Mutations in TSPAN12 gene causing familial exudative vitreoretinopathy.

BACKGROUND: To 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. RESULTS: Nine 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. CONCLUSIONS: Nine 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.

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.

Clinical phenotypic spectrum of CTNNB1 neurodevelopmental disorder.

Pathogenic heterozygous loss of function variants in CTNNB1 are associated with CTNNB1 neurodevelopmental disorder. We report the clinical phenotype of individuals with CTNNB1 neurodevelopmental disorder using both caregiver-reported data (medical history, adaptive function, quality of life, and behavior issues) and in-person clinical assessments (neurological, motor, and cognitive function) in 32 individuals with likely pathogenic or pathogenic CTNNB1 variants. Most individuals had truncal hypotonia, muscle weakness, hypertonia, dystonia, microcephaly, and many had a history of tethered cord. Visual problems included strabismus, hyperopia, and familial exudative vitreoretinopathy. Half of individuals walked without an assistive device. The mean Gross Motor Functional Measure-66 score was 56.6 (SD = 14.8). Average time to complete Nine-Hole Peg Test was slower than norms. Mean general conceptual ability composite scores from Differential Ability Scales Second Edition were very low (M = 58.3, SD = 11.3). Fifty-five percent of individuals had low adaptive functioning based on the Vineland Adaptive Behavioral Scales. Based upon the Child Behavior Checklist total problems score, the majority (65%) of individuals had behavioral challenges. The mean overall Quality of Life Inventory-Disability score was 81.7 (SD = 11.9). These data provide a detailed characterization of clinical features in individuals with CTNNB1 neurodevelopmental disorder.

Frameshift variants in the C-terminal of CTNNB1 cause familial exudative vitreoretinopathy by AXIN1-mediated ubiquitin-proteasome degradation condensation.

The ß-catenin has two intrinsically disordered regions in both C- and N-terminal domains that trigger the formation of phase-separated condensates. Variants in its C-terminus are associated with familial exudative vitreoretinopathy (FEVR), yet the pathogenesis and the role of these variants in inducing abnormal condensates, are unclear. In this study, we identified a novel heterozygous frameshift variant, c.2104-2105insCC (p.Gln703ProfsTer33), in CTNNB1 from a FEVR-affected family. This variant encodes an unstable truncated protein that was unable to activate Wnt signal transduction, which could be rescued by the inhibition of proteasome or phosphorylation. Further functional experiments revealed the propensity of the Gln703ProfsTer33 variant to form cytoplasmic condensates, exhibiting a lower turnover rate after fluorescent bleaching due to enhanced interaction with AXIN1. LiCl, which specifically blocks GSK3ß-mediated phosphorylation, restored signal transduction, cell proliferation, and junctional integrity in primary human retinal microvascular endothelial cells over-expressed with Gln703ProfsTer33. Finally, experiments on two reported FEVR-associated mutations in the C-terminal domain of ß-catenin exhibited several functional defects similar to the Gln703ProfsTer33. Together, our findings unravel that the C-terminal region of ß-catenin is pivotal for the regulation of AXIN1/ß-catenin interaction, acting as a switch to mediate nucleic and cytosolic condensates formation that is implicated in the pathogenesis of FEVR.

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.

Clinical and genetic characteristics and natural history of Finnish families with familial exudative vitreoretinopathy due to pathogenic FZD4 variants.

PURPOSE: To report clinical and genetic characteristics of familial exudative vitreoretinopathy (FEVR) in the Finnish population. METHODS: Detailed clinical and genetic data of 35 individuals with heterozygous pathogenic variants in FZD4 were gathered and analysed. RESULTS: Thirty-two individuals with FZD4 c.313A>G variant and three individuals with FZD4 c.40_49del were included in the study. The clinical phenotype was variable even among family members with the same FZD4 variant. Only 34% (N = 12/35) of variant-positive individuals had been clinically diagnosed with FEVR. The median age of the onset of symptoms was 2.3 years, ranging between 0 to 25 years. Median visual acuity was 0.1 logMAR (0.8 Snellen decimal), ranging between light perception and -0.1 logMAR (1.25 Snellen decimal). Most (N = 33/35, 94%) were classified as not visually impaired. Despite unilateral visual loss present in some, they did not meet the criteria of visual impairment according to the WHO classification. Two study patients (N = 2/35, 6%) had severe visual impairment. The most common FEVR stage in study patient's eyes (N = 28/70 eyes, 40%) was FEVR stage 1, that is, avascular periphery or abnormal vascularisation. Most of FZD4-variant-positive study patient's eyes (N = 31/50 eyes, 62%) were myopic. Two individuals presented with persistent hyperplastic primary vitreous expanding the phenotypic spectrum of FEVR. Shared haplotypes extending approximately 0.9 Mb around the recurrent FZD4 c.313A>G variant were identified. CONCLUSION: Most study patients were unaffected or had mild clinical manifestations by FEVR. Myopia seemed to be overly common in FZD4-variant-positive individuals.

Cyanoacrylate glue for iatrogenic retinal breaks during vitrectomy in stage 5 familial exudative vitreoretinopathy.

Purpose: To describe the role of cyanoacrylate glue in sealing iatrogenic retinal breaks (IRBs) during vitrectomy in stage 5 familial exudative vitreoretinopathy (FEVR) with funneled retinal detachment (RD). Methods: Nine eyes of nine patients diagnosed as stage 5 FEVR were treated with cyanoacrylate glue for IRBs during vitrectomy from July 2020 to January 2022. The clinical records, including patient information, surgical process, and follow-up examinations, were collected retrospectively. Anatomical outcomes and visual outcomes were summarized. Results: The average age at surgery was 19.6 months (range: 3.8-41.1 months). The mean post-operative follow-up period was 12.5 months (range: 9.8-18.8 months). Before surgery, five eyes had an open-funnel RD and four eyes had a closed-funnel RD. All the preretinal fibroplasia membranes were removed as thoroughly as possible in the nine eyes. IRBs formed at the posterior pole in two eyes and peripheral retina in seven eyes. All the IRBs were sealed successfully by the cyanoacrylate glue when they appeared. At the final post-operative visit, eight eyes had partial retinal reattachment without progression of fibroplasia tissues, while one eye had total retinal redetachment. The rate for stable anatomical outcome was 88.9% (8/9) in this study. The visual testing available for seven eyes demonstrated light perception in five eyes and no light perception in two eyes. No severe perioperative glue-related complications were noted during the follow-ups. Conclusion: The application of cyanoacrylate glue may be an alternative therapy for IRBs in stage 5 FEVR surgeries, while the long-term efficacy and safety still need further investigation.

Familial Exudative Vitreoretinopathy With and Without Pathogenic Variants of Norrin/ß-Catenin Signaling Genes.

Purpose: To determine the clinical characteristics of familial exudative vitreoretinopathy (FEVR) associated with or without pathogenic variants of the Norrin/ß-catenin genes. Design: This was a multicenter, cross-sectional, observational, and genetic study. Subjects: Two-hundred eighty-one probands with FEVR were studied. Methods: Whole-exome sequence and/or Sanger sequence was performed for the Norrin/ß-catenin genes, the FZD4, LRP5, TSPAN12, and NDP genes on blood collected from the probands. The clinical symptoms of the probands with or without the pathogenic variants were assessed as well as differences in the inter Norrin/ß-catenin genes. Main Outcome Measures: The phenotype associated with or without pathogenic variants of the Norrin/ß-catenin genes. Results: One-hundred eight probands (38.4%) had 88 different pathogenic or likely pathogenic variants in the genes: 24 with the FZD4, 42 with the LRP5, 10 with the TSPAN12, and 12 with the NDP gene. Compared with the 173 probands without pathogenic variants, the 108 variant-positive probands had characteristics of familial predisposition (63.9% vs. 37.6%, P < 0.0001), progression during infancy (75.0% vs. 53.8%, P = 0.0004), asymmetrical severity between the 2 eyes (50.0% vs. 37.6%, P = 0.0472), and nonsyndromic characteristics (10.2% vs. 17.3%, P = 0.1185). The most frequent stage at which the more severe eye conditions was present was at stage 4 in both groups (40.7% vs. 34.7%). However, the advanced stages of 3 to 5 in the more severe eye were found more frequently in probands with variants than in those without variants (83.3% vs. 58.4%, P < 0.0001). Patients with rhegmatogenous retinal detachments progressed from stage 1 or 2 were found less frequently in the variant-positive probands (8.3% vs. 17.3%, P = 0.0346). Nine probands with NDP variants had features different from probands with typical Norrin/ß-catenin gene variants including the sporadic, symmetrical, and systemic characteristics consistent with Norrie disease. Conclusions: The results showed that the clinical characteristics of FEVR of patients with variants in the Norrin/ß-catenin genes are different from those with other etiologies. We recommend that clinicians who diagnose a child with FEVR perform genetic testing so that the parents can be informed on the prognosis of the vision and general health in the child. Financial Disclosures: Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.

Familial exudative vitreoretinopathy (FEVR) in a child with a Jagged 1 variant identified on genetic testing.

INTRODUCTION: Familial Exudative Vitreoretinopathy (FEVR) is a heritable retinal vascular disease characterized by incomplete vascularization of the peripheral retina resulting in ischemia. Fifty percent of FEVR cases 10 are due to known pathogenic genetic variants, and disease phenotype can vary greatly. FEVR is a clinical diagnosis, however, genetic testing can play a key role in screening for FEVR in genetically susceptible populations, thus leading to early treatment and improved patient outcomes. CASE: A 2-year-old male with no known past ocular or medical history was diagnosed with FEVR upon examination under anesthesia and multimodal retinal imaging. Genetic testing identified a Jagged 1 (JAG1) variant of uncertain significance, 15 which has been linked to FEVR in recent studies. Despite close follow-up and treatment, the patient experienced a funnel retinal detachment in the right eye approximately one year after diagnosis. DISCUSSION: This case in conjunction with recent literature suggests that JAG1 variants are likely associated with FEVR. Further investigations are necessary to identify the frequency of JAG1 variants among patients with FEVR. Robust understanding of FEVR's heterogenous genetic profile will lead to improved treatment modalities 20 and patient outcomes.

Aggressive Onset of a Progressive FEVR Phenotype in a Child With Novel Mutations in LRP5 and TSPAN12.

Purpose: To describe a patient with familial exudative vitreoretinopathy (FEVR) and the treatment course. Methods: A case was evaluated. Results: A 3-year-old boy presented with severe onset of FEVR, with a subhyaloid hemorrhage in 1 eye and tractional retinal detachment (TRD) in the fellow eye. Aggressive treatment with retinal photocoagulation and repeated injections of intravitreal bevacizumab resulted in stability of the retinal disease. Lens-sparing vitrectomy was performed for the TRD. The treatment effect was durable, and the patient retained useful vision in the better eye at 19 years of age. A subsequent genetic analysis showed 2 novel heterozygous missense mutations in LRP5 and TSPAN12. Conclusions: The presence of 2 novel mutations associated with severe FEVR identified in our patient is in agreement with in vitro studies showing that a more severe reduction in Norrin/ß-catenin signal activity occurs with the combination of 2 mutations.

Successful Management of Familial Exudative Vitreoretinopathy with a Large Macular Hole Using Inverted Internal Limiting Membrane Flap Technique.

Introduction: This case report aims to shed light on a rare presentation of familial exudative vitreoretinopathy (FEVR) co-existing with a large full-thickness macular hole (FTMH) in a 16-year-old male and discuss its successful surgical management, thereby adding to the limited existing knowledge on this topic. Case Presentation: Over an 8-month period, the patient had experienced progressively worsening visual blurring and distortion in his left eye. Following a comprehensive examination, diagnosis confirmed FEVR and an accompanying large FTMH. It was hypothesized that this unusual manifestation resulted from the tractional forces exerted by a thick posterior vitreous membrane and a thin epiretinal membrane - a distinctive attribute of FEVR. The patient underwent surgical intervention, which included pars plana vitrectomy (PPV), internal limiting membrane (ILM) peeling, gas tamponade, and the inverted ILM flap technique. Postoperative outcomes were favorable, with the FTMH successfully closed and substantial improvement observed in the patient's visual acuity at the 3-month follow-up visit. Conclusion: This case report highlights a rare association of FEVR with FTMH, thereby broadening our understanding of potential complications in patients with FEVR. The successful surgical intervention reinforces the utility of the PPV and the inverted ILM flap technique in managing such complications. It underscores the need for clinicians to maintain vigilance for such atypical manifestations in FEVR patients.

Diagnostic Role of Oral Fluorescein Angiography in Pediatric Ambulatory Clinics.

Oral ingestion of fluorescein can be done in ambulatory pediatric clinics. We show that oral ultra-widefield fluorescein angiography is a non-invasive approach to rapidly diagnose and manage a diverse set of pediatric retinal vascular diseases.

Unveiling novel LRP5 pathogenic variant in familial exudative vitreoretinopathy: Diverse phenotypic expressions in a mother-daughter duo.

PURPOSE: This report aims to delineate distinct phenotypes of Familial Exudative Vitreoretinopathy (FEVR) observed in a mother and her daughter, both harboring a novel LRP5 pathogenic variation. METHODS: The investigation involves a retrospective review of medical records accompanied by multimodal imaging. Molecular characterization was performed using whole exon sequencing, and the pathogenic variant was subsequently confirmed through Sanger sequencing. RESULT: A 6-year-old girl diagnosed with anisometropic amblyopia exhibited macular dragging and peripheral avascular retina in her right eye. Whole exon sequencing identified a previously unreported heterozygous missense LRP5 pathogenic variation, Glu528Lys. Simultaneously, her 43-year-old mother also carried the same mutation, manifesting peripheral exudations, avascular areas, and multiple microaneurysms. Notably, both cases presented distinctive phenotypes of FEVR. CONCLUSION: Our findings underscore the diversity in clinical presentations associated with FEVR, emphasizing the pivotal role of genetic evaluation. Despite variations in severity between the eyes of the same patient, it is crucial to remain vigilant for potential progression to a pathological status in the seemingly normal eye. Additionally, this study contributes to expanding the genetic spectrum of FEVR.

Pediatric retinal vascular disorders: From translational sciences to clinical practice.

Pediatric retinal vascular diseases are a spectrum with overlapping phenotypes and related genes. Retinal vascular development is biphasic. Vasculogenesis is responsible for the formation of primordial vessels leading to the four major arcades in the posterior retina. Angiogenesis, which is vascular endothelial growth factor dependent, is responsible for the formation of new vessels through budding from existing vessels, forming the peripheral vessels, increasing the capillary density of the central retina, and forming the superficial and deep capillary plexus. This process is controlled by WNT signaling, which is important for cell proliferation, division, and migration. Disorders of WNT signaling, such as familial exudative vitreoretinopathy (FEVR), have overlapping clinical findings. Conversely, pathogenic variants in some of the FEVR-related genes are reported in conditions such as retinopathy of prematurity (ROP), persistent fetal vasculature, and Coats disease. The various overlapping features and underlying genetic basis in the pathogenesis of pediatric retinal vascular developmental diseases suggest that genetic variants may provide a framework or a background for these conditions, upon which further insults can affect the development at any phase (such as prematurity and oxygenation in ROP), influencing and determining the final phenotype.

De novel heterozygous copy number deletion on 7q31.31-7q31.32 involving TSPAN12 gene with familial exudative vitreoretinopathy in a Chinese family.

AIM: To investigate the genetic and clinical characteristics of patients with a large heterozygous copy number deletion on 7q31.31-7q31.32. METHODS: A family with familial exudative vitreoretinopathy (FEVR) phenotype was included in the study. Whole-exome sequencing (WES) was initially used to locate copy number variations (CNVs) on 7q31.31-31.32, but failed to detect the precise breakpoint. The long-read sequencing, Oxford Nanopore sequencing Technology (ONT) was used to get the accurate breakpoint which is verified by quantitative real-time polymerase chain reaction (QPCR) and Sanger Sequencing. RESULTS: The proband, along with her father and younger brother, were found to have a heterozygous 4.5 Mb CNV deletion located on 7q31.31-31.32, which included the FEVR-related gene TSPAN12. The specific deletion was confirmed as del(7)(q31.31q31.32)chr7:g.119451239_123956818del. The proband exhibited a phase 2A FEVR phenotype, characterized by a falciform retinal fold, macular dragging, and peripheral neovascularization with leaking of fluorescence. These symptoms led to a significant decrease in visual acuity in both eyes. On the other hand, the affected father and younger brother showed a milder phenotype. CONCLUSION: The heterozygous CNV deletion located on 7q31.31-7q31.32 is associated with the FEVR phenotype. The use of long-read sequencing techniques is essential for accurate molecular diagnosis of genetic disorders.

Retinopatía del prematuro con presentación atípica / Retinopathy of prematurity with atypical presentation

La retinopatía de la prematuridad es una enfermedad dinámica vasoproliferativa de la retina inmadura postnatal que afecta a los bebés prematuros. Cuando aparecen signos de atipicidad en su diagnóstico o evolución deben descartarse otras entidades vasculares de la retina, que generalmente tienen un trasfondo genético y semejan o coexisten con dicha entidad. Se presenta un caso con características de Retinopatía del prematuro y algunos signos de atipicidad. Se describe su manejo y evolución, así como una breve descripción de las entidades que conforman el diagnóstico diferencial(AU)

Retinopathy of prematurity is a dynamic vasoproliferative disease of the immature postnatal retina that affects premature babies. When signs of atypicality appear in its diagnosis or evolution, other vascular entities of the retina must be ruled out, which generally have a genetic background and resemble or coexist with said entity. We present a case with characteristics of Retinopathy of prematurity and some signs of atypicality. Its management and evolution are described, as well as a brief description of the entities that make up the differential diagnosis(AU)