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Katta M, de Guimaraes TAC, Fujinami-Yokokawa Y, Fujinami K, Georgiou M, Mahroo OA, Webster AR, Michaelides M. Congenital Stationary Night Blindness Structure, Function and Genotype-Phenotype Correlations in a Cohort of 122 Patients. Ophthalmol Retina 2024:S2468-6530(24)00121-0. [PMID: 38522615 DOI: 10.1016/j.oret.2024.03.017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2024] [Revised: 03/04/2024] [Accepted: 03/18/2024] [Indexed: 03/26/2024]
Abstract
OBJECTIVE To examine the molecular causes of Schubert-Bornschein (S-B) congenital stationary night blindness (CSNB), clinically characterize in detail, and assess genotype-phenotype correlations for retinal function and structure. DESIGN Retrospective, longitudinal, single-center case series. PARTICIPANTS One hundred twenty-two patients with S-B CSNB attending Moorfields Eye Hospital, United Kingdom. METHODS All case notes, results of molecular genetic testing, and OCT were reviewed. MAIN OUTCOME MEASURES Molecular genetics, presenting complaints, rates of nystagmus, nyctalopia, photophobia, strabismus, color vision defects and spherical equivalent refraction (SER). Retinal thickness, outer nuclear layer (ONL) thickness, and ganglion cell layer + inner plexiform layer (GCL+IPL) thickness from OCT imaging. RESULTS X-linked (CACNA1F and NYX) and autosomal recessive (TRPM1, GRM6, GPR179 and CABP4) genotypes were identified. The mean (± standard deviation) reported age of onset was 4.94 ± 8.99 years. Over the follow-up period, 95.9% of patients reported reduced visual acuity (VA), half had nystagmus, and 64.7% reported nyctalopia. Incomplete CSNB (iCSNB) patients more frequently had nystagmus and photophobia. Nyctalopia was similar for iCSNB and complete CSNB (cCSNB). Color vision data were limited but more defects were found in iCSNB. None of these clinical differences met statistical significance. There was no significant difference between groups in VA, with a mean of 0.46 logarithm of the minimum angle of resolution, and VA remained stable over the course of follow-up. Complete congenital stationary night blindness patients, specifically those with NYX and TRPM1 variants, were more myopic. CACNA1F patients showed the largest refractive variability, and the CABP4 patient was hyperopic. No significant differences were found in OCT structural analysis during the follow-up period. CONCLUSIONS Retinal structure in CSNB is stationary and no specific genotype-structure correlates were identified. Visual acuity seems to be relatively stable, with rare instances of progression. FINANCIAL DISCLOSURE(S) Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.
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Affiliation(s)
- Mohamed Katta
- UCL Institute of Ophthalmology, University College London, London, United Kingdom; Genetics Department, Moorfields Eye Hospital, London, United Kingdom
| | - Thales A C de Guimaraes
- UCL Institute of Ophthalmology, University College London, London, United Kingdom; Genetics Department, Moorfields Eye Hospital, London, United Kingdom
| | - Yu Fujinami-Yokokawa
- UCL Institute of Ophthalmology, University College London, London, United Kingdom; Laboratory of Visual Physiology, Division of Vision Research, National Institute of Sensory Organs, NHO Tokyo Medical Center, Tokyo, Japan; Department of Health Policy and Management, Keio University School of Medicine, Tokyo, Japan
| | - Kaoru Fujinami
- UCL Institute of Ophthalmology, University College London, London, United Kingdom; Genetics Department, Moorfields Eye Hospital, London, United Kingdom; Laboratory of Visual Physiology, Division of Vision Research, National Institute of Sensory Organs, NHO Tokyo Medical Center, Tokyo, Japan
| | - Michalis Georgiou
- UCL Institute of Ophthalmology, University College London, London, United Kingdom; Genetics Department, Moorfields Eye Hospital, London, United Kingdom; Jones Eye Institute, University of Arkansas for Medical Sciences, Little Rock, Arkansas
| | - Omar A Mahroo
- UCL Institute of Ophthalmology, University College London, London, United Kingdom; Genetics Department, Moorfields Eye Hospital, London, United Kingdom
| | - Andrew R Webster
- UCL Institute of Ophthalmology, University College London, London, United Kingdom; Genetics Department, Moorfields Eye Hospital, London, United Kingdom
| | - Michel Michaelides
- UCL Institute of Ophthalmology, University College London, London, United Kingdom; Genetics Department, Moorfields Eye Hospital, London, United Kingdom.
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The impact of modifier genes on cone-rod dystrophy heterogeneity: An explorative familial pilot study and a hypothesis on neurotransmission impairment. PLoS One 2022; 17:e0278857. [PMID: 36490268 PMCID: PMC9733859 DOI: 10.1371/journal.pone.0278857] [Citation(s) in RCA: 30] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2022] [Accepted: 11/23/2022] [Indexed: 12/13/2022] Open
Abstract
Cone-rod dystrophies (CORDs) are a heterogeneous group of inherited retinopathies (IRDs) with more than 30 already known disease-causing genes. Uncertain phenotypes and extended range of intra- and interfamilial heterogenicity make still difficult to determine a precise genotype-phenotype correlation. Here, we used a next-generation sequencing approach to study a Sicilian family with a suspected form of CORD. Affected family members underwent ophthalmological examinations and a proband, blind from 50 years, underwent whole genome and exome sequencing. Variant analysis was enriched by pathway analysis and relevant variants were, then, investigated in other family members and in 100 healthy controls from Messina. CORD diagnosis with an intricate pattern of symptoms was confirmed by ophthalmological examinations. A total of about 50,000 variants were identified in both proband's genome and exome. All affected family members presented specific genotypes mainly determined by mutated GUCY2D gene, and different phenotypical traits, mainly related to focus and color perception. Thus, we looked for possible modifier genes. According to relationship with GUCY2D, predicted functional effects, eye localization, and ocular disease affinity, only 9 variants, carried by 6 genes (CACNG8, PAX2, RXRG, CCDC175, PDE4DIP and LTF), survived the filtering. These genes encode key proteins involved in cone development and survival, and retina neurotransmission. Among analyzed variants, CACNG8c.*6819A>T and the new CCDC175 c.76C>T showed extremely low frequency in the control group, suggesting a key role on disease phenotypes. Such discovery could enforce the role of modifier genes into CORD onset/progression, contributing to improve diagnostic test towards a better personalized medicine.
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Fernandez-Gonzalez P, Mas-Sanchez A, Garriga P. Polyphenols and Visual Health: Potential Effects on Degenerative Retinal Diseases. Molecules 2021; 26:3407. [PMID: 34199888 PMCID: PMC8200069 DOI: 10.3390/molecules26113407] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2021] [Revised: 06/01/2021] [Accepted: 06/02/2021] [Indexed: 12/26/2022] Open
Abstract
Dietary polyphenols are a group of natural compounds that have been proposed to have beneficial effects on human health. They were first known for their antioxidant properties, but several studies over the years have shown that these compounds can exert protective effects against chronic diseases. Nonetheless, the mechanisms underlying these potential benefits are still uncertain and contradictory effects have been reported. In this review, we analyze the potential effects of polyphenol compounds on some visual diseases, with a special focus on retinal degenerative diseases. Current effective therapies for the treatment of such retinal diseases are lacking and new strategies need to be developed. For this reason, there is currently a renewed interest in finding novel ligands (or known ligands with previously unexpected features) that could bind to retinal photoreceptors and modulate their molecular properties. Some polyphenols, especially flavonoids (e.g., quercetin and tannic acid), could attenuate light-induced receptor damage and promote visual health benefits. Recent evidence suggests that certain flavonoids could help stabilize the correctly folded conformation of the visual photoreceptor protein rhodopsin and offset the deleterious effect of retinitis pigmentosa mutations. In this regard, certain polyphenols, like the flavonoids mentioned before, have been shown to improve the stability, expression, regeneration and folding of rhodopsin mutants in experimental in vitro studies. Moreover, these compounds appear to improve the integration of the receptor into the cell membrane while acting against oxidative stress at the same time. We anticipate that polyphenol compounds can be used to target visual photoreceptor proteins, such as rhodopsin, in a way that has only been recently proposed and that these can be used in novel approaches for the treatment of retinal degenerative diseases like retinitis pigmentosa; however, studies in this field are limited and further research is needed in order to properly characterize the effects of these compounds on retinal degenerative diseases through the proposed mechanisms.
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Affiliation(s)
| | | | - Pere Garriga
- Grup de Biotecnologia Molecular i Industrial, Centre de Biotecnologia Molecular, Departament d’Enginyeria Química, Universitat Politècnica de Catalunya, Edifici Gaia, 08222 Terrassa, Spain; (P.F.-G.); (A.M.-S.)
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Kobal N, Krašovec T, Šuštar M, Volk M, Peterlin B, Hawlina M, Fakin A. Stationary and Progressive Phenotypes Caused by the p.G90D Mutation in Rhodopsin Gene. Int J Mol Sci 2021; 22:ijms22042133. [PMID: 33669941 PMCID: PMC7924842 DOI: 10.3390/ijms22042133] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2021] [Revised: 02/15/2021] [Accepted: 02/18/2021] [Indexed: 12/30/2022] Open
Abstract
Mutations in rhodopsin gene (RHO) are a frequent cause of retinitis pigmentosa (RP) and less often, congenital stationary night blindness (CSNB). Mutation p.G90D has previously been associated with CSNB based on the examination of one family. This study screened 60 patients. Out of these 60 patients, 32 were affected and a full characterization was conducted in 15 patients. We described the clinical characteristics of these 15 patients (12 male, median age 42 years, range 8-71) from three families including visual field (Campus Goldmann), fundus autofluorescence (FAF), optical coherence tomography (OCT) and electrophysiology. Phenotypes were classified into four categories: CSNB (N = 3, 20%) sector RP (N = 3, 20%), pericentral RP (N = 1, 6.7%) and classic RP (N = 8, 53.3% (8/15)). The phenotypes were not associated with family, sex or age (Kruskal-Wallis, p > 0.05), however, cystoid macular edema (CME) was observed only in one family. Among the subjects reporting nyctalopia, 69% (22/32) were male. The clinical characteristics of the largest p.G90D cohort so far showed a large frequency of progressive retinal degeneration with 53.3% developing RP, contrary to the previous report.
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Affiliation(s)
- Nina Kobal
- Eye Hospital, University Medical Centre Ljubljana, Grablovičeva ulica 46, 1000 Ljubljana, Slovenia; (N.K.); (T.K.); (M.Š.); (M.H.)
| | - Tjaša Krašovec
- Eye Hospital, University Medical Centre Ljubljana, Grablovičeva ulica 46, 1000 Ljubljana, Slovenia; (N.K.); (T.K.); (M.Š.); (M.H.)
| | - Maja Šuštar
- Eye Hospital, University Medical Centre Ljubljana, Grablovičeva ulica 46, 1000 Ljubljana, Slovenia; (N.K.); (T.K.); (M.Š.); (M.H.)
| | - Marija Volk
- Clinical Institute of Medical Genetics, University Medical Centre Ljubljana, Šlajmerjeva ulica 4, 1000 Ljubljana, Slovenia; (M.V.); (B.P.)
| | - Borut Peterlin
- Clinical Institute of Medical Genetics, University Medical Centre Ljubljana, Šlajmerjeva ulica 4, 1000 Ljubljana, Slovenia; (M.V.); (B.P.)
| | - Marko Hawlina
- Eye Hospital, University Medical Centre Ljubljana, Grablovičeva ulica 46, 1000 Ljubljana, Slovenia; (N.K.); (T.K.); (M.Š.); (M.H.)
| | - Ana Fakin
- Eye Hospital, University Medical Centre Ljubljana, Grablovičeva ulica 46, 1000 Ljubljana, Slovenia; (N.K.); (T.K.); (M.Š.); (M.H.)
- Correspondence:
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Luo H, Xiao X, Li S, Sun W, Yi Z, Wang P, Zhang Q. Spectrum-frequency and genotype-phenotype analysis of rhodopsin variants. Exp Eye Res 2020; 203:108405. [PMID: 33347869 DOI: 10.1016/j.exer.2020.108405] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2020] [Revised: 11/23/2020] [Accepted: 12/14/2020] [Indexed: 12/18/2022]
Abstract
Mutations in RHO are the most common cause of autosomal dominant retinitis pigmentosa. However, the pathogenicity of many RHO variants is questionable. This study was designed to investigate the genotype-phenotype correlation for RHO variants. These RHO variants were collected from the in-house exome sequencing data of 7092 probands suffering from different types of eye conditions. The variants were classified using bioinformatics tools, family segregation, and clinical phenotypes. The RHO variants were assessed using multiple online tools and a genotype-phenotype analysis based on the data collected from of ours, gnomAD, and published literature. Totally, 52 heterozygous variants of RHO were detected in the 7092 probands. Of these 52, 17 were potentially pathogenic, were present in 35 families, and comprised 15 missense variants, one inframe deletion and one nonsense variant. All the 15 missense variants were predicted to be damaging by five different online tools. The analysis of the clinical data of the patients from the 35 families revealed certain common features, of an early damage to both the rods and the cones, relatively preserved visual acuity in adulthood, and mid-peripheral tapetoretinal degeneration with pigmentation or RPE atrophy. Our data, the data from gnomAD, and the systematic review of the 246 previously reported variants suggest that approximately two-thirds of the rare missense variants and most of the truncated variants involving upstream of K296 are likely benign. This study provides a brief summary of the characteristics of the pathogenic RHO variants. It emphasizes that the systematic evaluation of these variants at the individual-gene level is crucial in the current era of clinical genetic testing even for a well-known gene such as RHO.
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Affiliation(s)
- Hualei Luo
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, 510060, China
| | - Xueshan Xiao
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, 510060, China
| | - Shiqiang Li
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, 510060, China
| | - Wenmin Sun
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, 510060, China
| | - Zhen Yi
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, 510060, China
| | - Panfeng Wang
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, 510060, China
| | - Qingjiong Zhang
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, 510060, China.
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Owczarek-Lipska M, Song F, Jakšić V, Neidhardt J. Compound heterozygous RPE65 mutations associated with an early onset autosomal recessive retinitis pigmentosa. J Gene Med 2020; 22:e3211. [PMID: 32367544 DOI: 10.1002/jgm.3211] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2020] [Revised: 04/23/2020] [Accepted: 04/23/2020] [Indexed: 01/29/2023] Open
Abstract
BACKGROUND Retinitis pigmentosa (RP) is one of the most common form of inherited retinal dystrophies. Identification of disease-causing mutations is a prerequisite for applying targeted therapeutic approaches. The present study aimed to identify disease-associated mutations in a large Serbian family, in which two brothers have suffered from RP starting in the first decade of their lives. METHODS The index patient and 12 additional members of a four-generation family were analyzed. All participants underwent detailed ophthalmic examinations. Genomic DNA was isolated from family members to perform whole exome sequencing (WES) and Sanger sequencing of candidate genes. RESULTS An early onset RP phenotype was presented in both ocular fundi of the index patient and his brother: arteriolar attenuation, as well as retinal pigmentary changes in peripheral fundus and waxy disc pallor. Both brothers showed foveal thinning. The index patient showed epiretinal membranes in both eyes and a parafoveal cystic lesion in his right eye, whereas the brother of the index patient showed choroid folds and vitreomacular adhesion in his left eye. We identified compound heterozygous mutations in the RPE65 gene (a novel c.1338+1G>A splice donor site mutation in addition to the frame-shifting mutation c.1207_1210dup (p.Glu404Alafs*4)) using an in-house WES pipeline. CONCLUSIONS Evaluation of all previously described RPE65 mutations showed that the sequence variants identified in the present study located to rarely altered exons and likely effect a highly conserved region of the RPE65 protein. Gene augmentation therapies might be a promising treatment option for the patients described.
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Affiliation(s)
- Marta Owczarek-Lipska
- Human Genetics, Faculty VI - School of Medicine and Health Sciences, University of Oldenburg, Oldenburg, Germany.,Junior Research Group, Genetics of Childhood Brain Malformations, Faculty VI - School of Medicine and Health Sciences, University of Oldenburg, Oldenburg, Germany
| | - Fei Song
- Human Genetics, Faculty VI - School of Medicine and Health Sciences, University of Oldenburg, Oldenburg, Germany
| | - Vesna Jakšić
- Medical Faculty, University of Belgrade, Belgrade, Serbia
| | - John Neidhardt
- Human Genetics, Faculty VI - School of Medicine and Health Sciences, University of Oldenburg, Oldenburg, Germany.,Research Center Neurosensory Science, University Oldenburg, Oldenburg, Germany
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Korenke GC, Schulte B, Biskup S, Neidhardt J, Owczarek-Lipska M. A Novel de novo Frameshift Mutation in the BCL11A Gene in a Patient with Intellectual Disability Syndrome and Epilepsy. Mol Syndromol 2020; 11:135-140. [PMID: 32903878 DOI: 10.1159/000508566] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2020] [Accepted: 04/23/2020] [Indexed: 11/19/2022] Open
Abstract
Intellectual disability syndrome (IDS) associated with a hereditary persistence of fetal haemoglobin (HbF), also known as Dias-Logan syndrome, is commonly characterised by psychomotor developmental delay, intelectual disability, language delay, strabismus, thin upper lip, abnormalities of external ears, microcephaly, downslanting palpebral fissures. Sporadically, autism spectrum disorders and blue sclerae in infancy have been reported in IDS. Rarely, IDS-affected patients present with epilepsy and/or epileptic syndromes. It has been shown that a haploinsufficiency of the B cell leukaemia/lymphoma 11A gene (BCL11A) is responsible for IDS. Herein, we identified a novel de novo frameshift deletion (c.271delG; p.E91Afs*2) in the BCL11A gene in a boy affected with IDS. Interestingly, this heterozygous loss-of-function BCL11A mutation was also associated with a generalised idiopathic epilepsy and severe language delay observed in the patient. Moreover, our study showed that the combination of molecular genetic analyses with the monitoring of HbF was essential to make the final diagnosis of Dias-Logan syndrome. Because our patient suffered from well-controlled epilepsy, we propose to include the BCL11A gene in routinely used molecular genetic epilepsy-related gene panels. Additionally, many of the clinical features of IDS overlap with symptoms observed in patients with suspected alcohol spectrum disorders. Therefore, we also suggest monitoring HbF levels in patients with these syndromes to further facilitate clinical diagnosis.
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Affiliation(s)
- Georg Christoph Korenke
- Department of Neuropediatrics, University Children's Hospital, Klinikum Oldenburg, Oldenburg, Germany
| | - Björn Schulte
- Praxis für Humangenetik, Tübingen, Germany.,Center for Genomics and Transcriptomics, CeGaT GmbH, Tübingen, Germany
| | - Saskia Biskup
- Praxis für Humangenetik, Tübingen, Germany.,Center for Genomics and Transcriptomics, CeGaT GmbH, Tübingen, Germany
| | - John Neidhardt
- Human Genetics, Faculty VI - School of Medicine and Health Sciences, University of Oldenburg, Oldenburg, Germany.,Research Center Neurosensory Science, University of Oldenburg, Oldenburg, Germany.,Joint Research Training Group of the Faculty VI - School of Medicine and Health Sciences, University of Oldenburg, Oldenburg, Germany, and University Medical Center Groningen, Groningen, The Netherlands.,Junior Research Group, Genetics of Childhood Brain Malformations, Faculty VI - School of Medicine and Health Sciences, University of Oldenburg, Oldenburg, Germany
| | - Marta Owczarek-Lipska
- Human Genetics, Faculty VI - School of Medicine and Health Sciences, University of Oldenburg, Oldenburg, Germany
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Talib M, Boon CJF. Retinal Dystrophies and the Road to Treatment: Clinical Requirements and Considerations. Asia Pac J Ophthalmol (Phila) 2020; 9:159-179. [PMID: 32511120 PMCID: PMC7299224 DOI: 10.1097/apo.0000000000000290] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2020] [Accepted: 04/01/2020] [Indexed: 12/15/2022] Open
Abstract
: 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 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.
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Affiliation(s)
- Mays Talib
- Department of Ophthalmology, Leiden, The Netherlands
| | - Camiel J F Boon
- Department of Ophthalmology, Leiden, The Netherlands
- Department of Ophthalmology, Amsterdam UMC, Academic Medical Center, University of Amsterdam. Amsterdam, The Netherlands
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Athanasiou D, Aguila M, Bellingham J, Li W, McCulley C, Reeves PJ, Cheetham ME. The molecular and cellular basis of rhodopsin retinitis pigmentosa reveals potential strategies for therapy. Prog Retin Eye Res 2018; 62:1-23. [PMID: 29042326 PMCID: PMC5779616 DOI: 10.1016/j.preteyeres.2017.10.002] [Citation(s) in RCA: 213] [Impact Index Per Article: 35.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2017] [Revised: 10/03/2017] [Accepted: 10/13/2017] [Indexed: 12/12/2022]
Abstract
Inherited mutations in the rod visual pigment, rhodopsin, cause the degenerative blinding condition, retinitis pigmentosa (RP). Over 150 different mutations in rhodopsin have been identified and, collectively, they are the most common cause of autosomal dominant RP (adRP). Mutations in rhodopsin are also associated with dominant congenital stationary night blindness (adCSNB) and, less frequently, recessive RP (arRP). Recessive RP is usually associated with loss of rhodopsin function, whereas the dominant conditions are a consequence of gain of function and/or dominant negative activity. The in-depth characterisation of many rhodopsin mutations has revealed that there are distinct consequences on the protein structure and function associated with different mutations. Here we categorise rhodopsin mutations into seven discrete classes; with defects ranging from misfolding and disruption of proteostasis, through mislocalisation and disrupted intracellular traffic to instability and altered function. Rhodopsin adRP offers a unique paradigm to understand how disturbances in photoreceptor homeostasis can lead to neuronal cell death. Furthermore, a wide range of therapies have been tested in rhodopsin RP, from gene therapy and gene editing to pharmacological interventions. The understanding of the disease mechanisms associated with rhodopsin RP and the development of targeted therapies offer the potential of treatment for this currently untreatable neurodegeneration.
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Affiliation(s)
| | - Monica Aguila
- UCL Institute of Ophthalmology, 11-43 Bath Street, London EC1V 9EL, UK
| | - James Bellingham
- UCL Institute of Ophthalmology, 11-43 Bath Street, London EC1V 9EL, UK
| | - Wenwen Li
- UCL Institute of Ophthalmology, 11-43 Bath Street, London EC1V 9EL, UK
| | - Caroline McCulley
- UCL Institute of Ophthalmology, 11-43 Bath Street, London EC1V 9EL, UK
| | - Philip J Reeves
- School of Biological Sciences, University of Essex, Wivenhoe Park, Essex CO4 3SQ, UK.
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