Purpose: To assess the longitudinal vision-related quality of life among patients with CRB1-associated inherited retinal dystrophies.Methods: A longitudinal questionnaire study included 22 patients... Show morePurpose: To assess the longitudinal vision-related quality of life among patients with CRB1-associated inherited retinal dystrophies.Methods: A longitudinal questionnaire study included 22 patients with pathogenic CRB1 variants. The National Eye Institute Visual Function Questionnaire (39 items, NEI VFQ-39) was applied at baseline, two-year follow-up, and 4-year follow-up. Classical test theory was performed to obtain subdomain scores and in particular 'near activities' and 'total composite' scores. The Rasch analysis based on previous calibrations of the NEI VFQ-25 was applied to create visual functioning and socio-emotional subscales.Results: In total, 22 patients with pathogenic CRB1 variants were included, with a median age of 25.0 years (IQR: 13-31 years) at baseline and mean followup of 4.0 +/- 0.3 years. A significant decline at 4 years was observed for 'near activities' (51.0 +/- 23.8 vs 35.4 +/- 14.7, p = 0.004) and 'total composite' (63.0 +/- 13.1 vs 52.0 +/- 12.1, p = 0.001) subdomain scores. For the Rasch-scaled scores, the 'visual functioning' scale significantly decreased after 4 years (- 0.89 logits; p = 0.012), but not at 4-year follow-up (+0.01 logits; p = 0.975). The 'socio- emotional' scale also showed a significant decline after 2 years (-0.78 logits, p = 0.033) and 4 years (- 0.83 logits, p = 0.021).Conclusion: In the absence of an intervention, a decline in vision-related quality of life is present in patients with pathogenic CRB1 variants at 4-year follow-up. Patient-reported outcome measures should be included in future clinical trials, as they can be a potential indicator of disease progression and treatment efficacy. Show less
Retinal dystrophies comprise relatively rare but devastating causes of progressive vision loss. They represent a spectrum of diseases with marked genetic and clinical heterogeneity. Mutations in... Show moreRetinal dystrophies comprise relatively rare but devastating causes of progressive vision loss. They represent a spectrum of diseases with marked genetic and clinical heterogeneity. Mutations in the same gene may lead to different diagnoses, e.g. retinitis pigmentosa or cone dystrophy. Conversely, mutations in different genes may lead to the same phenotype. The age at symptom onset, as well as the rate of vision decline, may vary widely per disease group and even within families. For most IRD cases, no effective treatment is currently available. However, preclinical studies and phase I/II/III gene therapy trials are ongoing for several IRD subtypes, and recently the first retinal gene therapy has been approved by the United States Food and Drug Administration for RPE65-associated IRDs: voretigene neparvovec-rzyl (Luxturna®). With these rapid advances in gene therapy studies, insight into the phenotypic spectrum and long-term disease course becomes crucial. The vast clinical heterogeneity presents an important challenge in the evaluation of potential efficacy in future treatment trials, and in establishing treatment candidacy criteria. This thesis responds to these challenges, providing detailed clinical descriptions of several forms of IRD that are caused by genes of interest for ongoing and future gene or cell-based therapy trials. Show less
PURPOSE: To investigate the natural disease course of retinal dystrophies associated with crumbs cell polarity complex component 1 (CRB1) and identify clinical end points for future clinical trials... Show morePURPOSE: To investigate the natural disease course of retinal dystrophies associated with crumbs cell polarity complex component 1 (CRB1) and identify clinical end points 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 Early Treatment Diabetic Retinopathy Study charts, Goldmann kinetic perimetry (V4e isopter seeing retinal areas), microperimetry, full-field electroretinography, 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 pig mentosa (19 [86%]), cone-rod dystrophy (2 [9%]), or isolated macular dystrophy (1 [5%]). Analysis of the entire cohort at 2 years showed no significant changes in BCVA ( P = .069) or V4e isopter seeing retinal areas ( P = .616), although signs of clinical progression were present in individual patients. Macular sensitivity measured on microperimetry revealed a significant reduction at the 2-year follow-up ( P < .001). FST responses were measurable in patients with nonrecordable electroretinograms. 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 end point in future human treatment trials for CRB1-associated retinal dystrophies. (Am J Ophthalmol 2021;234: 37-48. (C) 2021 The Authors. Published by Elsevier Inc. Show less
Koster, C.; Hurk, K.T. van den; Lewallen, C.F.; Talib, M.; Brink, J.B. ten; Boon, C.J.F.; Bergen, A.A. 2021
Purpose: We developed and phenotyped a pigmented knockout rat model for lecithin retinol acyltransferase (LRAT) using CRISPR/Cas9. The introduced mutation (c.12delA) is based on a patient group... Show morePurpose: We developed and phenotyped a pigmented knockout rat model for lecithin retinol acyltransferase (LRAT) using CRISPR/Cas9. The introduced mutation (c.12delA) is based on a patient group harboring a homologous homozygous frameshift mutation in the LRAT gene (c.12delC), causing a dysfunctional visual (retinoid) cycle. Methods: The introduced mutation was confirmed by DNA and RNA sequencing. The expression of Lrat was determined on both the RNA and protein level in wildtype and knockout animals using RT-PCR and immunohistochemistry. The retinal structure and function, as well as the visual behavior of the Lrat(-/-) and control rats, were characterized using scanning laser ophthalmoscopy (SLO), optical coherence tomography (OCT), electroretinography (ERG) and vision-based behavioral assays. Results: Wildtype animals had high Lrat mRNA expression in multiple tissues, including the eye and liver. In contrast, hardly any expression was detected in Lrat(-/-) animals. LRAT protein was abundantly present in wildtype animals and absent in Lrat(-/-) animals. Lrat(-/-) animals showed progressively reduced ERG potentials compared to wildtype controls from two weeks of age onwards. Vison-based behavioral assays confirmed reduced vision. Structural abnormalities, such as overall retinal thinning, were observed in Lrat(-/-) animals. The retinal thickness in knockout rats was decreased to roughly 80% by four months of age. No functional or structural differences were observed between wildtype and heterozygote animals. Conclusions: Our Lrat(-/-) rat is a new animal model for retinal dystrophy, especially for the LRAT-subtype of early-onset retinal dystrophies. This model has advantages over the existing mouse models and the RCS rat strain and can be used for translational studies of retinal dystrophies. Show less
Talib, M.; Cauwenbergh, C. van; Zaeytijd, J. de; Wynsberghe, D. van; Baere, E. de; Boon, C.J.F.; Leroy, B.P. 2021
Aim To investigate the natural history in a Belgian cohort of CRB1-associated retinal dystrophies. Methods An in-depth retrospective study focusing on visual function and retinal structure. Results... Show moreAim To investigate the natural history in a Belgian cohort of CRB1-associated retinal dystrophies. Methods An in-depth retrospective study focusing on visual function and retinal structure. Results Forty patients from 35 families were included (ages: 2.5-80.1 years). In patients with a follow-up of >1 year (63%), the mean follow-up time was 12.0 years (range: 2.3-29.2 years). Based on the patient history, symptoms and/or electroretinography, 22 patients (55%) were diagnosed with retinitis pigmentosa (RP), 15 (38%) with Leber congenital amaurosis (LCA) and 3 (8%) with macular dystrophy (MD), the latter being associated with the p.(Ile167_Gly169del) mutation (in compound heterozygosity). MD later developed into a rod-cone dystrophy in one patient. Blindness at initial presentation was seen in the first decade of life in LCA, and in the fifth decade of life in RP. Eventually, 28 patients (70%) reached visual acuity-based blindness (<0.05). Visual field-based blindness (<10 degrees) was documented in 17/25 patients (68%). Five patients (13%) developed Coats-like exudative vasculopathy. Intermediate/posterior uveitis was found in three patients (8%). Cystoid maculopathy was common in RP (9/21; 43%) and MD (3/3; 100%). Macular involvement, varying from retinal pigment epithelium alterations to complete outer retinal atrophy, was observed in all patients. Conclusion Bi-allelic CRB1 mutations result in a range of progressive retinal disorders, most of which are generalised, with characteristically early macular involvement. Visual function and retinal structure analysis indicates a window for potential intervention with gene therapy before the fourth decade of life in RP and the first decade in LCA. Show less
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... Show morePurpose 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. Show less
Nguyen, X.T.A.; Talib, M.; Cauwenbergh, C. van; Schooneveld, M.J. van; Fiocco, M.; Wijnholds, J.; ... ; Boon, C.J.F. 2021
Purpose: To investigate the natural history of RHO-associated retinitis pigmentosa (RP). Methods: A multicenter, medical chart review of 100 patients with autosomal dominant RHO-associated RP.... Show morePurpose: To investigate the natural history of RHO-associated retinitis pigmentosa (RP). Methods: A multicenter, medical chart review of 100 patients with autosomal dominant RHO-associated RP. Results: Based on visual fields, time-to-event analysis revealed median ages of 52 and 79 years to reach low vision (central visual field <20 degrees) and blindness (central visual field <10 degrees), respectively. For the best-corrected visual acuity (BCVA), the median age to reach mild impairment (20/67 <= BCVA < 20/40) was 72 years, whereas this could not be computed for lower acuities. Disease progression was significantly faster in patients with a generalized RP phenotype (n = 75; 75%) than that in patients with a sector RP phenotype (n = 25; 25%), in terms of decline rates of the BCVA (P < 0.001) and V4e retinal seeing areas (P < 0.005). The foveal thickness of the photoreceptor-retinal pigment epithelium (PR + RPE) complex correlated significantly with BCVA (Spearman's rho = 0.733; P < 0.001). Conclusion: Based on central visual fields, the optimal window of intervention for RHO-associated RP is before the 5th decade of life. Significant differences in disease progression are present between generalized and sector RP phenotypes. Our findings suggest that the PR + RPE complex is a potential surrogate endpoint for the BCVA in future studies. Show less
Retinal dystrophies (RDs) comprise relatively rare but devastating causes of progressive vision loss. They represent a spectrum of diseases with marked genetic and clinical heterogeneity. Mutations... Show moreRetinal dystrophies (RDs) comprise relatively rare but devastating causes of progressive vision loss. They represent a spectrum of diseases with marked genetic and clinical heterogeneity. Mutations in the same gene may lead to different diagnoses, for example, retinitis pigmentosa or cone dystrophy. Conversely, mutations in different genes may lead to the same phenotype. The age at symptom onset, and the rate and characteristics of peripheral and central vision decline, may vary widely per disease group and even within families. For most RD cases, no effective treatment is currently available. However, preclinical studies and phase I/II/III gene therapy trials are ongoing for several RD subtypes, and recently the first retinal gene therapy has been approved by the US Food and Drug Administration for RPE65-associated RDs: voretigene neparvovec-rzyl (Luxturna). With the rapid advances in gene therapy studies, insight into the phenotypic spectrum and long-term disease course is crucial information for several RD types. The vast clinical heterogeneity presents another important challenge in the evaluation of potential efficacy in future treatment trials, and in establishing treatment candidacy criteria. This perspective describes these challenges, providing detailed clinical descriptions of several forms of RD that are caused by genes of interest for ongoing and future gene or cell-based therapy trials. Several ongoing and future treatment options will be described. Show less
Nguyen, X.T.A.; Talib, M.; Schooneveld, M.J. van; Brinks, J.; Brink, J. ten; Florijn, R.J.; ... ; Boon, C.J.F. 2020
This study describes the clinical, genetic, and histopathological features in patients with RPGR-associated retinal dystrophies. Nine male patients from eight unrelated families underwent a... Show moreThis study describes the clinical, genetic, and histopathological features in patients with RPGR-associated retinal dystrophies. Nine male patients from eight unrelated families underwent a comprehensive ophthalmic examination. Additionally, the histopathology of the right eye from a patient with an end-stage cone-rod-dystrophy (CRD)/sector retinitis pigmentosa (RP) phenotype was examined. All RPGR mutations causing a CRD phenotype were situated in exon ORF15. The mean best-corrected visual acuity (BCVA, decimals) was 0.58 (standard deviation (SD)): 0.34; range: 0.05-1.13); and the mean spherical refractive error was -4.1 D (SD: 2.11; range: -1.38 to -8.19). Hyperautofluorescent rings were observed in six patients. Full-field electroretinography responses were absent in all patients. The visual field defects ranged from peripheral constriction to central islands. The mean macular sensitivity on microperimetry was 11.6 dB (SD: 7.8; range: 1.6-24.4) and correlated significantly with BCVA (r = 0.907; p = 0.001). A histological examination of the donor eye showed disruption of retinal topology and stratification, with a more severe loss found in the peripheral regions. Reactive gliosis was seen in the inner layers of all regions. Our study demonstrates the highly variable phenotype found in RPGR-associated retinal dystrophies. Therapies should be applied at the earliest signs of photoreceptor degeneration, prior to the remodeling of the inner retina. Show less
Talib, M.; Schooneveld, M.J. van; Duuren, R.J.G. van; Cauwenbergh, C. van; Brink, J.B. ten; Baere, E. de; ... ; Boon, C.J.F. 2019
