常染色体显性遗传核性白内障合并小角膜的CRYAA基因突变研究

Objective To identify the gene mutation in a four-generation Chinese family with autosomal dominant congenital cataract associated with microcornea. Methods Experimental research.Twelve members in this family (including six affected and six unaffected individuals) were enrolled into this study. They underwent full ophthalmological and clinical examinations to rule out any concomitant disorders.Blood samples were collected and genomic DNA was extracted. Microsatellite markers near the reported loci,which are associated with congenital cataract and microcornea were selected and amplified from DNA samples using polymerase chain reaction. Linkage analysis was performed. The exons and exon/intron junction of candidate gene in the related chromosome were sequenced. The product of the first exon was digested by ApaL Ⅰ restriction enzyme to certify the mutation. Results The phenotype studied in this family was nuclear cataract accompanied with microcornea. At markers D21S1885 and D21S1890 near the locus 21q22. 3, the affected members had the same allele, but the unaffected did not. The Lod scores were 2. 11in both markers, indicating that this locus were linked to the congenital cataract in this family. DNA sequencing of candidate gene CRYAA showed a heterozygous mutation c. 34C ＞ T in exon 1, which led to condon 12 in peptide chain encoding arginine substituted by cysteine. ApaL Ⅰ enzyme digestion certified that all of the affected members had the same mutation c. 34C ＞T, but the unaffected and normal individuals did not. Conclusion Mutation (p. R12C) of CRYAA is the genetic change that causes the occurrence of congenital cataract with microcornea in this family.     

常染色体显性遗传核性白内障合并小角膜的CRYAA基因突变研究

Objective To identify the gene mutation in a four-generation Chinese family with autosomal dominant congenital cataract associated with microcornea. Methods Experimental research.Twelve members in this family (including six affected and six unaffected individuals) were enrolled into this study. They underwent full ophthalmological and clinical examinations to rule out any concomitant disorders.Blood samples were collected and genomic DNA was extracted. Microsatellite markers near the reported loci,which are associated with congenital cataract and microcornea were selected and amplified from DNA samples using polymerase chain reaction. Linkage analysis was performed. The exons and exon/intron junction of candidate gene in the related chromosome were sequenced. The product of the first exon was digested by ApaL Ⅰ restriction enzyme to certify the mutation. Results The phenotype studied in this family was nuclear cataract accompanied with microcornea. At markers D21S1885 and D21S1890 near the locus 21q22. 3, the affected members had the same allele, but the unaffected did not. The Lod scores were 2. 11in both markers, indicating that this locus were linked to the congenital cataract in this family. DNA sequencing of candidate gene CRYAA showed a heterozygous mutation c. 34C ＞ T in exon 1, which led to condon 12 in peptide chain encoding arginine substituted by cysteine. ApaL Ⅰ enzyme digestion certified that all of the affected members had the same mutation c. 34C ＞T, but the unaffected and normal individuals did not. Conclusion Mutation (p. R12C) of CRYAA is the genetic change that causes the occurrence of congenital cataract with microcornea in this family.     

常染色体显性遗传核性白内障合并小角膜的CRYAA基因突变研究

目的 研究一个4代常染色体显性遗传先天性核性白内障伴小角膜家系的致病基因.方法 实验研究.对12例家系成员(6例患者,6例非患者)进行眼部检查并采集静脉血,提取基因组DNA.在已知的与先天性白内障伴小角膜相关致病基因附近选择微卫星标记,进行聚合酶链反应扩增-变性聚丙烯酰胺凝胶电泳,并进行基因型分析和连锁分析.对连锁区域内候选基因的外显子、外显子和内含子交界区进行测序.限制性内切酶ApaL Ⅰ法在全部家系成员和正常人群中验证突变.结果 该家系患者表型为先天性核性白内障伴小角膜;在染色体21q22.3区域的D21S1885和D21S1890两个标记,家系患者均有共享基因型,并且两点连锁分析Lod值为2.11,提示该位点与家系致病基因连锁;对此区域内候选基因CRYAA测序发现cDNA序列第34位碱基存在C＞T杂合突变(c.34C＞T),导致其编码肽链第12位精氨酸变为半胱氨酸(p.R12C).ApaL Ⅰ酶切验证家系患者均携带c.34C＞T突变,家系中及对照正常个体均不携带此突变.结论 CRYAA的p.R12C突变可能是该先天性白内障伴小角膜家系发病的遗传基础.

Abstract：

Objective To identify the gene mutation in a four-generation Chinese family with autosomal dominant congenital cataract associated with microcornea. Methods Experimental research.Twelve members in this family (including six affected and six unaffected individuals) were enrolled into this study. They underwent full ophthalmological and clinical examinations to rule out any concomitant disorders.Blood samples were collected and genomic DNA was extracted. Microsatellite markers near the reported loci,which are associated with congenital cataract and microcornea were selected and amplified from DNA samples using polymerase chain reaction. Linkage analysis was performed. The exons and exon/intron junction of candidate gene in the related chromosome were sequenced. The product of the first exon was digested by ApaL Ⅰ restriction enzyme to certify the mutation. Results The phenotype studied in this family was nuclear cataract accompanied with microcornea. At markers D21S1885 and D21S1890 near the locus 21q22. 3, the affected members had the same allele, but the unaffected did not. The Lod scores were 2. 11in both markers, indicating that this locus were linked to the congenital cataract in this family. DNA sequencing of candidate gene CRYAA showed a heterozygous mutation c. 34C ＞ T in exon 1, which led to condon 12 in peptide chain encoding arginine substituted by cysteine. ApaL Ⅰ enzyme digestion certified that all of the affected members had the same mutation c. 34C ＞T, but the unaffected and normal individuals did not. Conclusion Mutation (p. R12C) of CRYAA is the genetic change that causes the occurrence of congenital cataract with microcornea in this family.     

A novel mutation of LIM2 causes autosomal dominant membranous cataract in a Chinese family

AIM: To determine the prevalence and associations of non-retinopathy ocular conditions among older Australian adults with diabetes. METHODS: Multistage random-cluster sampling was used to select 3098 non-indigenous Australians aged 50y or older (46.4% male) and 1738 indigenous Australians aged 40y or older (41.1% male) from all levels of geographic remoteness in Australia. Participants underwent a standardised questionnaire to ascertain diabetes history, and a clinical examination to identify eye disease. We determined the prevalence of uncorrected refractive error, visually significant cataract, cataract surgery, age-related macular degeneration, glaucoma, ocular hypertension, retinal vein occlusion and epiretinal membrane among those with and without self-reported diabetes. RESULTS: Participants with self-reported diabetes had a higher prevalence of cataract surgery than those without diabetes (28.8% vs 16.9%, OR 1.78, 95%CI: 1.35-2.34 among non-indigenous Australians, and 11.3% vs 5.2%, OR 1.62, 95%CI: 1.22-2.14 among indigenous Australians). Diabetic retinopathy (DR) increased the odds of cataract surgery among self-reported diabetic indigenous and non-indigenous Australians (OR 1.89, P=0.004 and OR 2.33, P<0.001 respectively). Having diabetes for ≥20y and having vision-threatening DR increased the odds of cataract surgery among indigenous Australians with diabetes (OR 3.73, P=0.001 and 7.58, P<0.001, respectively). CONCLUSION: Most non-retinopathy ocular conditions are not associated with self-reported diabetes. However, to account for Australia’s worsening diabetes epidemic, interventions to reduce the impact of diabetes-related blindness should include increased cataract surgery services.     

A nonsense mutation in the glucosaminyl (N-acetyl) transferase 2 gene (GCNT2): association with autosomal recessive congenital cataracts

PURPOSE: To identify the genetic defect associated with autosomal recessive congenital cataract in four Arab families from Israel. METHODS: Genotyping was performed using microsatellite markers spaced at approximately 10 cM intervals. Two-point lod scores were calculated using MLINK of the LINKAGE program package. Mutation analysis of the glucosaminyl (N-acetyl) transferase 2 gene (GCNT2) gene was performed by direct sequencing of PCR-amplified exons. RESULTS: The cataract locus was mapped to a 13.0-cM interval between D6S470 and D6S289 on Chr. 6p24. A maximum two-point lod score of 8.75 at theta = 0.019 was obtained with marker D6S470. Sequencing exons of the GCNT2 gene, mutations of which have been associated with cataracts and the i blood group phenotype, revealed in these families a homozygous G-->A substitution in base 58 of exon-2, resulting in the formation of premature stop codons W328X, W326X, and W328X, of the GCNT2A, -B, and -C isoforms, respectively. Subsequent blood typing of affected family members confirmed the possession of the rare adult i blood group phenotype. CONCLUSIONS: A nonsense mutation in the GCNT2 gene isoforms is associated with autosomal recessive congenital cataract in four distantly related Arab families from Israel. These findings provide further insight into the dual role of the I-branching GCNT2 gene in the lens and in reticulocytes.     

常染色体隐性遗传视网膜色素变性家系视紫红质基因突变的检测分析

目的 观察一个近亲婚配常染色体隐性遗传视网膜色素变性（ARRP）家系中视紫红质基因（RHO）的突变特征，并探讨其视网膜色素变性(RP)发病机制。 方法 抽取8例该ARRP家系成员及10例正常对照者的外周静脉血5~8 ml；提取基因组DNA；采用聚合酶链反应（PCR）方法扩增RHO基因第1~5外显子和第1内含子基因 片段 ，用直接DNA测序法筛查RHO基因突变。 结果 来自同一家系3例患者RHO 基因的第5外显子第344密码子发生了A→G碱基的错义突变，导致了谷氨酰胺变成了精氨酸(G ln344Arg)，3例患者为该突变的纯合子。患者近亲婚配父母及1例未患病家庭成员为该突变 的杂合子。2例未患病家庭成员及10例正常对照者均未发现RHO基因突变。 结论 Gln344Arg突变可能是该ARRP家系的致病原因；在近亲婚配ARRP家系中RHO基因突变频率可能增加。 （中华眼底病杂志，2004，20：145-148）     

A novel compound heterozygous mutation in the BEST1 gene causes autosomal recessive Best vitelliform macular dystrophy

Purpose

To determine the genetic basis of early onset autosomal recessive Best vitelliform macular dystrophy (arBVMD) in a family with three affected children.

Design

Clinical and family-based genetic study.

Methods

Seven subjects making up a family with three children affected by Best vitelliform macular dystrophy were studied. Standard ophthalmic exam with dilated ophthalmoscopy and imaging were performed in each individual. The eleven exons of BEST1were directly sequenced.

Results

All three affected children have the clinical characteristic features of Best vitelliform macular dystrophy: large macular vitelliform lesions, scattered vitelliform lesions along the arcades and in the peripheral retina, and an accumulation of serous retinal fluid. A novel compound heterozygous mutation in the BEST1gene was found in the three affected individuals (L41P and I201T). The unaffected parents and children only harbor one heterozygous mutation.

Conclusion

arBVMD can be caused by the compound heterozygous mutation L41P and I201T in the BEST1gene.     

A new locus for autosomal recessive nuclear cataract mapped to chromosome 19q13 in a Pakistani family

PURPOSE: To identify the disease locus of autosomal recessive congenital nuclear cataracts in a consanguineous Pakistani family. METHODS: A large Pakistani family with multiple individuals affected by autosomal recessive congenital cataracts was ascertained. Patients were examined, blood samples were collected, and DNA was isolated. A genome-wide scan was performed using 382 polymorphic microsatellite markers on genomic DNA from affected and unaffected family members. Two-point lod scores were calculated, and haplotypes were formed by inspection. RESULTS: In the genome-wide scan, a maximum lod score of 2.89 was obtained for marker D19S414 on 19q13. Fine mapping using D19S931, D19S433, D19S928, D19S225, D19S416, D19S213, D19S425, and D19S220 markers from the Généthon database showed that markers in a 14.3-cM (12.66-Mb) interval flanked by D19S928 and D19S420 cosegregated with the cataract locus. Lack of homozygosity further suggests that the cataract locus may lie in a 7-cM (4.3-Mb) interval flanked by D19S928 proximally and D19S425 distally. On fine mapping, a maximum lod score of 3.09 was obtained with D19S416 at theta = 0. CONCLUSIONS: Linkage analysis identified a new locus for autosomal recessive congenital nuclear cataracts on chromosome 19q13 in a consanguineous Pakistani family.     

Enhanced S-cone syndrome in a Japanese family with a nonsense NR2E3 mutation (Q350X)

PURPOSE: To describe the clinical characteristics of a Japanese male patient with enhanced S-cone syndrome (ESCS) and investigate the existence of mutations in the NR2E3 gene, which encodes a photoreceptor cell-specific nuclear receptor. METHODS: Fundus examinations, fluorescein angiography, colour vision tests, spectral sensitivity, and full-field and spectral electroretinography were performed. Mutation screening of the NR2E3 gene was performed with polymerase chain reaction (PCR) amplification and direct sequencing. RESULTS: We identified a novel homozygous mutation (c.1048C > T), that converts glutamine (CAA) to a termination codon (TAA) at amino acid position 350. The subject's unaffected parents were heterozygous for the mutation, consistent with autosomal recessive transmission. The electroretinographic findings revealed that the patient had neither rod nor 30-Hz flicker responses but did have cone responses with large a-wave and low b-wave amplitudes, similar to the rod-plus-cone responses, and also substantial short wavelength-sensitive (S) cone and extremely diminished long/middle wavelength-sensitive (L/M) cone responses. In the right eye, spectral sensitivity in the fovea revealed both functional S-cone and remarkably reduced L- and M-cone sensitivities, which was compatible with the decreased visual acuity (VA) and red/green colour vision defects noted in this eye. In contrast, the patient had good VA and normal red/green colour vision in the left eye. CONCLUSION: The nonsense mutation results in a truncated NR2E3 protein lacking 61 amino acids within the ligand-binding domain (LBD) that consists of 190 amino acids of the C-terminus end. Therefore, null function of the LBD is likely to cause ESCS in the patient. The clinical findings for this patient suggest that his left eye, with its functional L/M- and S-cones, was at an earlier stage of the syndrome than his right eye.     

ABCB6基因在一常染色体显性遗传脉络膜缺损家系中的突变筛查

目的:对一个常染色体显性遗传的先天性脉络膜缺损家系进行ABCB6基因的突变筛查,明确致病基因。方法:近来有报道ABCB6基因突变可导致先天性脉络膜缺损,我们搜集了一个中国汉族先天性脉络膜缺损家系,采集家系成员及一百位正常对照人群的静脉血5mL,使用PCR产物直接测序对ABCB6基因进行突变筛查。结果:在该家系中我们发现了一个新突变(c.1380c>a),该突变在家系中与疾病表型共分离,并且在100名正常对照中均未发现该突变。结论:我们的研究结果扩大了ABCB6基因的突变谱,进一步确认了该基因在眼组织缺损发病中发挥了重要作用。     

晶状体蛋白基因在一先天性白内障家系中的突变筛查

目的研究晶状体蛋白基因与先天性白内障的关系。方法收集1个先天性白内障家系,制备外周血白细胞基因组DNA。除对CRYGD基因直接测序外,在距离已知晶状体蛋白基因5个厘摩范围内选取微卫星标记进行连锁分析,计算微卫星位点与致病基因之间的最大优势对数值(LOD SCORE),来确定晶状体蛋白基因与此家系致病基因的关系。结果当重组分数分别为0.1、0.2、0.3、0.4时,所选取的位于晶状体蛋白基因附近的14个微卫星位点与该家系致病基因之间连锁的LOD值均为负值,故排除连锁。CRYGD基因测序后在基因编码区及启动子、内含子与外显子连接处的剪切位点均未见任何碱基改变。结论晶状体蛋白基因非此家系的致病基因,为进一步定位与克隆该家系的致病基因,需进行全基因组扫描,以探求先天性白内障的分子发病机制。     

中国北方一常染色体显性遗传先天性核性白内障家系CRYGD基因突变的鉴定

背景 先天性白内障是儿童致盲的主要原因之一,约1/3的先天性白内障由遗传因素引起,多为常染色体显性遗传,目前确定至少26个基因为常染色体显性遗传先天性白内障(ADCC)的致病基因,发现的致病基因突变已超过100种.目的 明确一ADCC家系的致病基因突变.方法 对2011年1月在北京同仁医院就诊的一来自河北的汉族ADCC家系进行分析,在获得受检者知情同意后,对所有家系成员进行详细的眼科检查并采集外周静脉血各5 ml,提取全基因组DNA.在已知的17个ADCC致病基因周围选取21个荧光标记的微卫星,经多重PCR扩增后进行连锁分析,两点法计算LOD值.对候选基因进行DNA直接测序分析,用ProtScale软件对基因突变前后蛋白局部的疏水性进行分析.用限制性片段长度多态性(RFLP)方法对所有家系成员及100个正常对照者进行基因突变共分离分析.结果 该家系共4代20名成员,其中患者9例,连续4代均有患者发病,符合常染色体显性遗传特征.临床检查证实9例患者均为双眼晶状体核性混浊.连锁分析发现微卫星D2S325和D2S2358与该家系中所有患者均连锁,重组分数(θ)为0时D2S325获得最大LOD值,为4.68.对位于D2S325附近的CRYGC和CR YGD基因进行DNA直接测序,发现CRYGD基因cDNA第127位一已知错义突变(c.T127C),导致编码蛋白第43位色氨酸变为精氨酸(p.W43R).ProtScale软件预测突变后的CRYGD蛋白第43位及其周围氨基酸疏水性明显增加.该突变与家系内所有患者表型共分离,家系中表型正常的成员及100名正常对照者均未发现此突变.结论 CRYGD基因c.T127C突变是该ADCC家系的致病基因突变,蛋白局部疏水性增加造成的空间结构异常可能是引起该ADCC家系发病的主要原因.     

A novel missense variant in IDH3A causes autosomal recessive retinitis pigmentosa

Background: Inherited retinal degenerations (IRDs) encompass a wide spectrum of genetic ocular diseases characterized by considerable genetic and clinical heterogeneity.

Methods: Complete ophthalmic examination and next-generation sequencing.

Results: We describe a patient with no family history of vision loss, who at the age of 28 years developed visual impairment consistent with a severe form of retinitis pigmentosa. Genetic testing by means of whole exome sequencing identified a homozygous variant in the gene IDH3A. To date, only three papers have reported mutations in IDH3A, in families with early-onset retinal degeneration with or without the presence of macular pseudocoloboma.

Conclusion: This study highlights the importance of including this rarely-mutated gene in the molecular diagnostic set-ups for IRDs, and further delineates the phenotypic spectrum elicited by mutations in IDH3A.