2型Usher综合征和视网膜色素变性家系USH2A基因突变及临床表型分析

目的观察2型Usher综合征(USH2)和视网膜色素变性(RP)患者的基因突变型及其临床表型。方法2018年8月至2019年1月于河南省立眼科医院就诊的USH2和RP 3个家系的4例患者和11名正常家系成员纳入研究。详细询问病史并行视力、眼底彩色照相、OCT、视野、全视野ERG检查。3个家系中,家系1为USH2;家系2、3为RP。采集患者及其家系成员外周静脉血,提取全基因组DNA,应用基于靶向捕获的二代测序技术进行基因测序,对可疑致病突变位点通过Sanger进行验证,并在家系成员中进行共分离。结果家系1先证者除眼底有RP表现外,同时合并神经性耳聋。基因检测结果显示,先证者USH2A基因第64、5号外显子分别存在c.13877-13880 del AGAC(p.Q4626P)(M1)、c.798 del T(p.F266L)(M2)2个杂合性移码突变。家系2、3先证者仅有眼底典型RP表现。基因检测结果显示,家系2先证者USH2A基因第70、37、29号外显子分别存在c.15178T>c(p.S5060P)(M3)、c.6986C>A(p.P2329H)(M4)2个杂合性错义突变和c.5836C>T(p.R1946X)(M5)终止突变。家系3先证者USH2A基因第67、57号外显子分别存在c.14951C>T(p.P4984L)(M6)、c.11156G>A(p.R3719H)(M7)2个杂合性错义突变。保守性分析结果显示,USH2A p.Q4626P、p.F266L、p.S5060P、p.P2329H、p.P4984L所对应的氨基酸位点在多个物种中均高度保守。检测出的7个致病突变中,M1~M4、M6为新发现突变位点。结论USH2A基因突变是导致USH2和非综合征性RP的主要原因;不同突变位点影响蛋白质翻译和合成,导致不同临床表型。     

Tractional retinal detachment in Usher syndrome type II

Retinal detachment is a rare complication in patients with retinitis pigmentosa. A case is reported of tractional retinal detachment in a patient with retinitis pigmentosa and sensorineural hearing loss, which was diagnosed as Usher syndrome type II. Because of the poor visual prognosis, the patient refused surgery in that eye. Tractional retinal detachment should be added to the differential diagnoses of visual loss in patients with retinitis pigmentosa.     

视网膜色素变性1基因在常染色体显性遗传视网膜色素变性家系中的突变分析

目的:研究常染色体显性遗传视网膜色素变性(autosomal dominant retinitis pigmentosa,ADRP)家系中视网膜色素变性1(retinitis pigmentosa-1,RP1)基因的突变特征及其在RP发病机制中的作用。方法:运用聚合酶链反应和直接测序方法,对6个ADRP家系的47例成员和50例对照者进行了RP1基因全编码区和邻近剪切位点的内含子区域序列突变的筛选与检测。运用单因素分析、多因素Logistic回归分析研究RP1基因点突变在RP发病中的作用。结果:ADRP家系成员和对照组RP1基因第4外显子上检测出2个变异位点。在1691和1725密码子存在杂合的两种类型的密码子(S1691P,Ser-Pro,TCT→CCT;Q1725Q,Gln-Gln,CAA→CAG)。ADRP家系成员中Ser-1691-Pro及Gln-1725-Gln位点突变率显著高于正常对照组(χ2=11.202,P<0.05)。结论:RP1基因Ser-1691-Pro及Gln-1725-Gln位点多态性可增高RP的危险性,具有潜在的致病性,考虑为ADRP家系的易感基因。     

Usher综合征一家系的致病基因分析

目的：对一Usher综合征家系的临床特征进行分析,探索该家系的致病基因。

方法：收集于我院就诊的一视网膜色素变性家系,详细询问患者病史并进行临床检查,诊断为Usher综合征,抽取家系成员静脉血4mL,提取全基因组DNA,对先证者进行靶向捕获高通量测序获得突变位点,对于筛选出的可疑突变扩展至家系全体成员进行Sanger测序验证,同时在100名正常对照者中验证。

结果：患者除视网膜色素变性表现外,还存在轻至中度感音神经性耳聋,测序结果发现家系患者USH2A基因复合杂合突变c.2310_2311insA(p.E771Rfs*8)和c.8559-2A>G(IVS42),而在与患者有直系血缘关系的亲属中发现仅存在其中1个突变,其他家属成员和正常人中未发现该两种突变。

结论：USH2A基因为该家系的致病基因,c.8559-2A>G(IVS42)突变为已报道的热点突变,而c.2310_2311insA(p.E771Rfs*8)突变则为首次报道,本研究扩展了USH2A基因导致Usher综合征的突变谱。     

中国人与欧美人USH2A基因突变谱不同

Usher综合征是一种常见的综合征性视网膜色素变性（RP）,为常染色体隐性遗传性疾病,具有临床和遗传高度异质性。迄今已将Usher综合征的致病基因定位了12个染色体位点,确定了其中的9个致病基因。很多研究证实USH2A基因是Usher综合征的主要致病基因,USH2A基因突变还可引起单纯性RP,但国内的一些研究结果发现,中国人USH2A基因突变谱与欧美人不同。中国人RP致病的热点基因谱尚有待进一步研究。     

Variants of RP1 gene in Chinese patients with autosomal dominant retinitis pigmentosa

BACKGROUND: The objective of this study was to determine the frequency and characteristics of mutations in the RP1 gene and to characterize mutations with the clinical features in the Chinese family with autosomal dominant retinitis pigmentosa (ADRP). METHODS: Forty-three affected, unrelated Chinese individuals with ADRP were recruited between 2002 and 2006. Polymerase chain reaction and direct DNA sequencing were used to screen in the entire coding region and splice sites of the RP1 gene. Cosegregation analysis and population frequency studies were performed for patients with identified mutations. The clinical features were determined by complete ophthalmologic examinations. RESULTS: The mutation detectable rate of the RP1 gene in Chinese patients with ADRP was 1/43. A missense mutation, N985Y, was identified in exon 4 of the RP1 gene in 8 affected individuals from a Chinese family with ADRP. The ophthalmic findings with an N985Y mutation were similar to those of typical retinitis pigmentosa with delayed onset after age 40 years and slow progression. In addition, a total of 9 distinct variants were detected in our study population, most of which were RP1 gene polymorphisms; the pathological significance of P903L, a novel missense mutation, was unconfirmed. INTERPRETATION: Mutations in the RP1 gene are relatively rare in Chinese patients with ADRP. In our cases, N985Y mutation segregated with the phenotype from 1 Chinese family with mild and late-onset ADRP, a finding that has not been documented in other races.     

常染色体隐性遗传视网膜色素变性CNGA1基因突变检测

目的检测常染色体隐性遗传视网膜色素变性患者杆体α—cGMP门离子通道基因（α—cGMP—gated cation channel，CNGA1）基因突变。设计对照性实验研究。研究对象35名常染色体隐性遗传视网膜色素变性（autosomal recessive retinitis pigmentosa，ARRP）家系的先证者和55名散发病例。随机收集100名正常人作为对照。方法采集患者外周血，应用DNA分离试剂盒提取DNA，应用11对CNGA1基因引物进行聚合酶链反应（polymerase chain reaction，PCR），扩增CNGA1基因的全部编码区及内含子外显子的拼接区。利用单链构象多态性（single strand conformation polymorphism，SSCP）技术，将PCR产物进行10％非变性聚丙烯酰胺凝胶电泳，用硝酸银染色，观察有无变异带。如果发现变异带，再将该PCR产物进行DNA测序。主要指标通过PCR，SSCP和DNA测序技术，发现CNGA1基因突变。结果未发现CNGA1基因突变。结论CNGA1基因突变在国人RP患者中的致病情况有待进一步研究。     

IMPDH1基因突变与视网膜色素变性的研究进展

视网膜色素变性(RP)是视网膜感光细胞和色素上皮细胞变性导致的最常见的遗传性致盲眼底病,具有高度的遗传异质性及临床异质性。IMPDH1存在于全身各处器官中。近年来对RP发病机制的探讨已成为研究热点。随着对IMPDH1基因研究的深入,人们发现IMPDH1基因对RP的发病机制研究有着重要意义。对于这种致病基因的结构、突变及其功能目前已有了新的研究进展。本文综述了IMPDH1基因在视网膜色素变性中的最新研究进展。     

常染色体显性遗传视网膜色素变性家系视紫红质基因突变分析

目的:观察常染色体显性遗传视网膜色素变性(autosomaldominantRP,ADRP)家系视紫红质基因(rhodopsin,RHO)的突变特征。方法:抽取11个ADRP家系成员的外周血3～5mL,提取DNA;应用聚合酶链反应(polymerasechainreaction,PCR)扩增RHO基因的第1至5外显子基因片断,对PCR产物进行直接测序。结果:在1个家系中有3例ADRP患者297密码子存在杂合的2种类型的密码子(AGC和AGT)。另外,该家系在第3外显子3'端下游第4个碱基处发生C-T转换,呈T纯合子的1例,8例呈杂合子状态。结论:Ser-297-Ser系基因多态现象。另外,RHO基因第3外显子3'端下游内含子处发生的C/T多态性是否与RP的发生存在相关性,需进一步研究。     

Genetic screening of Russian Usher syndrome patients toward selection for gene therapy

ABSTRACT

Background: Usher syndrome (USH) is heterogeneous in nature and requires genetic test for diagnosis and management. Mutations in USH associated genes are reported in some populations except Russians. Here, we first time represented the mutation spectrum of a Russian USH cohort.

Methods: Twenty-eight patients with USH were selected from 3214 patients from Deaf-Blind Support Foundation “Con-nection” during 2014–2016 following the observational study NCT03319524. Complete ophthalmologic, ENT, and vestibular medical tests were done for clinical characterization. NGS, MLPA, and Sanger sequencing were considered for genetic analysis.

Results: Around 53.57% and 39.28% patients had USH1 and USH2, respectively; 17.85% cases (n = 5/28) had no known mutation. Eleven (73.33%) subjects showed variations in USH1 associated genes MYO7A (72.72%), CDH23 (9.09%), PCDH15 (9.09%), and USH1C (9.09%). Eleven mutations are detected in MYO7A where 54.54% are novel. MYO7A: p.Q18* was most frequent (27.27%) mutation and is associated with early manifestation and most severe clinical picture. Two novel mutations (p.E1301* and c.158-?_318+?del) are detected in PCDH15 gene. Around 90.90% patients suspected to be USH2 are confirmed by genetic testing. Eleven mutations detected in the USH2A gene, where 27.27% were novel. Most common USH2A mutation is p.W3955* (50%) followed by p.E767fs, p.R1653*, and c.8682-9A> G (20% each).

Conclusion: The Russian USH cohort shows both novel and known USH mutations. Clinically the prevalence of USH2 is low (39.28%) and the frequency of MYO7A mutations responsible for USH1B is very high (63.63%, N = 7/11) compared to other cohorts. These seven patients carrying MYO7A mutations are preliminarily eligible for the UshStat® gene therapy.     

Usher综合征与USH2A基因的研究进展

Usher综合征(USH)是一种以先天性感音神经性聋和视觉功能进行性丧失为特征的遗传性疾病,具有高度的遗传异质性及临床异质性,目前尚无有效的预防和治愈方法。目前已知USH有14个致病基因,USH2A突变是其最常见的原因。随着对USH2A基因研究的深入,USH2A致病机制、动物模型建立、临床诊断以及基于基因治疗、细胞移植和RNA剪接的治疗等方面研究皆取得了巨大进展。如,USH2A的突变导致参与外周纤毛区运输功能的USH复合体蛋白产生缺陷;基于此致病机制的小鼠及斑马鱼动物模型被建立,但存在其各自局限性;通过成簇规律间隔的短回文重复序列及其相关蛋白9系统对患者来源诱导多功能干细胞进行纠正后,将其诱导为视器官以进行临床的功能纠正性移植和基于反义寡核苷酸的RNA剪接治疗在此病的治疗中属于前景性研究。     

A novel splice-site variant in CDH23 in a patient with Usher syndrome type 1

ABSTRACT

Background: Gene editing has shown huge potential in correcting aberrant splicing and Cas13 has been identified as being particularly suitable for targeting RNA. It has therefore become increasingly important to highlight new splice site mutations that may be correctable, particularly in genes that are too large to be encoded by AAV vectors. About 20% of Usher Type 1 cases are caused by mutations in CDH23.

Purpose: To report a novel splice site mutation of CDH23 associated with Usher Type 1D.

Materials and Methods: Case report.

Results: A 35-year-old Caucasian female who is congenitally deaf with vestibular dysfunction presented with visual acuity of 6/12 in both eyes. Fundus examination revealed findings typical of retinitis pigmentosa with foveal preservation of photoreceptor layer. Next generation sequencing analysis revealed a novel homozygous variant, c.9319 + 1G>T in CDH23 consistent with the diagnosis of Usher Syndrome Type 1D. The c.9319 + 1G>T variant is predicted to affect splicing at the exon 65/intron 65 boundary, which highly likely leads to complete skipping of exon 65.

Conclusions: We describe a case of a typical Usher Syndrome Type 1D caused by a novel splice site variant in CDH23. Currently there are no treatments for CDH23 related retinal degeneration, partly because the cDNA size of 10kb is too large for AAV vector gene augmentation therapy. Alternative strategies include CRISPR-Cas9 adenine base editors and RNA editing with CRISPR-Cas13. Single-nucleotide editing represents a promising approach for targeting this variant in CDH23 to restore the wildtype splice donor site at this position.     

常染色体显性遗传RP患者视紫红质基因突变的检测分析

目的研究常染色体显性遗传视网膜色素变性（ADRP）患者视紫红质（RHO）基因的突变特征及其在视网膜色素变性（RP）发病机制中的作用。方法应用变性高效液相色谱分析（DHPLC）技术和直接及克隆测序方法对RHO基因进行突变检测。结果一家系4例ADRP患者RHO基因的第297密码子存在杂合的两种类型密码子（AGC和AGT）。该家系的另3名患者未检测到该突变，对照组发现1例此类型沉默型突变。该家系在第3外显子3’端下游第4个碱基处发生C—T转换，其11个成员中该位点呈T纯合子1例，呈杂合子状态8例。对照组发现2例该位点的杂合子状态。结论视紫红质基因Ser-297-Ser突变与RP疾病未出现“共分离”现象，因此该沉默型突变不是该ADRP家系的致病原因，系RHO基因的多态现象。     

Retinitis pigmentosa in Usher syndrome in India: Electronic medical records driven big data analytics: Report III

Purpose:To describe the clinical presentation and demographic distribution of retinitis pigmentosa (RP) in patients with Usher syndrome (USH).Methods: This is a cross-sectional observational hospital-based study including patients presenting between March 2012 and October 2020. In total, 401 patients with a clinical diagnosis of USH and RP in at least one eye were included as cases. The data were retrieved from the electronic medical record database. For better analysis, all 401 patients were reclassified into three subtypes (type 1, type 2, and type 3) based on the USH criteria.Results: In total, there were 401 patients with USH and RP, with a hospital-based prevalence rate of 0.02% or 2/10,000 population. Further, 353/401 patients were subclassified, with 121 patients in type 1, 146 patients in type 2, and 86 patients in the type 3 USH group. The median age at presentation was 27 years (IQR: 17.5–38) years. There were 246 (61.35%) males and 155 (38.65%) females. Males were more commonly affected in all three subtypes. Defective night vision was the predominant presenting feature in all types of USH (type 1: 43 (35.54%), type 2: 68 (46.58%), and type 3: 40 (46.51%) followed by defective peripheral vision. Patients with type 2 USH had more eyes with severe visual impairment.Conclusion: RP in USH is commonly bilateral and predominantly affects males in all subtypes. Patients with USH and RP will have more affection of peripheral vision than central vision. The key message of our study is early visual and hearing rehabilitation in USH patients with prompt referral to otolaryngologists from ophthalmologists and vice versa.     

The ophthalmological course of Usher syndrome type III

Usher syndrome is a recessive hereditary disease group with clinical and genetical heterogeneity leading to handicapped hearing and visual loss until middle age. It is the most common cause for deaf-blindness. Three distinct phenotypes and five distinct genotypes are already known. In Finland the distribution of known Usher types is different than elsewhere. Usher syndrome type III (USH3) is common in Finland and it is thought to include 40% of patients. Progressive hearing loss is characteristic of USH3. Elsewhere USH3 has been regarded as a rarity covering only several percent of the whole Usher population. The aim of this paper is to describe, for the first time, the course of visual handicap and typical refractive errors in USH3 and compare it with other USH types. From a total patient sample consisting of 229 Finnish USH patients, 200 patients' visual findings were analyzed in a multicenter retrospective follow-up study. The average progress rate during a 10-year follow-up period in different USH types was similar. The essential progress occurred below the age of 40 and was continuous up to that age. Visual acuity dropped below 0.05 (severely impaired) at the age of 37 and the visual fields were of tubular shape without any peripheric islands at the average age of 30. Clinically significant hypermetropia with astigmatism seems to be a pathognomonic clinical sign of USH3.     

常染色体遗传型视网膜色素变性相关基因的研究进展

视网膜色素变性（RP）是常见的致盲性眼病,具有高度的遗传性和表型异质性。RP致病基因的确立对探讨该病的发病机制、预防和治疗具有重要的意义。近年来,RP的研究有了新的进展,就常染色体显性遗传RP（adRP）与常染色体隐性遗传RP（arRP）相关基因的研究进行综述,归纳其中常见致病基因的作用及其突变发病的可能机制,为RP的研究提供一定参考。     

Extended mutation spectrum of Usher syndrome in Finland

Purpose: The Finnish distribution of clinical Usher syndrome (USH) types is 40% USH3, 34% USH1 and 12% USH2. All patients with USH3 carry the founder mutation in clarin 1 (CLRN1), whereas we recently reported three novel myosin VIIA (MYO7A) mutations in two unrelated patients with USH1. This study was carried out to further investigate the USH mutation spectrum in Finnish patients. Methods: We analysed samples from nine unrelated USH patients/families without known mutations and two USH3 families with atypically severe phenotype. The Asper Ophthalmics USH mutation chip was used to screen for known mutations and to evaluate the chip in molecular diagnostics of Finnish patients. Results: The chip revealed a heterozygous usherin (USH2A) mutation, p.N346H, in one patient. Sequencing of MYO7A and/or USH2A in three index patients revealed two novel heterozygous mutations, p.R873W in MYO7A and c.14343+2T>C in USH2A. We did not identify definite pathogenic second mutations in the patients, but identified several probably nonpathogenic variations that may modify the disease phenotype. Possible digenism could not be excluded in two families segregating genomic variations in both MYO7A and USH2A, and two families with CLRN1 and USH2A. Conclusion: We conclude that there is considerable genetic heterogeneity of USH1 and USH2 in Finland, making molecular diagnostics and genetic counselling of patients and families challenging.     

视网膜色素变性患者视锥杆细胞同源盒基因突变的研究

目的:研究视锥杆细胞同源盒基因(CRX)在宁夏地区视网膜色素变性(rentinitis pigmentosa,RP)患者中的突变频率及特征,并进一步探讨其在RP发病机制中潜在的机制。方法:运用聚合酶链反应(PCR)和直接测序方法,对100例RP患者(包括18例ADRP患者,15例ARRP患者,67例SRP患者)进行了CRX基因全编码区序列突变的检测,运用多因素分析研究CRX基因突变位点对RP的作用。结果:在100例RP患者CRX基因上共检测出5个变异位点,其中p.Leu78Leu,p.Ala92Ala和p.Thr187Ile为新发现的突变。其余位点突变均证实为CRX基因的多态性。p.Thr187Ile突变位点仅在2例ARRP患者身上检出,在正常对照组未发现该位点突变。结论:宁夏地区RP患者中,CRX基因的突变率低于其他人群中(小于1%)。p.Thr187Ile不是RP的致病性突变,但它是否可能通过影响其它基因的表达,增加常染色体显性遗传视网膜色素变性(ARRP)的发生,有待于进一步研究。     

常染色体显性视网膜色素变性NRL基因的突变研究

目的 对中国人常染色体显性视网膜色素变性（RP）NRL基因的突变现状进行研究。方法 抽取120例RP先证者的静脉血提取DNA。行NRL基因的引物设计合成，PCR扩增，琼脂糖电泳鉴定，异源双连-SSCP电泳。结果 120例散发型RP患者未发现NRL基因突变。结论 中国人RP NRL基因的突变频率很低。     

视网膜色素变性光感受器发育相关基因分型的研究

目的 探讨一新近发现的与氧调节光感受器发育相关基因(0RPl)在常染色体显性遗传(RP)发病机制中的作用。方法 运用聚合酶链反应(PCR)、构象敏感凝胶电泳(CSGE)和DNA直接测序方法对92例RP患者0RPl基因全编码区进行突变的筛选与检测。结果 检出一0RPl致病突变因子R677X，并首次发现一非致病的无义突变出子R1933X。结论 预测香港地区大约有1．1％(95％的可信区间为5．4％以下)的RP是由0RPl基因突变所致。R1933X无致病意义，结合最近发现的Y1053(1—bPdel)的病理意义，推测密码子1052至1933区域的稳定对0RPl结构及功能的维持起着重要的作用。