Dystrophia canthorum in Waardenburg syndrome with a novel MITF mutation

AIM: To compare whether aphakic contact lenses or secondary iris-claw intraocular lenses are superior in the refractive management post-pars plana vitreolensectomy in a pedigree with a FBN1 mutation causing non-syndromic EL (NSEL) with retinal detachment (RRD). METHODS: Eight affected individuals had pars plana vitreolensectomy for bilateral EL. Twelve eyes of 6 patients had secondary iris-claw intraocular lenses inserted and 4 eyes of 2 patients were managed with contact lenses. Rhegmatogenous retinal detachment (RRD) was treated when necessary. Pre- and post-operative assessment included visual acuity, endothelial cell count and dilated fundal examination. RESULTS: Macula-on RRD was present in all individuals >18y, 64% (7/11 eyes) presenting post-vitreolensectomy with 57% having bilateral non-synchronous RRD. Surgical aphakia was managed with iris-fixated intraocular lenses (IOL group, n=6), or contact lenses (CL group, n=2). Visual acuity ≥0.3 logMAR (driving standard) was achieved in 75% of IOL group eyes and 25% of the CL group eyes. Mean loss of corneal endothelial cell count in the IOL group was 4% at 2y post-operative. CONCLUSION: In this cohort, refractive management with iris-claw IOLs provided superior outcomes to CLs and the authors recommend this as the main refractive correction in EL patients.     

A Novel PAX6 Mutation in Chinese Patients with Severe Congenital Aniridia

Purpose: We identified a novel mutation in Paired Box gene 6 (PAX6) and characterized its associated clinical features of severe ocular malformation in a Chinese family with congenital aniridia. Methods: We studied two patients with aniridia from a Chinese family. All patients and noncarriers in this family underwent full ophthalmologic, general and urinary examinations. Total genomic DNA was isolated from peripheral blood of two aniridia patients. PAX6 levels were determined by PCR and its mutational status was determined by sequencing. Direct sequencing detected variations in PAX6. Results: Patients had bilateral congenital nystagmus, anterior polar cataract, absence of iris tissue, and foveal hypoplasia with severely reduced visual acuity. A novel heterozygous PAX6 mutation in exon 6 c.662G>A (p.W100X) was identified which created a premature termination codon. This observed sequence alteration was not found in 100 normal controls and has not been previously reported. Conclusions: We identified a novel PAX6 mutation in a family with severe ocular malformation. Our study expands the mutational spectrum of PAX6 and enriches our knowledge of the relationship between genotype and phenotype due to these mutations.     

Prognostic DNA testing and counselling for dominant optic atrophy due to a novel OPA1 mutation

CASE REPORT: To report the case of a 26-year-old woman with a family history of dominant optic atrophy who requested DNA testing and counselling. Ophthalmologic examination showed her affected father had bilateral temporal papillary pallor. Direct genomic sequencing of the OPA1 gene revealed a novel heterozygous nonsense mutation (Arg879stop). Because no mutation in OPA1 was detected in the daughter, we could counsel her that the possibility was very low that she was a carrier or would pass the disease-causing gene to her children. COMMENTS: Our study provides evidence of the apparent value of molecular genetic analysis of OPA1 gene as predictive DNA testing, although the exact risk and benefit of this type of analysis awaits further study.     

回旋状脉络膜视网膜萎缩一家系的新型突变与临床观察

目的：探讨一个回旋状脉络膜视网膜萎缩(GA)中国家系各家庭成员OAT基因的致病性突变及临床表现。

方法：对该家系中的6名家庭成员均进行详细的眼科检查,通过全外显子组测序、生物信息学分析及Sanger验证明确基因测序结果及致病性突变。

结果：先证者因其临床表现及体征诊断为GA。全外显子组测序结果显示先证者OAT基因分别于第6外显子和第10外显子上发现致病突变c.722C>T(p.P241L)、c.1186C>T(p.R396X),该复合杂合性突变在家系中呈现共分离状态。先证者的父亲和哥哥均检出杂合型p.R396X致病变异,母亲检出杂合型p.P241L致病变异。除先证者外,其他家庭成员均无临床症状。

结论：该家系的先证者为复合杂合性突变,其中p.P241L为首次报道的基因突变类型。这一研究结果扩大了OAT基因变异的范围,有利于在分子基础水平进一步理解GA的致病因素。新型突变类型的发现与证实也将有助于为GA的临床诊断和基因治疗提供新的依据。     

A novel mutation of CYP4V2 gene associated with Bietti crystalline dystrophy complicated by choroidal neovascularization

AIM: To investigate the clinical characteristics and genetic features of a Bietti crystalline dystrophy (BCD) proband in a Chinese family. METHODS: A Chinese female diagnosed with BCD complicated by bilateral choroidal neovascularization (CNV) and her parents underwent complete ophthalmic examinations, including fundus autofluorescence (AF), fundus photography (FP), fundus fluorescein angiography (FFA), visual field testing, full-field electroretinography (ERG), optical coherence tomography (OCT) and optical coherence tomography angiography (OCTA). The sequencing of the CYP4V2 gene was performed to the whole family. RESULTS: Bilateral tiny glittering crystal-like deposits and differing extent of atrophy of the retinal pigment epithelium (RPE) were found in the posterior pole of her fundus. The diffuse hypo-fluorescence shown on AF images and window defects shown on FFA both indicated the atrophy of the RPE and choriocapillaris. OCT showed the thinning of the RPE and choriocapillaris layer, ellipsoid zone (EZ) band defect and CNV in both eyes. OCTA images proofed bilateral type 2 CNV. The visual field test showed central and paracentral scotoma. ERG showed a slightly decreased b-wave in scotopic ERG. Gene sequencing identified three mutations of the CYP4V2 gene, c.802_807del, c.810delT, and c.1388G>A. The mutation c.1388G>A was a novel substitution mutation. CONCLUSION: The novel mutation c.1388G>A may be a possible cause that could induce the clinical phenotype of BCD.     

Chinese family with atypical granular corneal dystrophy type I caused by the typical R555W mutation in TGFBI

AIM: To investigate the clinical features and genetic defects in four generations of a Chinese family affected with atypical granular corneal dystrophy type I (GCD type I).METHODS: Family history and clinical data were recorded. Genomic DNA samples were obtained from peripheral blood leukocytes of all participated. Exons of the transforming growth factor-β-induced(TGFBI) gene were directly sequenced after being amplified by polymerase chain reaction (PCR), and multi-point linkage analysis using microsatellite makers flanking the gene was applied to identify the disease-causing mutation.RESULTS: Clinical features were quite variable in patients, some patients only had opacities in the epithelium, and others revealed multiple bilateral circular, discrete, crumb-like opacities mainly in the epithelium, with several in different depths of corneal stroma, and the performance was different bilaterally, even in the same patient. Directly nucleotide sequencing revealed a heterozygous p.R555W mutation in the coding sequence of the TGFBI gene in all affected individuals of the family, but was not found in all unaffected. The maximum logarithm of odds (LOD) score obtained by multi-point analysis was detected at marker locus D5S393 (LOD=2.740; α=1.000).CONCLUSION: Our case presented with clinical futures and the pathogenic mutations in TGFBI gene, the phenotype of the pedigree was quite different from typical GCD type I, so we suggested that this phenotype was a variant of GCD type I. These findings expand the knowledge about GCD type I, and demonstrate that molecular genetic analysis is important to make an accurate diagnosis of patients with variable corneal dystrophies in clinic.     

A novel (Pro79Thr) mutation in the FKHL7 gene in a Japanese family with Axenfeld-Rieger syndrome

PURPOSE: To report the ocular and genetic findings of a Japanese family with Axenfeld-Rieger syndrome associated with a novel Pro79Thr mutation in the FKHL7 gene. METHODS: Observational case series. Genomic DNA of patients from a family with Axenfeld-Rieger syndrome was extracted from leukocytes, and exons of the FKHL7 gene were amplified by polymerase chain reaction for direct sequencing. RESULTS: Molecular genetic analysis disclosed that one Japanese family with Axenfeld-Rieger syndrome had a heterozygous C to A transversion in the first nucleotide at codon 79, designated Pro79Thr mutation in the FKHL7 gene. CONCLUSION: Considering this novel Pro79Thr mutation together with previously reported findings, it is indicated that the clinical features of Axenfeld-Rieger syndrome may depend on the portion of the FKHL7 gene affected by the mutation, although more case reports are needed to clarify genotype-phenotype correlations of the FKHL7 gene.     

A Novel Compound Heterozygous Mutation in the CYP4V2 Gene in a Japanese Patient with Bietti's Crystalline Corneoretinal Dystrophy

Purpose: To describe the clinical and genetic characteristics of a Japanese family in which one member exhibited Bietti's crystalline corneoretinal dystrophy (BCD). Methods: Using direct sequencing, mutation screening was performed in the CYP4V2 gene of both the patient with BCD and her daughter. Ophthalmic examinations were performed to determine the clinical features of both subjects. Results: The 64-year-old female patient had a bilateral visual acuity of 0.4. Slit lamp examination revealed bilateral crystalline-like deposits at the superior limbus of the cornea. Fundus examination revealed there was chorioretinal atrophy along with numerous glistening yellowish-white crystalline deposits that were scattered throughout the posterior pole and the mid-peripheral retina. Standard flash electroretinography showed an extinguished electroretinogram and Goldmann kinetic perimetry detected a relative scotoma. Genetic analysis revealed that the patient had a heterozygous mutation in the CYP4V2 gene (IVS6-8delTCATACAGGTCATCGCG/GC), which is the most commonly found mutation in Japanese patients with BCD. Furthermore, the patient was also shown to have a novel heterozygous point mutation in exon 9 of the CYP4V2 gene (c.1168C>T). In contrast, her daughter exhibited no clinical findings for BCD even though she carried the same heterozygous mutation in the CYP4V2 gene (c.1168C>T). Conclusion: A novel compound heterozygous mutation was found in the CYP4V2 gene of a patient with BCD. This previously unreported c.1168C>T mutation causes a missense mutation (p.R390C) in the CYP4V2 protein.     

格子状角膜营养不良一家系的TGFBI基因突变研究

目的对我国鄂西北地区一格子状角膜营养不良家系进行研究,探讨这一格子状角膜营养不良类型与TGFBI基因突变的关系。方法选取该家系共18例,包括第三代患者及配偶13例,第四代患者2例及无临床症状者3例。收集该家系所有研究对象外周血,提取基因组DNA,PCR扩增TGFBI基因4、11、12、14号外显子片段并进行直接测序,证实其突变位点。以家系内无近亲关系配偶5人和1名健康者为阴性对照。结果该家系基本符合常染色体显性遗传模式的特征,为LCD I/IIIA型。TGFBI基因编码区进行基因直接测序,发现10例患者和2例无症状者携带者共同突变点为H626R。结论该家系为格子状角膜营养不良LCD I/IIIA型家系,该家系角膜混浊的直接原因是TGFBI基因H626R突变。     

A novel deletion downstream of the PAX6 gene identified in a Chinese family with congenital aniridia

Purpose: Congenital aniridia, a severe bilateral panocular visual disorder, is an autosomal dominantly inherited eye anomaly. Mutations in the paired box 6 gene (PAX6) have been shown to be responsible for congenital aniridia in most patients. The purpose of the present study was to report clinical features of a Chinese family with congenital aniridia and to screen novel genetic mutations for congenital aniridia.

Methods: All members of a three-generation family underwent comprehensive ophthalmic examination, and 8 of its 25 members were diagnosed with congenital aniridia. The proband was analyzed by exome sequencing and whole genome sequencing, and linkage analysis was performed for the family. The mutation was confirmed by direct DNA sequencing.

Results: Using Illumina’s Human Linkage-12 beadchip microarray (including 6090 SNPs) whole genome scan, the LOD score value showed that the interval on chromosome 11 between rs1389423 to rs910090 exhibited a strong linkage. A novel heterozygous 469 kb deletion mutation within the downstream region of PAX6 (chr11:31189937–31659379) was identified in all affected family members, but not in unaffected family members or 2000 ethnically matched controls.

Conclusion: A novel deletion mutation was identified within the PAX6 downstream region that results in congenital aniridia.     

A novel mutation in the ABCR gene in four patients with autosomal recessive Stargardt disease

PURPOSE: To identify additional mutations in the ABCR gene and describe the clinical features of four affected siblings with autosomal recessive Stargardt disease. METHODS: A cohort of eight siblings was identified for study. Four of these individuals were diagnosed with Stargardt disease based on clinical evaluation and fluorescein angiography. Blood samples were obtained from seven of eight siblings, including all those affected. All 50 exons of the ABCR gene were analyzed by single-stranded confirmation polymorphism analysis, followed by direct sequencing of observed variants, to identify mutations in the ABCR gene. RESULTS: We identified a previously unreported kindred of eight siblings, four of whom had mutations in both of their ABCR alleles. A previously described G-to-C transversion of nucleotide 2588, predicting a Gly863Ala amino acid substitution, and a novel G-to-A transition of nucleotide 161, resulting in a Cys54Tyr substitution, were identified. These mutations co-segregated with the affected members of this family. Three of the siblings demonstrated clinical features characteristic of classic Stargardt disease, with bilateral regions of macular atrophy associated with yellow-white "flavimaculatus" flecks in the posterior pole at the level of the retinal pigment epithelium. The fourth affected sibling showed features of early Stargardt disease, with a beaten-bronze appearance to both maculas, as well as perimacular flecks. In all four affected patients, fluorescein angiography showed a characteristic peripheral dark choroid. CONCLUSIONS: We have identified both a previously described and a novel mutation in the ABCR gene in four patients with autosomal recessive Stargardt disease. In-depth knowledge of the ABCR mutation spectrum in patients with Stargardt disease will provide for more efficient screening and may provide potential therapies for Stargardt disease and other retinal diseases.     

A novel CRX mutation by whole-exome sequencing in an autosomal dominant cone-rod dystrophy pedigree

AIM: To identify the disease-causing gene mutation in a Chinese pedigree with autosomal dominant cone-rod dystrophy (adCORD). METHODS: A southern Chinese adCORD pedigree including 9 affected individuals was studied. Whole-exome sequencing (WES), coupling the Agilent whole-exome capture system to the Illumina HiSeq 2000 DNA sequencing platform was used to search the specific gene mutation in 3 affected family members and 1 unaffected member. After a suggested variant was found through the data analysis, the putative mutation was validated by Sanger DNA sequencing of samples from all available family members. RESULTS: The results of both WES and Sanger sequencing revealed a novel nonsense mutation c.C766T (p.Q256X) within exon 5 of CRX gene which was pathogenic for adCORD in this family. The mutation could affect photoreceptor-specific gene expression with a dominant-negative effect and resulted in loss of the OTX tail, thus the mutant protein occupies the CRX-binding site in target promoters without establishing an interaction and, consequently, may block transactivation. CONCLUSION: All modes of Mendelian inheritance in CORD have been observed, and genetic heterogeneity is a hallmark of CORD. Therefore, conventional genetic diagnosis of CORD would be time-consuming and labor-intensive. Our study indicated the robustness and cost-effectiveness of WES in the genetic diagnosis of CORD.     

Molecular genetic analysis of the BIGH3 gene in lattice type I (Biber-Haab-Dimmer) and granular type II (Avellino) corneal dystrophy: is indirect mutation analysis for hot spots recommended?

BACKGROUND: Mutations of the BIGH3 gene were delineated as the underlying gene defect for corneal dystrophy Lattice Type I (CDL1) and corneal dystrophy Avellino type (CDA) in families with different regional provenance. Missense mutations in exon 4 with single base pair substitution which result in amino acid alterations Arg124Cys (CDL1) and ARG124His are described as hot spots. We report on histopathological and molecular genetic investigations in 2 German families and a single patient with CDL1 and CDA. METHOD: In 3 affected family members and 1 unaffected family member and in one single patient with CDL1 and in 3 affected family members and 1 unaffected family member of a family with CDA mutation analysis in exon 4 of BIGH3 gene by direct sequencing of genomic DNA from peripheral blood was performed. Histopathological examination of corneal tissue of both index patients was performed after penetrating keratoplasty. RESULTS: We revealed a heterozygous single base pair substitution 417C-->T in family A and patient B (CDL1) and a heterozygous single base pair substitution 418G-->A in family C (CDA). In all index patient's diagnosis was confirmed by histopathological examination of corneal tissue. The sequencing results were confirmed by restriction digestion with HpyCH4V (NEB; CDL1) restriction endonuclease site and AvaII (NEB; CDA) restriction endonuclease site. The heterozygous 417C-->T transition in family A and patient B alters the amino acid sequence from Arg124Cys while the heterozygous 418G-->A transition in family C alters the amino acid sequence from Arg124His in the keratoepithelin. COMMENT: Codon 124 of the BIGH3 gene appears as a mutation hot spot also in German families with CDL1 and CDA. Indirect mutation analysis with restriction digestion is suggested as first step investigation in families with relevant corneal dystrophies. Direct sequencing of all exons is recommended as a second step if there are no results in restriction digestion.     

Novel mutation in FZD4 gene in a Japanese pedigree with familial exudative vitreoretinopathy

PURPOSE: To identify the genetic defect in the FZD4 gene responsible for familial exudative vitreoretinopathy (FEVR) in a Japanese family. DESIGN: Interventional case report. METHODS: Complete ophthalmologic examinations were performed, and the FZD4 gene was analyzed by direct genomic sequencing. RESULTS: Fundus examination of a 13-year-old Japanese girl who had had esotropia and exudative retinal detachment at 3 years exhibited peripheral avascular areas bilaterally, a dragged disk, and retinal holes unilaterally. In contrast, her asymptomatic father had only bilateral avascular areas in the peripheral retina. Molecular genetic analysis revealed that both the proband and her father had a heterozygous missense mutation of A to G at 1026 bp of the FZD4 gene (Met342Val). CONCLUSIONS: A novel mutation in the FZD4 gene was identified in Japanese patients with FEVR. Our observations support the hypothesis that the FZD4-associated FEVR might represent a milder form than that associated with other genetic origins.     

我国东北地区格子状角膜营养不良家系的TGFBI基因突变研究

目的：探讨我国东北地区一个格子状角膜营养不良(lattice corneal dysprothy,LCD)家系中TGFBI基因的突变类型与临床分型的相关性。

方法：对该家系中的2名正常人和患者进行眼科基本检查,抽取外周血进行基因突变检测。选取50名健康个人作为对照。应用聚合酶链反应(PCR)方法对TGFBI基因的所有外显子进行测序以检测突变位点。

结果：该家系中患者均检出TGFBI基因第4外显子R124C突变(c.370C>T)。该家系中正常成员及其他50名健康个体均未发现该位点的突变。

结论：确定该LCD家系患者的角膜病变由TGFBI基因R124C突变引起,同时也验证了R124C突变热点。     

The phenotype of arg555trp mutation in a large Turkish family with corneal granular dystrophy

PURPOSE: A large Turkish family with 52 members, 26 of whom had Groenouw type 1 corneal granular dystrophy was evaluated by genetic linkage studies and mutation analyses. Phenotype-genotype correlations were also assessed. METHODS: DNA from peripheral blood lymphocytes of 22 family members was used in establishing linkage to chromosome 5q31. Single-strand conformation polymorphism analysis was done to detect mutations in exons 4 and 12 of the human transforming growth factor beta-induced gene located on chromosome 5q31. Automated sequencing was performed on exon 12 of an affected patient. RESULTS: Patients yonger than 15 years of age had typical linear, granular opacities whereas adults had coarser, deeper granular stromal deposits. These changes were not associated with recurrent erosions or significant visual disabilities. The family was linked to chromosome 5q31 and a DNA shift was observed on exon 12 of affected patients. CGG to TGG transition producing R555W mutation was found. CONCLUSIONS: Segregation of Arg555Trp has been described as causing Groenouw type I corneal dystrophy of variable severity in patients of various ethnic backgrounds. In this large Turkish pedigree, the Arg555Trp mutation was associated with a mild phenotype that became clinically evident at five years of age but which remained asymptomatic in terms of corneal erosions.     

A new mutation (Leu569Arg) within exon 13 of the TGFBI (BIGH3) gene causes lattice corneal dystrophy type I

PURPOSE: To describe an American family with lattice corneal dystrophy type I, which associates with a novel mutation, Leu569Arg, of the TGFBI (BIGH3) gene. DESIGN: Experimental study. METHODS: Genomic DNA was extracted from buccal epithelial cells of four affected members of an American family with lattice corneal dystrophy type I. All 17 exons of the TGFBI gene were evaluated by PCR amplification and direct sequencing. Clinical and histologic data were also collected. RESULTS: Three generations of this family have been positively diagnosed with lattice corneal dystrophy, indicating autosomal dominant inheritance. We identified a heterozygous point mutation that associates with the disease phenotype. The single base-pair substitution (T1753G) results in an amino acid substitution (Leu569Arg) in exon 13 of the TGFBI gene. CONCLUSIONS: Substitution of arginine for leucine at position 569 of the TGFBI gene results in a form of lattice corneal dystrophy that is phenotypically similar to other genetically distinct forms of type I disease. This is the first report of disease correlated with changes in exon 13 of the TGFBI gene.     

A novel spontaneous missense mutation in VMD2 gene is a cause of a best macular dystrophy sporadic case

PURPOSE: To report the molecular characterization of a novel VMD2 mutation causing a Best macular dystrophy sporadic case. METHODS: All family members underwent ophthalmologic examination and genetic testing by single strand conformation polymorphism analysis and direct sequencing of the VMD2 gene. RESULTS: A single T to G transition at nucleotide 663 was identified in one of the VMD2 gene copies of the patient, which results in a Cys to Trp substitution at position 221 in the corresponding protein (C221W). Sequence analysis of the VMD2 exon 6 of both parents of the patient did not reveal any mutation. CONCLUSION: These data confirm the involvement of the VMD2 gene in Best macular dystrophy onset, even in sporadic cases of the disease, pointing out the relevance of molecular analysis in the diagnosis of this degenerative retinal disease.     

A novel p.R890C mutation in EPHA2 gene associated with progressive childhood posterior cataract in a Chinese family

AIM:To identify the genetic defect in a Chinese family with bilateral progressive childhood posterior cataract.METHODS: A two-generation family was recruited in this study. Family history and clinical data were recorded. All reported candidate genes associated with congenital posterior cataract were screened by direct DNA sequencing.RESULTS: All affected individuals presented posterior opacities in the lens. Direct sequencing of the candidate genes showed a heterozygous c. 2668C>T variation in EPHA2 gene, which resulted in the replacement of arginine by cysteine at codon 890 (p. R890C). This mutation was found in two affected individuals, but was not observed in 200 normal controls.CONCLUSION: We report a novel mutation (p. R890C) in the EPHA2 receptor tyrosine kinase gene. The finding expands the mutation spectrum of EPHA2 in association with posterior cataract.