Autosomal dominant exudative vitreoretinopathy

Angiographic characteristics in mild familial exudative vitreoretinopathy with genetically confirmed autosomal dominant inheritance

PURPOSE

To determine the ultra-widefield fluorescein angiographic (UWFA) characteristics of patients with mild familial exudative vitreoretinopathy (FEVR) who had been confirmed to have pathogenic variants of the autosomal dominant (AD) genes of FEVR.

DESIGN

Single center, observational case series.

SUBJECTS AND CONTROLS

Thirty-seven patients with mild FEVR from 27 families who had pathogenic variants of the Norrin/β-catenin genes were studied. The controls consisted of 32 family members who had been confirmed not to carry the pathogenic variants or had heterozygous variants of the autosomal recessive inheritance gene.

METHODS

Sixty-four UWFA images from the patients were compared to 60 UWFA images from the controls. The relative length of the temporal retina to the peripheral avascular retina was determined. The cut-off ratio of the relative lengths for a clinically significant avascular retina (csAR) associated with AD-FEVR was determined using the receiver operating characteristic (ROC) curves.

MAIN OUTCOME MEASURES

The presence or absence of six peripheral vascular changes: csAR, V-shaped vascular notch, brushy vascular ends, vascular stain, loop vessels and/or anastomosis, and capillary telangiectasia were compared between the patients and the controls.

RESULTS

The csAR was set at >12% of the length from the ora serrata to the optic disc. The AD-FEVR patients had more frequent retinal changes than the controls for the V-shaped vascular notch (69% vs 2%, P <0.001), brushy vascular ends (78% vs 3%, P <0.001), csAR (83% vs 22%, P <0.001), and vascular stain (70% vs 33%, P <0.001). Loop vessels and/or anastomosis of peripheral vessels were found significantly less frequently in the patients than in the controls (39% vs 73%, P <0.001). No significant difference was found for capillary telangiectasia between the two groups. The combination of the V-shaped vascular notches, brushy vascular ends, and csAR had a sensitivity of 82.8% and specificity of 98.3% with the highest ROC curve of 0.9.

CONCLUSIONS

The combination of V-shaped vascular notch, brushy vascular ends, and csAR can be used as a biomarker for AD-FEVR patients who have pathogenic variants of the Norrin/β-catenin genes. These findings will allow more accurate segregation analysis in FEVR families and allow better genetic counseling.

Multimodal imaging of white preretinal lesions in atypical familial exudative vitreoretinopathy: Case report and literature review

Purpose

To report a rare clinical finding of preretinal granules associated with atypical familial exudative vitreoretinopathy (FEVR) and perform a review of the literature.

Observations

An asymptomatic 18-year-old male was referred for unilateral peripheral avascular retina evaluation in association with presumed FEVR. He was first noted to have white preretinal granules on fundus examination at five years of age. The lesions remained unchanged over the subsequent years. Genetic testing did not reveal a pathogenic or likely pathogenic variant in a known FEVR gene. A review of the literature revealed five other cases of FEVR with similar findings.

Conclusions and Importance

Literature review suggests preretinal granules may present rarely in FEVR. Negative genetic screening of known FEVR genes in our patient with atypical FEVR suggests either a molecularly distinct etiology supporting the rarity of this association with FEVR or, alternatively, the presence of granules in developmental retinal vascular anomalies that are not specific to FEVR. Future study and genetic testing is necessary to better understand the cause of these preretinal granules and the clinical manifestations of FEVR.

Severe isolated exudative vitreoretinopathy caused by biallelic FZD4 variants

Familial exudative vitreoretinopathy (FEVR) is linked to disruption of the Norrin/Frizzled-4 signaling pathway, which plays an important role in retinal angiogenesis. Severe or complete knock-down of proteins in the pathway also causes syndromic forms of the condition. Both heterozygous and biallelic pathogenic variants in the FZD4 gene, encoding the pathway's key protein frizzled-4, are known to cause FEVR. However, it is not clear what effect different FZD4 variants have, and whether extraocular features should be expected in those with biallelic pathogenic FZD4 variants. Biallelic FZD4 variants were found in a young boy with isolated, severe FEVR. His parents were heterozygous for one variant each and reported normal vision. In-vitro studies of the two variants, demonstrated that it was the combination of the two which led to severe inhibition of the Norrin/Frizzled-4 pathway. Our observations demonstrate that biallelic FZD4-variants are associated with a severe form of FEVR, which does not necessarily include extraocular features. In addition, variants causing severe FEVR in combination, may have no or minimal effect in heterozygous parents as non-penetrance is also a major feature in dominant FZD4-FEVR disease. This underscores the importance of genetic testing of individuals and families with FEVR.

Genetic detection of two novel LRP5 pathogenic variants in patients with familial exudative vitreoretinopathy

BACKGROUND

Familial exudative vitreoretinopathy (FEVR) is a genetic eye disorder that leads to abnormal development of retinal blood vessels, resulting in vision impairment. This study aims to identify pathogenic variants by targeted exome sequencing in 9 independent pedigrees with FEVR and characterize the novel pathogenic variants by molecular dynamics simulation.

METHODS

Clinical data were collected from 9 families with FEVR. The causative genes were screened by targeted next-generation sequencing (TGS) and verified by Sanger sequencing. In silico analyses (SIFT, Polyphen2, Revel, MutationTaster, and GERP + +) were carried out to evaluate the pathogenicity of the variants. Molecular dynamics was simulated to predict protein conformation and flexibility transformation alterations on pathogenesis. Furthermore, molecular docking techniques were employed to explore the interactions and binding properties between LRP5 and DKK1 proteins relevant to the disease.

RESULTS

A 44% overall detection rate was achieved with four variants including c.4289delC: p.Pro1431Argfs*8, c.2073G > T: p.Trp691Cys, c.1801G > A: p.Gly601Arg in LRP5 and c.633 T > A: p.Tyr211* in TSPAN12 in 4 unrelated probands. Based on in silico analysis and ACMG standard, two of them, c.4289delC: p.Pro1431Argfs*8 and c.2073G > T: p.Trp691Cys of LRP5 were identified as novel pathogenic variants. Based on computational predictions using molecular dynamics simulations and molecular docking, there are indications that these two variants might lead to alterations in the secondary structure and spatial conformation of the protein, potentially impacting its rigidity and flexibility. Furthermore, these pathogenic variants are speculated to potentially influence hydrogen bonding interactions and could result in an increased binding affinity with the DKK1 protein.

CONCLUSIONS

Two novel genetic variants of the LRP5 gene were identified, expanding the range of mutations associated with FEVR. Through molecular dynamics simulations and molecular docking, the potential impact of these variants on protein structure and their interactions with the DKK1 protein has been explored. These findings provide further support for the involvement of these variants in the pathogenesis of the disease.

Novel Exon 7 Deletions in TSPAN12 in a Three-Generation FEVR Family: A Case Report and Literature Review

Familial exudative vitreoretinopathy (FEVR) is a severe clinically and genetically heterogeneous disease that is characterized by vascular disorder. FEVR exhibits strikingly variable clinical phenotypes, ranging from asymptomatic to total blindness. In this case, we present a patient who was first treated as having high myopia and retinopathy but was finally diagnosed with FEVR caused by the heterozygous deletion of exon 7 in TSPAN12 with the aid of whole genome sequencing (WGS). Typical vascular changes, including vascular leakage and an avascular zone in the peripheral retina, were observed in the proband using fundus fluorescein angiography (FFA), and the macular dragging was shown to be progressing in the follow-up visit. Furthermore, the proband showed unreported TSPAN12-related phenotypes of FEVR: ERG (full-field electroretinogram) abnormalities and retinoschisis. Only mild vascular changes were exhibited in the FFA for the other three family members who carried the same deletion of exon 7 in TSPAN12. This case expands our understanding of the phenotype resulting from TSPAN12 mutations and signifies the importance of combining both clinical and molecular analysis approaches to establish a complete diagnosis.

Rare eye diseases in India: A concise review of genes and genetics

Rare eye diseases (REDs) are mostly progressive and are the leading cause of irreversible blindness. The disease onset can vary from early childhood to late adulthood. A high rate of consanguinity contributes to India’s predisposition to RED. Most gene variations causing REDs are monogenic and, in some cases, digenic. All three types of Mendelian inheritance have been reported in REDs. Some of the REDs are related to systemic illness with variable phenotypes in affected family members. Approximately, 50% of the children affected by REDs show associated phenotypes at the early stages of the disease. A precise clinical diagnosis becomes challenging due to high clinical and genetic heterogeneity. Technological advances, such as next-generation sequencing (NGS), have improved genetic and genomic testing for REDs, thereby aiding in determining the underlying causative gene variants. It is noteworthy that genetic testing together with genetic counseling facilitates a more personalized approach in the accurate diagnosis and management of the disease. In this review, we discuss REDs identified in the Indian population and their underlying genetic etiology.

Identification of a novel mutation in KIF11 with functional analysis in a cohort of 516 familial patients with exudative vitreoretinopathy

Purpose

To identify a novel mutation in KIF11 with clinical and functional analysis among 516 familial patients with exudative vitreoretinopathy (FEVR).

Methods

Next-generation sequencing was performed on 516 patients with FEVR between January 2015 and October 2017. Clinical data were collected from patient charts, including sex, age at presentation, visual acuity if available, axial length, stage, and systemic clinical findings. Protein and mRNA levels were detected with western blotting and real-time quantitative PCR, respectively. Mass spectrometry was used to analyze the interacting protein of KIF11.

Results

In total, 304 of 516 patients were identified with at least one mutation in FEVR causative genes. Mutations in KIF11 were identified in 14.47% of all carriers. The novel mutation p. H718L accounted for the greatest proportion (12/44; 27.30%) among all mutations in KIF11. Fundus presentations in these 12 individuals varied from the avascular zone of the peripheral retina to total retinal detachment. The p. H718L mutation can reduce the proliferation of human retinal endothelial cells (HRECs) compared to the wild type. The mRNA level of vascular endothelial growth factor-α, transforming growth factor-α, metalloproteinase-1, and angiopoietin-like 4 were depressed in the KIF11 (p. H718L) groups under hypoxia stimuli. Mass spectrometry results demonstrated that eukaryotic elongation factor 2 (EEF2) was an interacting protein of KIF11 and that the p. H718L mutation can attenuate the binding activity.

Conclusions

Patients with the most frequent KIF11 mutation p. H718L showed typical FEVR presentations in this cohort. The mutation in KIF11 likely plays a role in the proliferation of HRECs, and the p. H718L mutation can reduce the proliferation.

Novel mutation in TSPAN12 associated with familial exudative vitreoretinopathy in a Chinese pedigree

BACKGROUND

Familial exudative vitreoretinopathy (FEVR) is a rare retinal disorder characterised by incomplete retinal vascular development. Symptoms vary widely from none to blindness even within the same family. Multiple genes related to the Wnt pathway have been found to be associated with FEVR. Recent studies identified tetraspanin 12 (TSPAN12) as a cause of the autosomal dominant inheritance form of FEVR. Here, we describe a novel TSPAN12 mutation in a Chinese family with FEVR.

METHODS

Targeted next-generation sequencing was performed on the proband to define the TSPAN12 mutation. Sanger sequencing was used to confirm the mutation in five family members (I-1, II-2, II-3, II-4, and III-3) in a three-generation FEVR pedigree. Ophthalmologic examinations and diagnostic imaging related to FEVR were performed.

RESULTS

The proband (II-3) was a 32-year-old man with early-stage peripheral retinal vascular anomalies, but no visual acuity problems. DNA sequencing identified a heterozygous missense mutation (c.241 G > A: p.Gly81Arg) in TSPAN12 in the proband. The mutation was in a highly conserved region and was predicted to affect the normal protein structure. The patient's father and daughter were also diagnosed with FEVR and carried the same mutation, with varying degrees of manifestations. Other family members had good vision and normal eye examinations with negative genetic testing.

CONCLUSIONS

We identified a novel missense mutation in TSPAN12 associated with autosomal dominant FEVR. These results will facilitate the diagnosis, prognosis, and genetic counselling for this disease. Further studies are needed to identify the mechanisms underlying clinical variations among individuals in the family.

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

Purpose

To determine the clinical characteristics of patients and family members with familial exudative vitreoretinopathy (FEVR) caused by mutations in the KIF11 gene.

Methods

Twenty-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).

Results

Sequence 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).

Conclusions

The 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 Relevance

These findings highlight more diverse mechanisms that underlie the pathological changes in patients with FEVR.

Analysis of Predisposing Clinical Features for Worsening Traction After Treatment of Familial Exudative Vitreoretinopathy in Children

PURPOSE

To determine the incidence of worsening vitreoretinal traction after laser treatment for familial exudative vitreoretinopathy (FEVR) and to determine whether any baseline clinical features are associated with worsening.

DESIGN

Retrospective cohort comparison study in a university tertiary referral center.

METHODS

All patients 0-21 years of age treated with laser from January 1, 2001, to June 1, 2018, were studied. Worsening traction after treatment was defined as the occurrence within 6 months of worsening or development of tractional retinal detachment, folds, dragging, breaks, rhegmatogenous detachment, or worsening tractional membranes. Comparisons of baseline features between groups with and without worsening were performed to determine features associated with higher risk.

RESULTS

A total of 46 eyes from 28 patients met inclusion criteria. Of the 46 eyes, 6 (13%) had worsening after treatment. There were no significant differences in age or other baseline demographics between the cohorts with and those without worsening traction. The presence of proliferative tissue in contact with the lens was found in 2 of 6 patients with worsening compared to 1 of 40 (3%) without worsening (P = .04). Mean follow-up was 57.8 months (range, 6.6-134 months). At the 6-month follow-up, median logMAR visual acuity in the cohorts with and without worsening was 1.7 (Snellen 20/1002; n = 5) and 0.24 (Snellen 20/35; n = 16), respectively.

CONCLUSIONS

Laser treatment resulted in worsening traction in a substantial proportion of eyes with FEVR. Children with proliferative tissue in contact with the lens may be at higher risk of worsening after laser. Potential measures to reduce risk will require further study to establish efficacy.

A start codon mutation of the TSPAN12 gene in Chinese families causes clinical heterogeneous familial exudative vitreoretinopathy

BACKGROUND

Familial exudative vitreoretinopathy (FEVR) is a severe clinically and genetically heterogeneous retinal disorder characterized with failure of vascular development of the peripheral retina. The symptoms of FEVR vary widely among patients in the same family, and even between the two eyes of a given patient. The purpose of this study was to investigate the molecular mechanisms by which the start codon mutation of the TSPAN12 causes difference in clinical manifestations between individuals in the same family.

METHODS

Next-generation sequencing (NGS)-based target capture sequencing was performed in proband with a diagnosis of FEVR and their normal visual acuity family members. Cosegregation analysis of the candidate causative variant was performed in additional family members by using Sanger sequencing. Complete fundus examination, fundus fluorescein angiography (FFA), and family history collection were performed in all family members. Potential candidate causative variants were verified with reference to guidelines and standards from the American College of Medical Genetics and Genomics.

RESULTS

We identified a novel heterozygous missense mutation (c.1A>G, p.M1V) localized in the start codon of the TSPAN12 and was detected as a potentially disease-causing variant for the proband. Retrospective analysis of clinical data, fundus examination, and FFA showed that the mutant carrier presented peripheral retinal vascular anomalies in early stages, and visual acuity did not show significant effects. However, the proband who carried this mutation and his cousin showed typical high-stage FEVR fundus changes coupled with a sharp decline in vision.

CONCLUSIONS

We report a novel start codon mutation (c.1A>G, p.M1V) in the TSPAN12 that causes clinically heterogeneous manifestations. Our results expand the mutation spectrums of TSPAN12, and will be valuable for disease diagnosis, prognosis, genetic counseling, and enriching our understanding of the role of the tetraspanin-12 protein in the pathogenesis of FEVR.

Variable reduction in Norrin signaling activity caused by novel mutations in FZD4 identified in patients with familial exudative vitreoretinopathy

Purpose

To identify novel mutations in FZD4 and to investigate their pathogenicity in a cohort of Chinese patients with familial exudative vitreoretinopathy (FEVR).

Methods

Next-generation sequencing was performed in patients with a clinical diagnosis of FEVR. Wide-field angiography was performed in probands and family members if available. Clinical data were collected from patient charts. The effect of the mutations in FZD4 on its biologic activity in the Norrin/β-catenin signaling pathway was analyzed with the luciferase reporter assay.

Results

Four novel mutations in FZD4 (c.1188_1192del/p.F396fs, c.1220delC/p.A407Vfs*24, c.905G>A/p.C302Y, c.1325T>A/p.V442E) were identified in four unrelated families. The mutations were not detected in 200 healthy individuals. The variability of the ocular phenotypes was not only observed in the probands and parents harboring the same mutation but also between two eyes in one individual. All four novel mutations introduced reduction in luciferase activity. Compared with the wild-type, the FZD4 level of the four mutants also decreased variably.

Conclusions

Four novel mutations in FZD4 were identified in Chinese patients with FEVR. No correlation in the reduced luciferase activity and the ocular phenotype was observed in this study. This study further emphasized the complexity of the FEVR-causing machinery.

Retinal detachments in the pediatric population

In this review, we present a concise summary of the more commonly seen types of retinal detachments (RDs) that one can encounter in pediatric patients. A spectrum of diseases from rhegmatogenous RD in Stickler syndrome, Marfan syndrome, and choroidal coloboma to exudative RD in Coats disease, to tractional RD in persistent fetal vasculature, and combined RDs in familial exudative vitreoretinopathy are described with the management pearls for each.

Familial Exudative Vitreoretinopathy: Pathophysiology, Diagnosis, and Management

Familial exudative vitreoretinopathy (FEVR) is a heritable vitreoretinopathy characterized by anomalous retinal vascular development. The principal feature of the disease is an avascular peripheral retina. This in turn can cause further pathological changes including neovascularization, exudation, hemorrhage, and retinal detachment. The biological basis of the disease is thought to be from defects in the Wnt signaling pathway. Many gene mutations have been implicated, and these can be inherited in an autosomal dominant (most common), autosomal recessive, and X-linked recessive fashion. Examination with wide-field fluorescein angiography is essential and can identify the disease in its earlier stages, enabling timely treatment, in addition to helping identify asymptomatic family members. The current treatment paradigm involves laser photocoagulation of the avascular peripheral retina for neovascular sequelae and vitreoretinal surgery for progressive retinal detachment. Further studies are underway to better characterize this complex vitreoretinopathy.

Genetic testing for familial exudative vitreoretinopathy

We studied the scientific literature and disease guidelines in order to summarize the clinical utility of genetic testing for familial exudative vitreoretinopathy (FEVR). There is insufficient data to determine the prevalence of FEVR. Variations in the FZD4 (OMIM gene: 604579; OMIM disease: 133780), TSPAN12 (OMIM gene: 613138; OMIM disease: 613310) and ZNF408 (OMIM gene: 616454; OMIM disease: 616468) genes have autosomal dominant inheritance, whereas variations in LRP5 (OMIM gene: 603506; OMIM disease: 601813) have autosomal dominant or recessive inheritance and variations in NDP (OMIM gene: 300658; OMIM disease: 305390) have X-linked inheritance. Clinical diagnosis is based on clinical findings, family history, ophthalmological examination, fundoscopy, slit-lamp examination and fluorescein angiography. The genetic test is useful for confirming diagnosis and for differential diagnosis, couple risk assessment and access to clinical trials.

Genotype-Phenotype Characterization of Novel Variants in Six Italian Patients with Familial Exudative Vitreoretinopathy

Familial exudative vitreoretinopathy (FEVR) is a complex disorder characterized by incomplete development of the retinal vasculature. Here, we report the results obtained on the spectrum of genetic variations and correlated phenotypes found in a cohort of Italian FEVR patients. Eight probands (age range 7–19 years) were assessed by genetic analysis and comprehensive age-appropriate ophthalmic examination. Genetic testing investigated the genes most widely associated in literature with FEVR: FZD4, LRP5, TSPAN12, and NDP. Clinical and genetic evaluations were extended to relatives of probands positive to genetic testing. Six out of eight probands (75%) showed a genetic variation probably related to the phenotype. We identified four novel genetic variants, one variant already described in association with Norrie disease and one previously described linked to autosomal dominant FEVR. Pedigree analysis of patients led to the classification of four autosomal dominant cases of FEVR (caused by FZD4 and TSPAN12 variants) and two X-linked FEVR probands (NDP variants). None of the patients showed variants in the LRP5 gene. This study represents the largest cohort study in Italian FEVR patients. Our findings are in agreement with the previous literature confirming that FEVR is a clinically and genetically heterogeneous retinal disorder, even when it manifests in the same family.

Atypical Presentation of Chorioretinal Folds-Related Maculopathy

PURPOSE

Chorioretinal folds are undulations that anatomically include the inner choroid, Bruch's membrane, and the retinal pigment epithelium, and secondarily affect the overlying neurosensory retina. We analyzed clinical data and management of six patients diagnosed with chorioretinal folds-related maculopathy with atypical presentations.

CASE REPORT

The mean age of the six patients (five women) was 77 years. Best-corrected visual acuity (BCVA) ranged between 20/200 and 20/80. None of the patients had history of hypertension, cardiovascular diseases, or autoimmune disease, and they were all diagnosed with idiopathic chorioretinal folds. Case 1, 2, and 3 received intravitreal antivascular endothelial growth factor (VEGF) therapy; case 4 received intravitreal anti-VEGF and photodynamic therapy; case 5 received only photodynamic therapy; and case 6 received intravitreal injections of sustained-release dexamethasone implant (Ozurdex). In case 1 and 2, the use of ranibizumab resulted in BCVA improvement and resolution of sub-/intraretinal exudation. In case 3, ranibizumab led to a mild reduction of the intraretinal exudation but no changes in BCVA. In case 4 and 5, six intravitreal injections of ranibizumab with two photodynamic therapies and three photodynamic therapies, respectively, led to a mild reduction of the sub-/intraretinal exudation but no changes in BCVA. In case 6, five intravitreal injections of Ozurdex in both eyes led to reduction of the subretinal or intraretinal fluid accumulation and BCVA improvement.

DISCUSSION

Choroidal vessel dilation and hyperpermeability may be involved in atypical presentations of chorioretinal folds-related maculopathy characterized by sub-/intraretinal fluid accumulation. Dilated and hyperpermeable choroidal vessels may result in focal retinal pigment epithelium alterations that can progress to choroidal neovascularization or chronic central serous chorioretinopathy-like maculopathy with or without telangiectatic retinal capillaries. Intravitreal anti-VEGF administration seems effective to treat choroidal neovascularization in stage 3 chorioretinal folds-related maculopathy, both anti-VEGF and photodynamic therapy seem to have only limited efficacy on chronic central serous chorioretinopathy-like maculopathy (and telangiectatic retinal capillaries), whereas intravitreal injection of Ozurdex seems efficacious to treat chronic central serous chorioretinopathy-like maculopathy.

Fzd4 Haploinsufficiency Delays Retinal Revascularization in the Mouse Model of Oxygen Induced Retinopathy

Mutations in genes that code for components of the Norrin-FZD4 ligand-receptor complex cause the inherited childhood blinding disorder familial exudative vitreoretinopathy (FEVR). Statistical evidence from studies of patients at risk for the acquired disease retinopathy of prematurity (ROP) suggest that rare polymorphisms in these same genes increase the risk of developing severe ROP, implying that decreased Norrin-FZD4 activity predisposes patients to more severe ROP. To test this hypothesis, we measured the development and recovery of retinopathy in wild type and Fzd4 heterozygous mice in the absence or presence of ocular ischemic retinopathy (OIR) treatment. Avascular and total retinal vascular areas and patterning were determined, and vessel number and caliber were quantified. In room air, there was a small delay in retinal vascularization in Fzd4 heterozygous mice that resolved as mice reached maturity suggestive of a slight defect in retinal vascular development. Subsequent to OIR treatment there was no difference between wild type and Fzd4 heterozygous mice in the vaso-obliterated area following exposure to high oxygen. Importantly, after return of Fzd4 heterozygous mice to room air subsequent to OIR treatment, there was a substantial delay in retinal revascularization of the avascular area surrounding the optic nerve, as well as delayed vascularization toward the periphery of the retina. Our study demonstrates that a small decrease in Norrin-Fzd4 dependent retinal vascular development lengthens the period during which complications from OIR could occur.

KIF11 mutations are a common cause of autosomal dominant familial exudative vitreoretinopathy

BACKGROUND/AIMS

To identify KIF11 mutations in patients with familial exudative vitreoretinopathy (FEVR) and to describe the associated phenotypes.

METHODS

Mutation analysis in a cohort of patients in a single institute was conducted. Bioinformatics was performed for whole exome sequencing, and the variants were confirmed by Sanger sequencing. Clinical data and DNA samples were collected from 814 unrelated Chinese probands, including 34 with FEVR, at the Pediatric and Genetic Eye Clinic, Zhongshan Ophthalmic Centre, Guangzhou, China.

RESULTS

Four novel heterozygous truncation mutations in KIF11, including c.131_132dupAT (p.P45Ifs*92), c.2230C>T (p.Q744*), c.2863C>T (p.Q955*) and c.2952_2955delGCAG (p.G985Ifs*6), were detected in four of 34 probands with FEVR. Combined with our previously identified mutations in FEVR cases (n=14), KIF11 mutations were identified in 8.3% (4/48) of all probands with FEVR. Ocular phenotypes documented in patients with KIF11 mutations showed a significant great variability of FEVR from the avascular zone in the peripheral retina to bilateral complete retinal detachment. Analysis of available family members in family QT1314 and QT937 showed segregation of KIF11 mutations with the phenotype of FEVR as expected. The family QT964 with two affected siblings and unaffected parents demonstrated a peculiar somatic mosaicism in the mother who had a low copy number variant (about 7% in her leucocyte DNA).

CONCLUSIONS

Identification of mutations in 8.3% patients suggests KIF11 mutations as a common cause of FEVR. Patients with KIF11 mutations showed typical, but variable, signs of FEVR with or without microcephaly, lymphoedema and mental retardation.

Complex genetics of familial exudative vitreoretinopathy and related pediatric retinal detachments

Familial exudative vitreoretinopathy (FEVR) is a hereditary vitreoretinal disorder that can cause various types of retinal detachments. The abnormalities in eyes with FEVR are caused by poor vascularization in the peripheral retina. The genetics of FEVR is highly heterogeneous, and mutations in the genes for Wnt signaling and a transcription factor have been reported to be responsible for FEVR. These factors have been shown to be the regulators of the pathophysiological pathways of retinal vascular development. Studies conducted to identify the causative genes of FEVR have uncovered a diverse and complex relationship between FEVR and other diseases; for example, Norrie disease, a Mendelian-inherited disease; retinopathy of prematurity, a multifactorial genetic disease; and Coats disease, a nongenetic disease, associated with pediatric retinal detachments.

Simultaneous fzd4 and lrp5 mutation in autosomal dominant familial exudative vitreoretinopathy

PURPOSE

The purpose of this study was to report simultaneous mutations of FZD4 and LRP5 genes associated with autosomal dominant familial exudative vitreoretinopathy in members of one family.

METHODS

Case report.

RESULTS

A 16-month-old white boy with a 6-month history of leukocoria was referred for possible retinoblastoma. On examination, the left eye displayed extensive white vitreoretinal fibrosis filling the entire vitreous cavity up to the lens and with additional dystrophic calcification and iris neovascularization. The right eye showed temporal peripheral fibrovascular ridge. Fluorescein angiography showed 360° of peripheral nonperfusion with leakage from the fibrovascular ridge of the right eye and diffuse leakage from the massive vitreoretinal fibrosis and iris neovascularization of the left eye, consistent with familial exudative vitreoretinopathy. Laser photocoagulation of the avascular areas of the right eye was performed with disease stabilization. Clinical examination and genetic testing of the family members demonstrated that the proband and a male sibling had similar clinical findings and simultaneous mutations in the FZD4 and LRP5 genes. Both affected patients had normal bone mineral dual-energy X-ray absorptiometry.

CONCLUSION

Familial exudative vitreoretinopathy is a retinal vascular disorder usually caused by a single mutation. Rarely, multiple simultaneous mutations can occur and, in this case, result in classic ophthalmic phenotypic and known risk for bone disorders.

Identification of FZD4 and LRP5 mutations in 11 of 49 families with familial exudative vitreoretinopathy

PURPOSE

To identify mutations in FZD4 and LRP5 in 49 Chinese families with familial exudative vitreoretinopathy (FEVR) and to reveal the mutation spectrum and frequency of these genes in the Chinese population.

METHODS

Clinical data and genomic DNA were collected for patients from 49 families with FEVR. The coding exons and adjacent intronic regions of FZD4 and LRP5 were amplified with polymerase chain reaction, and the resulting amplicons were analyzed with Sanger sequencing.

RESULTS

Eleven mutations were detected in 11 of the 49 families (22.4%), including five mutations in the FZD4 gene in six families and six mutations in the LRP5 gene in five families. Of the 11 mutations, eight were novel. Two families had the same FZD4 mutation, and one family had compound heterozygous mutations in LRP5. The phenotypes of the patients with the mutations showed great variability.

CONCLUSIONS

Our findings provide an overview of the mutation spectrum and frequency of FZD4 and LRP5 in Chinese patients with FEVR and emphasize the complexity of FEVR mutations and phenotypes.

Novel TSPAN12 mutations in patients with familial exudative vitreoretinopathy and their associated phenotypes

PURPOSE

Mutations in tetraspanin 12 (TSPAN12) have recently been identified as a cause of autosomal dominant familial exudative vitreoretinopathy (FEVR). The purpose of this study was to detect TSPAN12 mutations in Chinese patients with FEVR and to describe the associated phenotypes.

METHODS

Sanger sequencing was used to analyze the seven coding exons and their adjacent regions of TSPAN12 in 49 unrelated FEVR patients. Clinical phenotypes of the patients with TSPAN12 mutations were documented.

RESULTS

Three novel heterozygous mutations in TSPAN12 were identified in three patients from unrelated families: c.146C>T (p.Thr49Met), c.313T>C (p.Cys105Arg), and c.601delC (p.Leu201PhefsX14). All three mutations involved highly conserved residues and were not present in 180 normal individuals. Ocular phenotypes included retinal folds, inferotemporal dragging of the optic disc and macula, increased vessels in the equatorial region, and a peripheral avascular zone. A father and his daughter had the same mutation but the father only had mild peripheral fundus changes while his daughter had obvious dragged disc and macular ectopia.

CONCLUSIONS

Our results suggest that TSPAN12 mutations are responsible for FEVR. Similar to patients with mutations in NDP, LRP5, or FZD4, the phenotypes associated with TSPAN12 mutations showed great variations between different individuals within a family and between the two eyes in individual patients.

Mutations in TSPAN12 cause autosomal-dominant familial exudative vitreoretinopathy

Familial exudative vitreoretinopathy (FEVR) is an inherited blinding disorder of the retinal vascular system. Although mutations in three genes (LRP5, FZD4, and NDP) are known to cause FEVR, these account for only a fraction of FEVR cases. The proteins encoded by these FEVR genes form part of a signaling complex that activates the Norrin-beta-catenin signaling pathway. Recently, through a large-scale reverse genetic screen in mice, Junge and colleagues identified an additional member of this signaling complex, Tspan12. Here, we report that mutations in TSPAN12 also cause autosomal-dominant FEVR. We describe seven mutations identified in a cohort of 70 FEVR patients in whom we had already excluded the known FEVR genes. This study provides further evidence for the importance of the Norrin-beta-catenin signaling pathway in the development of the retinal vasculature and also indicates that more FEVR genes remain to be identified.

Autosomal dominant familial exudative vitreoretinopathy in two Japanese families withFZD4mutations (H69Y and C181R)

BACKGROUND

Familial exudative vitreoretinopathy (FEVR) is a hereditary disorder characterized by impaired vascularization of parts of the peripheral retina. Autosomal dominant FEVR (adFEVR), a major form of FEVR and assigned to chromosome 11q13-23 (EVR1) locus, is caused by deletion mutations in the C- terminal region of the frizzled-4 (FZD4) gene. This paper describes the clinical phenotype of adFEVR in two Japanese families with two different mutations in the FZD4 gene.

METHODS

We encountered three Japanese patients with adFEVR and studied them using mutation analysis of the FZD4 gene with PCR, sequencing, and a restriction enzyme digestion.

RESULTS

Two previously unreported missense mutations, p.H69Y and p.C181R, were identified in the N-terminal extra- cellular region of two of the patients. This region was highly conserved among other vertebrate species and FZD family members, unlike the C-terminal region. Co-segregation analysis revealed that all affected individuals carried one of these mutations, while unaffected individuals did not. The mutations were not detected in normal individuals (n=120). The affected individuals had mild to severe retinal abnormalities.

CONCLUSIONS

FZD4 mutations in either the N- or C-terminal region underlie adFEVR, which indicates that FZD4 plays an important role in retinal angiogenesis. Analysis of FZD4 mutations in families with adFEVR is useful for genetic counseling and for early diagnosis

[Mutations of the frizzled-4 gene. Their impact on medical care of patients with autosomal dominant exudative vitreoretinopathy]

PURPOSE

Autosomal dominant (familial) exudative vitreoretinopathy (adEVR) is a rare, congenital disease of the retinal vascular system, which may lead to blindness in severely affected eyes. One of the causative disease genes is located on chromosome 11q13-q23 and codes for "frizzled-4" (FZD4), a protein involved in vascular differentiation.

METHOD

Examination of two families with adEVR over six and four generations and FZD4 mutation analysis.

RESULTS

In family I, 18 examined affected members exhibited a heterozygous missense mutation (p.G492R) in the FZD4 gene. In family II, four examined family members were affected and carried a heterozygous deletion of five nucleotides (c.1286del5). Both mutations are novel and showed 100% penetrance and variable expressivity.

CONCLUSIONS

With detection of the "family-specific" FZD4 gene mutation, carriers amongst offspring of affected family members can be identified at an early time. The complete penetrance of FZD4 mutations may justify abandoning repeated examinations of offspring of affected family members, if no mutations were detected in FZD4.

Reduced bone mineral density and hyaloid vasculature remnants in a consanguineous recessive FEVR family with a mutation in LRP5

BACKGROUND/AIMS

Familial exudative vitreoretinopathy (FEVR) is an inherited blinding condition characterised by abnormal development of the retinal vasculature. FEVR has multiple modes of inheritance, and homozygous mutations in LRP5 have recently been reported as underlying the recessive form of this disease. The aim of this study was to examine LRP5 in a consanguineous recessive FEVR family and to clarify the eye and bone phenotype associated with recessive FEVR.

METHODS

All family members were examined by slit lamp biomicroscopy and indirect ophthalmoscopy. Linkage to LRP5 was determined by genotyping microsatellite markers, constructing haplotypes and calculating lod scores. Mutation screening of LRP5 was performed by polymerase chain reaction amplification of genomic DNA followed by direct sequencing. Bone mineral density (BMD) was evaluated in all family members using dual energy x ray absorptiometry (DEXA).

RESULTS

The clinical features observed in this family were consistent with a diagnosis of recessive FEVR. A homozygous LRP5 missense mutation, G550R, was identified in all affected individuals and all unaffected family members screened were heterozygous carriers of this mutation. Reduced BMD, hyaloid vasculature remnants, and nystagmus were features of the phenotype.

CONCLUSION

Recessive mutations in LRP5 can cause FEVR with reduced BMD and hyaloid vasculature remnants. Assessment of a patient with a provisional diagnosis of FEVR should therefore include investigation of BMD, with reduced levels suggestive of an underlying LRP5 mutation.

Further evidence of genetic heterogeneity in familial exudative vitreoretinopathy; exclusion of EVR1, EVR3, and EVR4 in a large autosomal dominant pedigree

BACKGROUND/AIMS

Familial exudative vitreoretinopathy (FEVR) is an inherited blinding condition characterised by abnormal development of the retinal vasculature. The aim of this study was to perform linkage analysis in a large family affected with FEVR to determine whether the mutation involved was in one of the three known autosomal dominant FEVR loci or in another as yet unidentified gene.

METHODS

Genomic DNA samples from family members were polymerase chain reaction (PCR) amplified with fluorescently tagged microsatellite markers spanning the EVR1/EVR4 locus (11q13-14) and the EVR3 locus (11p12-13). The resulting PCR products were resolved using an automated DNA sequencer and the alleles sized. These data were used to construct haplotypes across each locus and linkage analysis was performed to prove or exclude linkage.

RESULTS

The clinical evaluation in this family suggested features typical of FEVR, with deficient peripheral retinal vascularisation being the common phenotype in all affected individuals. However, linkage analysis proved that this family has a form of FEVR genetically distinct from the EVR1, EVR3 and EVR4 loci.

CONCLUSION

The exclusion of linkage in this family to any of the known FEVR loci proves the existence of a fourth locus for autosomal dominant FEVR and shows that this rare disorder is far more heterogeneous than previously thought.

Mutations in LRP5 or FZD4 underlie the common familial exudative vitreoretinopathy locus on chromosome 11q

Familial exudative vitreoretinopathy (FEVR) is an inherited blinding disorder of the retinal vascular system. Autosomal dominant FEVR is genetically heterogeneous, but its principal locus, EVR1, is on chromosome 11q13-q23. The gene encoding the Wnt receptor frizzled-4 (FZD4) was recently reported to be the EVR1 gene, but our mutation screen revealed fewer patients harboring mutations than expected. Here, we describe mutations in a second gene at the EVR1 locus, low-density-lipoprotein receptor-related protein 5 (LRP5), a Wnt coreceptor. This finding further underlines the significance of Wnt signaling in the vascularization of the eye and highlights the potential dangers of using multiple families to refine genetic intervals in gene-identification studies.

A new locus for autosomal dominant familial exudative vitreoretinopathy maps to chromosome 11p12-13

We report a new locus for familial exudative vitreoretinopathy (FEVR), on chromosome 11p12-13 in a large autosomal dominant pedigree. Statistically significant linkage was achieved across a 14-cM interval flanked by markers GATA34E08 and D11S4102, with a maximum multipoint LOD score of 6.6 at D11S2010. FEVR is a disease characterized by the failure of development of peripheral retinal blood vessels, and it is difficult to diagnose clinically because of the wide spectrum of fundus abnormalities associated with it. The identification of a new locus is important for genetic counseling and potentiates further studies aimed toward the identification of a gene with an important role in angiogenesis within neuroepithelial tissues. Such a gene may also have a role in the genetic predisposition to retinopathy of prematurity, a sporadic disorder with many clinical similarities to FEVR.

Genetic heterogeneity in familial exudative vitreoretinopathy; exclusion of the EVR1 locus on chromosome 11q in a large autosomal dominant pedigree

BACKGROUND/AIMS

Familial exudative vitreoretinopathy (FEVR) is associated with mutations in the Norrie disease gene in X linked pedigrees and with linkage to the EVR1 locus at 11q13 in autosomal dominant cases. A large autosomal dominant FEVR family was studied, both clinically and by linkage analysis, to determine whether it differed from the known forms of FEVR.

METHODS

Affected members and obligate gene carriers from this family were examined by slit lamp biomicroscopy, indirect ophthalmoscopy, and in some cases fluorescein angiography. Patient DNAs were genotyped for markers at the EVR1 locus on chromosome 11q13.

RESULTS

The clinical evaluation in this family is consistent with previous descriptions of FEVR pedigrees, but linkage analysis proves that it has a form of FEVR genetically distinct from the EVR1 locus on 11q.

CONCLUSION

This proves that there are at least three different loci associated with comparable FEVR phenotypes, a situation similar to that existing for many forms of retinal degeneration.

Vitrectomy for rhegmatogenous or tractional retinal detachment with familial exudative vitreoretinopathy

OBJECTIVE

To examine the anatomic features and surgical indications of familial exudative vitreoretinopathy (FEVR) complicated with rhegmatogenous or tractional retinal detachment.

DESIGN

Retrospective noncomparative case series.

PARTICIPANTS

Twenty-eight eyes of 25 patients who had either clinically suspected or fully diagnosed FEVR. Of these, 25 had rhegmatogenous retinal detachment, 2 had tractional retinal detachment, and 1 had tractional retinal detachment plus vitreous hemorrhage.

INTERVENTIONS

The authors carefully observed the vitreoretinal interface during surgery, studied the clinical and anatomic features of FEVR, and then evaluated the surgical results.

RESULTS

The vitreoretinal adhesions were so strong in the peripheral avascular area that iatrogenic retinal breaks easily occurred in 22 of 28 eyes. In all cases, the bimanual technique with vitreous scissors and forceps was required to dissect the posterior vitreous membrane from the retinal surface. The retina was reattached in 24 of 28 cases (85.7%), and visual acuity improved in 20 eyes (71.4%).

CONCLUSION

Dissection of the vitreous in the peripheral avascular area is very difficult in FEVR, and those patients for whom this procedure was not successfully performed may have a poorer prognosis.

Autosomal recessive familial exudative vitreoretinopathy: evidence for genetic heterogeneity

Two unrelated families with familial exudative vitreoretinopathy (FEVR) show apparent autosomal recessive inheritance rather than the previously reported autosomal dominant or X-linked recessive mode of inheritance. Compared with the other modes of inheritance, the inherited clinical features here include earlier onset (at birth) and a more severe progressive course.

Familial exudative vitreoretinopathy linked to D11S533 in a large Asian family with consanguinity

Familial exudative vitreoretinopathy (FEVR) is a disorder characterised by peripheral retinal vascularisation with subsequent traction of retinal vessels and detachment. Recently, autosomal dominant FEVR (ad FEVR) has been mapped to 11q13 by linkage in four northern European families. We describe a large consanguineous Asian family in which the severity of the proband's eye disease suggested homozygosity for a disease allele. Thirty family members were assessed by ophthalmological examination and fluorescein angiography. Thirteen had unequivocal features of FEVR. A further two were classified as unknown. Two point linkage analysis for DIIS533 and FEVR generated a lod score of 5.55 at a recombination fraction of 0.00. This supports autosomal dominant inheritance and demonstrates genetic homogeneity for the ad FEVR disease locus. The severely affected proband was heterozygous for alleles at this closely linked locus. Other causes, including non-genetic factors, should be considered to explain the extreme variability characteristic of ad FEVR.

Improved surgical treatment of familial exudative vitreoretinopathy in children

PURPOSE

To evaluate current surgical results in patients with familial exudative vitreoretinopathy and study the histologic findings of epiretinal membranes obtained at the time of surgery.

METHODS

We performed phakic pars plana vitrectomy and membrane peeling on five patients (six eyes) with familial exudative vitreoretinopathy, who ranged in age from 18 months to 9 years and had traction retinal detachment. Membranes from two eyes (two patients) were analyzed by light and electron microscopy.

RESULTS

The macula was reattached in all six eyes. Visual acuity improved after surgery in five of the six eyes, with two eyes improving from a preoperative visual acuity of 20/400 to a postoperative visual acuity of 20/25 and 20/60. Electron microscopic analysis of the membranes from two patients disclosed thick fibrocellular fragments with vascular elements and astrocytes.

CONCLUSION

With current surgical techniques, there appears to be improvement in the anatomic reattachment rate and visual outcome in patients with familial exudative vitreoretinopathy. Amblyopia, reproliferation, and vitreous hemorrhage may limit long-term improvement in vision.

Familial exudative vitreoretinopathy

PURPOSE

To evaluate the natural history of Familial Exudative Vitreoretinopathy (FEVR) with emphasis on the effect of the age of onset on its severity and on the development of late complications such as cataract and retinal detachment. Also, to evaluate affected patients for DNA abnormalities.

METHODS

The records of thirty-nine patients with FEVR were studied. All were asked to come in for a final follow-up examination. The referring physician was asked to provide the latest findings for those who could not. On 10 patients, karyotypes were prepared.

RESULTS

Only 2 of 28 patients whose onset of symptoms was prior to their third birthday had a final visual acuity of 20/200 or better. Older patients had a better prognosis, because they were more likely to have asymmetrical retinal deterioration with only one eye deteriorating. Preservation of good visual acuity into the teens and later was no guarantee that deterioration would not occur. In 3 eyes of 4 patients who were asymptomatic until 15 years of age, the final visual acuity was counting fingers or worse. In 5 patients, retinal detachment developed 6 to 17 years after apparent stabilization. The karyotype of 10 patients showed no evidence for rearrangement, altered size, translocations or deletions of chromosome 11 or any other chromosome. Of the 31 eyes in patients older than 15 years, 10 (32%) had a significant cataract. Three eyes underwent cataract surgery.

CONCLUSIONS

The prognosis for infants with FEVR is extremely poor and the long-term prognosis for patients with a later onset of the condition is guarded. Retinal detachment, macular dragging, and cataract are common late complications which can develop even in patients whose eye findings appear to be stable. Karyotype studies ruled out involvement of chromosome 11 or others at a gross level, but did not exclude them at the location for some genetic defect related to FEVR because single base changes and small deletions or insertions may be undetectable by the methods utilized.

X linked exudative vitreoretinopathy: clinical features and genetic linkage analysis

A four generation family in which familial exudative vitreoretinopathy is inherited as an X linked condition is described. Essentially the condition is one of abnormal vascularisation and signs at birth are those of a retinopathy superficially resembling retinopathy of prematurity, retinal folds, or, in advanced cases, enophthalmos or even phthisis. Prognosis depends on the progression of the retinal changes. The family members, including seven affected males and five obligate carrier females, have been types for 20 DNA markers, and linkage analysis suggests a gene locus either at Xq21.3 or at Xp11. As the latter region includes the locus for the gene for Norrie disease, it is possible that this and X linked vitreoretinopathy are allelic. We can further speculate that the differences in severity of the clinical manifestations are dependent only upon the timing of the insult.

X-linked recessive familial exudative vitreoretinopathy

Familial exudative vitreoretinopathy is an inherited disorder characterized by retinal traction, peripheral vitreous opacities, and subretinal and intraretinal exudates. We observed a family in which four boys (the children of three sisters) were affected with this disorder and an X-linked recessive inheritance was apparent. The differential diagnosis includes retinopathy of prematurity, primary hyperplastic primary vitreous, Coats' disease, peripheral uveitis, retinoblastoma, and Norrie's disease, but this differentiation can usually be made on the basis of clinical findings alone. Knowledge of X-linked recessive transmission is important for correct diagnosis and for genetic counseling.

Dominant exudative vitreoretinopathy: a sporadic case with a normal platelet aggregation study

Case report of a woman with the characteristics of dominant exudative vitreoretinopathy. These anomalies are however unilateral and the family study is not very contributive. A platelet aggregation study carried out on the patient and 3 family members is normal.