Familial Exudative Vitreoretinopathy Patients Research Articles

Mutations in TSPAN12 gene causing familial exudative vitreoretinopathy

BackgroundTo report newly found TSPAN12 mutations with a unique form of familial exudative vitreoretinopathy (FEVR) and find out the possible mechanism of a repeated novel intronic variant in TSPAN12 led to FEVR.ResultsNine TSPAN12 mutations with a unique form of FEVR were detected by panel-based NGS. MINI-Gene assay showed two splicing modes of mRNA that process two different bands A and B, and mutant-type shows replacement with the splicing mode of Exon11 hopping. Construction of wild-type and mutant TSPAN12 vector showed the appearance of premature termination codons (PTC). In vitro expression detection showed significant down-regulated expression level of TSPAN12 mRNAs and proteins in cells transfected with mutant vectors compared with in wild-type group. On the contrary, translation inhibitor CHX and small interfering RNA of UPF1 (si-UPF1) significantly increased mRNA or protein expression of TSPAN12 in cells transfected with the mutant vectors.ConclusionsNine mutations in TSPAN12 gene are reported in 9 FEVR patients with a unique series of ocular abnormalities. The three novel TSPAN12 mutations trigger NMD would cause the decrease of TSPAN12 proteins that participate in biosynthesis and assembly of microfibers, which might lead to FEVR, and suggest that intronic sequence analysis might be a vital tool for genetic counseling and prenatal diagnoses.

Refractive Status and Biometric Characteristics of Children With Familial Exudative Vitreoretinopathy.

To compare biometric characteristics between patients with early-stage familial exudative vitreoretinopathy (FEVR) and healthy controls. This case-control study included 50 FEVR eyes in stage 1-2 and 50 control eyes matched by age, gender and spherical equivalent (SE). Biometric parameters including axial length (AL), white-to-white diameter (WTW), central corneal thickness (CCT), anterior chamber depth (ACD), lens thickness (LT), pupil diameter, vitreous chamber depth, anterior and posterior corneal surface curvature radius (ACR and PCR), anterior lens surface curvature radius (ALR) and posterior lens surface curvature radius were measured using IOLMaster 700 and compared between cases and controls using paired t-test. Correlations between SE and biometric measures were assessed using Pearson correlation coefficient (r) in cases and controls. Both FEVR cases and matched controls had a mean age of 7.6 years, 48% female and mean SE of -5.3D (80% myopia). Compared to controls, FEVR eyes had smaller AL (P = 0.009), WTW (P = 0.001), ACD (P < 0.001), and ALR (P = 0.03), but larger CCT (P = 0.02) and LT (P = 0.01). In FEVR eyes, SE was negatively correlated with AL (r = -0.79, P < 0.001), positively correlated with ACR (r = 0.29, P = 0.04) and PCR (r = 0.33, P = 0.02), whereas in controls, SE was negatively correlated with AL (r = -0.82, P < 0.001) and LT (r = -0.34, P = 0.02), positively correlated with ALR (r = 0.29, P = 0.04). Patients at early stage of FEVR exhibited a unique eye morphology resembling ocular development arrest, which may help to develop screening and early detection tools for FEVR. In FEVR patients, myopia is very prevalent and significantly associated with corneal curvature increase.

Peripheral and central retinal vascular changes in asymptomatic family members of patients with familial exudative vitreoretinopathy.

To evaluate the peripheral vascular changes and effects of these on macular microvasculature in asymptomatic family members of familial exudative vitreoretinopathy (FEVR) patients. This is a retrospective study including 61 eyes of asymptomatic family members of FEVR patients. Retinal abnormalities were assessed via ultra-widefield fluorescein angiography (UWF-FA) and optical coherence tomography angiography (OCTA). The eyes were grouped into 3: the first group comprised of eyes with normal findings on UWF-FA; the second group comprised of eyes with abnormal findings on UWF-FA but without any retinal ischemia; and the third group involved eyes with retinal ischemia or neovascularization. Best corrected visual acuity (BCVA) was 20/20 in all eyes. Forty eyes (65.6%) had abnormalities on UWF-FA. The most common feature was peripheral vascular looping, increased tortuosity, and anastomosis (63.9%). ODM/ODD ratio was higher in group 3 compared to groups 1 and 2. Deep foveal VD was lower in group 1 compared to groups 2 and 3. The mean FAZ area and perimeter were smaller in groups 2 and 3 compared to group 1. Even asymptomatic family members of FEVR patients may have significant peripheral retinal vascular abnormalities which may be associated with smaller optic disc, macular ectopia, and macular microvascular changes.

Two types of childhood glaucoma secondary to familial exudative vitreoretinopathy

Glaucoma secondary to familial exudative vitreoretinopathy presents as angle closure by either neovascular or non-neovascular mechanisms. We analyze the presentation and outcomes of two types of childhood glaucoma secondary to familial exudative vitreoretinopathy (FEVR). This retrospective cross-sectional study included all patients <18 years of age diagnosed with glaucoma after or concurrently with a diagnosis of FEVR between 2010 and 2020 from Queen Sirikit National Institute of Child Health in Bangkok, Thailand. Two groups were analyzed: neovascular or non-neovascular angle-closure status. Primary outcome measures were final visual acuity and intraocular pressure (IOP) in both groups. Of 144 FEVR patients, 8 children (5.5%; 11 eyes, 3 bilateral cases) developed childhood glaucoma. Mean time between FEVR presentation and glaucoma was 42.2 ± 40.0 months. In the neovascular group, 3 of 9 eyes presented with glaucoma at FEVR diagnosis; 3 of 9 eyes (33%) required glaucoma surgery. In the non-neovascular group, 2 eyes presented with acute angle closure secondary to a phacomorphic lens. Both were treated with trabeculectomy, with resolution of pupillary block. All eyes had stage 4B FEVR or greater. Six of 8 eyes had stable or better visual acuity, and 10 eyes (91%) had IOP <21 mm Hg at final follow-up. Childhood glaucoma secondary to FEVR is a rare complication caused by later stages of the disease. It may present as neovascular or non-neovascular angle closure, often requiring complex care. Therefore, awareness and adequate management of FEVR can help prevent additional morbidity from childhood glaucoma.

The Characteristic of Optical Coherence Tomography Angiography and Retinal Arteries Angle in Familial Exudative Vitreoretinopathy with Inner Retinal Layer Persistence

Purpose To compare the angle of retinal arteries and macular vessel density and foveal avascular zone (FAZ) in early stage familial exudative vitreoretinopathy (FEVR) patients with inner retinal layer (IRL) persistence with FEVR patients without IRL persistence and normal people. Methods This study enrolled 113 early stage FEVR patients and 55 age-matched normal subjects. FEVR patients were divided into IRL group and non-IRL group based on the presence or absence of IRL in fovea. The angle of superior temporal and inferior temporal branch retinal arteries on ultra-wide-field fundus images were measured. Superficial and deep vessel density of whole image, fovea and parafovea, the area and perimeter of FAZ, A-circularity index (AI, perimeter/standard circle perimeter with equal area) and vessel density around the 300-μm width of the FAZ (FD), central macular thickness (CMT) on 3 mm × 3mm OCTA were measured. Results 30 FEVR patients in IRL group, 83 FEVR patients in non-IRL group, 55 normal people in control group were evaluated. BCVA were worst in IRL group (p < .001). The angle of retinal arteries was smaller in FEVR groups (p < .001) and were smallest in IRL group (p < .001). Superficial and deep vessel density of whole and parafovea area in FEVR patients were significantly lower than that in normal people (p < .05), AI were biggest (p = .01) and FD were smallest in IRL group (p < .001). CMT in IRL group were thicker than non-IRL group and control group (p < .05). Conclusion Worse BCVA, smaller angle of retinal arteries (more vessels traction), lower macular vessel density, smaller and more irregular FAZ and thicker CMT were observed in FEVR patients with IRL persistence even in early stage.

Decrease of FZD4 exon 1 methylation in probands from FZD4-associated FEVR family of phenotypic heterogeneity.

Familial exudative vitreoretinopathy (FEVR) is an important cause of childhood blindness and is clinically characterized by phenotypic heterogeneity. FEVR patients harboring the same genetic mutation vary widely in disease severity. The purpose of this study was to explore non-genetic factors that regulate FEVR phenotypic heterogeneity. We detected methylation levels of 21 CpG sites located at the FZD4 exon 1 region of 11 probands, 12 asymptomatic/paucisymptomatic carriers and 11 non-carriers from 10 unrelated FZD4-associated FEVR families using bisulfite amplicon sequencing (BSAS). Our results showed reduced methylation level of FZD4 exon 1 in probands, suggesting that FZD4 exon 1 methylation level may be negatively linked with FEVR disease severity. It provided a new research direction for follow-up research, helping us better understand the complexity of the FEVR-causing mechanism.

LRP5 BIALLELIC MUTATIONS CAUSE A HIGHER INCIDENCE OF SEVERE PHENOTYPE COMPARED WITH LRP5 MONOALLELIC MUTATION

To analyze the clinical features of LRP5 gene mutation-related familial exudative vitreoretinopathy and explore the potential phenotype-genotype correlation on LRP5 gene. Eighty-seven familial exudative vitreoretinopathy (FEVR) families with LRP5 mutations were selected from 722 FEVR patients, which were divided into 2 groups, including 22 autosomal-recessive FEVR (ar-FEVR) families and 65 autosomal-dominant FEVR (ad-FEVR) families. Clinical and genetic data were retrospectively analyzed. The potential phenotype-genotype correlation was explored from the mutation type and inheritance pattern. No significant difference between the LRP5 null mutation subgroup and the LRP5 missense mutation subgroup was observed in the proportion of FEVR stage and the ratio of ocular involvement. Instead, a significant difference between the LRP5 ar-FEVR subgroup and the LRP5 ad-FEVR subgroup was observed in the proportion of FEVR stage and the ratio of binocularly severe phenotype. The probands with LRP5 gene recessive mutation showed a higher incidence of severe phenotype. Moreover, the ratio of binocularly severe patients in ar-FEVR was nearly 3.5 times higher than that in ad-FEVR. The severity of phenotype was more likely to be related to the synergistic effect of the variants.

Long-term clinical prognosis of 335 infant single-gene positive FEVR cases

PurposeTo describe and analyze the clinical prognosis of infants diagnosed of familial exudative vitreoretinopathy (FEVR) with single gene mutation in long-term follow-up.MethodsA retrospective case study was conducted on 355 FEVR infants with single positive gene.ResultOf the 335 single-gene positive infant FEVR cases (under 3 years old), 20% (n = 67) was diagnosed of strabismus at first visit. Staging of various genotypes was different (P < 0.001). Patients with NDP mutations presented the most severe clinical phenotypes and patients with ZNF408 mutations presented the mildest clinical phenotypes. Most infants underwent surgery under 1 year old (5th stage 75 of 108 [69.44%]). The axial length of different genotypes showed no significant difference (P = 0.2891). The 1st to 3rd stage cases were given intravitreal injection and/or retina photocoagulation with the last follow-up vision above 20/67. The 4th to 5th stage cases received the transcorneal vitrectomy with lensectomy or lens sparing vitrectomy (LSV), whose lens maintained transparent after LSV (11/14[78.58%]). After 2 to 10 years of follow-up, 37.96% (41/108) of post-surgery cases showed retinal funnel-like unfold and posterior pole unfold, 69.57% (16/ 23) of which received second surgery for closure of pupil with good prognosis. At the last follow-up, 20% (60/300) were with vision above 20/200.ConclusionLRP5 gene mutation was the most common mutation in FEVR patients. The severity of the clinical phenotype varied with different gene mutations. The main surgical methods for cases at Stage 4–5 were transcorneal vitrectomy with lensectomy or LSV. The earlier FEVR occurred, the worse prognosis would be. Active surgical intervention and lens sparing were necessary for cases at Stage 4–5.

Dry-Lensectomy Assisted Lensectomy in the Management for End-Stage Familial Exudative Vitreoretinopathy Complicated With Anterior Segment Abnormalities.

PurposeTo report a modified technique of dry-lensectomy assisted lensectomy in the management of end-stage familial exudative vitreoretinopathy (FEVR) complicated with capsule-endothelial, iris-endothelial adhesion and secondary glaucoma.Methods24 eyes of 16 patients with severe complications of advanced pediatric total retinal detachment caused by FEVR who received limbus-based dry-lensectomy were studied retrospectively. Preoperative and postoperative clinical information was collected and reviewed.ResultsAmong the 24 eyes, three eyes (12.50%) underwent lensectomy combined with vitrectomy and membrane peeling simultaneously. 21 (87.50%) eyes underwent lensectomy without membrane peeling due to severe corneal opacity or retinal vascular activity, of which eight underwent another vitrectomy combined with membrane peeling. At the last visit (mean:13.86 ± 5.24 months of follow-up), all eyes had a reconstructed anterior chamber with normal depth. Among 21 eyes having preoperative corneal opacity, 15 (71.43%) had a clearer cornea with reduced opacity, 5 (23.81%) showed similar corneal opacification without deterioration. Among 11 eyes undergone retrolental fibroplasia peeling, seven (63.64%) eyes showed partial retinal reattachment in open-funnel type.ConclusionDry-lensectomy offered a simple way to lower the intraocular pressure and simplified the surgery, which helped to solve the severe anterior segment complications and offer a chance for following retrolental fibroplasia peeling and potential visual gain for selected end-stage FEVR patients.

Update on the Phenotypic and Genotypic Spectrum of KIF11-Related Retinopathy.

Background: This study aimed to report the frequency of KIF11-mutations in a large familial exudative vitreoretinopathy (FEVR) population, extend the clinical spectrum of KIF11-associated retinopathy and compare KIF11-associated retinopathy to FEVR with mutations in other genes. Methods: Genetic data collected from 696 FEVR families were reviewed. The ocular phenotypes in patients with KIF11 mutations were analyzed and compared with those of FEVR patients with mutations in other genes (FZD4, TSPAN12, LRP5, NDP and JAG1). Results: In a cohort of 696 FEVR families, disease-causing KIF11 mutations were identified in 3.6% of families (25/696). Among 25 KIF11 mutations, 80% (20/25) carried variants of loss of function and 48% (12/25) of variants were de novo. The phenotypes were variable. Compared with FEVR with disease-causing mutations in other genes, chorioretinal dysplasia was observed in 44.2% (31/70) of eyes with KIF11-associated retinopathy and in only 1.3% (1/70) of eyes with FEVR with mutations in other genes (p < 0.01). Increase and straightening of peripheral vessels (ISPV) was observed in 17.1% (12/70) of eyes with KIF11-associated retinopathy, and in 50% (39/78) of eyes with FEVR with mutations in other genes (p < 0.01). Conclusions: The frequency of the KIF11 mutation in FEVR was 3.6% in our database. The manifestation of KIF11-associated retinopathy was variable and different from the phenotype in FEVR caused by other genes. Chorioretinal dysplasia, instead of retinal folds, was the dominant phenotype in KIF11-associated retinopathy. ISPV was rare in KIF11-associated retinopathy. Moreover, our study revealed that most pathogenic KIF11 mutations were de novo.

Familial Exudative Vitreoretinopathy (FEVR); Pathophysiology, Findings, Diagnosis, and Treatment

Familial exudative vitreoretinopathy (FEVR) is an inherited disease occurring due to defective retinal angiogenesis. FEVR patients have an avascular peripheral retina which, depending on the degree of ischemia, causes the secondary complications of the disease (retinal neovascularization, exudation, hemorrhage, and retinal detachment) Mutations in the NDP, FZD4, LRP5, TSPAN12 and ZNF08 genes have been shown to contribute to FEVR. Cases can be inherited in an autosomal dominant, autosomal recessive, or X-linked manner, or can affect individuals with no family history. Examination with wide-field fluorescein angiography is essential and can identify the disease in its earlier stages, enabling the timely treatment, in addition to helping identify asymptomatic family members. The current treatment modalities involve laser photocoagulation of the avascular peripheral retina for neovascular complications and vitreoretinal surgery for retinal detachment. Studies are ongoing to better understand the pathogenesis of FEVR and to improve treatment

Whole-Gene Deletions of FZD4 Cause Familial Exudative Vitreoretinopathy.

Familial exudative vitreoretinopathy (FEVR) is an inherited disorder characterized by abnormalities in the retinal vasculature. The FZD4 gene is associated with FEVR, but the prevalence and impact of FZD4 copy number variation (CNV) on FEVR patients are unknown. The aim of this study was to better understand the genetic features and clinical manifestations of patients with FZD4 CNVs. A total of 651 FEVR families were recruited. Families negative for mutations in FEVR-associated genes were selected for CNV analysis using SeqCNV. Semiquantitative multiplex polymerase chain reaction and multiplex ligation-dependent probe amplification were conducted to verify the CNVs. Four probands were found to carry whole-gene deletions of FZD4, accounting for 5% (4/80) of probands with FZD4 mutations and 0.6% (4/651) of all FEVR probands. The four probands exhibited similar phenotypes of unilateral retinal folds. FEVR in probands with CNVs was not more severe than in probands with FZD4 missense mutations (p = 1.000). Although this is the first report of FZD4 CNVs and the associated phenotypes, the interpretation of FZD4 CNVs should be emphasized when analyzing the next-generation sequencing data of FEVR patients because of their high prevalence.

Retinal Features of Family Members With Familial Exudative Vitreoretinopathy Caused By Mutations in KIF11 Gene.

PurposeTo determine the clinical characteristics of patients and family members with familial exudative vitreoretinopathy (FEVR) caused by mutations in the KIF11 gene.MethodsTwenty-one patients from 10 FEVR families with mutations in the KIF11 gene were studied. The retinal and systemic features were examined. The genetic analyses performed included Sanger sequencing of the KIF11 gene, whole exome sequencing, as well as array comparative genomic hybridization (CGH) analysis and multiple ligation probe assay (MLPA).ResultsSequence analysis revealed seven different KIF11 mutations. Array CGH with MLPA revealed two different exon deletions. All probands had advanced FEVR with retinal detachments (RDs) and microcephaly with or without developmental disabilities. Patients with bilateral RDs were more frequently associated with developmental disabilities (P = 0.023). Multimodal imaging of the family members revealed that six of nine patients without RDs (66%) had varying degrees of chorioretinopathy. The retinal folds in FEVR patients were associated with severe retinal avascularization. However, funduscopic changes in the peripheral retina were unremarkable in family members without RDs. A score representing the peripheral vascular anomalies determined from the fluorescein angiograms was lower than that of control eyes of patients with mutations of the Wnt signaling genes (P = 0.0029).ConclusionsThe probands with KIF11 mutations were associated with severe ocular and systemic pathologies, whereas affected family members showed highly variable clinical manifestations. Peripheral vascular anomalies can often be unremarkable in eyes without RDs.Translational RelevanceThese findings highlight more diverse mechanisms that underlie the pathological changes in patients with FEVR.

Ultra-wide-field scanning laser ophthalmoscopy and optical coherence tomography in FEVR: findings and its diagnostic ability

Background/AimsTo describe some novel vitreoretinal microstructural findings in patients with mild familial exudative vitreoretinopathy (FEVR) on ultra-wide-field scanning laser ophthalmoscopy (UWF-SLO) and UWF optical coherence tomography (UWF-OCT) and to evaluate...

Novel variants in familial exudative vitreoretinopathy patients with KIF11 mutations and the Genotype–Phenotype correlation

Familial exudative vitreoretinopathy (FEVR) is an inherited disease characterized by abnormal development of retinal vasculature. KIF11 mutations were identified to be associated with FEVR in recent years. The purpose of this study was to investigate novel variants and describe associated ocular and extraocular phenotypes in FEVR patients with KIF11 mutations. Herein, 417 probands with clinical diagnosis of FEVR were enrolled. Genetic testing and ophthalmic examinations were performed in all subjects, and the genotype–phenotype correlation was analyzed. Overall, KIF11 mutation was identified in nine probands (9/417, 2.2%) among the patients with FEVR phenotype. There were six males and three females whose median age was six months (range: four months to six years old) at first visit. Among the detected mutations, five (55.6%) were frameshift, two (22.2%) were missense, one (11.1%) nonsense, and one (11.1%) splicing. Seven of these KIF11 mutations were detected as novel. Four (4/9, 44.4%) of the mutations were de novo. Clinical examinations showed that: four probands presented with bilateral falciform retinal fold; two with bilateral tractional retinal detachment; one was observed tractional retinal detachment in one eye and retinal fold in the other eye; one had falciform retinal fold in one eye and chorioretinal atrophy in the other eye; one exhibited rhegmatogenous retinal detachment in the left eye. Six of the probands were detected to have microcephaly. In conclusion: Most (5/9,55.6%) of the causative mutations were frameshift, and nearly half (4/9, 44.4%) of the mutations were de novo. Most (8/9, 88.9%) patients with KIF11 mutations showed typical ocular manifestations of severe FEVR. Majority (6/9, 66.7%) of the probands had a KIF11 mutation and were detected to have microcephaly. Seven of these harbored KIF11 mutations detected to be novel.

Diagnosis of complicated FEVR preoperatively and intra\u2212/post-operatively: characteristics and risk factors for diagnostic timing

BackgroundTo delineate the characteristics of complicated familial exudative vitreoretinopathy (FEVR) patients diagnosed before surgery or intra−/post-operatively and to analyze the risk factors for the diagnostic timing.MethodsForty-eight patients who underwent surgery and were diagnosed as FEVR in our department were retrospectively reviewed. Data were collected including the demographic and clinical characteristics of these patients. FEVR patients were divided into 2 groups according to the diagnostic timing: FEVR diagnosed pre-operatively (23 patients), FEVR diagnosed intra−/post-operatively (25 patients). Multivariable analysis was applied for analyzing the risk factors for diagnostic timing.ResultsThe clinical characteristics of the FEVR patients were of great variability, including retinal detachment (RD), disappear of anterior chamber, retrolental membrane, epiretinal membrane (ERM), vitreous hemorrhage (VH), myopic foveoschisis (MF), lamellar macular hole (LMH), high myopia (HM). And the referral diagnosis or pre-operative diagnosis were always non-specific. The majority of the referral or preoperative diagnosis were unilateral RD (52.1%), bilateral RD (8.3%), unilateral persistent fetal vasculature (PFV) (8.3%), bilateral PFV (4.2%). There are two risk factors for the complicated FEVR cases diagnosed as FEVR preoperatively: pre-operative ocular manifestations with RD only (OR, 0.104; p-value, 0.022), positive parent’s fluorescein angiography (FA) (OR, 0.105; p-value, 0.035).ConclusionsThe phenotypes of FEVR were greatly variable, they can mimic many non-specific vitreoretinal disorders. The most non-specific referral diagnosis/pre-operative diagnosis was unilateral RD, bilateral RD, unilateral PFV, bilateral PFV. A positive family history or a simple ocular presentation with RD only could contribute to diagnose FEVR preoperatively.

Correlating Changes in the Macular Microvasculature and Capillary Network to Peripheral Vascular Pathologic Features in Familial Exudative Vitreoretinopathy

To evaluate the macular microvasculature in patients with familial exudative vitreoretinopathy (FEVR) using OCT angiography (OCTA) and to assess for peripheral vascular changes using widefield fluorescein angiography (WFA). Multicenter, retrospective, comparative, observational case series. We identified 411 patients with FEVR, examined between September 2014 and June 2018. Fifty-seven patients with FEVR and 60 healthy controls had OCTA images of sufficient quality for analysis. Custom software was used to assess for layer-specific, quantitative changes in vascular density and morphologic features on OCTA by way of vessel density (VD), skeletal density (SD), fractal dimension (FD), vessel diameter index (VDI), and foveal avascular zone (FAZ). Widefield fluorescein angiography images were reviewed for peripheral vascular changes including capillary dropout, late-phase angiographic posterior and peripheral vascular leakage (LAPPEL), vascular dragging, venous-venous shunts, and arteriovenous shunts. Macular microvascular parameters on OCTA and peripheral angiographic findings on WFA. OCT angiography analysis of 117 patients (187 eyes; 92 FEVR patients and 95 control participants) demonstrated significantly reduced VD, SD, and FD and greater VDI in patients with FEVR compared with controls in the nonsegmented retina, superficial retinal layer (SRL), and deep retinal layer (DRL). The FAZ was larger compared with that in control eyes in the DRL (P < 0.0001), but not the SRL (P= 0.52). Subanalysis by FEVR stage showed the same microvascular changes compared with controls for all parameters. Widefield fluorescein angiography analysis of 95 eyes (53 patients) with FEVR demonstrated capillary nonperfusion in all eyes: 47 eyes (49.5%) showed LAPPEL, 32 eyes (33.7%) showed vascular dragging, 30 eyes (31.6%) had venous-venous shunts, and 33 eyes (34.7%) had arteriovenous shunts. Decreasing macular VD on OCTA correlated with increasing peripheral capillary nonperfusion on WFA. Decreasing fractal dimension on OCTA correlated with increasing LAPPEL severity on WFA. Patients with FEVR demonstrated abnormalities in the macular microvasculature and capillary network, in addition to the peripheral retina. The macular microvascular parameters on OCTA may serve as biomarkers of changes in the retinal periphery on WFA.

Optical Coherence Tomography Angiography in Familial Exudative Vitreoretinopathy: Clinical Features and Phenotype-Genotype Correlation

To evaluate the microstructure of the fovea in patients with familial exudative vitreoretinopathy (FEVR) compared to healthy controls using optical coherence tomography angiography (OCTA). In this consecutive, cross-sectional, observational case series, 41 eyes of 41 patients diagnosed as FEVR and 37 eyes in 37 control subjects were studied. OCTA was utilized to automatically measure the foveal avascular zone (FAZ) and the vessel density (VD). Inner retinal thicknesses (IRT) and central retinal thickness (CRT) were measured with the instrument caliper. Targeted next-generation sequencing was performed, and phenotype-genotype association was analyzed. Small FAZ was found in 31.70% (13/41) FEVR eyes but not in controls. Greater CRT and lower superficial foveal VD were noted in FEVR patients. FAZ is negatively correlated with IRT. Persistence of the inner retinal layer (IRL) in fovea was present in 48.78% (20/41) FEVR eyes but not found in controls. Zero percent (0/10) of patients with the low-density lipoprotein receptor-related protein 5 (LRP5) mutation, 50% (1/2) with the frizzled-4 (FZD4) mutation, and 66.67% (3/4) with the tetraspanin-12 (TSPAN12) mutation had preserved foveal IRL and small FAZ. Our data indicate FEVR status is associated with a significantly smaller FAZ, decreased vascular density in both the superficial and deep layers of parafoveal area, a thicker fovea, and an abnormally preserved IRL in fovea. In addition, patients with the LRP5 mutation had a milder phenotype than those with the FDZ4 or TSPAN12 mutations. These novel findings could provide insight into the understanding of the pathogenesis of FEVR.

Spectrum of Variants in 389 Chinese Probands With Familial Exudative Vitreoretinopathy.

To identify potentially pathogenic variants (PPVs) in Chinese familial exudative vitreoretinopathy (FEVR) patients in FZD4, LRP5, NDP, TSPAN12, ZNF408, and KIF11 genes. Blood samples were collected from probands and their parent(s). Genomic DNA was analyzed by next-generation sequencing, and the sequence of selected variants were validated by Sanger sequencing. The potential pathogenicity of a variant was evaluated by in silico analysis and by cosegregation of the variant with disease. Each proband was subjected to comprehensive retinal examinations, and the severity of FEVR was individually graded for each eye. Whenever possible, fundus fluorescein angiography was obtained and analyzed for parent(s) of each proband. Variation in mutation expressivity was analyzed. Three hundred eighty-nine consecutive FEVR patients from 389 families participated in this study. About 74% of the probands were children younger than 7 years old. One hundred one PPVs, 49 variants with unknown significance (VUS), were identified, including 73 novel PPVs and 38 novel VUS. One hundred ten probands carried PPV (28.3%), and 51 probands carried VUS (13.1%). PPVs in FZD4, LRP5, TSPAN12, NDP, ZNF408, and KIF11 were found in 8.48%, 9.00%, 5.91%, 4.63%, 0.77%, and 0.77% of the cohort, respectively. Probands carrying PPVs in NDP and KIF11 had more severe FEVR in general than those carrying PPVs in other genes. Overall, variants in LRP5 and FZD4 showed more significant variation in phenotype than variants in TSPAN12 and NDP genes. Our study expanded the spectrum of PPVs associated with FEVR.

Identification of LRP5 mutations in families with familial exudative vitreoretinopathy.

Familial exudative vitreoretinopathy (FEVR) is a hereditary eye disease characterized by defects in the development of periphery retinal vessels. However, the clinical phenotypes of FEVR vary widely from asymptomatic to complete blindness. We analyzed patients from three Chinese families and one sporadic patient with FEVR to investigate the clinical features and disease-causing mutations. Ocular phenotypes included increased ramification of the peripheral retinal vessels, a peripheral avascular zone, inferotemporal dragging of the optic disc and macula, and retinal folds. Peripheral blood DNA samples were obtained from patients with FEVR and their family members. Primers were designed to amplify the coding exons and adjacent intronic regions of the FEVR-causing genes FZD4, LRP5, NDP and TSPAN12. By polymerase chain reactions, each amplicon was subjected to direct Sanger sequencing analysis. Potential pathogenic changes of the sequence variants were analyzed by the orthologous protein sequence alignment and computational prediction software. We identified five LRP5 mutations: three novel heterozygous mutations-p.M181R, p.R399S and p.G503R and two known mutations that were never reported in FEVR patients: p.R494Q and p.G876S. All five mutations involved highly conserved residues and were predicted to be damaging by SIFT and PolyPhen-2. None was present in 500 normal individuals. To assess the pathogenesis of these mutations, wild-type and all five mutant LRP5 proteins were assayed for the ability to activate the Norrin/β-catenin pathway by established luciferase reporter assays, and all mutants failed to activate the pathway. This study extends the genetic database of the FEVR disease in China and provides a basis for molecular diagnosis of the disease.