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.

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

BACKGROUND/AIMS: To 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 their clinical significance. METHODS: A total of 32 patients and 32 healthy controls were studied. An additional independent 40 FEVR patients, 44 patients with non-FEVR retinopathies and 40 healthy controls participated in a diagnostic test to validate the abilities of novel findings in FEVR screening. RESULTS: A novel anatomic change, named Temporal Mid-Peripheral Vitreoretinal Interface Abnormality (TEMPVIA), was found on UWF-SLO in 88.3% of FEVR patients and in none of the healthy controls. The clinical significance of TEMPVIA was further validated by a diagnostic test in new independent cases, with satisfying sensitivity (91.5%) and specificity (98.8%) and Youden Index 0.90. In addition to foveal hypoplasia, some previously unrecognised, novel clinical changes in FEVR, for instance, retinoschisis, focal retinal thickening, sudden thinning of the retina and retinal ridge, were identified using UWF-OCT. CONCLUSION: The results of this study have led to an update of the clinical spectrum of FEVR and have improved our understanding of its pathogenesis. TEMPVIA is therefore suggested to be a useful biomarker in the screening strategy for mild FEVR.

Genotype Phenotype Correlation and Variability in Microcephaly Associated With Chorioretinopathy or Familial Exudative Vitreoretinopathy.

Purpose: The purpose of this study was to analyze the natural history and phenotypic overlap of patients with microcephaly and a chorioretinopathy or familial exudative vitreoretinopathy (FEVR) ocular phenotype caused by mutations in KIF11, TUBGCP4, or TUBGCP6. Methods: Patients diagnosed with congenital microcephaly and chorioretinopathy or FEVR were included. Molecular investigations consisted of targeted genetic sequencing. Data from medical records, ophthalmologic examination and imaging, electroretinography, and visual fields were analyzed for systemic and ophthalmic features and evidence of posterior segment disease progression. Results: Twelve patients from 9 families were included and had a median of 8 years of follow-up. Nine patients had KIF11 variants, two had heterozygous TUBGCP6 variants, and one had heterozygous variants in TUBGCP4. All patients had reduced visual function and multiple individuals and families showed features of both chorioretinopathy and FEVR. Progression of posterior segment disease was highly variable, with some degree of increased atrophy of the macula or peripheral retina or increased vitreoretinal traction observed in 9 of 12 patients. Conclusions: Microcephaly due to mutations in KIF11, TUBGCP4, or TUBGCP6 can be associated with retinal disease on a spectrum from chorioretinal atrophy to FEVR-like posterior segment changes. Visually significant disease progression can occur and patients should be monitored closely by a team experienced in ophthalmic genetics.

Modeling ZNF408-Associated FEVR in Zebrafish Results in Abnormal Retinal Vasculature.

Purpose: Familial exudative vitreoretinopathy (FEVR) is an inherited retinal disease in which the retinal vasculature is affected. Patients with FEVR typically lack or have abnormal vasculature in the peripheral retina, the outcome of which can range from mild visual impairment to complete blindness. A missense mutation (p.His455Tyr) in ZNF408 was identified in an autosomal dominant FEVR family. Little, however, is known about the molecular role of ZNF408 and how its defect leads to the clinical features of FEVR. Methods: Using CRISPR/Cas9 technology, two homozygous mutant zebrafish models with truncated znf408 were generated, as well as one heterozygous and one homozygous missense znf408 model in which the human p.His455Tyr mutation is mimicked. Results: Intriguingly, all three znf408-mutant zebrafish strains demonstrated progressive retinal vascular pathology, initially characterized by a deficient hyaloid vessel development at 5 days postfertilization (dpf) leading to vascular insufficiency in the retina. The generation of stable mutant lines allowed long-term follow up studies, which showed ectopic retinal vascular hyper-sprouting at 90 dpf and extensive vascular leakage at 180 dpf. Conclusions: Together, our data demonstrate an important role for znf408 in the development and maintenance of the vascular system within the retina.

PHOTODYNAMIC THERAPY-INDUCED ACUTE EXUDATIVE MACULOPATHY: Incidence, Clinical Features, and Long-Term Outcomes.

PURPOSE: To describe the incidence, clinical features, and long-term outcomes of photodynamic therapy (PDT)-induced acute exudative maculopathy (PAEM) in patients who underwent PDT for various indications. METHODS: This retrospective observational case series included all cases who developed massive serofibrinous macular exudation within a week after PDT. Medical records of patients with post-PDT exudative events were reviewed for relevant data and imaging abstraction including optical coherence tomography and indocyanine green angiography features and were subjected to analysis. RESULTS: The incidence rate of PAEM was 4.52%, being noted in 8 eyes (out of 177 PDT sessions in 155 eyes) with a mean age of 70.25 ± 6.65 years. Pre-PDT factors commonly associated with PAEM included age ≥65 years (87.5%), clinical diagnosis of polypoidal choroidal vasculopathy (75%), spot size ≥3,500 µm (100%), best-corrected visual acuity of 20/40 or better (87.5%), low-fluence PDT (87.5%), and the first exposure to PDT (75%). Photodynamic therapy-induced acute exudative maculopathy was noted at a mean interval of 2.9 ± 1.7 days (2-7 days) after PDT. Photodynamic therapy-induced acute exudative maculopathy resulted in significant decrease in mean best-corrected visual acuity from logMAR 0.29 ± 0.21 (approximate Snellen equivalent 20/39) to logMAR 0.91 ± 0.37 (approximate Snellen equivalent 20/163) [P = 0.0018], and significant increase in mean central macular thickness from 228.1 ± 71.8 µm to 481.4 ± 154.8 µm (P = 0.0029). Photodynamic therapy-induced acute exudative maculopathy resolved to baseline or even better tomographic status at a mean interval of 4.6 ± 1.2 weeks, resulting in complete visual recovery compared with baseline. During mean follow-up of 77.8 ± 46.4 weeks after PDT, no activity was noted for a mean duration of 26.3 ± 42.5 weeks after resolution. At final visit, mean best-corrected visual acuity and central macular thickness was logMAR 0.49 ± 0.28 (approximate Snellen equivalent 20/62) and 153.6 ± 40.0 µm, respectively, with underlying pathology being stable in 50% of the eyes. CONCLUSION: Photodynamic therapy-induced acute exudative maculopathy is an uncommon complication with self-resolving course and favorable prognosis. Patients undergoing PDT should be warned of the possibility of PAEM. The factors frequently associated with PAEM include elderly age (>65 years), clinical diagnosis of polypoidal choroidal vasculopathy, larger spot size (≥3,500 µm), pre-PDT best-corrected visual acuity of 20/40 or better, low-fluence PDT, and the first exposure to PDT.

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

PURPOSE: 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). DESIGN: Multicenter, retrospective, comparative, observational case series. PARTICIPANTS: 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. METHODS: 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. MAIN OUTCOME MEASURES: Macular microvascular parameters on OCTA and peripheral angiographic findings on WFA. RESULTS: 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. CONCLUSIONS: 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.

Hypoxia tolerance in the Norrin-deficient retina and the chronically hypoxic brain studied at single-cell resolution.

The mammalian CNS is capable of tolerating chronic hypoxia, but cell type-specific responses to this stress have not been systematically characterized. In the Norrin KO (NdpKO ) mouse, a model of familial exudative vitreoretinopathy (FEVR), developmental hypovascularization of the retina produces chronic hypoxia of inner nuclear-layer (INL) neurons and Muller glia. We used single-cell RNA sequencing, untargeted metabolomics, and metabolite labeling from 13C-glucose to compare WT and NdpKO retinas. In NdpKO retinas, we observe gene expression responses consistent with hypoxia in Muller glia and retinal neurons, and we find a metabolic shift that combines reduced flux through the TCA cycle with increased synthesis of serine, glycine, and glutathione. We also used single-cell RNA sequencing to compare the responses of individual cell types in NdpKO retinas with those in the hypoxic cerebral cortex of mice that were housed for 1 week in a reduced oxygen environment (7.5% oxygen). In the hypoxic cerebral cortex, glial transcriptome responses most closely resemble the response of Muller glia in the NdpKO retina. In both retina and brain, vascular endothelial cells activate a previously dormant tip cell gene expression program, which likely underlies the adaptive neoangiogenic response to chronic hypoxia. These analyses of retina and brain transcriptomes at single-cell resolution reveal both shared and cell type-specific changes in gene expression in response to chronic hypoxia, implying both shared and distinct cell type-specific physiologic responses.