一个中国视网膜色素变性家系的分子遗传学分析

发布时间：2018-07-10 00:09

本文选题：视网膜色素变性 + 基因　；参考：《南昌大学》2017年硕士论文

【摘要】：背景:视网膜色素变性(retinitis pigmentosa,RP)是与视锥细胞和视杆细胞(光感受器)或色素上皮结构或功能异常相关的一类进行性致盲性遗传眼病。国外患病率约为1/4000,我国患病率约为1/3467。视网膜色素变性的典型临床特征为:早期出现夜盲,随着病情进展逐渐出现进行性视野缩小和视力下降、视盘蜡黄色萎缩、视网膜骨细胞样色素沉着等。视网膜色素变性具有高度的遗传异质性,据其遗传方式可分为常染色体显性遗传(autosomal dominant RP,adRP)、常染色体隐性遗传、X-连锁遗传、双基因型遗传和线粒体DNA遗传。常染色体显性遗传在视网膜色素变性患者中所占比例为15%-20%,目前已确定与adRP有关的基因约有14个,包括CA4、CRX、GUCA1B、IMPDH1、NRL、PRPF8、PRPF3、PRPF31、RHO、RDS、ROM1、RP9、RP1、SEMA4A。NRL(neural retinal leucine zippe,神经视网膜亮氨酸拉链基因)基因编码碱性亮氨酸拉链蛋白(basic motif-leucine zipper,bZIP),其对光感受器特异性基因-视紫红质(rhodopsin,RHO)基因的表达起调控作用。目的:对一个视网膜色素变性家系进行临床特点分析和遗传学分析,明确其致病突变及可能发病机制。方法:收集一视网膜色素变性家系的所有家系成员的临床资料,对本家系的5例患者和数名正常家庭成员进行全面的眼科检查,各取外周血2ml,提取外周静脉血细胞基因组DNA。应用眼科RP候选基因芯片(共包含59个目标基因),采用目标区域捕获二代测序对先证者进行基因突变分析,应用一代测序验证对家系成员突变位点情况验证,应用UCSC在线及polyhpen-2对突变位点进行生物信息学分析。结果:该家系中连续3代,所有患者均有典型的色素型视网膜色素变性表现,临床上表现为不同程度夜盲、周边视野缩窄、中心视力下降,该家系遗传学研究发现该病在家系中呈现常染色体显性遗传,该家系3例患者的RP候选基因遗传分析结果显示,NRL基因第号外显子上中均发现单一杂合突变c.152CT,该家系其他正常成员均未发现此突变,与该家系涉及的疾病呈共分离的特点。在蛋白水平,此突变导致NRL基因51位上编码氨基酸由脯氨酸变为亮氨酸。结论:我们对一个中国视网膜色素变性家系进行了详细的临床检查,该本研究中家系成员共3代,每一代均有视网膜色素变性患者,家系中患者均有夜盲、视力下降、视野缩窄的临床表现;对该家系进行分子遗传学分析,发现了导致该家系患者患病的致病性突变c.152CT(p.Pro51Leu),该突变导致bZIP蛋白第152位脯胺酸被亮氨酸取代,进而影响蛋白质的功能。
[Abstract]:Background: retinitis pigmentosa RP (RP) is a kind of progressive blindness hereditary ophthalmopathy associated with conus cells and rod cells (photoreceptors) or abnormal structure or function of pigment epithelium. The prevalence rate in foreign countries is about 1 / 4 000 and in China is about 1 / 3 467. The typical clinical features of retinitis pigmentosa are as follows: early night-blindness, progressive narrowing of visual field and visual acuity, wax-yellow atrophy of optic disc, retinal osteocytoid pigmentation and so on. Retinitis pigmentosa has a high degree of genetic heterogeneity. According to its genetic pattern, it can be divided into autosomal dominant inheritance (autosomal dominant), autosomal recessive inheritance (X-), double genotype inheritance and mitochondrial DNA inheritance. The proportion of autosomal dominant inheritance in retinitis pigmentosa patients is 15 to 20. At present, there are about 14 genes related to adRP that have been identified. These genes include CA4, CRXG, GUCA1B, IMPDH1, NRLN, PRPF8, PRPF3, PRPF31, RDS-ROM1, RP9, RP1, SEMA4A.NRL (neural retinal leucine zippe, encoding basic leucine zipper protein (basic motif-leucine zipperbZIP), which plays a regulatory role in the expression of the photoreceptor specific gene rhodopsin Rho (rhodopsin Rho) gene. Objective: to analyze the clinical and genetic characteristics of a pedigree with retinitis pigmentosa, and to identify the mutation and possible pathogenesis of retinitis pigmentosa. Methods: the clinical data of all the family members of a family with retinitis pigmentosa were collected, and 5 patients and several normal family members were examined by ophthalmology. The peripheral blood 2ml was taken and the genomic DNA of peripheral venous blood cells (DNA) was extracted. Using ophthalmic RP candidate gene chip (including 59 target genes), the gene mutation of the proband was analyzed by target region capture second generation sequencing, and the mutation loci of the family members were verified by the first generation sequencing. UCSC and polyhpen-2 were used for bioinformatics analysis of mutation sites. Results: all the patients had typical pigmented retinitis pigmentosa. The clinical manifestations were night blindness, peripheral visual field constriction and central visual acuity decline. The pedigree genetic study found that autosomal dominant inheritance was present in the homelands. Genetic analysis of RP candidate genes in 3 patients in this family showed that a single heterozygous mutation c.152CTwas found in exon number 1 of the NRL gene, but no mutation was found in other normal members of the family, which was coisolated from the disease involved in the family. At the protein level, the mutation resulted in the conversion of amino acids from proline to leucine at position 51 of the NRL gene. Conclusion: a Chinese pedigree with retinitis pigmentosa was examined in detail. In this study, there were 3 generations of family members, each generation of patients with retinal pigmentosa, all the patients in the family had night blindness, visual acuity was decreased. The clinical manifestation of visual field constriction, molecular genetic analysis of the family, found the pathogenicity mutation c.152CT (p.Pro51Leu), which caused the 152nd proline of bZIP protein to be replaced by leucine, and then affected the function of protein.
【学位授予单位】：南昌大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：R774.1

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