Leber先天性黑蒙基因研究进展

Leber先天性黑蒙(LCA)是导致婴幼儿先天性盲的严重遗传性视网膜疾病。近年发现数种与LCA相关的致病基因,主要包括GUCY2D、RPE6 5、CRX、AIPL1、RPGRIP1和CRB1,其功能涉及视网膜光电信号的传导、维生素A在视网膜的代谢、光感受器细胞的分化和形态发育、蛋白的转运和分布等。针对RPE6 5的基因治疗在动物实验中取得了一定的成果,将是未来LCA临床治疗的主要研究方向。本文就当前LCA的致病基因及其可能的发病机制、基因治疗等方面的研究进展作一综述。     

Leber先天性黑矇的基因治疗研究进展

Leber先天性黑矇(LCA)是一种严重的先天性致肓遗传性视网膜疾病.近1O年来,随着分子遗传学的发展及基因治疗技术的进步,以腺相关病毒载体介导的LCA基因治疗研究取得了令人鼓舞的进展,尤其是对LCAⅡ患者进行的RPE65基因治疗的Ⅰ期临床试验的成功使其成为眼科遗传性疾病基因治疗领域中的先行者,为今后进行其他遗传性视网膜疾病的基因治疗开辟了光明的前景.本文就目前LCA基因治疗的临床前研究及Ⅰ期临床试验的进展等方面作一综述.

Abstract：

Leber congenital amaurosis (LCA)is an early onset retinal dystrophy that causes severe visual impairment. With the development of molecular genetics and the therapeutic gene replacement technology, the adeno-associated viral (AAV) vector-mediated gene therapy for LCA achieved encouraging progress in the past decade. The success of the Phase Ⅰ clinical trials of human RPE65 gene therapy for LCA Ⅱ patients makes it a pioneer in the field of retinal gene therapy and brings light to the cure of other hereditary retinopathy. This article briefly reviews the recent developments in the preclinical animal experiments and Phase Ⅰ clinical trials for LCA.     

Leber先天性黑蒙基因研究进展

Leber先天性黑蒙(LCA)是导致婴幼儿先天性盲的严重遗传性视网膜疾病。近年发现，数种与LCA相关的致病基因，主要包括GUCY2D、RPE65、CRX、AIPL1、RPGRIP1和CRB1，其功能涉及视网膜光电信号的传导、维生素A在视网膜的代谢、光感受器细胞的分化和形态发育、蛋白的转运和分布等。针对RPE65的基因治疗在动物实验中取得了一定的成果，将是未来LCA临床治疗的主要研究方向。本就当前LCA的致病基因及其可能的发病机制、基因治疗等方面的研究进展作一综述。     

利用目标区域捕获测序筛查Leber先天性黑矇的致病基因及其临床表型

目的探讨我国一个散发的Leber先天性黑矇（LCA）家系的致病基因变异位点及其临床表型。方法实验研究。收集嘉兴市妇幼保健院一个散发LCA家系共7名家庭成员的临床资料,其中1名LCA患者,6名正常家属。完善该家系内所有成员的眼科检查,采集该家系成员的外周静脉血,提取基因组DNA,运用目标区域捕获测序技术来筛查患者的283个视网膜疾病相关的基因,测序结果运用生物信息学分析得到候选基因,最后用Sanger测序验证。结果临床检查结果表明患者呈现典型的LCA临床症状。遗传学筛查结果证实患者在NMNAT1基因上存在2个复合杂合变异和1个纯合变异：具体为杂合的错义变异（c.634G>A,p.V212M）,杂合的内含子变异（c.-57+7T>G）和纯合的错义变异（c.764G>A,p.S255N）。结论本例患者的NMNAT1基因上存在3个不同的变异,很可能是导致其患有Leber 先天性黑矇的原因。     

Leber先天性黑矇致病基因研究及基因治疗进展

Leber先天性黑矇(LCA)是一种严重的遗传性视网膜病变,具有遗传异质性与表型多样性的特点。近年来的遗传学研究相继发现多个致病基因与LCA发病相关,并对这些致病基因的发病机制作了进一步研究。LCA基因治疗已经从临床前期动物研究阶段进入Ⅰ期临床试验阶段,尤其是在LCAⅡ型患者中进行的RPE65基因治疗方面取得了突破性进展,为其他遗传性视网膜疾病的基因治疗打下良好的基础。     

Leber先天性黑蒙临床与GUCY2D基因突变分析

目的 分析Leber先天性黑蒙的临床特点及其候选基因变异情况。方法 连续收集分析27例年龄4mo-18a的Leber先天性黑蒙先证者临床资料,应用PCR-异源双链-SSCP法分析GUCY2D基因外显子2和8,寻找可能的变异结果 27例患者均在2a以内出现视力差或对光、物体无反应,最最好视力小于0.1。症状年龄21例在3mo内,27例均有眼球震颤（其中15例为眼球扫视运动）,22例有眼底异常,5例眼底未见异常,3例有家族史并呈常染色体隐性遗传,ERG锥杆反应重度下降或记录不到波,未发现GUCY2D基因突变。结论 Leber先天 性黑蒙临床表现多样,诊断有赖于ERG。本组病例可能与GUCY2D外显子2、8突变无关。     

RPGRIP1基因新突变致Leber先天性黑矇一家系

目的确定1个汉族Leber先天性黑矇(LCA)家系的致病基因突变。方法回顾性研究。2018年10月在河南省立眼科医院就诊的LCA一家系1例患者和3名家系成员纳入研究。详细询问患者病史并行物体注视性质、追随试验、裂隙灯显微镜、散瞳验光、眼底照相及全视野ERG检查;家系成员行BCVA、裂隙灯显微镜联合前置镜、验光、眼底照相及全视野ERG检查。采集先证者及其兄长、父母的外周静脉血5 ml,提取全基因组DNA。应用包含441个致病基因的遗传眼病捕获芯片进行靶向捕获富集高通量测序以获得致病基因及突变。对可疑致病突变位点通过Sanger进行验证,并行生物信息学分析确定基因突变位点的致病性。结果患者表现为自幼不追物但有明显畏光和眼球震颤;双眼眼前节及眼底无异常;全视野ERG检查可见双眼视锥、视杆系统功能严重下降。基因检测结果显示,患者RPGRIP1基因存在c.1635dupA和c.3565C>T两个突变。其中,RPGRIP1 c.1635dupA为新发突变。RPGRIP1基因c.1635dupA和c.3565C>T构成复合杂合突变。生物信息学分析结果显示,c.3565C>T为致病突变,c.1635dupA为可能致病突变。结论RPGRIP1基因新发突变c.1635dupA与c.3565C>T构成复合杂合突变可能是本家系的致病原因。     

利用全外显子组测序法筛选Leber先天性黑矇一家系候选致病基因的实验研究

目的利用全外显子组测序法筛选Leber先天性黑矇(LCA)一个家系的候选致病基因,为补充或验证LCA致病基因的研究奠定基础。方法采用横断面研究方法。收集一个在深圳市眼科医院就诊的中国汉族LCA家系的临床资料。详细询问并记录全部家系成员的疾病史、家族史及婚育史,并对全部家系成员进行全面的身体检查。其中,眼部检查项目包括视力、眼位、眼压、验光、眼球运动情况、眼前段、眼底照相、光学相干断层扫描及视网膜电图检查等。提取先证者、另外1例患者及其父母的静脉血基因组DNA,采用磁珠提取法对DNA进行提纯。使用高通量测序平台对质量检测通过的DNA文库进行测序。在进行生物信息学分析时,对采集的数据行标准信息分析流程处理,同时对数据进行质控检测。采用GATK基因组分析网络工具库检索单核苷酸多态性位点和缺失标记位点的数量。测序结果经生物信息学分析工具Seattle Seq Annotation138注释后,与人类HAPMAP、db SNP138、Exome Sequencing Project及Exome Aggregation Consortium数据库进行比对。过滤掉已报道的常见变异后,再过滤掉位于非编码区的变异和同义突变,并进一步筛选出该LCA家系的候选致病基因。结果该家系成员共有3代16人。其中,3名LCA患者均为第Ⅱ代成员,第Ⅰ代及第Ⅲ代成员均无发病者,符合常染色体隐性遗传规律。经测序及分析后,得到17个LCA的候选致病基因,分别为ACTN1、C1QTNF3、FAN1、MMP28、MYO9B、NAV1、NUP62、PHLDB3、PRDM12、SLC24A4、ST3GAL3、TCIRG1、TP53、USP54、YIF1B、ZDHHC17及ZNF107。这些基因均与目前已报道的24个LCA相关的致病基因不同。结论对该家系的DNA进行分析后,发现了17个新的LCA候选致病基因,可为进一步明确该家系LCA致病基因的研究奠定了基础。     

AIPL1突变患者先天性Leber黑蒙表现型

目的：叙述26例先证者中芳香族羟基碳氢化合物受体蛋白样1蛋白质（AIPL1）突变的先天性Leber黑蒙（LCA）的表现型，并比较其他LCA相关性基因的表现型。叙述杂合子携带者的视网膜电图（ERG）。     

Comprehensive analysis of genetic variations in strictly-defined Leber congenital amaurosis with whole-exome sequencing in Chinese

AIM: To make a comprehensive analysis of the potential pathogenic genes related with Leber congenital amaurosis (LCA) in Chinese. METHODS: LCA subjects and their families were retrospectively collected from 2013 to 2015. Firstly, whole-exome sequencing was performed in patients who had underwent gene mutation screening with nothing found, and then homozygous sites was selected, candidate sites were annotated, and pathogenic analysis was conducted using softwares including Sorting Tolerant from Intolerant (SIFT), Polyphen-2, Mutation assessor, Condel, and Functional Analysis through Hidden Markov Models (FATHMM). Furthermore, Gene Ontology function and Kyoto Encyclopedia of Genes and Genomes pathway enrichment analyses of pathogenic genes were performed followed by co-segregation analysis using Fisher exact Test. Sanger sequencing was used to validate single-nucleotide variations (SNVs). Expanded verification was performed in the rest patients. RESULTS: Totally 51 LCA families with 53 patients and 24 family members were recruited. A total of 104 SNVs (66 LCA-related genes and 15 co-segregated genes) were submitted for expand verification. The frequencies of homozygous mutation of KRT12 and CYP1A1 were simultaneously observed in 3 families. Enrichment analysis showed that the potential pathogenic genes were mainly enriched in functions related to cell adhesion, biological adhesion, retinoid metabolic process, and eye development biological adhesion. Additionally, WFS1 and STAU2 had the highest homozygous frequencies. CONCLUSION: LCA is a highly heterogeneous disease. Mutations in KRT12, CYP1A1, WFS1, and STAU2 may be involved in the development of LCA.     

Peripapillary sparing in RDH12-associated Leber congenital amaurosis

Background: Peripapillary sparing is a characteristic that is traditionally described as pathognomonic for Stargardt disease.

Materials and methods: We present a multimodal assessment of four Leber congenital amaurosis (LCA) cases with congenital macular atrophy and severely attenuated electroretinogram findings caused by bilallelic mutations in RDH12.

Results: Fundus autofluorescence imaging revealed a general loss of retinal pigment epithelium across the macula except for the peripapillary region in both eyes of all patients. Spectral domain-optical coherence tomography confirmed relative preservation in this area along with retinal thinning and excavation throughout the rest of the macula. LCA was diagnosed based on clinical exam and retinal imaging, and subsequently confirmed with genetic testing.

Conclusions: Peripapillary sparing is a novel phenotypic feature of RDH12-associated LCA.     

A high prevalence of biallelic RPE65 mutations in Costa Rican children with Leber congenital amaurosis and early-onset retinal dystrophy

Background: Leber congenital amaurosis (LCA) and early-onset retinal dystrophy (EORD), are primary causes of inherited childhood blindness. Both are autosomal recessive diseases, with mutations in more than 25 genes explaining approximately ~70% of cases. However, the genetic cause for many cases remains unclear. Sequencing studies from genetically isolated populations with increased prevalence of a disorder has proven useful for rare variant studies, making Costa Rica an ideal place to study LCA/EORD genetics.

Materials and Methods: Twenty-eight affected children (25 LCA, three EORD) and their immediate family members, totaling 52 individuals (30 affected) from 22 families, were sequenced. Whole exome sequencing was performed on all affected individuals. Available parents were analyzed either by whole exome sequencing (WES) or Sanger sequencing to determine transmission.

Results: All affected individuals demonstrated compound heterozygous or homozygous mutations in known Inherited Retinal Disease (IRD) associated genes. Twelve variants were identified in at least one individual in three genes, RDH12, RPE65, and USH2A. Four recurrent RPE65 mutations were observed in 97% of individuals and 95% of families. All patients with LCA and two of the three individuals with EORD had biallelic mutations in RPE65; one child with EORD had a homozygous RDH12 mutation.

Conclusions: These data suggest that the majority of LCA/EORD in Costa Rica is due to four founder mutations in RPE65 which have been maintained in this genetically isolated population. This finding is of great clinical significance due to the availability of gene therapy recently approved in the US and European Union for patients with biallelic RPE65 defects.     

Analysis of three genes in Leber congenital amaurosis in Indonesian patients

PURPOSE: To assess the frequency, the pattern of disease causing mutations, and phenotypic variations in patients with Leber congenital amaurosis (LCA) from Indonesia. PATIENTS AND METHODS: Twenty-one unrelated index cases with a clinical diagnosis of LCA were screened for mutations in the coding sequence of RetGC1, RPE65 and AIPL1 gene with single strand conformation polymorphism analysis followed by direct sequencing and restriction enzyme digestion. RESULTS: Four novel disease causing mutations were identified: Three in the RPE65 gene (106del9bp, G32V and Y435C) in two of 21 index cases and one in the AIPL1 (K14E). Two of them were homozygous and one was compound-heterozygous. No disease causing mutation was identified in RetGC1. CONCLUSIONS: The four novel disease causing mutations identified in this study confirmed the diagnosis of LCA which has not been recognized before in Indonesia. The frequency of RPE65 mutations was 9.5%; and of AIPL1 mutations 4.8%. This was in general accordance with previous studies reported from other countries. Unlike in those studies, no disease causing RetGC1 mutations could be identified in our patients. Phenotypically, the RPE65 and AIPL1 mutations identified in this study caused nearly total blindness by the second decade of life, but had a different onset of symptoms. The patients with the RPE65 mutations retained some useful visual function until the end of the first decade, which progressed to total blindness during the second decade of life, whereas the (homozygous) AIPL1 mutation was associated with nearly total blindness from infancy on. Therefore, RPE65 mutations have to be considered to cause early onset severe retinal degeneration (EOSRD), and AIPL1 mutations a form of LCA.     

Mutation screen of the TUB gene in patients with retinitis pigmentosa and Leber congenital amaurosis

TUB is the first identified member of the TULP family of four proteins with unknown function. A spontaneous mutation in murine tub causes retinal degeneration, obesity, and deafness. Mutations in another member of the TULP family, TULP1, are a cause of autosomal recessive retinitis pigmentosa (RP). These findings prompted us to investigate TUB as a candidate gene for RP and Leber congenital amaurosis (LCA). A mutation screen of the entire coding region of the TUB gene in 159 unrelated patients with autosomal recessive RP, 114 unrelated patients with simplex RP, and 21 unrelated patients with LCA uncovered 18 sequence variations. Of these, seven were missense mutations, six were isocoding changes, and five were intronic polymorphisms. All seven missense mutations were identified as heterozygous changes and no defect could be found in the other allele. None of the isocoding variants or intronic polymorphisms are predicted to create or destroy splice donor or acceptor sites based on splice-site prediction software. Although variant alleles of the TUB gene were found, none could be definitively associated with a specific retinal disease.     

先天性特发性眼球震颤的遗传学研究进展

先天性特发性眼球震颤（CIN）是一种非自主性、有节律的眼球运动性疾病,是由于眼运动中枢传出机制缺陷而视觉及神经系统无明显受损的原发性疾患。CIN具有多种遗传方式,包括常染色体显性遗传、常染色体隐性遗传及X连锁遗传。近年来,通过基因定位的方法已发现多个与CIN相关的基因位点,同时也筛选了一些候选致病基因。就CIN的基因定位及相关致病基因的克隆进行综述。