视网膜色素变性分子遗传学研究现状

视网膜色素变性是由于视网膜感光细胞和色素上皮细胞变性导致夜盲和进行性视野缺损的最常见的遗传性眼底病 ,具有大的临床和遗传异质性。其遗传方式可为常染色体显性、常染色体隐性、X染色体连锁遗传和散发型。目前已发现RP相关基因 1 4种 ,其中常染色体显性遗传 4种 ,常染色体隐性遗传 8种 (包括视紫质 ) ,X染色体连锁遗传 2种。本文着重阐述了已知RP相关基因的研究现状。     

家族性渗出性玻璃体视网膜病变致病基因及信号传导途径

家族性渗出性玻璃体视网膜病变(FEVR)是一种遗传性视网膜血管发育异常的疾病。其遗传方式包括常染色体显性遗传、常染色体隐性遗传和X染色体连锁隐性遗传等3种。其中，常染色体显性遗传主要与Wnt受体Frizzled-4 (FZD4)和共受体低密度脂蛋白受体相关蛋白5(LRP5)基因位点突变相关;X染色体隐性遗传主要与Norrie病(NDP)基因突变相关；常染色体隐性遗传主要是LRP5基因位点的突变。3种与FEVR相关的致病基因均与Wnt信号传导途径有紧密关联。位于常染色体7q31的四旋蛋白12(Tspan-12)位点的突变也可以导致FEVR，它参与了Norrin-β-catenin信号传导途径。     

视网膜色素变性的相关基因研究进展

视网膜色素变性(RP)是由于视网膜感光细胞和色素上皮细胞变性导致夜盲和进行性视野缺损的一种常见的、遗传性、致盲性眼底病,具有较大的临床和遗传异质性。迄今通过连锁分析和侯选基因筛查,已有14个常染色体显性遗传ADRP;20个常染色体隐性遗传ARRP和5个X-染色体连锁遗传型XLRP位点被定位,其中32个基因已被克隆,每种遗传方式都有多个基因被克隆。对于这些致病基因的结构、突变及其功能目前已经有了新的研究进展。     

常染色体显性遗传视网膜色素变性患者视紫红质基因和视网膜变性慢基因突变检测分析

视网膜色素变性(RP)是一组常见的视网膜感光细胞和色素上皮细胞变性导致夜盲和进行性视野缺损的遗传性眼底病,其发病机制尚未完全明确.RP具有高度的遗传异质性,其遗传方式非常复杂,分为常染色体显性遗传(ADRP)、常染色体隐性遗传(ARRP)、X-连锁遗传(XLRP)和双基因型遗传(Digenic RP),最近报道还有线粒体遗传方式(mitochondrial RP)[1].视紫红质基因(RHO)是最早被识别的RP基因,在ADRP中发病率占30%～40%[2],而盘膜周边蛋白/视网膜变性慢基因(peripherin/RDS)在ADRP中占5%[3].我们对13个ADRP家系进行了RHO和视网膜变性慢基因(RDS)检测分析,观察其突变特征,现将其结果报道如下.     

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。     

视网膜色素变性发病机制及治疗进展

视网膜色素变性（retintis pigmentosa,RP）是指以进行性感光细胞及色素上皮功能丧失为共同表现的遗传性、退行性的疾病,RP是主要的致盲性眼病。其遗传方式包括X连锁遗传、常染色体隐性或者显性遗传,也有散发。临床表现为典型的三联征:骨细胞样色素沉着、视网膜血管缩窄和视盘蜡样苍白。RP具有高度的基因异质性(多个突变位点引起同一疾病）及表型异质性。本文对RP的发病机制和治疗方法进行简要综述。     

视网膜色素变性一家系5′次黄嘌呤核苷磷酸脱氢酶基因突变检测

视网膜色素变性(RP)是一组视网膜感光细胞和视网膜色素上皮细胞变性导致的具有遗传和临床异质性的渐进性视网膜退化性疾病.RP是单基因遗传病,在遗传和表型上均具有较大的异质性.其遗传方式主要为:常染色体显性遗传(ADRP)、常染色体隐性遗传(ARRP)、X-染色体连锁遗传(XLRP)、双基因突变遗传(digenic RP)、线粒体遗传(mitochondrial RP)及不完全显性遗传.无家族史,则称为散发性[1].RP分子发病机制相当复杂.许多基因突变可导致RP,但没有任何一个单独突变可以解释超过10%的散发病例[2].随着分子生物学技术的发展及其在眼科遗传领域的应用,人们已能在DNA分子水平认识RP基因及其分子缺陷.随着克隆技术及人类基因组全序列测定的重大突破,人们对于其分子病理有了一定的了解和认识,极大地加快了人类疾病相关基因的定位克隆.我们对一个苏格兰RP家系进行5'次黄嘌呤核苷一磷酸脱氢酶(IMPDHI)基因突变的检测,并探讨其临床应用价值.现将结果报道如下.志谢本文为第一作者在英国攻读博士学位课题的一部分,导师授权本部分内容在国内报道;本工作得到哈尔滨医科大学傅松滨教授的大力支持,特致谢意     

视网膜色素变性分子遗传学研究现状

视网膜色素变性是由于视网膜感光细胞和色素上皮细胞变性导致夜盲和进行性视野缺损的最常见的遗传性眼底病,具有大的临床和遗传异质性。其遗传方式可为常染色体显性、常染色体隐性、Ｘ染色体连锁遗传和散发型。目前已发现ＲＰ相关基因１４种,其中常染色体显性遗传４种,常染色体隐性遗传８种（包括视紫质）,Ｘ染色体连锁遗传２种,本文着重阐述了已知ＲＰ相关基因的研究现状。     

家族性渗出性玻璃体视网膜病变基因研究进展

家族性渗出性玻璃体视网膜病变(FEVR)是以周边视网膜血管发育异常或不发育为特征的遗传性视网膜血管疾病,临床表现多样,遗传异质性明显.近年来发现数种与FEVR相关的致病基因,包括FZD4、LRP5、TSPAN12、NDP和ZNF408,致常染色体隐性遗传、常染色体显性遗传及X染色体连锁隐性遗传.FZD4编码卷曲蛋白4,与LRP5及TSPAN12蛋白组成受体复合物,结合Wnt或NDP编码的Norrin蛋白,参与活化典型Wnt或Norrin通路,在视网膜血管发育中起重要作用.ZNF408编码锌指蛋白,致常染色体显性遗传FEVR.本文就FEVR基因研究进展进行综述.     

先天性白内障的基因遗传学研究

先天性白内障(congenital cataract)是儿童常见的致盲性眼病,发病机制多种多样,其中约1/3的患者与遗传有关,常见的为外显率较高的常染色体显性遗传,但也有过X连锁和常染色体隐性遗传方式的报道。现已明确了先天性白内障的十四个基因,二十几个独立位点上的突变,其中有十四个基因已被完全克隆出来。基因遗传学的研究,有助于揭示先天性白内障的发病机制,进一步了解遗传,环境及营养等因素对晶状体代谢的影响。     

Novel 2336-2337delCT mutation in RP1 gene in a Japanese family with autosomal dominant retinitis pigmentosa

PURPOSE: To determine the frequency and kinds of mutations in the RP1 gene, and to characterize the clinical features of a Japanese family with autosomal dominant retinitis pigmentosa (ADRP) with a novel 2336 to 2337delCT mutation in the RP1 gene. DESIGN: Case reports and results of DNA analysis. METHODS: Mutational screening by direct sequencing was performed on 96 unrelated patients with ADRP. The clinical features were determined by complete ophthalmologic examinations. RESULTS: A novel 2336 to 2337delCT mutation in the RP1 gene was identified in two patients from a Japanese family with ADRP. In addition, three families with ADRP carried a previously reported nonpathogenic Arg1933X mutation. The ophthalmic findings with a 2336 to 2337delCT mutation were similar to those of typical retinitis pigmentosa with rapid progression after age 40 years. CONCLUSIONS: The most common Arg677X mutation in the white population was not found in the Japanese population; instead a novel mutation was found.     

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。     

De novo mutation in the RP1 gene (Arg677ter) associated with retinitis pigmentosa

PURPOSE: The Arg677ter mutation in the RP1 gene is one of the most common causes of autosomal dominant retinitis pigmentosa (RP). In the current study, a de novo Arg677ter RP1 gene mutation was identified in a patient with RP. METHODS: RP1 gene mutation screening was performed in probands with simplex RP. In one proband with the RP1 mutation, paternity was established by analyzing 24 short tandem repeat polymorphisms. Additional candidate RP genes, including rhodopsin, RDS/peripherin, RP2, and RPGR, were also examined in this proband. Phenotype was characterized with psychophysics, electroretinography, and optical coherence tomography. RESULTS: An RP1 (Arg677ter) mutation was identified in one of the patients with simplex RP, but the sequence change was not detected in his parents. Parentage was confirmed, and other candidate genes were negative for mutations. Retinal function and cross-sectional imaging studies in the patient indicated greater rod than cone dysfunction with a photoreceptor basis for the abnormalities. CONCLUSIONS: The de novo origin of an RP1 (Arg677ter) mutation in a patient with simplex RP suggests that this common autosomal dominant RP mutation can arise independently in the population and supports the hypothesis of a mutational hotspot in the RP1 gene.     

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。     

An atypical phenotype of macular and peripapillary retinal atrophy caused by a mutation in the RP2 gene

AIMS: To determine the molecular basis and describe the phenotype of an atypical retinal dystrophy in a family presenting with bilateral, progressive central visual loss. METHODS: Family members were examined. Investigations included Goldman perimetry, electrophysiology, and autofluorescence imaging. Candidate gene screening was performed using SSCP and sequence analysis. The proband's lymphoblastoid cells were examined for protein expression. RESULTS: Fundal examination of the proband, his mother, and brother revealed peripapillary and macular atrophy. Autosomal dominant retinal dystrophy was suspected, but less severe disease in the mother led to screening for mutations in X linked genes. A 4 bp microdeletion in exon 3 of the RP2 gene, segregating with disease, was identified. No RP2 protein expression was detected. CONCLUSION: The distinct phenotype in this family, caused by this frameshifting mutation in RP2, broadens the phenotypic spectrum of X linked retinitis pigmentosa. The absence of RP2 protein suggests that loss of protein function and not novel gain of function could account for the atypical phenotype. A definitive diagnosis of X linked retinitis pigmentosa permits appropriate genetic counselling with important implications for other family members. Clinicians should have a low threshold for screening RP2 in families with retinal dystrophy, including posterior retinal disease, not immediately suggestive of X linked inheritance.     

RP1 protein truncating mutations predominate at the RP1 adRP locus

PURPOSE: Recent reports have shown that the autosomal dominant retinitis pigmentosa (adRP) phenotype linked to the pericentric region of chromosome 8 is associated with mutations in a gene designated RP1. Screening of the whole gene in a large cohort of patients has not been undertaken to date. To assess the involvement and character of RP1 mutations in adRP, the gene was screened in a panel of 266 unrelated patients of British origin and a Pakistani family linked to this locus. METHODS: Patients exhibiting the adRP phenotype were screened for mutations in the four exons of the RP1 gene by heteroduplex analysis and direct sequencing. Linkage of the Pakistani family was achieved using microsatellite markers. Polymerase chain reaction (PCR) products were separated by nondenaturing polyacrylamide gel electrophoresis. Alleles were assigned to individuals, which allowed calculation of LOD scores. Microsatellite marker haplotyping was used to determine ancestry of patients carrying the same mutation. RESULTS: In the 266 British patients and 1 Pakistani family analyzed, 21 loss-of-function mutations and 7 amino acid substitutions were identified, some of which may also be disease-causing. The mutations, many of which were deletion or insertion events, were clustered in the 5' end of exon 4. Most mutations resulted in a premature termination codon in the mRNA. Haplotype analysis of nine patients carrying an R677X mutation suggested that these patients are not ancestrally related. CONCLUSIONS: RP1 mutations account for 8% to 10% of the mutations in our cohort of British patients. The most common disease-causing mechanism is deduced to be one involving the presence of a truncated protein. Mutations in RP1 have now been described in adRP patients of four ethnically diverse populations. The different disease haplotype seen in the nine patients carrying the same mutation suggests that this mutation has arisen independently many times, possibly due to a mutation hot spot in this part of the gene.     

Mutation of human retinal fascin gene (FSCN2) causes autosomal dominant retinitis pigmentosa

PURPOSE: To characterize the clinical features of 14 Japanese patients with autosomal dominant retinitis pigmentosa (ADRP) who were found to have a mutation in the FSCN2 gene. METHODS: Mutation screening by single-strand conformation polymorphism (SSCP) was performed in 120 unrelated patients with ADRP, 200 unrelated patients with autosomal recessive retinitis pigmentosa (ARRP), and 100 patients with simplex RP (SRP). The DNA fragment that showed abnormal mobility on SSCP was sequenced. The clinical features of these patients were determined by visual acuity, slit lamp biomicroscopy, electroretinography, fluorescein angiography, and kinetic visual field testing. RESULTS: A novel 208delG mutation in the FSCN2 gene was identified in 14 patients from four unrelated families with ADRP. The ophthalmic findings were typical of RP. CONCLUSIONS: The findings show that a 208delG mutation in the FSCN2 gene produces ADRP. This mutation was found in 3.3% of the patients with ADRP in Japan, which suggests that it may be relatively common in Japanese patients with ADRP.     

Molecular analysis of RIM1 in autosomal recessive Retinitis pigmentosa

Retinitis pigmentosa (RP) is a frequent retinal dystrophy characterized by a progressive loss of photoreceptors along with retinal degeneration. RIM1, encoding a presynaptic protein involved in the glutamate neurotransmission, is the responsible gene for autosomal dominant cone-rod dystrophy CORD7, whose locus overlaps partially with a locus of autosomal recessive RP (arRP), RP25. Given the genetic heterogeneity that features RP, it is plausible that mutations in RIM1 are also implicated in the disease in arRP families genetically linked to the CORD7 region. To test our hypothesis we analysed the complete RIM1 gene in 8 arRP families by DNA sequencing. Even though the absence of pathogenic mutations suggests that RIM1 is notinvolved in arRP, a role for this gene in other inherited forms of RP as well as other retinal dystrophies needs to be elucidated.     

Mutations in the gene coding for guanylate cyclase-activating protein 2 (<Emphasis Type="Italic">GUCA1B</Emphasis> gene) in patients with autosomal dominant retinal dystrophies

Background We investigated mutations in the gene coding for guanylate-cyclase activating protein 2 (GCAP2), also known as GUCA1B gene, in Japanese patients with retinitis pigmentosa (RP) and tried to identify phenotypic characteristics associated with mutations in the gene.Subjects and methods Genomic DNA samples from 63 unrelated patients with autosomal dominant retinitis pigmentosa (ADRP) and 33 patients with autosomal recessive retinitis pigmentosa (ARRP) were screened by single-strand conformational polymorphism analysis followed by direct sequencing. Clinical features associated with a mutation were demonstrated by visual acuity, visual field testing, fundus photography, and electroretinography.Results A novel transitional mutation converting GGA to AGA at codon 157 (G157R) was identified. This mutation has been found in three index patients from three independent families. Phenotypic examination of seven members of the three families revealed that this mutation was associated with RP with or without macular involvement in five members, macular degeneration in one member, and asymptomatic normal phenotype in one member. In addition, previously unknown polymorphic changes including V29V, Y57Y, T87I, and L180L were identified.Conclusions A racial difference exists in the spectrum of mutations and/or polymorphisms in the GCAP 2 gene between British and Japanese populations. Our findings suggest that the mutation in the GCAP 2 gene can cause one form of autosomal dominant retinal dystrophy, with variable phenotypic expression and incomplete penetrance.     

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.