Publications by authors named "Carel B Hoyng"

273 Publications

RESPONSE OF CHOROIDAL ABNORMALITIES TO PHOTODYNAMIC THERAPY VERSUS MICROPULSE LASER IN CHRONIC CENTRAL SEROUS CHORIORETINOPATHY: Place Trial Report No. 4.

Retina 2021 Oct;41(10):2122-2131

Departments of Ophthalmology, and.

Purpose: To compare the effects of half-dose photodynamic therapy (PDT) and high-density subthreshold micropulse laser on choroidal dysfunction evaluated by degree and extent of hyperfluorescence on indocyanine green angiography (ICGA) in chronic central serous chorioretinopathy.

Methods: Data from the multicenter, randomized, controlled PLACE trial were used in this study. Hyperfluorescent and hypofluorescent areas on ICGA, their association with subretinal fluid and visual function were assessed.

Results: In total, 146 patients were included (72 in the PDT and 74 in the high-density subthreshold micropulse laser treatment arm). A significantly greater decrease in the size of hyperfluorescent areas on ICGA at first visit after treatment was seen after PDT compared with high-density subthreshold micropulse laser (mean, -1.41 ± 2.40 mm2 vs. -0.04 ± 0.73 mm2, respectively; P < 0.001). A reduction in the degree of hyperfluorescence on ICGA decreased the odds of having persistent subretinal fluid on optical coherence tomography at first visit after treatment (B = 0.295; P = 0.019). There were no significant differences in best-corrected visual acuity and retinal sensitivity between the subgroup with novel hypofluorescence (n = 20, 28%) on ICGA at first visit post PDT, compared with the subgroup without novel hypofluorescence on ICGA after PDT.

Conclusion: Choroidal abnormalities in chronic central serous chorioretinopathy can be effectively treated by ICGA-guided half-dose PDT but not with high-density subthreshold micropulse laser application.
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http://dx.doi.org/10.1097/IAE.0000000000003157DOI Listing
October 2021

Systemic complement levels in patients with age-related macular degeneration carrying rare or low frequency variants in the CFH gene.

Hum Mol Genet 2021 Sep 11. Epub 2021 Sep 11.

Department of Ophthalmology, Donders Institute for Brain, Cognition and Behavior, Radboud University Medical Center, 6525 GA Nijmegen, The Netherlands.

Age-related macular degeneration (AMD) is a major cause of vision loss among the elderly in the Western world. Genetic variants in the complement factor H (CFH) gene are associated with AMD, but the functional consequences of many of these variants are currently unknown. In this study we aimed to determine the effect of 64 rare and low frequency variants in the CFH gene on systemic levels of factor H (FH) and complement activation marker C3bBbP using plasma samples of 252 carriers and 159 non-carriers. Individuals carrying a heterozygous nonsense, frameshift or missense variant in CFH presented with significantly decreased FH levels, and significantly increased C3bBbP levels in plasma compared to non-carrier controls. FH and C3bBbP plasma levels were relatively stable over time in samples collected during follow-up visits. Decreased FH and increased C3bBbP concentrations were observed in carriers compared to non-carriers of CFH variants among different AMD stages, with the exception of C3bBbP levels in advanced AMD stages, which were equally high in carriers and non-carriers. In AMD families, FH levels were decreased in carriers compared to non-carriers, but C3bBbP levels did not differ. Rare variants in the CFH gene can lead to reduced FH levels or reduced FH function as measured by increased C3bBbP levels. The effects of individual variants in the CFH gene reported in this study will improve the interpretation of rare and low frequency variants observed in AMD patients in clinical practice.
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http://dx.doi.org/10.1093/hmg/ddab256DOI Listing
September 2021

Stargardt disease: monitoring incidence and diagnostic trends in the Netherlands using a nationwide disease registry.

Acta Ophthalmol 2021 Aug 25. Epub 2021 Aug 25.

Department of Ophthalmology, Radboud University Medical Centre, Nijmegen, the Netherlands.

Purpose: To assess the incidence of Stargardt disease (STGD1) and to evaluate demographics of incident cases.

Methods: For this retrospective cohort study, demographic, clinical and genetic data of patients with a clinical diagnosis of STGD1 were registered between September 2010 and January 2020 in a nationwide disease registry. Annual incidence (2014-2018) and point prevalence (2018) were assessed on the basis of this registry.

Results: A total of 800 patients were registered, 56% were female and 83% were of European ancestry. The incidence was 1.67-1.95:1,000,000 per year and the point prevalence in 2018 was approximately 1:22,000-1:19,000 (with and without 10% of potentially unregistered cases). Age at onset was associated with sex (p = 0.027, Fisher's exact); 1.9x more women than men were observed (140 versus 74) amongst patients with an age at onset between 10 and 19 years, while the sex ratio in other age-at-onset categories approximated one. Late-onset STGD1 (≥45 years) constituted 33% of the diagnoses in 2014-2018 compared to 19% in 2004-2008. Diagnostic delay (≥2 years between the first documentation of macular abnormalities and diagnosis) was associated with older age of onset (p = 0.001, Mann-Whitney). Misdiagnosis for age-related macular degeneration (22%) and incidental STGD1 findings (14%) was common in patients with late-onset STGD1.

Conclusion: The observed prevalence of STGD1 in real-world data was lower than expected on the basis of population ABCA4 allele frequencies. Late-onset STGD1 was more frequently diagnosed in recent years, likely due to higher awareness of its phenotype. In this pretherapeutic era, mis- and underdiagnosis of especially late-onset STGD1 and the role of sex in STGD1 should receive special attention.
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http://dx.doi.org/10.1111/aos.14996DOI Listing
August 2021

PRPH2 mutation update: In silico assessment of 245 reported and 7 novel variants in patients with retinal disease.

Hum Mutat 2021 Aug 19. Epub 2021 Aug 19.

Department of Human Genetics, Radboud University Medical Center, Nijmegen, The Netherlands.

Mutations in PRPH2, encoding peripherin-2, are associated with the development of a wide variety of inherited retinal diseases (IRDs). To determine the causality of the many PRPH2 variants that have been discovered over the last decades, we surveyed all published PRPH2 variants up to July 2020, describing 720 index patients that in total carried 245 unique variants. In addition, we identified seven novel PRPH2 variants in eight additional index patients. The pathogenicity of all variants was determined using the ACMG guidelines. With this, 107 variants were classified as pathogenic, 92 as likely pathogenic, one as benign, and two as likely benign. The remaining 50 variants were classified as variants of uncertain significance. Interestingly, of the total 252 PRPH2 variants, more than half (n = 137) were missense variants. All variants were uploaded into the Leiden Open source Variation and ClinVar databases. Our study underscores the need for experimental assays for variants of unknown significance to improve pathogenicity classification, which would allow us to better understand genotype-phenotype correlations, and in the long-term, hopefully also support the development of therapeutic strategies for patients with PRPH2-associated IRD.
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http://dx.doi.org/10.1002/humu.24275DOI Listing
August 2021

Computer-assisted photoreceptor assessment on Heidelberg Engineering Spectralis™ High Magnification Module™ images.

Graefes Arch Clin Exp Ophthalmol 2021 Aug 6. Epub 2021 Aug 6.

Department of Ophthalmology, Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Centre (Radboudumc), Philips van Leydenlaan 15, 6525 EX, Nijmegen, The Netherlands.

Purpose: To evaluate reliability and repeatability of computer-assisted measurements of cone photoreceptor metrics on Heidelberg Engineering Spectralis™ High Magnification Module (HMM™) Automatic Real-time Tracking (ART™) images.

Methods: We analyzed HMM™ images in three separate study arms. Computer-assisted cone identification software was validated using an open-access adaptive optics (AO) dataset. We compared results of the first arm to data from AO and histology. We evaluated intersession repeatability of our computer-assisted cone analysis in the second arm. We assessed the capability of HMM™ to visualize cones in the presence of pathology in the third arm.

Results: We included 10 healthy subjects in the first arm of our study, 5 additional healthy participants in the second arm and 5 patients in the third arm. In total, we analyzed 225 regions of interest on HMM™ images. We were able to automatically identify cone photoreceptors and assess corresponding metrics at all eccentricities between 2 and 9° from the fovea. Cone density significantly declined with increasing eccentricity (p = 4.890E-26, Friedman test). With increasing eccentricity, we found a significant increase in intercell distance (p = 2.196E-25, Friedman test) and nearest neighbor distance (p = 1.997E-25, Friedman test). Cone hexagonality ranged between 71 and 85%. We found excellent automated intersession repeatability of cone density counts and spacing measurements. In pathology, we were also able to repeatedly visualize photoreceptors.

Conclusion: Computer-assisted cone photoreceptor analysis on Spectralis™ HMM™ images is feasible, and most cone metrics show excellent repeatability. HMM™ imaging may be useful for photoreceptor analysis as progression marker in outer retinal disease.
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http://dx.doi.org/10.1007/s00417-021-05326-6DOI Listing
August 2021

Charles Bonnet syndrome in patients with Stargardt disease: prevalence and risk factors.

Br J Ophthalmol 2021 Aug 4. Epub 2021 Aug 4.

Department of Ophthalmology, Radboudumc, Nijmegen, The Netherlands

Aims: To describe the prevalence of the Charles Bonnet syndrome (CBS) and search for potential CBS risk factors in a Dutch Stargardt disease (STGD1) cohort.

Methods: Eighty-three patients with STGD1 were screened for CBS. They underwent a full eye examination. All patients completed the social functioning domain of the 36-Item Short Form Health Survey questionnaire. Participants suspected of CBS were interviewed to further evaluate their visual hallucinations.

Results: CBS prevalence was 8.4%. Six out of seven patients with CBS were women. CBS was not associated with age (p=0.279, Mann-Whitney). Patients with CBS had a significant lower social functioning score (p<0.05, Mann-Whitney). All seven patients with CBS were in the category of vision impairment (visual acuity <6/12, but ≥3/60). Moreover, first hallucinations manifested after a drop in visual acuity. The retinal atrophic area of the worst eye tended to be lower in the CBS group (range 0.11-9.86 mm) as compared with controls (range 0-180 mm). There was no relation between the position of the scotoma and the location of the visual hallucinations.

Conclusion: The relative high CBS prevalence in STGD1 suggests that CBS may be more prevalent in younger ophthalmic patients than currently presumed. In this specific group of patients, we established social isolation and acquired vision impairment as risk factors for CBS. There was a female preponderance among patients with CBS. Age and retinal pigment epithelium atrophy were not identified as significant risk factors. We should actively diagnose CBS in patients of any age who fulfil the criteria for the category vision impairment, especially in cases where social isolation is suspected.
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http://dx.doi.org/10.1136/bjophthalmol-2021-319525DOI Listing
August 2021

CRB1-associated retinal dystrophies: a prospective natural history study in anticipation of future clinical trials.

Am J Ophthalmol 2021 Jul 25. Epub 2021 Jul 25.

Department of Ophthalmology, Leiden University Medical Center, Leiden, the Netherlands; Department of Ophthalmology, Amsterdam UMC, Academic Medical Center, Amsterdam, the Netherlands. Electronic address:

Purpose: To describe the natural disease course of CRB1-associated retinal dystrophies, and to identify clinical endpoints for future clinical trials.

Design: Single center, prospective case series.

Methods: An investigator-initiated nationwide collaborative study that included 22 patients with CRB1-associated retinal dystrophies. Patients underwent ophthalmic assessment at baseline and 2 years after baseline. Clinical examination included best-corrected visual acuity (BCVA) using ETDRS charts, Goldmann kinetic perimetry (V4e isopter seeing retinal areas), microperimetry, full-field electroretinography (ERG), full-field stimulus threshold (FST), fundus photography, spectral-domain optical coherence tomography and fundus autofluorescence imaging.

Results: Based on genetic, clinical and electrophysiological data, patients were diagnosed with retinitis pigmentosa (n = 19; 86%), cone-rod dystrophy (n = 2; 9%) or isolated macular dystrophy (n = 1; 5%). Two-year analysis of the entire cohort showed no significant changes in BCVA (p = 0.069) or V4e isopter seeing retinal areas (p = 0.616), although signs of clinical progression were present in individual patients. Macular sensitivity measured on microperimetry revealed a significant reduction at 2-year follow-up (p < 0.001). FST responses were measurable in patients with non-recordable ERGs. On average, FST responses remained stable during follow-up.

Conclusion: In CRB1-associated retinal dystrophies, visual acuity and visual field measures remain relatively stable over the course of 2 years. Microperimetry showed a significant decrease in retinal sensitivity during follow-up, and may be a more sensitive progression marker. Retinal sensitivity on microperimetry may serve as a functional clinical endpoint in future human treatment trials for CRB1-associated retinal dystrophies.
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http://dx.doi.org/10.1016/j.ajo.2021.07.021DOI Listing
July 2021

Common haplotypes at the CFH locus and low-frequency variants in CFHR2 and CFHR5 associate with systemic FHR concentrations and age-related macular degeneration.

Am J Hum Genet 2021 08 13;108(8):1367-1384. Epub 2021 Jul 13.

Department of Ophthalmology, Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, Nijmegen, 6525EX, the Netherlands; Department of Human Genetics, Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Centre, 6525GA, the Netherlands. Electronic address:

Age-related macular degeneration (AMD) is the principal cause of blindness in the elderly population. A strong effect on AMD risk has been reported for genetic variants at the CFH locus, encompassing complement factor H (CFH) and the complement-factor-H-related (CFHR) genes, but the underlying mechanisms are not fully understood. We aimed to dissect the role of factor H (FH) and FH-related (FHR) proteins in AMD in a cohort of 202 controls and 216 individuals with AMD. We detected elevated systemic levels of FHR-1 (p = 1.84 × 10), FHR-2 (p = 1.47 × 10), FHR-3 (p = 1.05 × 10) and FHR-4A (p = 1.22 × 10) in AMD, whereas FH concentrations remained unchanged. Common AMD genetic variants and haplotypes at the CFH locus strongly associated with FHR protein concentrations (e.g., FH p.Tyr402His and FHR-2 concentrations, p = 3.68 × 10), whereas the association with FH concentrations was limited. Furthermore, in an International AMD Genomics Consortium cohort of 17,596 controls and 15,894 individuals with AMD, we found that low-frequency and rare protein-altering CFHR2 and CFHR5 variants associated with AMD independently of all previously reported genome-wide association study (GWAS) signals (p = 5.03 × 10 and p = 2.81 × 10, respectively). Low-frequency variants in CFHR2 and CFHR5 led to reduced or absent FHR-2 and FHR-5 concentrations (e.g., p.Cys72Tyr in CFHR2 and FHR-2, p = 2.46 × 10). Finally, we showed localization of FHR-2 and FHR-5 in the choriocapillaris and in drusen. Our study identifies FHR proteins as key proteins in the AMD disease mechanism. Consequently, therapies that modulate FHR proteins might be effective for treating or preventing progression of AMD. Such therapies could target specific individuals with AMD on the basis of their genotypes at the CFH locus.
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http://dx.doi.org/10.1016/j.ajhg.2021.06.002DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8387287PMC
August 2021

Half-dose photodynamic therapy versus eplerenone in chronic central serous chorioretinopathy (SPECTRA): a randomized controlled trial.

Am J Ophthalmol 2021 Jun 29. Epub 2021 Jun 29.

Department of Ophthalmology, Leiden University Medical Center, P.O. Box 9600, 2300 RC Leiden, the Netherlands; Department of Ophthalmology, Amsterdam University Medical Centers, University of Amsterdam, P.O. Box 22660, 1100 DD Amsterdam, the Netherlands. Electronic address:

Purpose: To compare the efficacy and safety between half-dose photodynamic therapy (PDT) and eplerenone for treating chronic central serous chorioretinopathy (cCSC).

Design: Multicenter, open-label, randomized controlled trial.

Methods: This investigator-initiated trial was conducted in 3 academic medical centers in the Netherlands. Eligible patients were randomized at a 1:1 ratio to receive either indocyanine green angiography-guided half-dose PDT or oral eplerenone for 12 weeks. Both anatomical and functional outcomes were evaluated at 3 months after the start of treatment.

Results: A total of 107 patients were randomly assigned to receive either half-dose PDT (n=53) or eplerenone treatment (n=54). Thirteen patients (3 in the PDT group and 10 in the eplerenone group) did not adhere to the study protocol. At the 3-month evaluation visit, 78% of patients in the PDT group had complete resolution of SRF, compared to only 17% of patients in the eplerenone group (p<0.001). Mean best-corrected visual acuity in Early Treatment of Diabetic Retinopathy Study letters at the evaluation visit was 83.7±10.8 and 82.8±9.0 in the PDT and eplerenone groups, respectively (p=0.555). In addition, mean retinal sensitivity on microperimetry was 25.4±3.4 dB and 23.9±4.0 dB in the PDT and eplerenone groups, respectively (p=0.041). Finally, mean vision-related quality of life scores were 87.2±8.5 and 83.8±12.1 in the PDT and eplerenone groups, respectively (p=0.094). Three patients in the PDT group (6%) experienced adverse events during the study, compared to 18 patients in the eplerenone group (33%).

Conclusions: Half-dose PDT is superior to oral eplerenone for cCSC with respect to both short-term safety and efficacy outcomes.
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http://dx.doi.org/10.1016/j.ajo.2021.06.020DOI Listing
June 2021

Systemic complement activation levels in Stargardt disease.

PLoS One 2021 25;16(6):e0253716. Epub 2021 Jun 25.

Department of Ophthalmology, Radboud University Medical Center, Nijmegen, The Netherlands.

Purpose: Preclinical research provides evidence for the complement system as a potential common pathway in Stargardt disease (STGD1) and age-related macular degeneration (AMD) leading to retinal pigment epithelium (RPE) loss. However, systemic complement activation has not yet been assessed in STGD1 patients. We conducted a cross-sectional case-control study to assess systemic complement activation in STGD1 patients and its association with disease severity.

Methods: Systemic concentrations of complement component C3 and its degradation product C3d were compared between 80 STGD1 patients and 80 controls that were frequency matched for age and sex. The C3d/C3 ratio was used as parameter of systemic complement activation. Within the STGD1 cohort, we additionally examined the association between the C3d/C3 ratio, demographic and behavioural factors (age, sex, smoking and BMI), and measures of disease severity (age at onset, visual acuity, and area of atrophy).

Results: The C3d/C3 ratio did not significantly differ between patients (mean C3d/C3 ratio 3.5±1.4) and controls (mean C3d/C3 ratio 3.6±1.0), mean difference -0.156 (p = 0.804, independent samples t-test). The overall effect size was 8% (95% confidence interval, 3-15%). Elevated C3d/C3 ratios (>8.1) were found in three patients who all had a concomitant inflammatory condition at the time of blood draw. Within the patient cohort, C3 levels were associated with sex (mean difference -134, p = 0.001, independent samples t-test) and BMI (correlation coefficient 0.463, p<0.001, Spearman's Correlation).

Conclusions: Systemic complement levels were not elevated in STGD1 patients compared to age and sex matched controls and was not associated with STGD1 severity. Considering the continued absent proof of a systemic contribution of the complement system to RPE loss in STGD1 patients, we hypothesize that complement activation in STGD1 is more likely a local process. In light of upcoming complement-targeted therapies, further studies are needed that measure complement levels in the eye of STGD1 patients.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0253716PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8232401PMC
June 2021

Tackling the Challenges of Product Development Through a Collaborative Rare Disease Network: The Foundation Fighting Blindness Consortium.

Transl Vis Sci Technol 2021 04;10(4):23

Institut de la Vision, Sorbonne Université, INSERM, CNRS, Paris, France.

The Foundation Fighting Blindness, a 501(c)(3) nonprofit organization, established an international consortium of inherited retinal disease specialists in 2016, with a mission to accelerate the development of treatments for rare, inherited retinal degenerations, such as retinitis pigmentosa, Stargardt disease, Leber congenital amaurosis, Usher syndrome, choroideremia, and achromatopsia. The Consortium accomplishes its mission by evaluating novel outcome measures, sharing standardized study protocols and datasets, and disseminating findings. Having established research infrastructure in the first 3 years, including 39 global research sites, the network is now poised to expand its infrastructure for trials of new therapies in partnership with industry. This model represents an innovative approach to overcome challenges of therapeutic development for rare diseases.
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http://dx.doi.org/10.1167/tvst.10.4.23DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8083110PMC
April 2021

Correlation of Morphology and Function of Flecks Using Short-Wave Fundus Autofluorescence and Microperimetry in Patients With Stargardt Disease.

Transl Vis Sci Technol 2021 03;10(3):18

Department of Ophthalmology, Radboud University Medical Center, Nijmegen, The Netherlands.

Purpose: The purpose of this study was to evaluate the functional relevance of longitudinal changes in hyperautofluorescent areas and flecks in Stargardt disease (STGD1) using short-wavelength autofluorescence (SW-AF) imaging.

Methods: In this prospective, longitudinal study, 31 patients with STGD1 (56 eyes) underwent microperimetry (MP) and SW-AF imaging twice in 3 to 5 years. A total of 760 MP test points were included in the statistical analysis based on stable fixation and accurate alignment of SW-AF and MP. Autofluorescence intensity was qualitatively assessed in all MP test points. Small circumscriptive hyperautofluorescent lesions were defined as flecks. Longitudinal imaging characteristics observed on SW-AF were classified into the following categories: appearing, disappearing, and stable flecks, stable hyperautofluorescent, and stable background autofluorescence. The relationship between SW-AF intensity changes and MP changes was analyzed using a linear mixed model corrected for baseline sensitivity.

Results: Retinal sensitivity declined most in locations without change in SW-AF intensity. Functional decline per year was significantly larger in flecks that disappeared (-0.72 ± 1.30 dB) compared to flecks that appeared (-0.34 ± 0.65 dB), if baseline sensitivity was high (≥10 dB; P < 0.01). The correlation between the change observed on SW-AF and the sensitivity change significantly depended on the sensitivity at baseline (P = 0.000).

Conclusions: Qualitative longitudinal assessment of SW-AF poorly reflected the retinal sensitivity loss observed over the course of 3 to 5 years.

Translational Relevance: When aiming to assess treatment effect on lesion level, a multimodal end point including MP focused on hyperautofluorescent lesions appears essential but needs further studies on optimizing MP grids, eye-tracking systems, and alignment software.
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http://dx.doi.org/10.1167/tvst.10.3.18DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7991959PMC
March 2021

branchpoint variant is associated with non-syndromic retinitis pigmentosa.

J Med Genet 2021 Apr 28. Epub 2021 Apr 28.

Department of Human Genetics, Radboudumc, Nijmegen, The Netherlands

Background: Inherited retinal diseases (IRDs) can be caused by variants in >270 genes. The Bardet-Biedl syndrome 1 () gene is one of these genes and may be associated with syndromic and non-syndromic autosomal recessive retinitis pigmentosa (RP). Here, we identified a branchpoint variant in and assessed its pathogenicity by in vitro functional analysis.

Methods: Whole genome sequencing was performed for three unrelated monoallelic cases with non-syndromic RP. A fourth case received MGCM 105 gene panel analysis. Functional analysis using a midigene splice assay was performed for the putative pathogenic branchpoint variant in . After confirmation of its pathogenicity, patients were clinically re-evaluated, including assessment of non-ocular features of Bardet-Biedl syndrome.

Results: Clinical assessments of probands showed that all individuals displayed non-syndromic RP with macular involvement. Through detailed variant analysis and prioritisation, two pathogenic variants in , the most common missense variant, c.1169T>G (p.(Met390Arg)), and a branchpoint variant, c.592-21A>T, were identified. Segregation analysis confirmed that in all families, probands were compound heterozygous for c.1169T>G and c.592-21A>T. Functional analysis of the branchpoint variant revealed a complex splicing defect including exon 8 and exon 7/8 skipping, and partial in-frame deletion of exon 8.

Conclusion: A putative severe branchpoint variant in , together with a mild missense variant, underlies non-syndromic RP in four unrelated individuals. To our knowledge, this is the first report of a pathogenic branchpoint variant in IRDs that results in a complex splice defect. In addition, this research highlights the importance of the analysis of non-coding regions in order to provide a conclusive molecular diagnosis.
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http://dx.doi.org/10.1136/jmedgenet-2020-107626DOI Listing
April 2021

Increased pro-MMP9 plasma levels are associated with neovascular age-related macular degeneration and with the risk allele of rs142450006 near .

Mol Vis 2021 2;27:142-150. Epub 2021 Apr 2.

Department of Ophthalmology, Radboud University Medical Center, Donders Institute for Brain, Cognition and Behaviour, Nijmegen, The Netherlands.

Purpose: To evaluate the plasma levels of matrix metalloproteinase 9 (MMP9) and tissue inhibitors of metalloproteinase 3 (TIMP3) in neovascular age-related macular degeneration (nAMD) patients compared to controls, and to explore the potential effect of AMD-associated genetic variants on MMP9 and TIMP3 protein levels.

Methods: nAMD and control patients were selected from the European Genetic Database (EUGENDA) based on different genotypes of rs142450006 near and rs5754227 near Plasma total MMP9, active MMP9 and TIMP3 levels were measured using the enzyme linked immunosorbent assay (ELISA) and compared between nAMD patients and controls, as well as between different genotype groups.

Results: nAMD patients had significantly higher total MMP9 levels compared to controls (median 46.58 versus 26.90 ng/ml; p = 0.0004). In addition, the median MMP9 level in the homozygous genotype group for the AMD-risk allele (44.23 ng/ml) was significantly higher than the median for the heterozygous genotype group (26.90 ng/ml; p = 0.0082) and the median for the homozygous group for the non-risk allele (28.55 ng/ml; p = 0.0355). No differences were detected for the active MMP9. TIMP3 levels did not significantly differ between the AMD and control groups, nor between the different genotype groups for rs5754227.

Conclusions: The results of our MMP9 analyses indicate that nAMD patients have on average higher systemic MMP9 levels than control individuals, and that this is partly driven by the rs142450006 variant near . This finding might be an interesting starting point for further exploration of MMP9 as a therapeutic target in nAMD, particularly among individuals carrying the risk-conferring allele rs142450006.
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8056465PMC
April 2021

Long-term follow-up of chronic central serous chorioretinopathy after successful treatment with photodynamic therapy or micropulse laser.

Acta Ophthalmol 2021 Feb 10. Epub 2021 Feb 10.

Department of Ophthalmology, Leiden University Medical Center, Leiden, The Netherlands.

Purpose: To describe the treatment outcomes and recurrence risk of chronic central serous chorioretinopathy (cCSC) in patients who had complete resolution of subretinal fluid (SRF) after either primary half-dose photodynamic therapy (PDT) or high-density subthreshold micropulse laser (HSML) in the PLACE trial.

Methods: This multicentre prospective follow-up study evaluated cCSC patients at 1 year after completion of the PLACE trial. Outcomes included: complete resolution of SRF on OCT, best-corrected visual acuity (BCVA) in Early Treatment of Diabetic Retinopathy Study (ETDRS) letters, retinal sensitivity on microperimetry and a visual function questionnaire (NEI-VFQ25).

Results: Twenty-nine out of 37 patients who received half-dose PDT and 15 out of 17 patients who received HSML could be evaluated at final visit. At final visit, 93% of the patients treated with half-dose PDT had complete resolution of SRF, compared with 53% of HSML-treated patients (p = 0.006). At final visit, the mean estimate increase in the PDT group compared with the HSML group was + 2.1 ETDRS letters, +0.15 dB for the retinal sensitivity and + 5.1 NEI-VFQ25 points (p = 0.103, p = 0.784 and p = 0.071, respectively). The mean estimated central retinal thickness in the half-dose PDT group was -7.0 µm compared with the HSML group (p = 0.566). The mean estimated subfoveal choroidal thickness in the half-dose PDT group was -16.6 µm compared with the HSML group (p = 0.359).

Conclusion: At 20 months after treatment, cCSC patients successfully treated with half-dose PDT are less likely to have recurrences of SRF compared with those successfully treated with HSML. However, functional outcomes did not differ.
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http://dx.doi.org/10.1111/aos.14775DOI Listing
February 2021

Defining inclusion criteria and endpoints for clinical trials: a prospective cross-sectional study in CRB1-associated retinal dystrophies.

Acta Ophthalmol 2021 May 2;99(3):e402-e414. Epub 2021 Feb 2.

Department of Ophthalmology, Leiden University Medical Center, Leiden, The Netherlands.

Purpose: To investigate the retinal structure and function in patients with CRB1-associated retinal dystrophies (RD) and to explore potential clinical endpoints.

Methods: In this prospective cross-sectional study, 22 patients with genetically confirmed CRB1-RD (aged 6-74 years), and who had a decimal best-corrected visual acuity (BCVA) ≥ 0.05 at the last visit, were studied clinically with ETDRS BCVA, corneal topography, spectral-domain optical coherence tomography (SD-OCT), fundus autofluorescence, Goldmann visual field (VF), microperimetry, full-field electroretinography (ERG) and full-field stimulus testing (FST). Ten patients were from a genetic isolate (GI).

Results: Patients had retinitis pigmentosa (n = 19; GI and non-GI), cone-rod dystrophy (n = 2; GI) or macular dystrophy (n = 1; non-GI). Median age at first symptom onset was 3 years (range 0.8-49). Median decimal BCVA in the better and worse-seeing eye was 0.18 (range 0.05-0.83) and 0.08 (range light perception-0.72), respectively. Spectral-domain optical coherence tomography (SD-OCT) showed cystoid maculopathy in 8 subjects; inner retinal thickening (n = 20), a well-preserved (para)foveal outer retina (n = 7) or severe (para)foveal outer retinal atrophy (n = 14). All retinal layers were discernible in 13/21 patients (62%), with mild to moderate laminar disorganization in the others. Nanophthalmos was observed in 8 patients (36%). Full-field stimulus testing (FST) provided a subjective outcome measure for retinal sensitivity in eyes with (nearly) extinguished ERG amplitudes.

Conclusions: Despite the generally severe course of CRB1-RDs, symptom onset and central visual function are variable, even at advanced ages. Phenotypes may vary within the same family. Imaging and functional studies in a prospective longitudinal setting should clarify which endpoints may be most appropriate in a clinical trial.
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http://dx.doi.org/10.1111/aos.14597DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8248330PMC
May 2021

Quantitative multiplex profiling of the complement system to diagnose complement-mediated diseases.

Clin Transl Immunology 2020 9;9(12):e1225. Epub 2020 Dec 9.

Laboratory of Medical Immunology Department of Laboratory Medicine Radboud Institute for Molecular Life Sciences Radboud University Medical Center Nijmegen The Netherlands.

Objectives: Complement deficiencies are difficult to diagnose because of the variability of symptoms and the complexity of the diagnostic process. Here, we applied a novel 'complementomics' approach to study the impact of various complement deficiencies on circulating complement levels.

Methods: Using a quantitative multiplex mass spectrometry assay, we analysed 44 peptides to profile 34 complement proteins simultaneously in 40 healthy controls and 83 individuals with a diagnosed deficiency or a potential pathogenic variant in 14 different complement proteins.

Results: Apart from confirming near or total absence of the respective protein in plasma of complement-deficient patients, this mass spectrometry-based profiling method led to the identification of additional deficiencies. In many cases, partial depletion of the pathway up- and/or downstream of the absent protein was measured. This was especially found in patients deficient for complement inhibitors, such as angioedema patients with a C1-inhibitor deficiency. The added value of complementomics was shown in three patients with poorly defined complement deficiencies.

Conclusion: Our study shows the potential clinical utility of profiling circulating complement proteins as a comprehensive read-out of various complement deficiencies. Particularly, our approach provides insight into the intricate interplay between complement proteins due to functional coupling, which contributes to the better understanding of the various disease phenotypes and improvement of care for patients with complement-mediated diseases.
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http://dx.doi.org/10.1002/cti2.1225DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7724921PMC
December 2020

Genetic Risk, Lifestyle, and Age-Related Macular Degeneration in Europe: The EYE-RISK Consortium.

Ophthalmology 2021 Jul 28;128(7):1039-1049. Epub 2020 Nov 28.

Department of Ophthalmology, Erasmus University Medical Center, Rotterdam, The Netherlands; Department of Epidemiology, Erasmus University Medical Center, Rotterdam, The Netherlands; Department of Ophthalmology, Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, Nijmegen, The Netherlands; Institute of Molecular and Clinical Ophthalmology, Basel, Switzerland. Electronic address:

Purpose: Age-related macular degeneration (AMD) is a common multifactorial disease in the elderly with a prominent genetic basis. Many risk variants have been identified, but the interpretation remains challenging. We investigated the genetic distribution of AMD-associated risk variants in a large European consortium, calculated attributable and pathway-specific genetic risks, and assessed the influence of lifestyle on genetic outcomes.

Design: Pooled analysis of cross-sectional data from the European Eye Epidemiology Consortium.

Participants: Seventeen thousand one hundred seventy-four individuals 45 years of age or older participating in 6 population-based cohort studies, 2 clinic-based studies, and 1 case-control study.

Methods: Age-related macular degeneration was diagnosed and graded based on fundus photographs. Data on genetics, lifestyle, and diet were harmonized. Minor allele frequencies and population-attributable fraction (PAF) were calculated. A total genetic risk score (GRS) and pathway-specific risk scores (complement, lipid, extra-cellular matrix, other) were constructed based on the dosage of SNPs and conditional β values; a lifestyle score was constructed based on smoking and diet.

Main Outcome Measures: Intermediate and late AMD.

Results: The risk variants with the largest difference between late AMD patients and control participants and the highest PAFs were located in ARMS2 (rs3750846) and CHF (rs570618 and rs10922109). Combining all genetic variants, the total genetic risk score ranged from -3.50 to 4.63 and increased with AMD severity. Of the late AMD patients, 1581 of 1777 (89%) showed a positive total GRS. The complement pathway and ARMS2 were by far the most prominent genetic pathways contributing to late AMD (positive GRS, 90% of patients with late disease), but risk in 3 pathways was most frequent (35% of patients with late disease). Lifestyle was a strong determinant of the outcome in each genetic risk category; unfavorable lifestyle increased the risk of late AMD at least 2-fold.

Conclusions: Genetic risk variants contribute to late AMD in most patients. However, lifestyle factors have a strong influence on the outcome of genetic risk and should be a strong focus in patient management. Genetic risks in ARMS2 and the complement pathway are present in most late AMD patients but are mostly combined with risks in other pathways.
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http://dx.doi.org/10.1016/j.ophtha.2020.11.024DOI Listing
July 2021

Outcome of half-dose photodynamic therapy in chronic central serous chorioretinopathy with fovea-involving atrophy.

Graefes Arch Clin Exp Ophthalmol 2021 Apr 29;259(4):905-910. Epub 2020 Oct 29.

Department of Ophthalmology, Leiden University Medical Center, P.O. Box 9600, 2300 RC, Leiden, The Netherlands.

Purpose: To evaluate the clinical outcomes after half-dose photodynamic therapy (PDT) in chronic central serous chorioretinopathy (cCSC) patients with pre-existent fovea-involving atrophy.

Methods: In this retrospective study, cCSC patients who had a window defect of the retinal pigment epithelium (RPE) on fluorescein angiography (FA), compatible with RPE atrophy, prior to half-dose PDT were included.

Results: Thirty-four cCSC eyes with typical findings of cCSC on multimodal imaging, and fovea-involving RPE atrophy on FA, were included. At the first visit after PDT (at a median of 1.8 months after half-dose PDT), 20 eyes (59%) had a complete resolution of SRF (p < 0.001), while this was the case in 19 eyes (56%) at final visit (median of 11.3 months after half-dose PDT; p < 0.001). The mean BCVA in Early Treatment of Diabetic Retinopathy Study letters was 71. 2 ± 15.9 at last visit before PDT, which increased to 74.1 ± 14.1 at first visit after PDT (p = 0.093, compared with baseline), and changed to 73.0 ± 19.1 at final visit (p = 0.392, compared with baseline). Both at first visit after PDT and at final visit, a significant decrease in subfoveal choroidal thickness was observed (p = 0.032 and p = 0.004, respectively).

Conclusions: Half-dose PDT in cCSC patients with pre-existing fovea-involving atrophy may lead to anatomical changes, but not to functional improvements. Ideally, cCSC should be treated with half-dose PDT before the occurrence of such atrophy.
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http://dx.doi.org/10.1007/s00417-020-04959-3DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8016744PMC
April 2021

Association of plasma trace element levels with neovascular age-related macular degeneration.

Exp Eye Res 2020 12 21;201:108324. Epub 2020 Oct 21.

Wellcome Trust Centre for Cell-Matrix Research, Division of Cell-Matrix Biology & Regenerative Medicine, School of Biological Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester Academic Health Science Centre, Oxford Road, Manchester, M13 9PT, UK; Lydia Becker Institute of Immunology and Inflammation, Faculty of Biology, Medicine and Health, University of Manchester, Manchester Academic Health Science Centre, Oxford Road, Manchester, M13 9PT, UK. Electronic address:

Although the triggers causing angiogenesis in the context of neovascular age-related macular degeneration (nAMD) are not fully understood, oxidative stress is likely involved. Oxidative stress in the eye can occur through exposure of macular tissues to sunlight and local or systemic exposure to oxidative stressors associated with environmental or lifestyle factors. Because trace elements have been implicated as regulators of oxidative stress and cellular antioxidant defense mechanisms, we hypothesized that they may play a role as a risk factor, modifying the progression toward nAMD. Herein, we determined whether levels of human plasma trace elements are different in 236 individuals with nAMD compared to 236 age-matched controls without AMD. Plasma levels of 16 trace elements including arsenic, barium, calcium, cadmium, cobalt, chromium, copper, iron, magnesium, manganese, molybdenum, lead, antimony, selenium, vanadium and zinc were measured using inductively coupled plasma mass spectrometry. Associations of trace elements with demographic, environmental and lifestyle factors and AMD-associated genetic variants were assessed. Elevated levels of barium and cadmium and reduced levels of chromium were observed in nAMD patients compared to controls. Mean plasma concentrations of barium were 1.35 μg/L (standard deviation [SD] 0.71) in nAMD and 1.15 μg/L (SD 0.63) in controls (P = 0.001). Mean levels of chromium were 0.37 μg/L (SD 0.22) in nAMD and 0.46 μg/L (SD 0.34) in controls (P = 0.001). Median levels for cadmium, which were not normally distributed, were 0.016 μg/L (interquartile range [IQR] 0.001-0.026) in nAMD and 0.012 μg/L (IQR 0.001-0.022) in controls (P = 0.002). Comparison of the Spearman's correlation coefficients between nAMD patients and controls identified a difference in correlations for 8 trace elements. Cadmium levels were associated with the smoking status (P < 0.001), while barium levels showed a trend of association with the usage of antihypertensive drugs. None of the AMD-associated genetic variants were associated with any trace element levels. In conclusion, in this case-control study we detected elevated plasma levels of barium and cadmium and reduced plasma levels of chromium in nAMD patients. An imbalance in plasma trace elements, which is most likely driven by environmental and lifestyle factors, might have a role in the pathogenesis of AMD. These trace elements may be incorporated as biomarkers into models for prediction of disease risk and progression. Additionally, population-based preventive strategies to decrease Cd exposure, especially by the cessation of smoking, could potentially reduce the burden of nAMD. Future studies are warranted to investigate whether supplementation of Cr would have a beneficial effect on nAMD.
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http://dx.doi.org/10.1016/j.exer.2020.108324DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7773981PMC
December 2020

Genetic and environmental risk factors for extramacular drusen.

Mol Vis 2020 4;26:661-669. Epub 2020 Oct 4.

Department of Ophthalmology, University of Cologne, Faculty of Medicine and University Hospital Cologne, Germany.

Purpose: To analyze risk factors for extramacular drusen (EMD) in patients with age-related macular degeneration (AMD) and healthy control individuals.

Methods: This case-control study included 1,520 patients from the prospective multicenter European Genetic Database (EUGENDA). Color fundus photographs and optical coherence tomography scans were evaluated for the presence of AMD and EMD. EMD was considered present if ten or fewer drusen including at least one intermediate-sized drusen were detected outside the macula. Association of EMD was evaluated with various genetic and non-genetic risk factors (31 single nucleotide polymorphisms, systemic complement activation, smoking, cardiovascular factors, and sunlight exposure) using logistic regression models adjusted for age, gender, and AMD.

Results: EMD was found in 608 subjects (40%) and AMD in 763 (50%) of 1,520 participants. EMD was strongly associated with AMD (p = 2.83 × 10-63, odds ratio [OR] 7.63). After adjustment for AMD, age (p = 0.06, OR 1.02), female gender (p = 3.34 × 10-24, OR 4.44), history of sunlight exposure ≥ 8 h /day (p = 0.0004, OR 1.99), serum complement activation (p = 0.004, OR 1.61), and polymorphisms in ARMS2 (p = 0.00016, OR 1.43) and CFI (p = 0.043, OR 1.20) were identified as risk factors for EMD. The final prediction model including these variants showed an area under the curve of 0.820.

Conclusions: The comprehensive analysis of various risk factors revealed a common genetic and pathological pathway of EMD with AMD. Future longitudinal studies are needed to evaluate the role of EMD in otherwise healthy subjects as an expanded phenotype of AMD.
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7553721PMC
July 2021

Structural Variants Create New Topological-Associated Domains and Ectopic Retinal Enhancer-Gene Contact in Dominant Retinitis Pigmentosa.

Am J Hum Genet 2020 11 5;107(5):802-814. Epub 2020 Oct 5.

University of Cape Town/MRC Genomic and Precision Medicine Research Unit, Division of Human Genetics, Department of Pathology, Institute of Infectious Disease and Molecular Medicine, Faculty of Health Sciences, University of Cape Town, Cape Town, 7935, South Africa.

The cause of autosomal-dominant retinitis pigmentosa (adRP), which leads to loss of vision and blindness, was investigated in families lacking a molecular diagnosis. A refined locus for adRP on Chr17q22 (RP17) was delineated through genotyping and genome sequencing, leading to the identification of structural variants (SVs) that segregate with disease. Eight different complex SVs were characterized in 22 adRP-affected families with >300 affected individuals. All RP17 SVs had breakpoints within a genomic region spanning YPEL2 to LINC01476. To investigate the mechanism of disease, we reprogrammed fibroblasts from affected individuals and controls into induced pluripotent stem cells (iPSCs) and differentiated them into photoreceptor precursor cells (PPCs) or retinal organoids (ROs). Hi-C was performed on ROs, and differential expression of regional genes and a retinal enhancer RNA at this locus was assessed by qPCR. The epigenetic landscape of the region, and Hi-C RO data, showed that YPEL2 sits within its own topologically associating domain (TAD), rich in enhancers with binding sites for retinal transcription factors. The Hi-C map of RP17 ROs revealed creation of a neo-TAD with ectopic contacts between GDPD1 and retinal enhancers, and modeling of all RP17 SVs was consistent with neo-TADs leading to ectopic retinal-specific enhancer-GDPD1 accessibility. qPCR confirmed increased expression of GDPD1 and increased expression of the retinal enhancer that enters the neo-TAD. Altered TAD structure resulting in increased retinal expression of GDPD1 is the likely convergent mechanism of disease, consistent with a dominant gain of function. Our study highlights the importance of SVs as a genomic mechanism in unsolved Mendelian diseases.
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http://dx.doi.org/10.1016/j.ajhg.2020.09.002DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7675008PMC
November 2020

Pathogenic variants in cause autosomal dominant and autosomal recessive retinitis pigmentosa.

J Med Genet 2021 Aug 17;58(8):570-578. Epub 2020 Aug 17.

Institute for Neurosciences of Montpellier, University of Montpellier, Montpellier, France

Background: Inherited retinal disorders are a clinically and genetically heterogeneous group of conditions and a major cause of visual impairment. Common disease subtypes include vitelliform macular dystrophy (VMD) and retinitis pigmentosa (RP). Despite the identification of over 90 genes associated with RP, conventional genetic testing fails to detect a molecular diagnosis in about one third of patients with RP.

Methods: Exome sequencing was carried out for identifying the disease-causing gene in a family with autosomal dominant RP. Gene panel testing and exome sequencing were performed in 596 RP and VMD families to identified additional variants. In vivo analysis in the medaka fish system by knockdown assays was performed to screen possible pathogenic role.

Results: Exome sequencing of a family with RP revealed a splice variant in . Subsequently, the same variant was identified in individuals from two families with either RP or VMD. A retrospective study of patients with RP or VMD revealed eight additional families with different missense or nonsense variants in . In addition, the clinical diagnosis of the retinopathy-associated variant, originally described as benign concentric annular macular dystrophy, was also revised to RP with early macular involvement. Using morpholino-mediated ablation of and its paralog in medaka fish, we confirmed a phenotype consistent with that observed in the families, including a decreased length of rod and cone photoreceptor outer segments.

Conclusion: This study discusses a previously unreported association between monoallelic or biallelic variants and RP. Notably, similar observations have been reported for .
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http://dx.doi.org/10.1136/jmedgenet-2020-107150DOI Listing
August 2021

Association of Sex With Frequent and Mild ABCA4 Alleles in Stargardt Disease.

JAMA Ophthalmol 2020 10;138(10):1035-1042

Department of Human Genetics, Radboud University Medical Center, Nijmegen, the Netherlands.

Importance: The mechanisms behind the phenotypic variability and reduced penetrance in autosomal recessive Stargardt disease (STGD1), often a blinding disease, are poorly understood. Identification of the unknown disease modifiers can improve patient and family counseling and provide valuable information for disease management.

Objective: To assess the association of incompletely penetrant ABCA4 alleles with sex in STGD1.

Design, Setting, And Participants: Genetic data for this cross-sectional study were obtained from 2 multicenter genetic studies of 1162 patients with clinically suspected STGD1. Unrelated patients with genetically confirmed STGD1 were selected. The data were collected from June 2016 to June 2019, and post hoc analysis was performed between July 2019 and January 2020.

Main Outcomes And Measures: Penetrance of reported mild ABCA4 variants was calculated by comparing the allele frequencies in the general population (obtained from the Genome Aggregation Database) with the genotyping data in the patient population (obtained from the ABCA4 Leiden Open Variation Database). The sex ratio among patients with and patients without an ABCA4 allele with incomplete penetrance was assessed.

Results: A total of 550 patients were included in the study, among which the mean (SD) age was 45.7 (18.0) years and most patients were women (311 [57%]). Five of the 5 mild ABCA4 alleles, including c.5603A>T and c.5882G>A, were calculated to have incomplete penetrance. The women to men ratio in the subgroup carrying c.5603A>T was 1.7 to 1; the proportion of women in this group was higher compared with the subgroup not carrying a mild allele (difference, 13%; 95% CI, 3%-23%; P = .02). The women to men ratio in the c.5882G>A subgroup was 2.1 to 1, and the women were overrepresented compared with the group carrying no mild allele (difference, 18%; 95% CI, 6%-30%; P = .005).

Conclusions And Relevance: This study found an imbalance in observed sex ratio among patients harboring a mild ABCA4 allele, which concerns approximately 25% of all patients with STGD1, suggesting that STGD1 should be considered a polygenic or multifactorial disease rather than a disease caused by ABCA4 gene mutations alone. The findings suggest that sex should be considered as a potential disease-modifying variable in both basic research and clinical trials on STGD1.
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http://dx.doi.org/10.1001/jamaophthalmol.2020.2990DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7441467PMC
October 2020

Development of a Genotype Assay for Age-Related Macular Degeneration: The EYE-RISK Consortium.

Ophthalmology 2020 Jul 25. Epub 2020 Jul 25.

Department of Ophthalmology, Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, Nijmegen, The Netherlands. Electronic address:

Purpose: To develop a genotype assay to assess associations with common and rare age-related macular degeneration (AMD) risk variants, to calculate an overall genetic risk score (GRS), and to identify potential misdiagnoses with inherited macular dystrophies that mimic AMD.

Design: Case-control study.

Participants: Individuals (n = 4740) from 5 European cohorts.

Methods: We designed single-molecule molecular inversion probes for target selection and used next generation sequencing to sequence 87 single nucleotide polymorphisms (SNPs), coding and splice-site regions of 10 AMD-(related) genes (ARMS2, C3, C9, CD46, CFB, CFH, CFI, HTRA1, TIMP3, and SLC16A8), and 3 genes that cause inherited macular dystrophies (ABCA4, CTNNA1, and PRPH2). Genetic risk scores for common AMD risk variants were calculated based on effect size and genotype of 52 AMD-associated variants. Frequency of rare variants was compared between late AMD patients and control individuals with logistic regression analysis.

Main Outcome Measures: Genetic risk score, association of genetic variants with AMD, and genotype-phenotype correlations.

Results: We observed high concordance rates between our platform and other genotyping platforms for the 69 successfully genotyped SNPs (>96%) and for the rare variants (>99%). We observed a higher GRS for patients with late AMD compared with patients with early/intermediate AMD (P < 0.001) and individuals without AMD (P < 0.001). A higher proportion of pathogenic variants in the CFH (odds ratio [OR] = 2.88; P = 0.006), CFI (OR = 4.45; P = 0.005), and C3 (OR = 6.56; P = 0.0003) genes was observed in late AMD patients compared with control individuals. In 9 patients, we identified pathogenic variants in the PRPH2, ABCA4, and CTNNA1 genes, which allowed reclassification of these patients as having inherited macular dystrophy.

Conclusions: This study reports a genotype assay for common and rare AMD genetic variants, which can identify individuals at intermediate to high genetic risk of late AMD and enables differential diagnosis of AMD-mimicking dystrophies. Our study supports sequencing of CFH, CFI, and C3 genes because they harbor rare high-risk variants. Carriers of these variants could be amendable for new treatments for AMD that currently are under development.
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http://dx.doi.org/10.1016/j.ophtha.2020.07.037DOI Listing
July 2020

Detailed Phenotyping and Therapeutic Strategies for Intronic ABCA4 Variants in Stargardt Disease.

Mol Ther Nucleic Acids 2020 Sep 12;21:412-427. Epub 2020 Jun 12.

Department of Human Genetics, Radboud University Medical Center, Nijmegen, the Netherlands; Donders Institute for Brain, Cognition and Behavior, Radboud University Medical Center, Nijmegen, the Netherlands. Electronic address:

Stargardt disease is a progressive retinal disorder caused by bi-allelic mutations in the ABCA4 gene that encodes the ATP-binding cassette, subfamily A, member 4 transporter protein. Over the past few years, we and others have identified several pathogenic variants that reside within the introns of ABCA4, including a recurrent variant in intron 36 (c.5196+1137G>A) of which the pathogenicity so far remained controversial. Detailed clinical characterization of this variant confirmed its pathogenic nature, and classified it as an allele of intermediate severity. Moreover, we discovered several additional ABCA4 variants clustering in intron 36. Several of these variants resulted in aberrant splicing of ABCA4, i.e., the inclusion of pseudoexons, while the splicing defects caused by the recurrent c.5196+1137G>A variant strongly increased upon differentiation of patient-derived induced pluripotent stem cells into retina-like cells. Finally, all splicing defects could be rescued by the administration of antisense oligonucleotides that were designed to specifically block the pseudoexon insertion, including rescue in 3D retinal organoids harboring the c.5196+1137G>A variant. Our data illustrate the importance of intronic variants in ABCA4 and expand the therapeutic possibilities for overcoming splicing defects in Stargardt disease.
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http://dx.doi.org/10.1016/j.omtn.2020.06.007DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7352060PMC
September 2020

Long-term outcomes of vitrectomy for proliferative diabetic retinopathy.

Acta Ophthalmol 2021 Feb 9;99(1):83-89. Epub 2020 Jul 9.

Department of Ophthalmology, Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, Nijmegen, The Netherlands.

Purpose: To investigate the long-term outcomes of patients who underwent vitrectomy for proliferative diabetic retinopathy.

Methods: Cumulative incidences were calculated for low vision (<0.3), re-vitrectomy in the study eye and fellow eye vitrectomy. To identify potential prognostic factors that associate with these outcomes, we used multivariable Cox regression models.

Results: In a total of 217 patients, we found 1-, 5- and 10-year cumulative incidences of low vision in the study eye of 24%, 31% and 39%, respectively. For both eyes, these rates were, respectively, 10%, 14% and 14%. Low vision in both eyes was associated with higher age and worse contralateral visual acuity. The 1-, 5- and 10-year cumulative incidences for re-vitrectomy in the study eye were 16%, 27% and 27%, respectively, and for a vitrectomy in the fellow eye 24%, 40% and 54%, respectively. Re-vitrectomy of the study eye was associated with worse contralateral visual acuity, while vitrectomy of the fellow eye was associated with shorter diabetes duration, worse contralateral visual acuity, higher HbA1c level and worse diabetic retinopathy severity stage of the fellow eye.

Conclusion: Functional visual acuity in at least one eye was achieved or preserved in most patients. After 10 years, about a quarter of all patients underwent a re-vitrectomy, while more than half of the patients needed a vitrectomy of the fellow eye. Knowledge of these long-term outcomes is essential when counselling patients for a vitrectomy.
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http://dx.doi.org/10.1111/aos.14482DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7891313PMC
February 2021

Integrating Metabolomics, Genomics, and Disease Pathways in Age-Related Macular Degeneration: The EYE-RISK Consortium.

Ophthalmology 2020 12 14;127(12):1693-1709. Epub 2020 Jun 14.

Department of Ophthalmology, Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, Nijmegen, The Netherlands. Electronic address:

Purpose: The current study aimed to identify metabolites associated with age-related macular degeneration (AMD) by performing the largest metabolome association analysis in AMD to date, as well as aiming to determine the effect of AMD-associated genetic variants on metabolite levels and investigate associations between the identified metabolites and activity of the complement system, one of the main AMD-associated disease pathways.

Design: Case-control association analysis of metabolomics data.

Participants: Five European cohorts consisting of 2267 AMD patients and 4266 control participants.

Methods: Metabolomics was performed using a high-throughput proton nuclear magnetic resonance metabolomics platform, which allows quantification of 146 metabolite measurements and 79 derivative values. Metabolome-AMD associations were studied using univariate logistic regression analyses. The effect of 52 AMD-associated genetic variants on the identified metabolites was investigated using linear regression. In addition, associations between the identified metabolites and activity of the complement pathway (defined by the C3d-to-C3 ratio) were investigated using linear regression.

Main Outcome Measures: Metabolites associated with AMD.

Results: We identified 60 metabolites that were associated significantly with AMD, including increased levels of large and extra-large high-density lipoprotein (HDL) subclasses and decreased levels of very low-density lipoprotein (VLDL), amino acids, and citrate. Of 52 AMD-associated genetic variants, 7 variants were associated significantly with 34 of the identified metabolites. The strongest associations were identified for genetic variants located in or near genes involved in lipid metabolism (ABCA1, CETP, APOE, and LIPC) with metabolites belonging to the large and extra-large HDL subclasses. Also, 57 of 60 metabolites were associated significantly with complement activation levels, independent of AMD status. Increased large and extra-large HDL levels and decreased VLDL and amino acid levels were associated with increased complement activation.

Conclusions: Lipoprotein levels were associated with AMD-associated genetic variants, whereas decreased essential amino acids may point to nutritional deficiencies in AMD. We observed strong associations between the vast majority of the AMD-associated metabolites and systemic complement activation levels, independent of AMD status. This may indicate biological interactions between the main AMD disease pathways and suggests that multiple pathways may need to be targeted simultaneously for successful treatment of AMD.
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http://dx.doi.org/10.1016/j.ophtha.2020.06.020DOI Listing
December 2020

Effect of rare coding variants in the CFI gene on Factor I expression levels.

Hum Mol Genet 2020 08;29(14):2313-2324

Department of Ophthalmology, Donders Institute for Brain, Cognition and Behavior, Radboud University Medical Center, 6525 GA Nijmegen, The Netherlands.

Factor I (FI) is one of the main inhibitors of complement activity, and numerous rare coding variants have been reported in patients with age-related macular degeneration, atypical hemolytic uremic syndrome and C3 glomerulopathy. Since many of these variants are of unknown clinical significance, this study aimed to determine the effect of rare coding variants in the complement factor I (CFI) gene on FI expression. We measured FI levels in plasma samples of carriers of rare coding variants and in vitro in the supernatants of epithelial cells expressing recombinant FI. FI levels were measured in 177 plasma samples of 155 individuals, carrying 24 different rare coding variants in CFI. In carriers of the variants p.Gly119Arg, p.Leu131Arg, p.Gly188Ala and c.772G>A (r.685_773del), significantly reduced FI plasma levels were detected. Furthermore, recombinant FI expression levels were determined for 126 rare coding variants. Of these variants 68 (54%) resulted in significantly reduced FI expression in supernatant compared to wildtype (WT). The recombinant protein expression levels correlated significantly with the FI level in plasma of carriers of CFI variants. In this study, we performed the most comprehensive FI expression level analysis of rare coding variants in CFI to date. More than half of CFI variants lead to reduced FI expression, which might impair complement regulation in vivo. Our study will aid the interpretation of rare coding CFI variants identified in clinical practice, which is in particular important in light of patient inclusion in ongoing clinical trials for CFI gene supplementation in AMD.
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http://dx.doi.org/10.1093/hmg/ddaa114DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7424754PMC
August 2020
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