ObjectiveTo reveal the pathogenic mutation in a three-generation Chinese family with autosomal dominant familial exudative vitreoretinopathy (FEVR). MethodsThree patients and a healthy spouse from the index family with FEVR were recruited. The proband was a 5 years old boy. His mother and grandpa were presented with typical FEVR presentations, while his father with normal ocular fundus. DNA was extracted from peripheral blood samples taken from all four participants. All coding and exon-intron boundary regions of five targeted genes, including NDP, FZD4, LRP5, TSPAN12 and ZNF408 were amplified with polymerase chain reaction and sequenced using direct sequencing. In silico analyses were applied to determine the conservation of the mutation site, pathogenic effect and the potential protein crystal structural changes caused by the mutation. ResultsFZD4 c.478G > A, a susceptible mutation was found after four high frequency mutation sites which MAF values were higher than 0.001 was filtered among 5 single nucleotide variations detected in four participants, leading to the residue 160 changing from glutamate to lysine (p.E160K). Co-segregation analysis between genotypes and phenotypes revealed FZD4 p.E160K as the disease-causing mutation for this family. Conservational analysis suggested that this mutation site was highly conserved among all tested species. Functional analysis predicated that this mutation may be a damaging mutation. Crystal structural analysis also indicated that this mutation could lead to the elimination of the hydrogen bond between residue 160 and asparagine at residue 152, thus altering the tertiary structure of the protein and further impairing the protein function. ConclusionOur study demonstrates FZD4 p.E160K as a novel pathogenic mutation for FEVR.
Objective To analyze the BEST1 gene mutations and clinical features in patients with multifocal vitelliform retinopathy (MVR). Methods This is a retrospective case series study. Five MVR families with MVR, including 9 patients and 10 healthy family members were recruited. Clinical evaluations were performed in all MVR patients and their family members, including best-corrected visual acuity (BCVA), intraocular pressure (IOP), refraction, slit-lamp examination, 90 D preset lens examination, gonioscopy, color fundus photography, optical coherence tomography (OCT), fundus autofluorescence (AF), ultrasound biomicroscopy (UBM) and axial length measurement. Electro-oculogram (EOG) was performed in 12 eyes and visual field were performed in 13 eyes. Peripheral blood samples were collected in all subjects to extract genomic DNA. Coding exons and flanking intronic regions of BEST1 were amplified by polymerase chain reaction and analyzed by Sanger sequencing. Results Among the 5 MVR families, 3 probands from three families had family history, including 1 family had autosomal dominant inheritance pattern. Two patients from 2 families were sporadic cases. Screening of BEST1 gene identified four mutations, including three missense mutations (c.140G>T, p.R47L; c.232A>T, p.I78F; c.698C>T, p.P233L) and 1 deletion mutation (c.910_912del, p.D304del). Two mutations (p.R47L and p.I78F) were novel. The BCVA of affected eyes ranged from hand motion to 1.0. The mean IOP was (30.39±11.86) mmHg (1 mmHg=0.133 kPa). The mean refractive diopter was (-0.33±1.68) D. Twelve eyes had angle-closure glaucoma (ACG) and 4 eyes had angle closure (AC). EOG Arden ratio was below 1.55 in all patients. The mean anterior chamber depth was (2.17±0.29) mm. Visual field showed defects varied from paracentral scotoma to diffuse defects. The mean axial length was (21.87±0.63) mm. All MVR patients had multifocal vitelliform lesions in the posterior poles of retina. ACG eyes demonstrated pale optic disc with increased cup-to-disc ratio. OCT showed retinal edema, extensive serous retinal detachment and subretinal hyper-reflective deposits which had high autofluorescence in AF. The genetic testing and clinical examination were normal in 10 family members. Conclusions MVR patients harbored heterozygous mutation in the BEST1 gene. Two novel mutations (p.R47L and p.I78F) were identified. These patients had clinical features of multifocal vitelliform retinopathy and abnormal EOG. Most patients suffered from AC/ACG.
Familial exudative vitreoretinopathy (FEVR) is a hereditary disease with high geneticheterogeneity, including autosomal dominant inheritance, autosomal recessive inheritance, snd X-linked recessive inheritance. So far, six genes have been found to be associated with FEVR: Wnt receptor fizzled protein (FZD4), Norrie disease (NDP), co-receptor low-densitylipoprotein receptor-related protein 5 (LRP5), and tetrasin 12 (TSPANI2), zinc finger protein408 (ZNF408), kinesin family member 11 (KIF11) gene. Among them, FZD4, NDP, LRPS, TSPANI2 and other four genes play an important role in the Norrin/Frizzled 4 signaling pathway. In retinal capillary endothelial cells, Norrin specifically controls the occurrence of ocular capillaries by activating the Norrin/Frizzled 4 signaling pathway. ZNF408 and KIF11 are newly discovered pathogenic genes related to FEVR in the past 5 years. ZNF408 encodes the transcription factor that plays an important role in retinal angiogenesis. KIF11 plays a role in eye development and maintenance of retinal morphology and function.
Familial exudative vitreoretinopathy (FEVR) is a hereditary retinal vascular dysplasia. So far, 6 genes have been found to be associated with FEVR: Wnt receptor Frizzled Protein 4, Norrie's disease, co-receptor low-density lipoprotein receptor-related protein 5, tetraspanin 12, zinc finger protein 408, and kinesin family members 11 genes. Its clinical manifestations, pathological processes and genetic patterns are diverse, and it shows the relationship between gene polymorphism and clinical manifestation diversity. It is characterized by different symptoms between the same individual, the same family, and the same gene mutation; different clinical stages and gene mutation types of parents or unilateral genetic children; different clinical characteristics and gene mutation patterns of full-term and premature infant; combined with other eye disease and systemic diseases; double gene mutations and single gene mutations have different clinical manifestations and gene mutation characteristics. A comprehensive understanding of the different clinical manifestations and diverse genetics of FEVR can provide better guidance for the treatment of FEVR.
ObjectiveTo identify the pathogenic mutation in a patient with Oguchi disease.MethodsA Japanese patient with Oguchi disease was enrolled in this study, and underwent a comprehensive medical history assessment and multiple ophthalmic examinations, including BCVA, OCT, color fundus photography and full field electroretinogram. Genomic deoxyribonucleic acid (DNA) was extracted from peripheral blood samples for whole exome sequencing. The gene mutation was detected, and the analysis software was used to determine the conservation of the mutation and the possible structural changes.ResultsThe patient, 71 years old, with consanguineous parents, complained of night blindness since early childhood. BCVA in both eyes was 0.7 and the golden-yellowish reflex appeared in the grey retina. The scotopic 0.01 ERGs showed a extinguished reaction in both eyes. The scotopic 3.0 ERGs showed a “negative” configuration with a significantly reduced a wave and a nearly absent b wave. A homozygous deletion mutation in the SAG gene (c.924delA, p.N309Tfs*12) in this patient was founded by DNA sequencing, which was predicted to generate prematurely truncated SAG protein and result in severe structural change. Homology analysis of the protein sequence indicated that the mutation resulted in an altered amino acid which was evolutionarily highly conserved among different species, strongly suggesting the potential pathogenicity of this homozygous mutation.ConclusionThe mutation c.924delA(309Tfs*12) in SAG cause Oguchi disease in this patient.
The rapid development of genetic diagnosis-related technologies has paved a wide road for gene therapy. Different gene therapy clinical trials for retinal disorders, including gene-replacement therapy, anti-neovascular gene therapy and opotogenetic gene therapy, have been developed and achieved fruitful results, which have gradually confirmed the efficacy and safety of adeno-associated virus (AAV)-mediated gene therapy for recessive retinal diseases. In recent years, novel gene editing technologies also shows great potential to treat dominant retinal disease, or recessive retinal disease when the therapeutic gene fragments are too long to fit into the AAV vectors. These results make it possible for most of the patients with inherited retinal diseases to be treated by the safe and effective AAV-mediated gene therapy, which will also benefit Chinese patients soon.
Hereditary ocular fundus disease is an important cause of irreversible damage to patients' visual acuity. It has attracted much attention due to its poor prognosis and lack of effective clinical interventions. With the discovery of a large number of hereditary ocular fundus genes and the development of gene editing technology and stem cell technology, gene and stem cell therapy emerged as the new hope for curing such diseases. Gene therapy is more directed at early hereditary ocular fundus diseases, using wild-type gene fragments to replace mutant genes to maintain existing retinal cell viability. Stem cell therapy is more targeted at advanced hereditary ocular fundus diseases, replacing and filling the disabled retinal cell with healthy stem cells. Although gene and stem cell therapy still face many problems such as gene off-target, differentiation efficiency, cell migration and long-term efficacy, the results obtained in preclinical and clinical trials should not be underestimated. With the emergence of various new technologies and new materials, it is bound to further assist gene and stem cell therapy, bringing unlimited opportunities and possibilities for the clinical cure of hereditary ocular fundus diseases.
ObjectiveTo observe and analyze the genotype and clinical phenotype in 34 families of familial exudative vitreoretinopathy associated with (FEVR) gene variation.MethodsCohort study. Thirty-four FEVR families, in which the patients and both of their parents were all found to have FEVR-related gene mutations (proband 34 cases, 67 eyes; parents 68 cases, 136 eyes), were included in the study. These patients were identifIed from 722 FEVR patients through genetic screening, which diagnosed in Department of Ophtalmology of Xinhua Hospital and Tianjin Medical University Eye Hospital from January 2010 to December 2018. The probands and their parents underwent a comprehensive ophthalmological examination appropriate to their age, including BCVA, intraocular pressure, axial length, slit lamp examination, indirect ophthalmoscopy, FFA or color fundus photography or wide field color fundus photography. According to the severity of the disease, the clinical manifestations were divided into severe phenotype and mild phenotype. Thirty-four normal healthy people over 40 years old were included as the control group. The peripheral blood samples of FEVR family members and control group members were collected, and the genes known to be involved in FEVR, such as FZD4, LRP5, NDP, TSPAN12, ZNF408 and KIF11, were analyzed by next generation sequencing molecular genetics. The data were statistically analyzed by SPSS. The counting data was expressed in numbers or rates, and tested by Kruskal-Wallis test and χ2 test to find out the existence of significant difference.ResultsIn 67 eyes of the 34 probands, 48 eyes (71.64%) were classified into severe phenotype and 19 eyes (28.36%) were mild phenotype. In 136 eyes of 68 parents of the proband patients, 76 eyes (55.88%) were normal, 60 eyes (44.12%) were classified into mild phenotype, and no severe phenotype was found. A total of 65 variants of FEVR-related genes were detected in the 34 probands, of which LRP5 mutation was the most common (64.61%), followed by FZD4 (12.31%), NDP (10.77%), TSPAN12 (6.15%), ZNF408 (4.62%) and KIF11 (1.54%). Missense mutations were the most common variant in FEVR-related genes. However, the results of correlation analysis indicated that there was no significant correlation between the type of mutation and the severity of clinical phenotype (H=1.775, P=0.620). Among the 65 mutation types, 21 types have been previously identified and 44 were novel in this study. Thirty-nine eyes of 20 cases had only one single pathogenic mutation gene but with multiple mutation sites, 26 eyes of 13 cases carried 2 relevant pathogenic mutation genes, and 2 eyes in one case had 3 pathogenic mutation genes. The mutation frequencies of LRP5, NDP, ZNF408, FZD4, TSPAN12 and KIF11 genes in probands were significantly higher than those in control group, and the difference was statistically significant. The total mutation frequencies of LRP5, NDP, ZNF408, FZD4, TSPAN12 and KIF11 genes in proband group were significantly higher than those in control group (χ2=64.702, P＜0.001).ConclusionsIn the FEVR families, the most frequent mutations were those in LRP5, followed by FZD4, NDP, TSPAN12,ZNF408 and KIF11. Missense mutation is the most common type of FEVR-related gene mutation, but there is no significant correlation between the clinical phenotype and gene variation type. Most of the probands were with severe clinical phenotype, while most of the parents with FEVR pathogenic gene mutation showed normal or mild manifestations.
Familial exudative vitreoretinopathy (FEVR) is a rare inherited disorder of retinal angiogenesis, including autosomal dominant, autosomal recessive, or X-linked forms. Zinc finger protein 408 (ZNF408) was recently found to be associated with FEVR. Cell transfection showed that it was a dominant negative regulator of FEVR pathogenesis. Knocking down ZNF408 in zebrafish by antisense morpholino oligonucleotides indicated it involved in retinal blood vessel development. Understanding the protein structure, gene localization, basic functions and the role of ZNF408 in retinal development will contribute to uncover the pathogenesis of FEVR.
Adeno-associated viral vector (AAV) is the most important viral tool and has been widely used in gene therapy. Because of its small size, non-enveloped, non-pathogenic and other characteristics, so it is one of the main means to treat hereditary retinal diseases. Aiming at MERTK for retinitis pigmentosa, ND4 for Leber hereditary optic neuropathy or RPE1 for choroideremia, AAV gene therapy improved half patients’ visual acuity in clinic tests. Besides, there are some clinic tests in progress for Leber’s congenital amaurosis, X-linked retinoschisis, Achromatopsia, age-related macular degeneration. But more researches need to be found before clinic test for Stargardt disease, Usher syndrome and nanophthalmos. At present, AAV gene therapy is mainly used for recessive hereditary retinal diseases, and technology is needed to intervene for dominant retinal diseases. For the treatment of hereditary retinal diseases, this will be an important and complex systematic project, which requires more human and material resources to participate in and study together, and we expect to have a great breakthrough in the near future.