DNA,利用Sanger测序法鉴定突变位点。

结果：共收集2个BCD先证者,先证者均表现为渐进性视力下降,眼底均可见典型的结晶样物质沉积。测序发现先证者1及其患病的哥哥,妹妹均在CYP4V2基因上存在c.802-8_810del17insGC的纯合突变。而先证者2则在CYP4V2基因上存在c.219T>A(p.F73L)、c.802-8_810del17insGC杂合突变。

结论： 中国BCD患者中最常见的c.802-8_810del17insGC突变在先证者1家系中为纯合突变,是其家系的致病突变。而先证者2则携带了中国BCD患者最常见的c.802-8_810del17insGC杂合突变,同时先证者2还携带c.219T>A(p.F73L)错义突变,突变均影响了CYP4V2基因的正常编码,进而导致疾病。     

《眼科》第五届编辑委员会名单

本期以眼病的基因诊断作为重点报道内容。近年来随着分子生物学理论和技术的不断发展,遗传疾病的基因诊断技术有了长足的进步,基因诊断与治疗研究一直是眼科界的热门课题。李杨在述评“结晶样视网膜色素变性临床与基础研究的机遇与挑战”中提出,对结晶样视网膜色素变性患者自然史和CYP4V2基因突变致病的机制研究,将对确定此类患者基因治疗的时间窗、临床研究中治疗效果评定、以及探索其他治疗方法均至关重要。     

儿童视网膜色素变性临床特点分析

目的探讨儿童视网膜色素变性在诊断和治疗方面的临床特点。方法将符合准入标准的27名14岁以下视网膜色素变性患者在进行视野检查后,分为有家族史患者组和无家族史患者组,用二十二碳六烯酸胶囊、β-胡萝卜素胶囊、血脂康胶囊治疗1年,以中心视力和视野平均缺损敏感度（MD）作为疗效的观察指标。观察总结儿童视网膜色素变性患者在诊断和治疗中的临床特点。结果归纳儿童视网膜色素变性患者的临床特点有：（1）他人发现患者患病;（2）全自动视野检测是首选的检查手段;（3）可能会有极少数患者被误诊;（4）无家族史患者比有家族史患者的治疗效果好。结论儿童视网膜色素变性患者具有4个临床特点。     

载脂蛋白E基因变异与视网膜色素变性关系的研究

目的通过检测中国汉族人视网膜色素变性患者的载脂蛋白Ｅ表型，探讨其基因变异与视网膜色素变性发病的关系。方法采用等电聚焦及免疫印迹方法检测正常人和视网膜色素变性患者的ａｏｐＥ表型。结果视网膜色素变性患者中ε４基因频率明显上升（χ２＝１２．９８３，Ｐ＜０．０１），ε２，ε３基因频率与正常对照组无差异。ａｏｐＥ　ε４等位基因与视网膜色素变性的发病有关联（ＲＲ＝２５．０７１，Ｐ＜０．０１）。结论ａｏｐＥ　ε４基因可能是视网膜色素变性发病的又一遗传因素。     

视网膜色素变性遗传致病基因peripherin/RDS的突变筛选

目的 了解中国视网膜色素变性患者（RP）中peripherin/RDS基因的突变谱及突变率。方法 应用聚合酶链-异源双链-单链构象多态性（PCR-SSCP）及DNA序列分析技术对收集的15个常染色体显性遗传视网膜色谱变性家系和55例散发视网膜色素变性患者peripherin/RDS基因的第一，第二外显子进行检测。结果 15个家系及55例散发患者未检测到peripherin/RDS基因突变。结论 本研究所检测的视网膜色素变性患者与RDS基因无关，显示视网膜色素变性的遗传异质性。     

直肌埋藏术治疗视网膜色素变性的临床观察

视网膜色素变性为一种慢性进行性疾病，本病具有隐性遗传特点，是临床上治疗非常棘手的难题之一。目前，多采用保守治疗，很少有手术治疗的报道。我院近3年来对37例（64眼）视网膜色素变性患者，采用直肌埋藏术治疗视网膜色素变性，取得了良好效果，现报告如下。     

视网膜色素变性患者血清脂肪代谢的异常变化

目的　对比原发性视网膜色素变性（primary retinitis pigmentosa，PRP）、结晶样视网膜色素变性（bietti crystalline dystrophy，BCD）患者血清中游离脂肪酸（free fatty acid，FFA）及心型脂肪酸结合蛋白（heart fatty acid binding proteins，HFABP）含量的变化，为探索其发病机理和防治提供参考。方法　采用回顾性研究方法，纳入临床诊断标准的首都医科大学附属北京同仁医院眼科中心门诊PRP患者80例，BCD患者50例，与正常对照组60例进行比较，按盲法由专业技术人员完成血清中FFA及HFABP浓度检查。分析PRP、BCD患者体内FFA和HFABP含量与正常对照组的差别。结果　PRP患者血清FFA、HFABP浓度分别为（0.547±0.214）mmol·L^-1、（3.594±0.791）mmol·L^-1；BCD患者血清FFA、HFABP浓度分别为（0.529±0.108）mmol·L^-1、（4.237±1.258）mmol·L^-1；正常对照组的FFA、HFABP浓度分别为（0.386±0.251）mmol·L^-1、（5.261±1.471）mmol·L^-1。与正常对照组比较，两种退行性视网膜疾病的FFA浓度显著升高（均为P<0.05），而HFABP浓度显著降低（均为P<0.05）。结论　PRP及BCD患者血清FFA及HFABP浓度存在异常变化，提示了其可能与退行性视网膜疾病的发生发展有关，对疾病的治疗具有一定的指导意义。     

视网膜色素变性合并青光眼5例

本文报告了视网膜色素变性合并青光眼患者5例，其中男性2例，女性3例。视网膜色素变性的发病年龄为15~33岁，平均年龄为20.8岁；青光眼的发病年龄23~51岁，平均年龄37.6岁；青光眼的类型：闭角型青光眼4例，开角型青光眼1例。本文就视网膜色素变性的遗传及视网膜色素变性合并青光眼的发病机理等问题进行了讨论。 （中华眼底病杂志，1992，8：183-184）     

原发性视网膜色素变性合并结晶样视网膜变性一例

原发性视网膜色素变性合并结晶样视网膜变性一例汪铭（贵阳市近视眼专科医院５５０００２）康玲玲（贵州省人民医院眼科）原发性视网膜色素变性是一种较为常见的遗传性眼病，具有遗传质疾病特性，结晶样视网膜变性属少见遗传性眼病，遗传方式至今未明。近来作者遇见一例具...     

A Novel Compound Heterozygous Mutation in the CYP4V2 Gene in a Japanese Patient with Bietti's Crystalline Corneoretinal Dystrophy

Purpose: To describe the clinical and genetic characteristics of a Japanese family in which one member exhibited Bietti's crystalline corneoretinal dystrophy (BCD). Methods: Using direct sequencing, mutation screening was performed in the CYP4V2 gene of both the patient with BCD and her daughter. Ophthalmic examinations were performed to determine the clinical features of both subjects. Results: The 64-year-old female patient had a bilateral visual acuity of 0.4. Slit lamp examination revealed bilateral crystalline-like deposits at the superior limbus of the cornea. Fundus examination revealed there was chorioretinal atrophy along with numerous glistening yellowish-white crystalline deposits that were scattered throughout the posterior pole and the mid-peripheral retina. Standard flash electroretinography showed an extinguished electroretinogram and Goldmann kinetic perimetry detected a relative scotoma. Genetic analysis revealed that the patient had a heterozygous mutation in the CYP4V2 gene (IVS6-8delTCATACAGGTCATCGCG/GC), which is the most commonly found mutation in Japanese patients with BCD. Furthermore, the patient was also shown to have a novel heterozygous point mutation in exon 9 of the CYP4V2 gene (c.1168C>T). In contrast, her daughter exhibited no clinical findings for BCD even though she carried the same heterozygous mutation in the CYP4V2 gene (c.1168C>T). Conclusion: A novel compound heterozygous mutation was found in the CYP4V2 gene of a patient with BCD. This previously unreported c.1168C>T mutation causes a missense mutation (p.R390C) in the CYP4V2 protein.     

Crystal deposits on the lens capsules in Bietti crystalline corneoretinal dystrophy associated with a mutation in the CYP4V2 gene

Purpose: We report a patient (Case 1) with Bietti crystalline corneoretinal dystrophy (BCD) associated with previously unknown findings of crystal‐like deposits on the anterior and posterior lens capsules. This patient is one of four (Cases 1–4) in whom we have found BCD associated with the same mutation in the CYP4V2 gene. Methods: We present a case report with molecular diagnosis. A 45‐year‐old man (Case 1) was referred to our clinic with complaints of gradual progression of visual disturbances and night blindness. His visual acuity was limited to hand movement bilaterally. Slit‐lamp biomicroscopy disclosed glistening, crystal‐like deposits on the anterior and posterior lens capsules, as well as on the corneal stroma near the corneoscleral limbus. No such deposit was found in the lens stroma. Fundus examination disclosed profound chorioretinal atrophy with scarce crystal deposits. Full‐field electroretinography showed extinguished responses of isolated rods, isolated cones, and mixed rods and cones. Results: Molecular genetic analysis revealed that the subject had a homozygous mutation in the CYP4V2 gene (IVS6–8delTCATACAGGTCATCGCG/insGC), which is most commonly found in Japanese patients with BCD. Three other cases (Cases 2–4) of BCD associated with the same mutation did not show such crystal‐like deposits on the lens surface. Conclusions: Although their exact origin remains unknown, crystal‐like deposits may appear on the lens capsule of patients with BCD associated with a mutation in the CYP4V2 gene.     

A novel mutation in the CYP4V2 gene in a Chinese patient with Bietti’s crystalline dystrophy

Bietti crystalline corneoretinal dystrophy (BCD, MIM 210370) is a type of hereditary retinal disorder which commonly occurs in China. It is known that mutations in the CYP4V2 gene result in BCD. The purpose of this study was to investigate the case of a Chinese family and characterize the polymorphisms of the CYP4V2 gene. A 29-year-old male (the son of a Chinese family) with typical clinical symptoms of BCD and his family were recruited into this study. Ophthalmologic examination, including best-corrected visual acuity, slit-lamp, and fundus examination with dilated pupils, was conducted to determine the clinical characteristics of the whole family. The entire coding region and adjacent intronic sequences of 11 coding regions of the CYP4V2 gene of the whole family were then amplified by polymerase chain reaction and sequenced. Our results show that the son had typical clinical features of BCD. His bilateral decimal visual acuity was 0.06 (left eye) and 0.01 (right eye). Bilateral crystal-like deposits were found in the posterior pole of his fundus, and differing extent of atrophy of the retinal pigment epithelium, and carpet-like retinal degeneration along with numerous tiny glittering crystals were also clearly observed. However, such characteristics were not found on the fundus of his parents’ eyes. Five mutations within the CYP4V2 gene (c.64C>G, c.775C>A, c.810T>G, c.1091-2A>G, and c.1399T>C) were identified in the son. Among the five mutations, four had previously been reported and the c.1399T>C was discovered for the first time. This novel mutation causes an amino acid substitution (C467R) in the CYP4V2 protein, but it was not detected in the parents. As there is no apparent relationship in genotype–phenotype correlation between the CYP4V2 gene and the occurrence of BCD, this novel mutation may be a possible cause that could induce the clinical phenotype of BCD.     

Screening for mutations in CYP4V2 gene in Japanese patients with Bietti's crystalline corneoretinal dystrophy

PURPOSE: To describe the clinical and genetic characteristics of six Japanese families with Bietti's crystalline corneoretinal dystrophy (BCD). DESIGN: Case reports and results of DNA analysis. METHODS: Mutation screening was performed on six unrelated patients with BCD by direct sequencing. The clinical features were characterized by the visual acuity, slit-lamp biomicroscopy, electroretinography, fluorescein angiography, and kinetic visual field testing. RESULTS: An identical IVS6 to 8delTCATACAGGTCATCGCG/insGC mutation in the CYP4V2 gene was identified in five of the patients with BCD; the sixth patient had a novel Trp340X mutation in the CYP4V2 gene. Three patients showed crystalline-like deposits at the limbus by specular microscopy. Ophthalmic findings of all patients had a rapid progression after age 50 years. CONCLUSIONS: Our findings suggest that the IVS6 to 8delTCATACAGGTCATCGCG/insGC mutation is a common mutation in Japanese patients with BCD. Although phenotypic variability was found, the natural course was almost the same in all of our patients.     

Genotype phenotype analysis of Bietti's crystalline dystrophy in patients with CYP4V2 mutations

PURPOSE: To evaluate the genotypic and phenotypic correlations of Bietti's crystalline dystrophy (BCD) in patients with the CYP4V2 gene by mutation screening and clinical and electrophysiological assessment. METHODS: Eighteen Chinese patients in 13 families with BCD were recruited for full ophthalmic examinations, optical coherence tomography (OCT), and visual electrophysiological tests, including electrooculography (EOG), full-field electroretinography (ERG), and multifocal electroretinography (mfERG). Peripheral venous blood was obtained from all index patients and their family members for genomic DNA extraction and CYP4V2 sequence screening by direct sequencing. RESULTS: All 18 patients with BCD had mutations in the CYP4V2 gene: five were novel (Y219H, W244X, D324V, P396L, and R400C) and four had been reported. A common mutation occurred at the splice site IVS6-8del17bp/insGC of 12 patients, four being homozygous. OCT showed the presence of intraretinal crystals in all patients. Patients with more severe thinning of the retina had worse visual acuity, and there was moderate correlation between the OCT central foveal thickness and visual acuity (Spearman rho = 0.46, P = 0.005). Patients with splice site mutations (i.e., homozygous IVS6-8del17bp/insGC or compound heterozygous IVS6-8del17bp/insGC and IVS8-2A>G) had lower EOG Arden index (P = 0.014) and were more likely to have a nonrecordable scotopic full-field ERG (P = 0.003) and nonrecordable 30-Hz flicker ERG (P = 0.043). CONCLUSIONS: BCD patients with homozygous IVS6-8del17bp/insGC or compound heterozygous IVS6-8del17bp/insGC and IVS8-2A>G mutations appeared to have more severe disease phenotype based on electrophysiological testing. The level of visual loss in BCD is related to the severity of retinal thinning.     

Novel CYP4V2 mutations associated with Bietti crystalline corneoretinal dystrophy in Chinese patients

AIM: To analyze the CYP4V2 mutations in five unrelated Chinese patients with Bietti crystalline corneoretinal dystrophy (BCD) and to provide clinical features of these patients. BCD is a rare monogenic autosomal recessively inherited disorder characterized by the presence of crystals in the retina and retinal pigment epithelium atrophy. Mutations in the CYP4V2 gene have been found to be causative for BCD.METHODS:Ophthalmic examinations were carried out in the affected individuals. Peripheral blood samples were collected and genomic DNA was extracted. All exons and flanking intronic regions of the CYP4V2 gene were amplified with polymerase chain reaction and screened for mutations by direct DNA sequencing. One hundred control chromosomes were also screened to exclude nonpathogenic polymorphisms.RESULTS: Fundus examination revealed the presence of tiny yellowish-sparkling crystals at the posterior pole of the fundus and atrophy of the retinal pigment epithelium in all patients. Choroid neovascularization was noted in one patient. Five different CYP4V2 mutations were identified, including two missense mutations (p.F73L, p.R400H), two splice site mutations (c.802-8_810del17insGC, c.1091-2A>G), and one single base-pair deletion (p.T479TfsX7 or c.1437delC). The two splice site mutations were identified in three of the patients with BCD. Mutation p.T479TfsX7 was a novel mutation not observed in any of 100 ethnically matched control chromosomes.CONCLUSION: Mutation c.802-8_810del17insGC and c.1091-2A>G are common mutations in Chinese patients with BCD. Our results expand the allelic heterogeneity of BCD.     

Characterization of Bietti crystalline dystrophy patients with CYP4V2 mutations

PURPOSE: Mutations of the CYP4V2 gene, a novel family member of the cytochrome P450 genes on chromosome 4q35, have recently been identified in patients with Bietti crystalline dystrophy (BCD). The aim of this study was to investigate the spectrum of mutations in this gene in BCD patients from Singapore, and to characterize their phenotype. METHODS: Nine patients with BCD from six families were recruited into the study. The 11 exons of the CYP4V2 gene were amplified from genomic DNA of patients by polymerase chain reaction and then sequenced. Detailed characterization of the patients' phenotype was performed with fundal photography, visual field testing, fundal fluorescein angiography, and electroretinography (ERG). RESULTS: Three pathogenic mutations were identified; two mutations, S482X and K386T, were novel and found in three patients. The third mutation, a previously identified 15-bp deletion that included the 3' splice site for exon 7, was found in all nine patients, with six patients carrying the deletion in the homozygous state. Haplotype analysis in patients and controls indicated a founder effect for this deletion mutation in exon 7. Clinical heterogeneity was present in the patients. Compound heterozygotes for the deletion in exon 7 seemed to have more severe disease compared to patients homozygous for the deletion. There was good correlation between clinical stage of disease and ERG changes, but age did not correlate with disease severity. CONCLUSIONS: This study identified novel mutations in the CYP4V2 gene as a cause of BCD. A high carrier frequency for the 15-bp deletion in exon 7 may exist in the Singapore population. Phenotype characterization showed clinical heterogeneity, and age did not correlate with disease severity.