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Purpose: To determine the relationship between the full-field stimulus test (FST) and self-reported visual function using the Michigan Retinal Degeneration Questionnaire (MRDQ) in patients with retinitis pigmentosa (RP)., Methods: In this cross-sectional study, patients with clinically diagnosed RP (n = 31) performed FST to determine retinal sensitivity thresholds for blue, red and white stimuli. The difference between the blue and red thresholds was used to identify photoreceptor mediation type. Patients completed the MRDQ from which disability (Θ) scores were derived across seven visual function domains. Correlations between the FST thresholds and MRDQ domain Θ-scores were analysed using Spearman's rank correlation., Results: The median age was 38.0 years, and photoreceptor mediation was rod-based in 11 patients (35.5%), cone-based in seven patients (22.6%) and mixed in 13 patients (41.9%). The highest disability scores were reported in the domains of 'mesopic peripheral function' and 'scotopic function'. Significant correlations were found between all chromatic stimuli thresholds and the MRDQ domains of 'scotopic function', 'mesopic peripheral function' and 'photopic peripheral function'. The strongest correlations of these domains were observed with the blue FST (p < 0.001). The threshold on blue stimulus FST and age were significant predictors of the domain scores on 'scotopic function' (p < 0.001), 'mesopic peripheral function' (p < 0.001) and 'photopic peripheral function' (p < 0.001)., Conclusions: Strong correlations between MRDQ domains related to rod function and FST were found in patients with RP. These findings confirm that FST can be used as an informative and clinically relevant endpoint in RP trials when evaluating therapeutic interventions., (© 2024 The Author(s). Acta Ophthalmologica published by John Wiley & Sons Ltd on behalf of Acta Ophthalmologica Scandinavica Foundation.)

Purpose: This study aims to answer a key question: is MYO7A-inherited retinal dystrophy (MYO7A-IRD) a photoreceptor-first or retinal pigment epithelium-first disease? A second aim was to determine the most useful biomarkers to monitor disease progression in pediatric patients with Usher syndrome type 1B (USH1) secondary to MYO7A mutation., Methods: Fifty-two eyes from 26 patients with genetically-confirmed MYO7A-IRD underwent swept-source optical coherence tomography (SS-OCT). Structural abnormalities were evaluated and correlated with follow-up time and best corrected visual acuity (BCVA). All patients were evaluated at baseline and after ≥ 40 months of follow-up., Results: The mean (SD) patient age was 9.92 (± 4.1) years. Mean follow-up time was 43 (± 3.2) months. At the final evaluation, the most common qualitative abnormalities in the subfoveal area were alterations in the photoreceptor outer segments (76.9% of eyes) and in the interdigitation zone (IZ) (80.8%). The presence of cystoid macular edema at baseline was independently associated with worse BCVA at the final assessment (increase in LogMAR estimate = 0.142; t(45.00) = 2.78, p = 0.009). The mean width of the ellipsoid and interdigitation zones decreased significantly (by 668 μm and 278 μm, respectively; both p < 0.001)., Conclusion: This study shows that disruption of the photoreceptor outer segments and the IZ are the first alterations detected by SS-OCT in the early phases of MYO7A-IRD. These data highlight the potential value of measuring the width of the ellipsoid and IZ to evaluate disease progression. These findings also demonstrate the utility of monitoring for the emergence of cystic lesions as biomarkers of worse visual prognosis in patients with MYO7A-IRD., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Purpose: Bardet-Biedl Syndrome (BBS) is an autosomal recessive disorder characterized by pleiotropism that affects multiple organ systems. The primary features of BBS include rod-cone dystrophy, renal anomalies, post axial polydactyly, and neurologic deficits. The clinical picture of BBS is extensively heterogenous, with inter and intra familial patients varying in levels of syndromic manifestations and severity of symptoms., Methods: In this study we examined a monocular BBS patient who was compound heterozygous for mutations in the ARL6 (BBS3) gene., Results: The patient reported visual complaints consistent with a clinical picture of cone or cone-rod dystrophy. Fundus imaging showed retinal mottling on color photos and a parafoveal hyperfluorescent ring on short wave autofluorescence (SW-AF). Full field electroretinogram (ffERG) revealed normal scotopic step tracings and diminished amplitudes in the photopic steps., Conclusion: This rod-sparing result was consistent with cone-dystrophy and is the first known case of a rod-sparing ffERG phenotype in a BBS patient with mutations in the ARL6 gene. This contributes to the existing phenotype and may potentially contribute to furthering our understanding of BBS pathophysiology., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Mitochondria are vital for retinal cell function and survival, and there is growing evidence linking mitochondrial dysfunction to retinal degenerations. Although ARL3 mutations have been linked to multiple forms of retinal degeneration, the relationship between ARL3 and mitochondria remains unexplored. Herein, we investigated the effects of ARL3 T31A , ARL3 mutations on mitochondrial function in fibroblasts obtained from patients with ARL3-related rod-cone dystrophy. Our findings revealed that these mutations led to a decrease in mitochondrial respiration, an increase in the accumulation mitochondrial reactive oxygen species (ROS), and induction of apoptosis in fibroblasts. Additionally, we conducted a comparative analysis of the effects of ARL3 C118F , and ARL3 T31A/C118F mutations on mitochondrial function in fibroblasts obtained from patients with ARL3-related rod-cone dystrophy. Our findings revealed that these mutations led to a decrease in mitochondrial respiration, an increase in the accumulation mitochondrial reactive oxygen species (ROS), and induction of apoptosis in fibroblasts. Additionally, we conducted a comparative analysis of the effects of ARL3 T31A , ARL3 C118F , and ARL3 T31A/C118F proteins on mitochondria in ARPE-19 cells. Results showed that ARL3 T31A and ARL3 T31A/C118F not only affected mitochondrial function but also induced apoptosis in ARPE-19 cells. Conversely, ARL3 C118F primarily influenced cell apoptosis with minimal effects on mitochondrial function in ARPE-19 cells. Transcriptome analysis further suggested the involvement of respiratory electron transport, response to ROS, and apoptotic signaling pathways in ARL3 T31A/C118F cells. Our study demonstrated that ARL3 -related mutations play a significant role in the diversity of mitochondrial function, providing novel insights into the functional analysis of ARL3 -related mutations., Competing Interests: The authors declare no conflict of interest., (© 2024 The Author(s). FASEB BioAdvances published by Wiley Periodicals LLC on behalf of The Federation of American Societies for Experimental Biology.)

Purpose: Economic evaluations of interventions for ocular disease require utility scores that accurately represent quality of life in the target population. This study aimed to describe the distribution of EQ-5D-5L utility values among Australian adults with symptomatic inherited retinal diseases (IRDs) and to assess the relationship between these scores and vision-related quality of life., Methods: A survey was administered predominantly online in 2021. Participants completed the EQ-5D-5L general health utility instrument, the EQ vertical visual analogue scale (EQ-VAS) and the National Eye Institute Visual Functioning Questionnaire (NEI-VFQ-25). Self-reported IRD diagnoses were classified as being associated with central or widespread retinal involvement., Results: Responses from 647 participants aged 18-93 years were included, 50.1% were men and 77.6% had an IRD associated with widespread retinal involvement. The majority reported no problems with self-care and no pain/discomfort but did report anxiety/depression and problems with work, study, housework, or family/leisure activities. Most people with widespread involvement reported problems with mobility. Median EQ-5D-5L utility was 0.88 and 0.91 among people with widespread and central involvement, respectively (age and sex-adjusted p = 0.029); and median EQ-VAS was 75 and 80, respectively (adjusted p = 0.003). A moderate curvilinear correlation was observed between EQ-5D-5L and NEI-VFQ-25 composite score (Spearman's ρ 0.69), but not all people with poor vision-related quality of life had low EQ-5D-5L utility values., Conclusions: EQ-5D-5L health utility values are correlated with vision-related quality of life among adults with IRDs. However, the EQ-5D-5L may not be sensitive to the full impact of vision impairment on quality of life., (© 2024 The Authors. Acta Ophthalmologica published by John Wiley & Sons Ltd on behalf of Acta Ophthalmologica Scandinavica Foundation.)

Purpose: Inherited retinal diseases (IRDs) are a group of monogenic conditions that can lead to progressive blindness. Their missing heritability is still considerable, due in part to the presence of disease genes that await molecular identification. The purpose of this work was to identify novel genetic associations with IRDs., Methods: Patients underwent a comprehensive ophthalmological evaluation using standard-of-care tests, such as detailed retinal imaging (macular optical coherence tomography and short-wavelength fundus autofluorescence) and electrophysiological testing. Exome and genome sequencing, as well as computer-assisted data analysis were used for genotyping and detection of DNA variants. A minigene-driven splicing assay was performed to validate the deleterious effects of 1 of such variants., Results: We identified 8 unrelated families from Hungary, the United States, Israel, and The Netherlands with members presenting with a form of autosomal recessive and nonsyndromic retinal degeneration, predominantly described as rod-cone dystrophy but also including cases of cone/cone-rod dystrophy. Age of disease onset was very variable, with some patients experiencing first symptoms during their fourth decade of life or later. Myopia greater than 5 diopters was present in 5 of 7 cases with available refractive data, and retinal detachment was reported in 2 cases. All ascertained patients carried biallelic loss-of-function variants in UBAP1L (HGNC: 40028), a gene with unknown function and with homologies to UBAP1, encoding a protein involved in ubiquitin metabolism. One of these pathogenic variants, the intronic NM&#95;001163692.2:c.910-7G>A substitution, was identified in 5 unrelated families. Minigene-driven splicing assays in HEK293T cells confirmed that this DNA change is responsible for the creation of a new acceptor splice site, resulting in aberrant splicing., Conclusion: We identified UBAP1L as a novel IRD gene. Although its function is currently unknown, UBAP1L is almost exclusively expressed in photoreceptors and the retinal pigment epithelium, hence possibly explaining the link between pathogenic variants in this gene and an ocular phenotype., Competing Interests: Conflict of Interest The authors declare no conflicts of interest., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

Background: Biallelic variants in RTN4IP1 are a well-established cause of syndromic and nonsyndromic early-onset autosomal recessive optic neuropathy. They have more recently been reported to cause a concomitant but later-onset rod-cone dystrophy with or without syndromic features., Methods: A comprehensive evaluation was performed that included assessment of visual and retinal function, clinical examination, and retinal imaging. Childhood ophthalmic records as well as the results of genetic testing were evaluated., Results: A 24-year-old female described longstanding reduced visual acuity with more recent subjective impairment of dark adaptation. Visual acuity was subnormal in both eyes. Goldmann kinetic perimetry demonstrated scotomas in a pattern consistent with the presence of both optic neuropathy and rod-cone dystrophy with fundus exam as well as retinal imaging showing corroborating findings. Full-field electroretinography further confirmed the presence of a rod-cone dystrophy. Genetic testing demonstrated biallelic variants in RTN4IP1, one of which was novel, in association with the ocular findings., Conclusions: RTN4IP1-associated early-onset bilateral optic neuropathy with rod-cone dystrophy is a recently described clinical entity with limited reports available to-date. The present case provides additional support for this dual phenotype and identifies a novel causative variant.

Purpose: To explore the mechanisms of cone sensitivity loss in retinitis pigmentosa by combining two-colour perimetry with threshold versus intensity (tvi) testing., Methods: Seven subjects with autosomal recessive retinitis pigmentosa and 10 normal subjects were recruited and underwent perimetric testing of one eye using 480- and 640-nm Goldman size V targets presented under scotopic conditions (no background illumination) and against a white background ranging in luminance from -1.5 to 2 log cd m -2 in 0.5 log cd m -2 steps. Data were fitted with tvi functions of the form logT = logT 0  + log ((A + A 0 )/A 0 ) n , where T is the threshold, T 0 is the absolute threshold, A is the background intensity, A 0 is the 'dark-light' constant and n is a gain constant., Results: Reliable tvi functions could not be obtained within the region of the visual field corresponding to loss of the ellipsoid zone on optical coherence tomography. At fixation, changes in both T 0 and A 0 were observed, consistent with a d 1 mechanism loss, which resulted in an upwards and rightwards shift of the tvi function. Losses at [±3°, ±3°] demonstrated changes in T 0 , consistent with a d 3 mechanism loss, resulting in an upwards translation of the tvi curve., Conclusions: Although the absolute cone threshold was elevated at each location, shifts in the tvi function (so-called d 1 mechanism loss) at fixation minimise threshold elevation in the presence of white adapting backgrounds, such as those typically employed in standard two-colour perimetry. At more peripheral testing locations, changes in threshold occurred independent of background luminance (so-called d 3 mechanism loss). These findings suggest that backgrounds which selectively adapt rods while maintaining cones at, or near, absolute threshold may be preferable to conventional two-colour perimetry for assessing loss of cone sensitivity, especially at the point of fixation., (© 2024 The Authors. Ophthalmic and Physiological Optics published by John Wiley & Sons Ltd on behalf of College of Optometrists.)

Purpose: The goal of the study was to search for novel bi-allelic CRB1 mutations, and then to analyze the CRB1 literature at the genotypic and phenotypic levels., Approach: We screened various variables such as the CRB1 mutation types, domains, exons, and genotypes and their relation with specific ocular phenotypes. An emphasis was given to the bi-allelic missense and nonsense mutations because of their high prevalence compared to other mutation types. Finally, we quantified the effect of various non-modifiable factors over the best-corrected visual acuity oculus uterque (BCVA OU) using multivariate linear regression models and identified genetic interactions., Results: A novel bi-allelic missense in the exon 9 of CRB1; c.2936G > A; p.(Gly979Asp) was found to be associated with rod-cone dystrophy (RCD). CRB1 mutation type, exons, domains, and genotype distribution varied significantly according to fundus characteristics, such as peripheral pigmentation and condition, optic disc, vessels, macular condition, and pigmentation (P < 0.05). Of the 154 articles retrieved from PubMed, 96 studies with 439 bi-allelic CRB1 patients were included. Missense mutations were significantly associated with an absence of macular pigments, pale optic disc, and periphery pigmentation, resulting in a higher risk of RCD (P < 0.05). In contrast, homozygous nonsense mutations were associated with macular pigments, periphery pigments, and a high risk of LCA (P < 0.05) and increased BCVA OU levels. We found that age, mutation types, and inherited retinal diseases were critical determinants of BCVA OU as they significantly increased it by 33% 26%, and 38%, respectively (P < 0.05). Loss of function alleles additively increased the risk of LCA, with nonsense having a more profound effect than indels. Finally, our analysis showed that p.(Cys948Tyr) and p.(Lys801Ter) and p.(Lys801Ter); p.(Cys896Ter) might interact to modify BCVA OU levels., Conclusion: This meta-analysis updated the literature and identified genotype-phenotype associations in bi-allelic CRB1 patients., (© 2024. The Author(s).)

Purpose: Retinitis pigmentosa (RP) associated with biallelic variants in CDHR1 has rarely been reported, and detailed phenotyping data are not available. RP implies relative preservation of foveal cones, when compared to cone-rod dystrophy associated with biallelic null variants in CDHR1. We hypothesize that RP may occur in association with one or more hypomorphic CDHR1 alleles., Materials and Methods: Retrospective report of a 48-year-old patient with CDHR1-associated RP with a hypomorphic missense variant c.562 G>A, p. (Gly188Ser) and a novel, unreported variant affecting a canonical splice acceptor site (c.784-1 G>C). Clinical examination, multimodal retinal imaging, electroretinography, visual field testing, and mesopic microperimetry were undertaken 8 years apart. Scotopic microperimetry was also performed. The DNA sequence context of the variants was examined to identify theoretical CRISPR-Cas9 base-editing strategies., Results: The patient presented at 35 years with a 12-year history of nyctalopia. His best corrected visual acuity was 20/20. Clinical presentation, multimodal retinal imaging studies, electroretinography, and mesopic microperimetry were typical of a progressive rod-cone dystrophy (i.e. classic RP). There were no scotomas within the central field as would be expected at this age in CDHR1-associated cone-rod dystrophy. Scotopic microperimetry suggested some preservation of macular cone over rod function, although both were severely impaired. A suitable CRISPR adenine base editor was identified that could theoretically correct the missense variant c.562 G>A, p. (Gly188Ser)., Conclusions: CDHR1-associated RP shows a relative preservation of cone function in the presence of a presumed hypomorphic allele and may be considered a hypomorphic disease phenotype. Further work is required to identify modifying factors that determine disease phenotype since macular dystrophy, with relative sparing of rods, may also occur with hypomorphic CDHR1 alleles.

Background and Objectives . Retinitis pigmentosa (RP) is the most common inherited rod-cone dystrophy (RCD), resulting in nyctalopia, progressive visual field, and visual acuity decay in the late stages. The autosomal dominant form (ADRP) accounts for about 20% of RPs. Among the over 30 genes found to date related to ADRP, RP1 pathogenic variants have been identified in 5-10% of cases. In a cohort of RCD patients from the Palermo province on the island of Sicily, we identified a prevalent nonsense variant in RP1 , which was associated with ADRP. The objective of our study was to analyse the clinical and molecular data of this patient cohort and to evaluate the potential presence of a founder effect. Materials and Methods . From 2005 to January 2023, 84 probands originating from Western Sicily (Italy) with a diagnosis of RCD or RP and their relatives underwent deep phenotyping, which was performed in various Italian clinical institutions. Molecular characterisation of patients and familial segregation of pathogenic variants were carried out in different laboratories using Sanger and/or next-generation sequencing (NGS). Results. Among 84 probands with RCD/RP, we found 28 heterozygotes for the RP1 variant c.2219C>G, p.Ser740* ((NM&#95;006269.2)*, which was therefore significantly prevalent in this patient cohort. After a careful interview process, we ascertained that some of these patients shared the same pedigree. Therefore, we were ultimately able to define 20 independent family groups with no traceable consanguinity. Lastly, analysis of clinical data showed, in our patients, that the p.Ser740* nonsense variant was often associated with a late-onset and relatively mild phenotype. Conclusions . The high prevalence of the p.Ser740* variant in ADRP patients from Western Sicily suggests the presence of a founder effect, which has useful implications for the molecular diagnosis of RCD in patients coming from this Italian region. This variant can be primarily searched for in RP-affected subjects displaying compatible modes of transmission and phenotypes, with an advantage in terms of the required costs and time for analysis. Moreover, given its high prevalence, the RP1 p.Ser740* variant could represent a potential candidate for the development of therapeutic strategies based on gene editing or translational read-through therapy for suppression of nonsense variants.

Introduction: Mutational screening of inherited retinal disorders is prerequisite for gene targeted therapy. Our aim was to report and analyze the proportions of mutations in inherited retinal disease (IRD)-causing genes from a single center in Switzerland in order to describe the distribution of IRDs in Western Switzerland., Methods: We conducted a retrospective study of patient records. Criteria for inclusion were residence in Western Switzerland for patients and relatives presenting a clinical diagnosis of IRDs and an established molecular diagnosis managed by the genetics service of the Jules-Gonin Eye Hospital (JGEH) of Lausanne between January 2002 and December 2022. We initially investigated the IRD phenotypes in all patients (full cohort) with a clinical diagnosis, then calculated the distribution of IRD gene mutations in the entire cohort (genetically determined cohort). We analyzed a sub-group that comprised pediatric patients (≤18 years of age). In addition, we calculated the distribution of gene mutations within the most represented IRDs. Comprehensive gene screening was performed using a combined approach of different generation of DNA microarray analysis, direct sequencing, and Sanger sequencing., Results: The full cohort comprised 899 individuals from 690 families with a clinical diagnosis of IRDs. We identified 400 individuals from 285 families with an elucidated molecular diagnosis (variants in 84 genes) in the genetically determined cohort. The pediatric cohort included 89 individuals from 65 families with an elucidated molecular diagnosis. The molecular diagnosis rate for the genetically determined cohort was 58.2% (family ratio) and the 5 most frequently implicated genes per family were ABCA4 (11.6%), USH2A (7.4%), EYS (6.7%), PRPH2 (6.3%), and BEST1 (4.6%). The pediatric cohort had a family molecular diagnosis rate of 64.4% and the 5 most common mutated genes per family were RS1 (9.2%), ABCA4 (7.7%), CNGB3 (7.7%), CACNA1F (6.2%), CEP290 (4.6%)., Conclusions: This study describes the genetic mutation landscape of IRDs in Western Switzerland in order to quantify their disease burden and contribute to a better orientation of the development of future gene targeted therapies., (© 2023 The Author(s). Published by S. Karger AG, Basel.)

Background: Inosine monophosphate dehydrogenase (IMPDH) is a key regulatory enzyme in the de novo synthesis of the purine base guanine. Mutations in the inosine monophosphate dehydrogenase 1 gene (IMPDH1) are causative for RP10 autosomal dominant retinitis pigmentosa (adRP). This study reports a novel variant in a family with IMPDH1-associated retinopathy. We also performed a comprehensive review of all reported IMPDH1 disease causing variants with their associated phenotype., Materials and Methods: Multimodal imaging and functional studies documented the phenotype including best-corrected visual acuity (BCVA), fundus photograph, fundus autofluorescence (FAF), full field electroretinogram (ffERG), optical coherence tomography (OCT) and visual field (VF) data were collected. A literature search was performed in the PubMed and LOVD repositories., Results: We report 3 cases from a 2-generation family with a novel heterozygous likely pathogenic variant p. (Lys314Gln) (exon 10). The ophthalmic phenotype showed diffuse outer retinal atrophy with mild pigmentary changes with sparse pigmentary changes. FAF showed early macular involvement with macular hyperautofluorescence (hyperAF) surrounded by hypoAF. Foveal ellipsoid zone island can be found in the youngest patient but not in the older ones. The literature review identified a further 56 heterozygous, 1 compound heterozygous, and 2 homozygous variant. The heterozygous group included 43 missense, 3 in-frame, 1 nonsense, 2 frameshift, 1 synonymous, and 6 intronic variants. Exon 10 was noted as a hotspot harboring 18 variants., Conclusions: We report a novel IMPDH1 variant. IMPDH1 -associated retinopathy presents most frequently in the first decade of life with early macular involvement.

Adaptive optics (AO) retinal imaging enables individual photoreceptors to be visualized in the clinical setting. AO imaging can be a powerful clinical tool for detecting photoreceptor degeneration at a cellular level that might be overlooked through conventional structural assessments, such as spectral-domain optical coherence tomography (SD-OCT). Therefore, AO imaging has gained significant interest in the study of photoreceptor degeneration, one of the most common causes of inherited blindness. Growing evidence supports that AO imaging may be useful for diagnosing early-stage retinal dystrophy before it becomes apparent on fundus examination or conventional retinal imaging. In addition, serial AO imaging may detect structural disease progression in early-stage disease over a shorter period compared to SD-OCT. Although AO imaging is gaining popularity as a structural endpoint in clinical trials, the results should be interpreted with caution due to several pitfalls, including the lack of standardized imaging and image analysis protocols, frequent ocular comorbidities that affect image quality, and significant interindividual variation of normal values. Herein, we summarize the current state-of-the-art AO imaging and review its potential applications, limitations, and pitfalls in patients with inherited retinal diseases.

The genes CNGA1 and CNGB1 encode the alpha and beta subunits of the rod CNG channel, a ligand-gated cation channel whose activity is controlled by cyclic guanosine monophosphate (cGMP). Autosomal inherited mutations in either of the genes lead to a progressive rod-cone retinopathy known as retinitis pigmentosa (RP). The rod CNG channel is expressed in the plasma membrane of the outer segment and functions as a molecular switch that converts light-mediated changes in cGMP into a voltage and Ca 2+ signal. Here, we will first review the molecular properties and physiological role of the rod CNG channel and then discuss the characteristics of CNG-related RP. Finally, we will summarize recent activities in the field of gene therapy aimed at developing therapies for CNG-related RP., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

Genetic characteristics and a long-term clinical follow-up of 18 Slovenian retinitis pigmentosa GTPase regulator (RPGR) patients from 10 families with retinitis pigmentosa (RP) or cone/cone-rod dystrophy (COD/CORD) are reported. RP (eight families) was associated with two already known (p.(Ser407Ilefs*46) and p.(Glu746Argfs*23)) and five novel variants (c.1245+704&#95;1415-2286del, p.(Glu660*), p.(Ala153Thr), c.1506+1G>T, and p.(Arg780Serfs*54)). COD (two families) was associated with p.(Ter1153Lysext*38). The median age of onset in males with RP (N = 9) was 6 years. At the first examination (median age of 32 years), the median best corrected visual acuity (BCVA) was 0.30 logMAR, and all patients had a hyperautofluorescent ring on fundus autofluorescence (FAF) encircling preserved photoreceptors. At the last follow-up (median age of 39 years), the median BCVA was 0.48 logMAR, and FAF showed ring constriction transitioning to patch in 2/9. Among females (N = 6; median age of 40 years), two had normal/near-normal FAF, one had unilateral RP (male pattern), and three had a radial and/or focal pattern of retinal degeneration. After a median of 4 years (4-21) of follow-up, 2/6 exhibited disease progression. The median age of onset in males with COD was 25 years. At first examination (median age of 35 years), the median BCVA was 1.00 logMAR, and all patients had a hyperautofluorescent FAF ring encircling foveal photoreceptor loss. At the last follow-up (median age of 42 years), the median BCVA was 1.30 logMAR, and FAF showed ring enlargement. The majority of the identified variants (75%; 6/8) had not been previously reported in other RPGR cohorts, which suggested the presence of distinct RPGR alleles in the Slovenian population.

Inherited retinal dystrophies (IRDs) are congenital retinal degenerative diseases that have various inheritance patterns, including dominant, recessive, X-linked, and mitochondrial. These diseases are most often the result of defects in rod and/or cone photoreceptor and retinal pigment epithelium function, development, or both. The genes associated with these diseases, when mutated, produce altered protein products that have downstream effects in pathways critical to vision, including phototransduction, the visual cycle, photoreceptor development, cellular respiration, and retinal homeostasis. The aim of this manuscript is to provide a comprehensive review of the underlying molecular mechanisms of pathogenesis of IRDs by delving into many of the genes associated with IRD development, their protein products, and the pathways interrupted by genetic mutation.

Purpose: The aim of this study was to elucidate the type of low vision devices (LVDs) prescribed for patients with cone dystrophy, cone-rod dystrophy, and rod-cone dystrophy and to analyze the visual improvement with the devices., Methods: A retrospective review of 300 electronic medical records of patients with cone dystrophy, cone-rod dystrophy, and rod-cone dystrophy referred to the low vision care (LVC) clinic for the first time between 2014 and 2016 at a tertiary eye care center was done. Collected data included the demographic profile of patients, details of LVDs, and best-corrected vision., Results: Out of 300 patients, 62.6% (n = 188) were male and 37.3% (n = 112) were female. Of the cases, 50% (n = 150) had cone-rod dystrophy, 45% (n = 135) had cone dystrophy, and 5% (n = 15) had rod-cone dystrophy. The most commonly prescribed LVD was SEE-TV binocular telescope (n = 6, 2.0%) for distance and dome magnifier (n = 60, 20%) for near. ET-40 dark grey tint (20.6%) was preferred for managing photophobia. There was a statistically significant difference in both distance and near visual acuities with LVDs (P < 0.05) in all categories, except rod-cone dystrophy., Conclusion: Early diagnosis with appropriate prescription of LVDs including tints helps in achieving good quality of vision in patients with cone-related dystrophies.

Purpose: To evaluate the clinical and genetic spectrum of inherited retinal diseases (IRDs) in a Kuwaiti tribe., Methods: Forty four patients with IRDs from 28 nuclear families from the tribe, were evaluated for presenting symptoms, visual acuity, fundus examination, OCT, microperimetry, full-field (ff), and multifocal electroretinography (mERG) and genotyping., Results: Seventeen patients were diagnosed with autosomal recessive retinitis pigmentosa (arRP) associated with RP1 c.606C>A with onset of nictalopia in the third decade, myopia, and macular atrophy by the age of 50; eleven with autosomal recessive cone/rod dystrophy or macular dystrophy associated with RP1 c.606C>A (p.Asp202Glu) mutation with color and central vision deterioration in teenage, myopia, paracentral ring scotoma and macular atrophy; eleven were with arRP associated with PDE6B c.992 + 1 G > A mutation with onset around 5 years, myopia, cataract, retained central fixation, and ellipsoid zone and late perimacular atrophy; five-with Leber congenital amaurosis associated with homozygous RPGRIP1 for c.1107delA mutation with extinguished ffERG and electrophysiological phenotype of rod and cone; and one patient-with autosomal recessive rod-cone dystrophy associated with homozygous PDE6B c.992 + 1 G > A, who was homozygous ABCA4 c.5882 G > A and heterozygous EYS ; c.2137 + 1 G > A., Conclusions: This study represents a typical tribe from the Middle East with high rate of consanguinity for many generations that harbors multiple mutated genes associated with IRD. It demonstrates the predominant phenotype and its variability in retinal disorders caused by identical mutations and illustrates the nuances in the clinical presentation and disease progression of patients with pathogenic mutations in more than one gene.

Non-syndromic rod-cone dystrophy (RCD) is the most common condition in inherited retinal diseases. The aim of this study was to evaluate the research output and productivity related to RCD genetics per countries as classified by the human development index (HDI), by analyzing publication frequency and citations, the choice of journals and publishers, since 2000 to date. We have also analyzed the use of next-generation sequencing (NGS) in publications originating from countries with different HDIs. One thousand four hundred articles focusing on non-syndromic RCD were downloaded and analyzed. Citations and published articles were adjusted per one million individuals. The research output is significantly higher in very high HDI countries (86% of the total publications and 95% of the citations) than countries with lower HDIs in all aspects. High and medium HDI countries published together 13.6% of the total articles worldwide and received 4.6% of the citations. On the publication level, the USA (26%), United Kingdom (10%), and Japan (7%) were the top 3 among very high HDI countries, while China (6%) and India (2%) ranked first in high and medium HDI countries respectively. On the citation level, similar profiles were found. Following adjustment for population size, Switzerland (~14%), Jordan (~ 1%) and Morocco (<0.2%) showed the highest rates of publications in very high, high and medium HDI countries respectively. Very high HDI countries published 71% of their papers in first quartile journals (first quartile in Scimago journal rank; Q1), and 23% in Q2 journals. High and medium HDI countries showed a similar profile in quartiles with ~ 40% of their papers published in Q1 journals and ~ 30% in Q2 journals. The first publication using NGS was issued in 2009 in very high HDI countries, while it appeared in 2012 in high HDI countries, and in 2017 in medium HDI countries, with a respective lag of 3 to 8 years compared to very high HDI countries. A profound gap exists between very high HDI countries and the rest of the world. To fill it in, we propose implementing NGS, supporting international collaborations, building capacities and infrastructures, improving accessibility of patients to services, and increasing national and international funding., (© 2022. The Author(s).)

The RPGR gene encodes Retinitis Pigmentosa GTPase Regulator, a known interactor with ciliary proteins, which is involved in maintaining healthy photoreceptor cells. Variants in RPGR are the main contributor to X-linked rod-cone dystrophy (RCD), and RPGR gene therapy approaches are in clinical trials. Hence, elucidation of the pathogenicity of novel RPGR variants is important for a patient therapy opportunity. Here, we describe a novel intronic RPGR variant, c.1415 − 9A>G, in a patient with RCD, which was classified as a variant of uncertain significance according to current clinical diagnostic criteria. The variant lay several base pairs intronic to the canonical splice acceptor site, raising suspicion of an RPGR RNA splicing abnormality and consequent protein dysfunction. To investigate disease causation in an appropriate disease model, induced pluripotent stem cells were generated from patient fibroblasts and differentiated to retinal pigment epithelium (iPSC-RPE) and retinal organoids (iPSC-RO). Abnormal RNA splicing of RPGR was demonstrated in patient fibroblasts, iPSC-RPE and iPSC-ROs, leading to a predicted frameshift and premature stop codon. Decreased RPGR expression was demonstrated in these cell types, with a striking loss of RPGR localization at the ciliary transitional zone, critically in the photoreceptor cilium of the patient iPSC-ROs. Mislocalisation of rhodopsin staining was present in the patient’s iPSC-RO rod photoreceptor cells, along with an abnormality of L/M opsin staining affecting cone photoreceptor cells and increased photoreceptor apoptosis. Additionally, patient iPSC-ROs displayed an increase in F-actin expression that was consistent with an abnormal actin regulation phenotype. Collectively, these studies indicate that the splicing abnormality caused by the c.1415 − 9A>G variant has an impact on RPGR function. This work has enabled the reclassification of this variant to pathogenic, allowing the consideration of patients with this variant having access to gene therapy clinical trials. In addition, we have identified biomarkers of disease suitable for the interrogation of other RPGR variants of uncertain significance.

Introduction: Mutations in the cone-rod homeobox ( CRX ) gene, a known cause of inherited retinal dystrophy, are characterized by extensive phenotypic heterogeneity. We describe a novel presentation of rod-cone dystrophy (RCD) phenocopying pigmented paravenous retinochoroidal atrophy associated with a mutation in CRX ., Case Description: A 53-year-old man and his 48-year-old brother presented with a history of progressive vision loss and nyctalopia. Fundus examination revealed a bull's eye lesion with chorioretinal atrophy and intraretinal pigment migration, while spectral-domain optical coherence tomography (SD-OCT) demonstrated retinal thinning with outer retinal atrophy. On short-wavelength autofluorescence (SW-AF) imaging, an atypical paravenous pattern of atrophy with a surrounding hyperautofluorescent border was observed. Full-field electroretinogram (ffERG) revealed a rod-cone pattern of dysfunction. A heterozygous pathogenic variant, c.119G>A:p.(Arg40Gln), in the CRX gene was identified in both brothers and segregated in their family., Conclusion: This case report broadens the currently known phenotypic presentations of CRX -associated retinopathy and suggests that mutations in CRX may be associated with pigmented paravenous retinochoroidal atrophy.

The gateway reflex is a mechanism by which neural inputs regulate chemokine expression at endothelial cell barriers, thereby establishing gateways for the invasion of autoreactive T cells into barrier-protected tissues. In this study, we hypothesized that rod photoreceptor dysfunction causes remodeling of retinal neural activity, which influences the blood-retinal barrier and the development of retinal inflammation. We evaluated this hypothesis using Gnat1 rd17 mice, a model of night blindness with late-onset rod-cone dystrophy, and experimental autoimmune uveoretinitis (EAU). Retinal remodeling and its effect on EAU development were investigated by transcriptome profiling, target identification, and functional validation. We showed that Gnat1 rd17 mice primarily underwent alterations in their retinal dopaminergic system, triggering the development of an exacerbated EAU, which was counteracted by dopamine replacement with L-DOPA administered either systemically or locally. Remarkably, dopamine acted on retinal endothelial cells to inhibit NF-κB and STAT3 activity and the expression of downstream target genes such as chemokines involved in T cell recruitment. These results suggest that rod-mediated dopamine release functions in a gateway reflex manner in the homeostatic control of immune cell entry into the retina, and the loss of retinal dopaminergic activity in conditions associated with rod dysfunction increases the susceptibility to autoimmune uveitis.

Pathogenic variants in CRB1 lead to diverse recessive retinal disorders from severe Leber congenital amaurosis to isolated macular dystrophy. Until recently, no clear phenotype-genotype correlation and no appropriate mouse models existed. Herein, we reappraise the phenotype-genotype correlation of 50 patients with regards to the recently identified CRB1 isoforms: a canonical long isoform A localized in Müller cells (12 exons) and a short isoform B predominant in photoreceptors (7 exons). Twenty-eight patients with early onset retinal dystrophy (EORD) consistently had a severe Müller impairment, with variable impact on the photoreceptors, regardless of isoform B expression. Among them, two patients expressing wild type isoform B carried one variant in exon 12, which specifically damaged intracellular protein interactions in Müller cells. Thirteen retinitis pigmentosa patients had mainly missense variants in laminin G-like domains and expressed at least 50% of isoform A. Eight patients with the c.498&#95;506del variant had macular dystrophy. In one family homozygous for the c.1562C>T variant, the brother had EORD and the sister macular dystrophy. In contrast with the mouse model, these data highlight the key role of Müller cells in the severity of CRB1 -related dystrophies in humans, which should be taken into consideration for future clinical trials.

Retinitis pigmentosa 11 (RP11) is caused by dominant mutations in PRPF31 , however a significant proportion of mutation carriers do not develop retinopathy. Here, we investigated the relationship between CNOT3 polymorphism, MSR1 repeat copy number and disease penetrance in RP11 patients and non-penetrant carriers (NPCs). We further characterized PRPF31 and CNOT3 expression in fibroblasts from eight RP11 patients and one NPC from a family carrying the c.1205C>T variant. Retinal organoids (ROs) and retinal pigment epithelium (RPE) were differentiated from induced pluripotent stem cells derived from RP11 patients, an NPC and a control subject. All RP11 patients were homozygous for the 3-copy MSR1 repeat in the PRPF31 promoter, while 3/5 NPCs carried a 4-copy MSR1 repeat. The CNOT3 rs4806718 genotype did not correlate with disease penetrance. PRFP31 expression declined with age in adult cadaveric retina. PRPF31 and CNOT3 expression was reduced in RP11 fibroblasts, RO and RPE compared with controls. Both RP11 and NPC RPE displayed shortened primary cilia compared with controls, however a subpopulation of cells with normal cilia lengths was present in NPC RPE monolayers. Our results indicate that RP11 non-penetrance is associated with the inheritance of a 4-copy MSR1 repeat, but not with CNOT3 polymorphisms.

The purpose of this work was to identify the gene defect underlying a relatively mild rod-cone dystrophy (RCD), lacking disease-causing variants in known genes implicated in inherited retinal disorders (IRD), and provide transcriptomic and immunolocalization data to highlight the best candidate. The DNA of the female patient originating from a consanguineous family revealed no large duplication or deletion, but several large homozygous regions. In one of these, a homozygous frameshift variant, c.244&#95;246delins17 p.(Trp82Valfs*4); predicted to lead to a nonfunctional protein, was identified in CCDC51 . CCDC51 encodes the mitochondrial coiled-coil domain containing 51 protein, also called MITOK. MITOK ablation causes mitochondrial dysfunction. Here we show for the first time that CCDC51/MITOK localizes in the retina and more specifically in the inner segments of the photoreceptors, well known to contain mitochondria. Mitochondrial proteins have previously been implicated in IRD, although usually in association with syndromic disease, unlike our present case. Together, our findings add another ultra-rare mutation implicated in non-syndromic IRD, whose pathogenic mechanism in the retina needs to be further elucidated.

Background: Bardet-Biedl syndrome is an autosomal recessive disease characterized by rod-cone dystrophy, postaxial polydactyly, kidney defects, obesity, mental retardation and hypogonadism. Here, we report different genotypes in two Bardet-Biedl syndrome affected sisters with a different clinical phenotype regarding severity., Materials and Methods: The proband of the family was examined by Next Generation Sequencing (NGS) using clinical exome and filtering by syndromic and non-syndromic genes associated with retinal dystrophies., Results: Targeted NGS revealed two novel variants in the MKKS and CEP290 genes in homozygosis state in the proband. Segregation analysis revealed the presence of the same MKKS homozygous variant in her younger affected sister but not the CEP290 variant. Both sisters presented different clinical manifestation, at different ages, with a more severe renal and retinal defect in the case of the sister carrying mutations in both genes. Another unaffected sister showed only homozygosity for the CEP290 variant, thus supporting the non-pathogenic role of this mutation in BBS phenotype., Conclusions: In this study, NGS proved to be a powerful and efficient sequencing method to identify causal variants in different genes. However, it remarks the importance of the segregation analysis and clinical information to establish the pathogenicity of new variants. The two affected sisters present different genotypes and clinical manifestation, suggesting that the novel CEP290 variant could be acting as a modifier, making the phenotype more severe in the sister homozygote for MKKS and CEP290 genes. On the other hand, the difference in the age of both sisters highlight the important role of monitoring disease progression also to confirm the modifier role of genetic variants., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

Cyclic nucleotide-gated channel β1 (CNGB1) encodes the 240-kDa β subunit of the rod photoreceptor cyclic nucleotide-gated ion channel. Disease-causing sequence variants in CNGB1 lead to autosomal recessive rod-cone dystrophy/retinitis pigmentosa (RP). We herein present a comprehensive review and analysis of all previously reported CNGB1 sequence variants, and add 22 novel variants, thereby enlarging the spectrum to 84 variants in total, including 24 missense variants (two of which may also affect splicing), 21 nonsense, 19 splicing defects (7 at noncanonical positions), 10 small deletions, 1 small insertion, 1 small insertion-deletion, 7 small duplications, and 1 gross deletion. According to the American College of Medical Genetics and Genomics classification criteria, 59 variants were considered pathogenic or likely pathogenic and 25 were variants of uncertain significance. In addition, we provide further phenotypic data from 34 CNGB1-related RP cases, which, overall, are in line with previous findings suggesting that this form of RP has long-term retention of useful central vision despite the early onset of night blindness, which is valuable for patient counseling, but also has implications for it being considered a priority target for gene therapy trials., (© 2021 The Authors. Human Mutation Published by Wiley Periodicals LLC.)

Retinitis pigmentosa (RP) is an inherited retinal dystrophy that causes progressive vision loss. The G56R mutation in NR2E3 is the second most common mutation causing autosomal dominant (ad) RP, a transcription factor that is essential for photoreceptor development and maintenance. The G56R variant is exclusively responsible for all cases of NR2E3 -associated adRP. Currently, there is no treatment for NR2E3 -related or, other, adRP, but genome editing holds promise. A pertinent approach would be to specifically knockout the dominant mutant allele, so that the wild type allele can perform unhindered. In this study, we developed a CRISPR/Cas strategy to specifically knockout the mutant G56R allele of NR2E3 and performed a proof-of-concept study in induced pluripotent stem cells (iPSCs) of an adRP patient. We demonstrate allele-specific knockout of the mutant G56R allele in the absence of off-target events. Furthermore, we validated this knockout strategy in an exogenous overexpression system. Accordingly, the mutant G56R-CRISPR protein was truncated and mis-localized to the cytosol in contrast to the (peri)nuclear localizations of wild type or G56R NR2E3 proteins. Finally, we show, for the first time, that G56R iPSCs, as well as G56R-CRISPR iPSCs, can differentiate into NR2E3-expressing retinal organoids. Overall, we demonstrate that G56R allele-specific knockout by CRISPR/Cas could be a clinically relevant approach to treat NR2E3 -associated adRP.

Purpose: (ADP-ribosylation factor-like 3) variants cause autosomal dominant retinitis pigmentosa (RP) or autosomal recessive Joubert syndrome. We found a family with rod-cone dystrophy (RCD) and verified it was associated with compound heterozygous variants in ARL3 (ADP-ribosylation factor-like 3) variants cause autosomal dominant retinitis pigmentosa (RP) or autosomal recessive Joubert syndrome. We found a family with rod-cone dystrophy (RCD) and verified it was associated with compound heterozygous variants in ARL3 gene. Methods: Ophthalmic examinations including optical coherence tomography and electroretinogram (ERG) were performed. Targeted next generation sequencing (NGS) was performed for the proband using a custom designed panel. Sanger sequencing and co-segregation were conducted in the family members. Changes of protein structure mediated by the variants were studied in vitro . ARL3 protein stability and its interaction with RP2 protein were assessed by cycloheximide chase assay and co-immunoprecipitation (Co-IP) assay. Results: Visual acuity of the 18-year-old male proband was 0.25 in the right and 0.20 in the left eye, while his non-consanguineous parents and sister was normal. The proband showed signs of RCD, including nyctalopia, peripheral field loss, bone-spicule deposits in the retina, and reduced ERG responses. The father, aged 50 years old, showed visual acuity of 1.0 in both eyes. Unlike the proband, he presented late onset and mild cone-rod dystrophy (CRD), including macular atrophy, central scotomata, moderate reduction in photopic ERG responses. None of all the family members had hearing abnormality, mental dysplasia or gait instability. We identified two novel compound heterozygous variants (c.91A>G, p.T31A; c.353G>T, p.C118F) in ARL3 in the proband, while his father only had variant c.91A>G. Bioinformatics analysis indicated amino acid positions of the two variants are highly conserved among species. The in silico tools predicted the variants to be harmful. Protein structure analysis showed the two variants had potential to alter the protein structure. Based on the ACMG guidelines, the two variants were likely pathogenic. In addition, the ARL3 mutations destabilized ARL3 protein, and the mutation c.353G>T disrupted the interaction between ARL3 and RP2 in HEK293T cells. Conclusions: We showed novel compound heterozygous variants in ARL3 were associated with early onset of autosomal recessive RCD, while c.91A>G along may be associated with a late onset of dominant CRD. The two variants in ARL3 could be causative by destabilizing ARL3 protein and impairing its interaction with RP2 protein., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2021 Fu, Li, Yao, Guo, You, Zhu and Lei.)

Background: Retinal vessel oximetry (RO) has been used to show altered metabolic function in patients with inherited retinal diseases (IRDs). The aim of this study was to investigate RO parameters of children with IRDs and presumed IRD carriers (pIRDc) and to compare them to controls., Methods: In this cross-sectional cohort study, 142 eyes from 71 Caucasian subjects were included: 40 eyes with IRDs, 26 eyes with pIRDc and 76 control eyes. The oxygen saturation was measured with the Retinal Vessel Analyser (IMEDOS Systems UG, Jena, Germany). Mean oxygen saturations in the peripapillary retinal arterioles (A-SO 2 ; %) and venules (V-SO 2 ; %) were estimated, and their difference (A-V SO 2 ; %) was calculated. In addition, we evaluated the mean diameter in all major retinal arterioles (D-A; μm) and venules (D-V; μm). anova-based linear mixed-effects models were calculated with SPSS ® ., Results: In general, children suffering from IRDs differed from controls when the A-SO 2 and A-V SO 2 were taken into account: both the A-SO 2 and the A-V SO 2 were significantly increased (p = 0.012). In subgroup analyses, children suffering from rod-cone dystrophy (RCD) presented an A-SO 2 increase (99.12 ± 8.24%) when compared to controls (91.33 ± 10.34%, p = 0.014) and pIRDc (92.37 ± 6.57%, p = 0.065). For V-SO 2 significant changes in RCD (67.42 ± 9.19%) were found in comparison with controls (58.24 ± 11.74%, p < 0.041), pIRDc (56.67 ± 7.16%, p = 0.007), cone-rod dystrophies (CRD, 52.17 ± 5.32%, p < 0.001) and inherited macular dystrophies (IMD, 55.74 ± 6.96%, p = 0.004), In addition, A-V SO 2 was decreased in RCD (31.69 ± 3.92%) when measured against CRD (41.9 ± 8.87%, p = 0.017) or IMD (39.52 ± 8.95%, p = 0.059)., Conclusion: In general, we found that children with IRDs presented early metabolic changes. Within IRDs, children with RCD showed more affected metabolic changes. Thus, RO may support early screening to rule out IRDs in children, and more precisely may help to differentiate those suffering from RCD., (© 2020 Acta Ophthalmologica Scandinavica Foundation. Published by John Wiley & Sons Ltd.)

Background: Heterozygous c.440 G > T mutation in the S-antigen visual arrestin (SAG) gene has been described as a cause of autosomal dominant retinitis pigmentosa (adRP) in a series of patients of Hispanic origin. This study presents the early and late clinical features and disease progression rates in an Australian family with SAG adRP., Materials and Methods: An observational case series of four family members with adRP. They were examined clinically, with multi-modal retinal imaging and electroretinography (ERG) to ascertain phenotype. Disease progression rate was measured using optical coherence tomography (OCT) and fundus autofluorescence (FAF). A retinal dystrophy panel was used for the proband and cascade testing with targeted Sanger sequencing was conducted in other available family members., Results: The proband presented at 36 years of age with profoundly reduced full-field ERG responses despite a sector RP phenotype. This progressed to a classic RP pattern over several decades leaving a small residual island of central visual field. The horizontal span of the residual outer nuclear layer and the area of hyperautofluorescent ring contracted at a rate of 8-11% and 9-14% per year, respectively. DNA sequencing confirmed the segregation of SAG c.440 G > T mutation with disease., Conclusion: SAG adRP presents with a reduced full-field ERG response consistent with a rod-cone dystrophy in mid-life despite a sector RP phenotype. Centripetal progression of the disease into the macula can be tracked by OCT and FAF imaging.

Purpose: Microperimetry is commonly used to assess retinal function. We perform cross-sectional and longitudinal analysis on microperimetry parameters in USH2A retinopathy and explore end points suitable for future clinical trials., Methods: Microperimetry was performed using two grids, Grid 1 (18° diameter) and Grid 2 (6° diameter). In Grid 1, four parameters (number of nonscotomatous loci, mean sensitivity [MS], responding point sensitivity [RPS], and edge of scotoma sensitivity [ESS]) were analyzed. In Grid 2, number of nonscotomatous loci and MS were examined. Interocular symmetry was also examined. Longitudinal analysis was conducted in a subset of eyes., Results: Microperimetry could be performed in 16 of 21 patients. In Grid 1 ( n = 15; average age, 35.6 years), average number of nonscotomatous loci, MS, RPS, and ESS were 46.6 loci, 10.0 dB, 14.7 and 9.6 dB, respectively. In Grid 2 ( n = 13; average age, 37.4 years), 12 eyes had measurable sensitivity across the entire grid. Average MS was 23.8 dB. Interocular analysis revealed large 95% confidence intervals for all parameters. Longitudinally, Grid 1 ( n = 12, average follow-up 2.6 years) ESS showed the fastest rate of decline (-1.84 dB/y) compared with MS (-0.34 dB/y) and RPS (-0.90 dB/y)., Conclusions: Our data suggest that ESS may be more useful than MS and RPS in test grids that cover a large extent of the macula. We caution the use of contralateral eye as an internal control., Translational Relevance: ESS may decrease the duration or sample size of treatment trials in USH2A retinopathy., Competing Interests: Disclosure: J. Charng, None; T.M. Lamey, None; J.A. Thompson, None; T.L. Mclaren, None; M.S. Attia, None; I.L. McAllister, None; I.J. Constable, None; D.A. Mackey, None; J.N. De Roach, None; F.K. Chen, None, (Copyright 2020 The Authors.)

Retinitis pigmentosa (RP) is a generic term for a group of genetic diseases characterized by loss of rod and cone photoreceptor cells. Although the genetic causes of RP frequently only affect the rod photoreceptor cells, cone photoreceptors become stressed in the absence of rods and undergo a secondary degeneration. Changes in the gene expression profile of cone photoreceptor cells are likely to occur prior to observable physiological changes. To this end, we sought to achieve greater understanding of the changes in cone photoreceptor cells early in the degeneration process of the Rho -/- mouse model. To account for gene expression changes attributed to loss of cone photoreceptor cells, we normalized PCR in the remaining number of cones to a cone cell reporter ( OPN1-GFP ). Gene expression profiles of key components involved in the cone phototransduction cascade were correlated with tests of retinal cone function prior to cell loss. A significant downregulation of the photoreceptor transcription factor Crx was observed, which preceded a significant downregulation in cone opsin transcripts that coincided with declining cone function. Our data add to the growing understanding of molecular changes that occur prior to cone dysfunction in a model of rod-cone dystrophy. It is of interest that gene supplementation of CRX by adeno-associated viral vector delivery prior to cone cell loss did not prevent cone photoreceptor degeneration in this mouse model.

Background: Recent advances in genetic sequencing techniques have improved the overall diagnostic yield for finding genetic causes for inherited retinal dystrophies (IRD). Rod-cone dystrophy is the most common IRD and is characterized by the primary involvement of the rod photoreceptors. Over 80 causal genes have been identified so far giving clinicians insight into the pathogenesis. SLC4A7 encodes a sodium bicarbonate cotransporter responsible acid disposal which, within the retina, is prevalent in the photoreceptor synaptic terminals. Thus far, there have been no published reports of variants in this gene known to cause rod-cone dystrophy., Material and Methods: Case report of a rod-cone dystrophy patient with a novel mutation in SLC4A7 , whole exome sequencing with CLIA-certified NGS and Sanger confirmation, and, review of a SLC4A7 knockout mouse model phenotype., Results: A 66-year-old male presented with slowly progressing night blindness, constricted visual field and relatively stable visual acuity. Fundus examination showed diffuse intraretinal pigment in the mid- and peripheral retina, diffuse retinal pigment epithelial atrophy, and intact macula in both eyes. There has been mild macular edema in both eyes which remained stable with the use of topical dorzolamide eyedrops. Whole exome sequencing found, and a subsequent vision panel confirmed, the pathogenic variant to be a homozygous frameshift mutation in SLC4A7 which results in termination of the protein., Conclusions: We report a case of progressive rod-cone dystrophy caused by a novel mutation in SLC4A7 , a gene coding the sodium bicarbonate cotransporter NBC3, underscoring the importance of ion homeostasis for photoreceptor function and maintenance.

Purpose: To report the clinical and genetic features of a 9-year-old female Japanese patient with Bardet-Biedl syndrome (BBS)., Methods: Genetic analysis using whole-exome sequencing (WES) was performed for the patient and her parents to identify disease-causing variants. Reverse transcriptase-polymerase chain reaction (RT-PCR) was performed to investigate the impact of splice-site variants. Comprehensive ophthalmic and systemic examinations, including electroretinography (ERG), were performed., Results: In the patient, WES identified novel compound heterozygous splice-site variants (c.124+2T>G and c.723+2T>G) in the BBS1 gene, and RT-PCR revealed skipping of exons 2 and 8 (p.N17AfsX56 and p.T198&#95;K241del). Each parent had one of the variants. Ophthalmologically, the patient's decimal best-corrected visual acuity was 0.6 in the right eye and 0.4 in the left eye. Funduscopy revealed no apparent retinal degeneration or narrowed blood vessels in the periphery, but macular abnormalities were found on fundus autofluorescence imaging and optical coherence tomography images. Unexpectedly, non-recordable responses in rod ERG were found, with a non-recordable response of the right eye and an extremely reduced and delayed a-wave of the left eye in standard ERG, non-recordable responses in cone ERG, and extremely decreased responses in 30 Hz flicker ERG. Finally, the patient fulfilled four primary features of BBS diagnostic criteria: rod-cone dystrophy, polydactyly, central obesity, and learning disabilities, being diagnosed with BBS., Conclusions: This is the first report of a BBS patient with biallelic splice-site BBS1 variants in the Japanese population. Disparity between funduscopic and ERG findings may be a feature of BBS1-associated rod-cone dystrophy.

Purpose: Current sequencing strategies can genetically solve 55-60% of inherited retinal degeneration (IRD) cases, despite recent progress in sequencing. This can partially be attributed to elusive pathogenic variants (PVs) in known IRD genes, including copy-number variations (CNVs), which have been shown as major contributors to unsolved IRD cases., Methods: Five hundred IRD patients were analyzed with targeted next-generation sequencing (NGS). The NGS data were used to detect CNVs with ExomeDepth and gCNV and the results were compared with CNV detection with a single-nucleotide polymorphism (SNP) array. Likely causal CNV predictions were validated by quantitative polymerase chain reaction (qPCR)., Results: Likely disease-causing single-nucleotide variants (SNVs) and small indels were found in 55.6% of subjects. PVs in USH2A (11.6%), RPGR (4%), and EYS (4%) were the most common. Likely causal CNVs were found in an additional 8.8% of patients. Of the three CNV detection methods, gCNV showed the highest accuracy. Approximately 30% of unsolved subjects had a single likely PV in a recessive IRD gene., Conclusion: CNV detection using NGS-based algorithms is a reliable method that greatly increases the genetic diagnostic rate of IRDs. Experimentally validating CNVs helps estimate the rate at which IRDs might be solved by a CNV plus a more elusive variant.

DRAM2 -associated retinopathy is a rare inherited retinal dystrophy, and its outcome has not been determined. A single retinal involvement by a mutation of the DRAM2 gene is unexplained. We found three unrelated patients with a disease-causing DRAM2 variant in a biallelic state from 1555 Japanese individuals of 1314 families with inherited retinal dystrophy. We reviewed their medical records and examined their peripheral lymphocytes by transmission electron microscopy (TEM). Patient 1 was a 38-year-old woman who complained of night blindness and reduced vision. She developed macular degeneration at age 43 years. Patients 2 and 3 were a man and a woman both of whom noticed night blindness in their 30s. Both had a degeneration in the macula and midperiphery in their 40s, which progressed to a diffuse retinal degeneration in their 60s when their vision was reduced to hand motions. Three novel DRAM2 variants were identified. TEM of the lymphocytes of Patients 1 and 2 showed abnormal structures in 40.6% and 0.3% of the peripheral lymphocytes, respectively. We concluded that the DRAM2 -associated retinopathy of our patients was a progressive rod-cone dystrophy, and the visual outcome was poor. The systemic effect of DRAM2 mutations may be compensable and have variations.

Introduction : Mutations in Kizuna ( KIZ) , a gene involved in ciliary function, have been previously associated with rod-cone dystrophy with relative macular sparing and a number of other systemic abnormalities. Purpose : We present a patient with a phenotype dominated by retinal dystrophy and macular cysts as a result of a homozygous nonsense mutation in KIZ. Methods : A 32-year-old female of Ashkenazi Jewish ancestry presented with progressive central vision loss and peripheral visual field loss following decades of night-blindness. She was noted to have a bull's-eye pattern of macular hyper-autofluorescence, intraretinal cystoid macular changes and outer retinal atrophy in both eyes. Visual fields were constricted to <10 degrees centrally with inferior preserved islands of vision. Genetic testing revealed a homozygous KIZ c.226 C > T (p.Arg76*) nonsense mutation. The patient was treated with topical dorzolamide and showed significant improvement in the degree of macular cysts. Conclusion : Mutations in KIZ can present with a predominantly macular phenotype and develop cystoid macular changes responsive to carbonic anhydrase inhibitor treatment. Because of the importance of KIZ in cilia function, it is critical to look for associated systemic manifestations to ensure best patient care.

Retinitis pigmentosa (RP) encompasses a group of inherited retinal dystrophies characterized by the primary degeneration of rod and cone photoreceptors. RP is a leading cause of visual disability, with a worldwide prevalence of 1:4000. Although the majority of RP cases are non-syndromic, 20-30% of patients with RP also have an associated non-ocular condition. RP typically manifests with night blindness in adolescence, followed by concentric visual field loss, reflecting the principal dysfunction of rod photoreceptors; central vision loss occurs later in life due to cone dysfunction. Photoreceptor function measured with an electroretinogram is markedly reduced or even absent. Optical coherence tomography (OCT) and fundus autofluorescence (FAF) imaging show a progressive loss of outer retinal layers and altered lipofuscin distribution in a characteristic pattern. Over the past three decades, a vast number of disease-causing variants in more than 80 genes have been associated with non-syndromic RP. The wide heterogeneity of RP makes it challenging to describe the clinical findings and pathogenesis. In this review, we provide a comprehensive overview of the clinical characteristics of RP specific to genetically defined patient subsets. We supply a unique atlas with color fundus photographs of most RP subtypes, and we discuss the relevant considerations with respect to differential diagnoses. In addition, we discuss the genes involved in the pathogenesis of RP, as well as the retinal processes that are affected by pathogenic mutations in these genes. Finally, we review management strategies for patients with RP, including counseling, visual rehabilitation, and current and emerging therapeutic options., (Copyright © 2018 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Rod-cone dystrophy (RCD), also called retinitis pigmentosa, is the most common form of progressive inherited retinal disorders secondary to photoreceptor degeneration. It is a genetically heterogeneous disease characterized by night blindness, followed by visual field constriction and, in most severe cases, total blindness. The aim of our study was to identify the underlying gene defect leading to severe RCD in a 60-year-old woman. The patient's DNA was investigated by targeted next generation sequencing followed by whole exome sequencing. A novel nonsense variant, c.267G>A p.(Trp89*), was identified at a homozygous state in the proband in REEP6 gene, recently reported mutated in 7 unrelated families with RCD. Further functional studies will help to understand the physiopathology associated with REEP6 mutations that may be linked to a protein trafficking defect., (© 2017 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

We identified herein additional patients with rod-cone dystrophy (RCD) displaying mutations in KIZ , encoding the ciliary centrosomal protein kizuna and performed functional characterization of the respective protein in human fibroblasts and of its mouse ortholog PLK1S1 in the retina. Mutation screening was done by targeted next generation sequencing and subsequent Sanger sequencing validation. KIZ mRNA levels were assessed on blood and serum-deprived human fibroblasts from a control individual and a patient, compound heterozygous for the c.52G>T (p.Glu18*) and c.119&#95;122del (p.Lys40Ilefs*14) mutations in KIZ . KIZ localization, documentation of cilium length and immunoblotting were performed in these two fibroblast cell lines. In addition, PLK1S1 immunolocalization was conducted in mouse retinal cryosections and isolated rod photoreceptors. Analyses of additional RCD patients enabled the identification of two homozygous mutations in KIZ , the known c.226C>T (p.Arg76*) mutation and a novel variant, the c.3G>A (p.Met1?) mutation. Albeit the expression levels of KIZ were three-times lower in the patient than controls in whole blood cells, further analyses in control- and mutant KIZ patient-derived fibroblasts unexpectedly revealed no significant difference between the two genotypes. Furthermore, the averaged monocilia length in the two fibroblast cell lines was similar, consistent with the preserved immunolocalization of KIZ at the basal body of the primary cilia. Analyses in mouse retina and isolated rod photoreceptors showed PLK1S1 localization at the base of the photoreceptor connecting cilium. In conclusion, two additional patients with mutations in KIZ were identified, further supporting that defects in KIZ/PLK1S1, detected at the basal body of the primary cilia in fibroblasts, and the photoreceptor connecting cilium in mouse, respectively, are involved in RCD. However, albeit the mutations were predicted to lead to nonsense mediated mRNA decay, we could not detect changes upon expression levels, protein localization or cilia length in KIZ -mutated fibroblast cells. Together, our findings unveil the limitations of fibroblasts as a cellular model for RCD and call for other models such as induced pluripotent stem cells to shed light on retinal pathogenic mechanisms of KIZ mutations., Competing Interests: The authors declare no conflict of interest.