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Georgiou M, Robson AG, Fujinami K, de Guimarães TAC, Fujinami-Yokokawa Y, Daich Varela M, Pontikos N, Kalitzeos A, Mahroo OA, Webster AR, Michaelides M. Phenotyping and genotyping inherited retinal diseases: Molecular genetics, clinical and imaging features, and therapeutics of macular dystrophies, cone and cone-rod dystrophies, rod-cone dystrophies, Leber congenital amaurosis, and cone dysfunction syndromes. Prog Retin Eye Res 2024; 100:101244. [PMID: 38278208 DOI: 10.1016/j.preteyeres.2024.101244] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2023] [Revised: 01/12/2024] [Accepted: 01/15/2024] [Indexed: 01/28/2024]
Abstract
Inherited retinal diseases (IRD) are a leading cause of blindness in the working age population and in children. The scope of this review is to familiarise clinicians and scientists with the current landscape of molecular genetics, clinical phenotype, retinal imaging and therapeutic prospects/completed trials in IRD. Herein we present in a comprehensive and concise manner: (i) macular dystrophies (Stargardt disease (ABCA4), X-linked retinoschisis (RS1), Best disease (BEST1), PRPH2-associated pattern dystrophy, Sorsby fundus dystrophy (TIMP3), and autosomal dominant drusen (EFEMP1)), (ii) cone and cone-rod dystrophies (GUCA1A, PRPH2, ABCA4, KCNV2 and RPGR), (iii) predominant rod or rod-cone dystrophies (retinitis pigmentosa, enhanced S-Cone syndrome (NR2E3), Bietti crystalline corneoretinal dystrophy (CYP4V2)), (iv) Leber congenital amaurosis/early-onset severe retinal dystrophy (GUCY2D, CEP290, CRB1, RDH12, RPE65, TULP1, AIPL1 and NMNAT1), (v) cone dysfunction syndromes (achromatopsia (CNGA3, CNGB3, PDE6C, PDE6H, GNAT2, ATF6), X-linked cone dysfunction with myopia and dichromacy (Bornholm Eye disease; OPN1LW/OPN1MW array), oligocone trichromacy, and blue-cone monochromatism (OPN1LW/OPN1MW array)). Whilst we use the aforementioned classical phenotypic groupings, a key feature of IRD is that it is characterised by tremendous heterogeneity and variable expressivity, with several of the above genes associated with a range of phenotypes.
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Affiliation(s)
- Michalis Georgiou
- Moorfields Eye Hospital, London, United Kingdom; UCL Institute of Ophthalmology, University College London, London, United Kingdom; Jones Eye Institute, University of Arkansas for Medical Sciences, Little Rock, AR, USA.
| | - Anthony G Robson
- Moorfields Eye Hospital, London, United Kingdom; UCL Institute of Ophthalmology, University College London, London, United Kingdom.
| | - Kaoru Fujinami
- Moorfields Eye Hospital, London, United Kingdom; UCL Institute of Ophthalmology, University College London, London, United Kingdom; Laboratory of Visual Physiology, Division of Vision Research, National Institute of Sensory Organs, National Hospital Organization Tokyo Medical Center, Tokyo, Japan.
| | - Thales A C de Guimarães
- Moorfields Eye Hospital, London, United Kingdom; UCL Institute of Ophthalmology, University College London, 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, National Hospital Organization Tokyo Medical Center, Tokyo, Japan; Department of Health Policy and Management, Keio University School of Medicine, Tokyo, Japan.
| | - Malena Daich Varela
- Moorfields Eye Hospital, London, United Kingdom; UCL Institute of Ophthalmology, University College London, London, United Kingdom.
| | - Nikolas Pontikos
- Moorfields Eye Hospital, London, United Kingdom; UCL Institute of Ophthalmology, University College London, London, United Kingdom.
| | - Angelos Kalitzeos
- Moorfields Eye Hospital, London, United Kingdom; UCL Institute of Ophthalmology, University College London, London, United Kingdom.
| | - Omar A Mahroo
- Moorfields Eye Hospital, London, United Kingdom; UCL Institute of Ophthalmology, University College London, London, United Kingdom; Section of Ophthalmology, King s College London, St Thomas Hospital Campus, London, United Kingdom; Physiology, Development and Neuroscience, University of Cambridge, Downing Street, Cambridge, United Kingdom; Department of Translational Ophthalmology, Wills Eye Hospital, Philadelphia, PA, USA.
| | - Andrew R Webster
- Moorfields Eye Hospital, London, United Kingdom; UCL Institute of Ophthalmology, University College London, London, United Kingdom.
| | - Michel Michaelides
- Moorfields Eye Hospital, London, United Kingdom; UCL Institute of Ophthalmology, University College London, London, United Kingdom.
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Corradetti G, Verma A, Tojjar J, Almidani L, Oncel D, Emamverdi M, Bradley A, Lindenberg S, Nittala MG, Sadda SR. Retinal Imaging Findings in Inherited Retinal Diseases. J Clin Med 2024; 13:2079. [PMID: 38610844 PMCID: PMC11012835 DOI: 10.3390/jcm13072079] [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: 02/14/2024] [Revised: 03/19/2024] [Accepted: 03/27/2024] [Indexed: 04/14/2024] Open
Abstract
Inherited retinal diseases (IRDs) represent one of the major causes of progressive and irreversible vision loss in the working-age population. Over the last few decades, advances in retinal imaging have allowed for an improvement in the phenotypic characterization of this group of diseases and have facilitated phenotype-to-genotype correlation studies. As a result, the number of clinical trials targeting IRDs has steadily increased, and commensurate to this, the need for novel reproducible outcome measures and endpoints has grown. This review aims to summarize and describe the clinical presentation, characteristic imaging findings, and imaging endpoint measures that are being used in clinical research on IRDs. For the purpose of this review, IRDs have been divided into four categories: (1) panretinal pigmentary retinopathies affecting rods or cones; (2) macular dystrophies; (3) stationary conditions; (4) hereditary vitreoretinopathies.
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Affiliation(s)
- Giulia Corradetti
- Doheny Eye Institute, Pasadena, CA 91103, USA (J.T.); (L.A.)
- Department of Ophthalmology, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095, USA
| | - Aditya Verma
- Doheny Eye Institute, Pasadena, CA 91103, USA (J.T.); (L.A.)
- Department of Ophthalmology and Visual Sciences, University of Louisville, Louisville, KY 40202, USA
| | - Jasaman Tojjar
- Doheny Eye Institute, Pasadena, CA 91103, USA (J.T.); (L.A.)
- Department of Ophthalmology, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095, USA
| | - Louay Almidani
- Doheny Eye Institute, Pasadena, CA 91103, USA (J.T.); (L.A.)
- Wilmer Eye Institute, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Deniz Oncel
- Doheny Eye Institute, Pasadena, CA 91103, USA (J.T.); (L.A.)
- Stritch School of Medicine, Loyola University Chicago, Chicago, IL 60153, USA
| | - Mehdi Emamverdi
- Doheny Eye Institute, Pasadena, CA 91103, USA (J.T.); (L.A.)
| | - Alec Bradley
- Department of Ophthalmology and Visual Sciences, University of Louisville, Louisville, KY 40202, USA
| | | | | | - SriniVas R. Sadda
- Doheny Eye Institute, Pasadena, CA 91103, USA (J.T.); (L.A.)
- Department of Ophthalmology, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095, USA
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Ballios BG, Mandola A, Tayyib A, Tumber A, Garkaby J, Vong L, Heon E, Roifman CM, Vincent A. Deep phenotypic characterization of the retinal dystrophy in patients with RNU4ATAC-associated Roifman syndrome. Eye (Lond) 2023; 37:3734-3742. [PMID: 37225827 PMCID: PMC10697969 DOI: 10.1038/s41433-023-02581-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2022] [Revised: 05/01/2023] [Accepted: 05/11/2023] [Indexed: 05/26/2023] Open
Abstract
PURPOSE To characterize the retinal phenotype in RNU4ATAC-associated Roifman syndrome. METHODS Ten patients (including 8 males) with molecularly confirmed Roifman syndrome underwent detailed ophthalmologic evaluation including fundus imaging, fundus autofluorescence (FAF) imaging, spectral-domain optical coherence tomography (SD-OCT), and electroretinography (ERG). Six patients had follow-up eye exams. All patients also underwent comprehensive examination for features of extra-retinal Roifman syndrome. RESULTS All patients had biallelic RNU4ATAC variants. Nyctalopia was common (7/10). Visual acuity at presentation ranged from 20/20 to 20/200 (Age Range: 5-41 years). Retinal exam revealed features of generalized retinopathy with mid-peripheral pigment epithelial changes. A para or peri-foveal ring of hyper-autofluorescence was the commonest FAF abnormality noted (6/8). The SD-OCT demonstrated relative preservation of the foveal ellipsoid zone in six cases; associated features included cystoid changes (5/10) and posterior staphyloma (3/10). The ERG was abnormal in all patients; nine showed generalized rod-cone dystrophy, whilst one patient with sectoral retinal involvement only had isolated rod dystrophy (20 years old). On follow-up examination (Mean duration: 8.16 years), progressive loss of visual acuity (2/6), mid-peripheral retinal atrophy (3/6) or shortening of ellipsoid zone width (1/6) were observed. CONCLUSION This study has characterized the retinal phenotype in RNU4ATAC-associated Roifman syndrome. Retinal involvement is universal, early-onset, and overall, the retinal and FAF features are consistent with rod-cone degeneration that is slowly progressive over time. The sub-foveal retinal ultrastructure is relatively preserved in majority of patients. Phenotypic variability independent of age exists, and more study of allelic- and sex-based determinants of disease severity are necessary.
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Affiliation(s)
- Brian G Ballios
- Department of Ophthalmology and Vision Sciences, University of Toronto, Toronto, ON, Canada
| | - Amarilla Mandola
- Division of Immunology and Allergy, The Hospital for Sick Children and the University of Toronto, Toronto, ON, Canada
| | - Alaa Tayyib
- Department of Ophthalmology and Vision Sciences, University of Toronto, Toronto, ON, Canada
- Department of Ophthalmology and Vision Sciences, The Hospital for Sick Children, Toronto, ON, Canada
| | - Anupreet Tumber
- Department of Ophthalmology and Vision Sciences, The Hospital for Sick Children, Toronto, ON, Canada
| | - Jenny Garkaby
- Division of Immunology and Allergy, The Hospital for Sick Children and the University of Toronto, Toronto, ON, Canada
| | - Linda Vong
- The Canadian Centre for Primary Immunodeficiency and The Jeffrey Modell Research Laboratory for the Diagnosis of Primary Immunodeficiency, The Hospital for Sick Children, Toronto, ON, Canada
| | - Elise Heon
- Department of Ophthalmology and Vision Sciences, University of Toronto, Toronto, ON, Canada
- Department of Ophthalmology and Vision Sciences, The Hospital for Sick Children, Toronto, ON, Canada
| | - Chaim M Roifman
- Division of Immunology and Allergy, The Hospital for Sick Children and the University of Toronto, Toronto, ON, Canada
- The Canadian Centre for Primary Immunodeficiency and The Jeffrey Modell Research Laboratory for the Diagnosis of Primary Immunodeficiency, The Hospital for Sick Children, Toronto, ON, Canada
| | - Ajoy Vincent
- Department of Ophthalmology and Vision Sciences, University of Toronto, Toronto, ON, Canada.
- Department of Ophthalmology and Vision Sciences, The Hospital for Sick Children, Toronto, ON, Canada.
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Wang H, Xu W, Li L. Tefluthrin induced toxicities in zebrafish: Focusing on enantioselectivity. PESTICIDE BIOCHEMISTRY AND PHYSIOLOGY 2023; 195:105572. [PMID: 37666624 DOI: 10.1016/j.pestbp.2023.105572] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/23/2023] [Revised: 07/25/2023] [Accepted: 08/07/2023] [Indexed: 09/06/2023]
Abstract
Tefluthrin is one of widely used chiral pyrethroid pesticides. The potential enantioselective risk posed by tefluthrin to the aquatic ecosystem is still unclear. In this study, the toxicity differences and corresponding mechanism of tefluthrin on zebrafish were investigated at the enantiomeric level. The results indicated that two tefluthrin enantiomers showed different acute toxicity, developmental toxicity and oxidative stress to zebrafish. The acute toxicity of (1R,3R)-tefluthrin was 130-176 fold as that of (1S,3S)-tefluthrin on zebrafish embryos, larvae and adults. (1R,3R)-Tefluthrin presented approximately 10, 3 and 2 times inhibition effect on the deformity rate, hatching rate and spontaneous movements on embryos as that of (1S,3S)-tefluthrin. Meanwhile, (1R,3R)-tefluthrin caused stronger oxidative stress on zebrafish embryo than (1S,3S)-tefluthrin. The molecular docking results revealed that there were stereospecific binding affinities between tefluthrin enantimers and sodium channel protein (Nav1.6), which may lead to acute toxicity differences. Transcriptome analysis showed that the two tefluthrin enantiomers markedly disturbed differential embryonic genes expression, thereby potentially causing the chronic enantioselective toxicity. The findings of the study reveal the toxicity differences and potential mechanism of tefluthrin enantiomers on zebrafish. These results also provides a foundation for a systematic evaluation of tefluthrin at enantiomer level.
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Affiliation(s)
- Hongjie Wang
- Hebei Key Laboratory of Close-to-Nature Restoration Technology of Wetlands, School of Eco-Environment, Hebei University, Baoding 071002, China; Institute of Xiong'an New Area, Hebei university, Baoding 071002, China; College of Life Science, Hebei University, Baoding 071002, China
| | - Weiye Xu
- Hebei Key Laboratory of Close-to-Nature Restoration Technology of Wetlands, School of Eco-Environment, Hebei University, Baoding 071002, China
| | - Lianshan Li
- Hebei Key Laboratory of Close-to-Nature Restoration Technology of Wetlands, School of Eco-Environment, Hebei University, Baoding 071002, China; Institute of Xiong'an New Area, Hebei university, Baoding 071002, China.
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Li S, Ma H, Yang F, Ding X. cGMP Signaling in Photoreceptor Degeneration. Int J Mol Sci 2023; 24:11200. [PMID: 37446378 PMCID: PMC10342299 DOI: 10.3390/ijms241311200] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2023] [Revised: 07/04/2023] [Accepted: 07/05/2023] [Indexed: 07/15/2023] Open
Abstract
Photoreceptors in the retina are highly specialized neurons with photosensitive molecules in the outer segment that transform light into chemical and electrical signals, and these signals are ultimately relayed to the visual cortex in the brain to form vision. Photoreceptors are composed of rods and cones. Rods are responsible for dim light vision, whereas cones are responsible for bright light, color vision, and visual acuity. Photoreceptors undergo progressive degeneration over time in many hereditary and age-related retinal diseases. Despite the remarkable heterogeneity of disease-causing genes, environmental factors, and pathogenesis, the progressive death of rod and cone photoreceptors ultimately leads to loss of vision/blindness. There are currently no treatments available for retinal degeneration. Cyclic guanosine 3', 5'-monophosphate (cGMP) plays a pivotal role in phototransduction. cGMP governs the cyclic nucleotide-gated (CNG) channels on the plasma membrane of the photoreceptor outer segments, thereby regulating membrane potential and signal transmission. By gating the CNG channels, cGMP regulates cellular Ca2+ homeostasis and signal transduction. As a second messenger, cGMP activates the cGMP-dependent protein kinase G (PKG), which regulates numerous targets/cellular events. The dysregulation of cGMP signaling is observed in varieties of photoreceptor/retinal degenerative diseases. Abnormally elevated cGMP signaling interferes with various cellular events, which ultimately leads to photoreceptor degeneration. In line with this, strategies to reduce cellular cGMP signaling result in photoreceptor protection in mouse models of retinal degeneration. The potential mechanisms underlying cGMP signaling-induced photoreceptor degeneration involve the activation of PKG and impaired Ca2+ homeostasis/Ca2+ overload, resulting from overactivation of the CNG channels, as well as the subsequent activation of the downstream cellular stress/death pathways. Thus, targeting the cellular cGMP/PKG signaling and the Ca2+-regulating pathways represents a significant strategy for photoreceptor protection in retinal degenerative diseases.
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Affiliation(s)
| | | | | | - Xiqin Ding
- Department of Cell Biology, College of Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA; (S.L.); (H.M.); (F.Y.)
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6
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Kazmierczak de Camargo JP, Prezia GNDB, Shiokawa N, Sato MT, Rosati R, Beate Winter Boldt A. New Insights on the Regulatory Gene Network Disturbed in Central Areolar Choroidal Dystrophy-Beyond Classical Gene Candidates. Front Genet 2022; 13:886461. [PMID: 35656327 PMCID: PMC9152281 DOI: 10.3389/fgene.2022.886461] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2022] [Accepted: 04/04/2022] [Indexed: 11/13/2022] Open
Abstract
Central areolar choroidal dystrophy (CACD) is a rare hereditary disease that mainly affects the macula, resulting in progressive and usually profound visual loss. Being part of congenital retinal dystrophies, it may have an autosomal dominant or recessive inheritance and, until now, has no effective treatment. Given the shortage of genotypic information about the disease, this work systematically reviews the literature for CACD-causing genes. Three independent researchers selected 33 articles after carefully searching and filtering the Scielo, Pubmed, Lilacs, Web of Science, Scopus, and Embase databases. Mutations of six genes (PRPH2, GUCA1A, GUCY2D, CDHR1, ABCA4, and TTLL5) are implicated in the monogenic dominant inheritance of CACD. They are functionally related to photoreceptors (either in the phototransduction process, as in the case of GUCY2D, or the recovery of retinal photodegradation in photoreceptors for GUCA1A, or the formation and maintenance of specific structures within photoreceptors for PRPH2). The identified genetic variants do not explain all observed clinical features, calling for further whole-genome and functional studies for this disease. A network analysis with the CACD-related genes identified in the systematic review resulted in the identification of another 20 genes that may influence CACD onset and symptoms. Furthermore, an enrichment analysis allowed the identification of 13 transcription factors and 4 long noncoding RNAs interacting with the products of the previously mentioned genes. If mutated or dysregulated, they may be directly involved in CACD development and related disorders. More than half of the genes identified by bioinformatic tools do not appear in commercial gene panels, calling for more studies about their role in the maintenance of the retina and phototransduction process, as well as for a timely update of these gene panels.
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Affiliation(s)
| | - Giovanna Nazaré de Barros Prezia
- Post-Graduation Program in Biotechnology Applied to Child and Adolescent Health, Faculdades Pequeno Príncipe and Pelé Pequeno Príncipe Research Institute, Curitiba, Brazil
| | - Naoye Shiokawa
- Retina and Vitreo Consulting Eye Clinic, Curitiba, Brazil
| | - Mario Teruo Sato
- Retina and Vitreo Consulting Eye Clinic, Curitiba, Brazil.,Department of Ophthalmol/Otorhinolaryngology, Federal University of Paraná, Curitiba, Brazil
| | - Roberto Rosati
- Post-Graduation Program in Biotechnology Applied to Child and Adolescent Health, Faculdades Pequeno Príncipe and Pelé Pequeno Príncipe Research Institute, Curitiba, Brazil
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Stockman A, Henning GB, Rider AT. Clinical vision and molecular loss: Integrating visual psychophysics with molecular genetics reveals key details of normal and abnormal visual processing. Prog Retin Eye Res 2020; 83:100937. [PMID: 33388434 DOI: 10.1016/j.preteyeres.2020.100937] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2020] [Revised: 12/11/2020] [Accepted: 12/17/2020] [Indexed: 01/08/2023]
Abstract
Over the past two decades we have developed techniques and models to investigate the ways in which known molecular defects affect visual performance. Because molecular defects in retinal signalling invariably alter the speed of visual processing, our strategy has been to measure the resulting changes in flicker sensitivity. Flicker measurements provide not only straightforward clinical assessments of visual performance but also reveal fundamental details about the functioning of both abnormal and normal visual systems. Here, we bring together our past measurements of patients with pathogenic variants in the GNAT2, RGS9, GUCA1A, RPE65, OPA1, KCNV2 and NR2E3 genes and analyse the results using a standard model of visual processing. The model treats flicker sensitivity as the result of the actions of a sequence of simple processing steps, one or more of which is altered by the genetic defect. Our analyses show that most defects slow down the visual response directly, but some speed it up. Crucially, however, other steps in the processing sequence can make compensatory adjustments to offset the abnormality. For example, if the abnormal step slows down the visual response, another step is likely to speed up or attenuate the response to rebalance system performance. Such compensatory adjustments are probably made by steps in the sequence that usually adapt to changing light levels. Our techniques and modelling also allow us to tease apart stationary and progressive effects, and the localised molecular losses help us to unravel and characterise individual steps in the normal and abnormal processing sequences.
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Affiliation(s)
- Andrew Stockman
- UCL Institute of Ophthalmology, 11-43 Bath Street, London, EC1V 9EL, England, UK.
| | - G Bruce Henning
- UCL Institute of Ophthalmology, 11-43 Bath Street, London, EC1V 9EL, England, UK
| | - Andrew T Rider
- UCL Institute of Ophthalmology, 11-43 Bath Street, London, EC1V 9EL, England, UK
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Abstract
Inherited retinal diseases (IRD) are a leading cause of blindness in the working age population. The advances in ocular genetics, retinal imaging and molecular biology, have conspired to create the ideal environment for establishing treatments for IRD, with the first approved gene therapy and the commencement of multiple therapy trials. The scope of this review is to familiarize clinicians and scientists with the current landscape of retinal imaging in IRD. Herein we present in a comprehensive and concise manner the imaging findings of: (I) macular dystrophies (MD) [Stargardt disease (ABCA4), X-linked retinoschisis (RS1), Best disease (BEST1), pattern dystrophy (PRPH2), Sorsby fundus dystrophy (TIMP3), and autosomal dominant drusen (EFEMP1)], (II) cone and cone-rod dystrophies (GUCA1A, PRPH2, ABCA4 and RPGR), (III) cone dysfunction syndromes [achromatopsia (CNGA3, CNGB3, PDE6C, PDE6H, GNAT2, ATF6], blue-cone monochromatism (OPN1LW/OPN1MW array), oligocone trichromacy, bradyopsia (RGS9/R9AP) and Bornholm eye disease (OPN1LW/OPN1MW), (IV) Leber congenital amaurosis (GUCY2D, CEP290, CRB1, RDH12, RPE65, TULP1, AIPL1 and NMNAT1), (V) rod-cone dystrophies [retinitis pigmentosa, enhanced S-Cone syndrome (NR2E3), Bietti crystalline corneoretinal dystrophy (CYP4V2)], (VI) rod dysfunction syndromes (congenital stationary night blindness, fundus albipunctatus (RDH5), Oguchi disease (SAG, GRK1), and (VII) chorioretinal dystrophies [choroideremia (CHM), gyrate atrophy (OAT)].
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Affiliation(s)
- Michalis Georgiou
- UCL Institute of Ophthalmology, University College London, London, UK.,Moorfields Eye Hospital NHS Foundation Trust, London, UK
| | - Kaoru Fujinami
- UCL Institute of Ophthalmology, University College London, London, UK.,Moorfields Eye Hospital NHS Foundation Trust, London, UK.,Laboratory of Visual Physiology, Division of Vision Research, National Institute of Sensory Organs, National Hospital Organization Tokyo Medical Center, Tokyo, Japan
| | - Michel Michaelides
- UCL Institute of Ophthalmology, University College London, London, UK.,Moorfields Eye Hospital NHS Foundation Trust, London, UK
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Role of GUCA1C in Primary Congenital Glaucoma and in the Retina: Functional Evaluation in Zebrafish. Genes (Basel) 2020; 11:genes11050550. [PMID: 32422965 PMCID: PMC7288452 DOI: 10.3390/genes11050550] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2020] [Revised: 05/06/2020] [Accepted: 05/12/2020] [Indexed: 12/29/2022] Open
Abstract
Primary congenital glaucoma (PCG) is a heterogeneous, inherited, and severe optical neuropathy caused by apoptotic degeneration of the retinal ganglion cell layer. Whole-exome sequencing analysis of one PCG family identified two affected siblings who carried a low-frequency homozygous nonsense GUCA1C variant (c.52G > T/p.Glu18Ter/rs143174402). This gene encodes GCAP3, a member of the guanylate cyclase activating protein family, involved in phototransduction and with a potential role in intraocular pressure regulation. Segregation analysis supported the notion that the variant was coinherited with the disease in an autosomal recessive fashion. GCAP3 was detected immunohistochemically in the adult human ocular ciliary epithelium and retina. To evaluate the ocular effect of GUCA1C loss-of-function, a guca1c knockout zebrafish line was generated by CRISPR/Cas9 genome editing. Immunohistochemistry demonstrated the presence of GCAP3 in the non-pigmented ciliary epithelium and retina of adult wild-type fishes. Knockout animals presented up-regulation of the glial fibrillary acidic protein in Müller cells and evidence of retinal ganglion cell apoptosis, indicating the existence of gliosis and glaucoma-like retinal damage. In summary, our data provide evidence for the role of GUCA1C as a candidate gene in PCG and offer new insights into the function of this gene in the ocular anterior segment and the retina.
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10
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GCAP neuronal calcium sensor proteins mediate photoreceptor cell death in the rd3 mouse model of LCA12 congenital blindness by involving endoplasmic reticulum stress. Cell Death Dis 2020; 11:62. [PMID: 31980596 PMCID: PMC6981271 DOI: 10.1038/s41419-020-2255-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2019] [Revised: 01/09/2020] [Accepted: 01/10/2020] [Indexed: 01/01/2023]
Abstract
Loss-of-function mutations in the retinal degeneration 3 (RD3) gene cause inherited retinopathy with impaired rod and cone function and fast retinal degeneration in patients and in the natural strain of rd3 mice. The underlying physiopathology mechanisms are not well understood. We previously proposed that guanylate cyclase-activating proteins (GCAPs) might be key Ca2+-sensors mediating the physiopathology of this disorder, based on the demonstrated toxicity of GCAP2 when blocked in its Ca2+-free form at photoreceptor inner segments. We here show that the retinal degeneration in rd3 mice is substantially delayed by GCAPs ablation. While the number of retinal photoreceptor cells is halved in 6 weeks in rd3 mice, it takes 8 months to halve in rd3/rd3 GCAPs-/- mice. Although this substantial morphological rescue does not correlate with recovery of visual function due to very diminished guanylate cyclase activity in rd3 mice, it is very informative of the mechanisms underlying photoreceptor cell death. By showing that GCAP2 is mostly in its Ca2+-free-phosphorylated state in rd3 mice, we infer that the [Ca2+]i at rod inner segments is permanently low. GCAPs are therefore retained at the inner segment in their Ca2+-free, guanylate cyclase activator state. We show that in this conformational state GCAPs induce endoplasmic reticulum (ER) stress, mitochondrial swelling, and cell death. ER stress and mitochondrial swelling are early hallmarks of rd3 retinas preceding photoreceptor cell death, that are substantially rescued by GCAPs ablation. By revealing the involvement of GCAPs-induced ER stress in the physiopathology of Leber's congenital amaurosis 12 (LCA12), this work will aid to guide novel therapies to preserve retinal integrity in LCA12 patients to expand the window for gene therapy intervention to restore vision.
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Brader HS, Athappilly GK, Loewenstein J. Retinal Toxicity Associated With Excessive Sildenafil Ingestion. JAMA Ophthalmol 2019; 137:326-328. [PMID: 30629106 DOI: 10.1001/jamaophthalmol.2018.3652] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
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Gill JS, Georgiou M, Kalitzeos A, Moore AT, Michaelides M. Progressive cone and cone-rod dystrophies: clinical features, molecular genetics and prospects for therapy. Br J Ophthalmol 2019; 103:bjophthalmol-2018-313278. [PMID: 30679166 PMCID: PMC6709772 DOI: 10.1136/bjophthalmol-2018-313278] [Citation(s) in RCA: 109] [Impact Index Per Article: 21.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2018] [Revised: 11/23/2018] [Accepted: 11/29/2018] [Indexed: 12/16/2022]
Abstract
Progressive cone and cone-rod dystrophies are a clinically and genetically heterogeneous group of inherited retinal diseases characterised by cone photoreceptor degeneration, which may be followed by subsequent rod photoreceptor loss. These disorders typically present with progressive loss of central vision, colour vision disturbance and photophobia. Considerable progress has been made in elucidating the molecular genetics and genotype-phenotype correlations associated with these dystrophies, with mutations in at least 30 genes implicated in this group of disorders. We discuss the genetics, and clinical, psychophysical, electrophysiological and retinal imaging characteristics of cone and cone-rod dystrophies, focusing particularly on four of the most common disease-associated genes: GUCA1A, PRPH2, ABCA4 and RPGR Additionally, we briefly review the current management of these disorders and the prospects for novel therapies.
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Affiliation(s)
- Jasdeep S Gill
- UCL Institute of Ophthalmology, University College London, London, UK
| | - Michalis Georgiou
- UCL Institute of Ophthalmology, University College London, London, UK
- Moorfields Eye Hospital NHS Foundation Trust, London, UK
| | - Angelos Kalitzeos
- UCL Institute of Ophthalmology, University College London, London, UK
- Moorfields Eye Hospital NHS Foundation Trust, London, UK
| | - Anthony T Moore
- UCL Institute of Ophthalmology, University College London, London, UK
- Ophthalmology Department, University of California San Francisco School of Medicine, San Francisco, California, USA
| | - Michel Michaelides
- UCL Institute of Ophthalmology, University College London, London, UK
- Moorfields Eye Hospital NHS Foundation Trust, London, UK
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Peshenko IV, Cideciyan AV, Sumaroka A, Olshevskaya EV, Scholten A, Abbas S, Koch KW, Jacobson SG, Dizhoor AM. A G86R mutation in the calcium-sensor protein GCAP1 alters regulation of retinal guanylyl cyclase and causes dominant cone-rod degeneration. J Biol Chem 2019; 294:3476-3488. [PMID: 30622141 DOI: 10.1074/jbc.ra118.006180] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2018] [Revised: 01/04/2019] [Indexed: 11/06/2022] Open
Abstract
The guanylyl cyclase-activating protein, GCAP1, activates photoreceptor membrane guanylyl cyclase (RetGC) in the light, when free Ca2+ concentrations decline, and decelerates the cyclase in the dark, when Ca2+ concentrations rise. Here, we report a novel mutation, G86R, in the GCAP1 (GUCA1A) gene in a family with a dominant retinopathy. The G86R substitution in a "hinge" region connecting EF-hand domains 2 and 3 in GCAP1 strongly interfered with its Ca2+-dependent activator-to-inhibitor conformational transition. The G86R-GCAP1 variant activated RetGC at low Ca2+ concentrations with higher affinity than did the WT GCAP1, but failed to decelerate the cyclase at the Ca2+ concentrations characteristic of dark-adapted photoreceptors. Ca2+-dependent increase in Trp94 fluorescence, indicative of the GCAP1 transition to its RetGC inhibiting state, was suppressed and shifted to a higher Ca2+ range. Conformational changes in G86R GCAP1 detectable by isothermal titration calorimetry (ITC) also became less sensitive to Ca2+, and the dose dependence of the G86R GCAP1-RetGC1 complex inhibition by retinal degeneration 3 (RD3) protein was shifted toward higher than normal concentrations. Our results indicate that the flexibility of the hinge region between EF-hands 2 and 3 is required for placing GCAP1-regulated Ca2+ sensitivity of the cyclase within the physiological range of intracellular Ca2+ at the expense of reducing GCAP1 affinity for the target enzyme. The disease-linked mutation of the hinge Gly86, leading to abnormally high affinity for the target enzyme and reduced Ca2+ sensitivity of GCAP1, is predicted to abnormally elevate cGMP production and Ca2+ influx in photoreceptors in the dark.
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Affiliation(s)
- Igor V Peshenko
- From the Pennsylvania College of Optometry, Salus University, Elkins Park, Pennsylvania 19027
| | - Artur V Cideciyan
- the Department of Ophthalmology, University of Pennsylvania, Philadelphia, Pennsylvania 19104, and
| | - Alexander Sumaroka
- the Department of Ophthalmology, University of Pennsylvania, Philadelphia, Pennsylvania 19104, and
| | - Elena V Olshevskaya
- From the Pennsylvania College of Optometry, Salus University, Elkins Park, Pennsylvania 19027
| | - Alexander Scholten
- the Department of Neuroscience, University of Oldenburg, Oldenburg D-26129, Germany
| | - Seher Abbas
- the Department of Neuroscience, University of Oldenburg, Oldenburg D-26129, Germany
| | - Karl-Wilhelm Koch
- the Department of Neuroscience, University of Oldenburg, Oldenburg D-26129, Germany
| | - Samuel G Jacobson
- the Department of Ophthalmology, University of Pennsylvania, Philadelphia, Pennsylvania 19104, and
| | - Alexander M Dizhoor
- From the Pennsylvania College of Optometry, Salus University, Elkins Park, Pennsylvania 19027,
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Vocke F, Weisschuh N, Marino V, Malfatti S, Jacobson SG, Reiff CM, Dell'Orco D, Koch KW. Dysfunction of cGMP signalling in photoreceptors by a macular dystrophy-related mutation in the calcium sensor GCAP1. Hum Mol Genet 2017; 26:133-144. [PMID: 28025326 DOI: 10.1093/hmg/ddw374] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2016] [Accepted: 10/27/2016] [Indexed: 12/28/2022] Open
Abstract
Macular dystrophy leads to progressive loss of central vision and shows symptoms similar to age-related macular degeneration. Genetic screening of patients diagnosed with macular dystrophy disclosed a novel mutation in the GUCA1A gene, namely a c.526C > T substitution leading to the amino acid substitution p.L176F in the guanylate cyclase-activating protein 1 (GCAP1). The same variant was found in three families showing an autosomal dominant mode of inheritance. For a full functional characterization of the L176F mutant we expressed and purified the mutant protein and measured key parameters of its activating properties, its Ca2+/Mg2+-binding, and its Ca2+-induced conformational changes in comparison to the wildtype protein. The mutant was less sensitive to changes in free Ca2+, resulting in a constitutively active form under physiological Ca2+-concentration, showed significantly higher activation rates than the wildtype (90-fold versus 20-fold) and interacted with an higher apparent affinity with its target guanylate cyclase. However, direct Ca2+-binding of the mutant was nearly similar to the wildtype; binding of Mg2+ occurred with higher affinity. We performed molecular dynamics simulations for comparing the Ca2+-saturated inhibiting state of GCAP1 with the Mg2+-bound activating states. The L176F mutant exhibited significantly lower flexibility, when three Ca2+ or two Mg2+ were bound forming probably the structural basis for the modified GCAP1 function.
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Affiliation(s)
- Farina Vocke
- Department of Neuroscience, Biochemistry Group, University of Oldenburg, Oldenburg, Germany
| | - Nicole Weisschuh
- Molecular Genetics Laboratory, Institute for Ophthalmic Research, University of Tübingen, Germany
| | - Valerio Marino
- Department of Neurosciences, Biomedicine and Movement Sciences, Section of Biological Chemistry, University of Verona, Verona, Italy and
| | - Silvia Malfatti
- Department of Neurosciences, Biomedicine and Movement Sciences, Section of Biological Chemistry, University of Verona, Verona, Italy and
| | - Samuel G Jacobson
- Scheie Eye Institute, Department of Ophthalmology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Charlotte M Reiff
- Molecular Genetics Laboratory, Institute for Ophthalmic Research, University of Tübingen, Germany
| | - Daniele Dell'Orco
- Department of Neurosciences, Biomedicine and Movement Sciences, Section of Biological Chemistry, University of Verona, Verona, Italy and
| | - Karl-Wilhelm Koch
- Department of Neuroscience, Biochemistry Group, University of Oldenburg, Oldenburg, Germany
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GUCA1A mutation causes maculopathy in a five-generation family with a wide spectrum of severity. Genet Med 2017; 19:945-954. [PMID: 28125083 PMCID: PMC5548935 DOI: 10.1038/gim.2016.217] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2016] [Accepted: 11/18/2016] [Indexed: 12/19/2022] Open
Abstract
PURPOSE The aim of this study was to investigate the genetic basis and pathogenic mechanism of variable maculopathies, ranging from mild photoreceptor degeneration to central areolar choroidal dystrophy, in a five-generation family. METHODS Clinical characterizations, whole-exome sequencing, and genome-wide linkage analysis were carried out on the family. Zebrafish models were used to investigate the pathogenesis of GUCA1A mutations. RESULTS A novel mutation, GUCA1A p.R120L, was identified in the family and predicted to alter the tertiary structure of guanylyl cyclase-activating protein 1, a photoreceptor-expressed protein encoded by the GUCA1A gene. The mutation was shown in zebrafish to cause significant disruptions in photoreceptors and retinal pigment epithelium, together with atrophies of retinal vessels and choriocapillaris. Those phenotypes could not be fully rescued by exogenous wild-type GUCA1A, suggesting a likely gain-of-function mechanism for p.R120L. GUCA1A p.D100E, another mutation previously implicated in cone dystrophy, also impaired the retinal pigment epithelium and photoreceptors in zebrafish, but probably via a dominant negative effect. CONCLUSION We conclude that GUCA1A mutations could cause significant variability in maculopathies, including central areolar choroidal dystrophy, which represents a severe pattern of maculopathy. The diverse pathogenic modes of GUCA1A mutations may explain the phenotypic diversities.Genet Med advance online publication 26 January 2017.
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Marino V, Scholten A, Koch KW, Dell'Orco D. Two retinal dystrophy-associated missense mutations in GUCA1A with distinct molecular properties result in a similar aberrant regulation of the retinal guanylate cyclase. Hum Mol Genet 2015; 24:6653-66. [PMID: 26358777 DOI: 10.1093/hmg/ddv370] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2015] [Accepted: 09/04/2015] [Indexed: 11/13/2022] Open
Abstract
Two recently identified missense mutations (p. L84F and p. I107T) in GUCA1A, the gene coding for guanylate cyclase (GC)-activating protein 1 (GCAP1), lead to a phenotype ascribable to cone, cone-rod and macular dystrophies. Here, we present a thorough biochemical and biophysical characterization of the mutant proteins and their distinct molecular features. I107T-GCAP1 has nearly wild-type-like protein secondary and tertiary structures, and binds Ca(2+) with a >10-fold lower affinity than the wild-type. On the contrary, L84F-GCAP1 displays altered tertiary structure in both GC-activating and inhibiting states, and a wild type-like apparent affinity for Ca(2+). The latter mutant also shows a significantly high affinity for Mg(2+), which might be important for stabilizing the GC-activating state and inducing a cooperative mechanism for the binding of Ca(2+), so far not been observed in other GCAP1 variants. Moreover, the thermal stability of L84F-GCAP1 is particularly high in the Ca(2+)-bound, GC-inhibiting state. Molecular dynamics simulations suggest that such enhanced stability arises from a deeper burial of the myristoyl moiety within the EF1-EF2 domain. The simulations also support an allosteric mechanism connecting the myristoyl moiety to the highest-affinity Ca(2+) binding site EF3. In spite of their remarkably distinct molecular features, both mutants cause constitutive activation of the target GC at physiological Ca(2+). We conclude that the similar aberrant regulation of the target enzyme results from a similar perturbation of the GCAP1-GC interaction, which may eventually cause dysregulation of both Ca(2+) and cyclic GMP homeostasis and result in retinal degeneration.
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Affiliation(s)
- Valerio Marino
- Department of Neurological, Biomedical and Movement Sciences, Section of Biological Chemistry
| | - Alexander Scholten
- Department of Neurosciences, Biochemistry Group, University of Oldenburg, 26111 Oldenburg, Germany
| | - Karl-Wilhelm Koch
- Department of Neurosciences, Biochemistry Group, University of Oldenburg, 26111 Oldenburg, Germany
| | - Daniele Dell'Orco
- Department of Neurological, Biomedical and Movement Sciences, Section of Biological Chemistry, Centre for BioMedical Computing (CBMC), University of Verona, 37134 Verona, Italy and
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Boye SL, Peterson JJ, Choudhury S, Min SH, Ruan Q, McCullough KT, Zhang Z, Olshevskaya EV, Peshenko IV, Hauswirth WW, Ding XQ, Dizhoor AM, Boye SE. Gene Therapy Fully Restores Vision to the All-Cone Nrl(-/-) Gucy2e(-/-) Mouse Model of Leber Congenital Amaurosis-1. Hum Gene Ther 2015; 26:575-92. [PMID: 26247368 DOI: 10.1089/hum.2015.053] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Mutations in GUCY2D are the cause of Leber congenital amaurosis type 1 (LCA1). GUCY2D encodes retinal guanylate cyclase-1 (retGC1), a protein expressed exclusively in outer segments of photoreceptors and essential for timely recovery from photoexcitation. Recent clinical data show that, despite a high degree of visual disturbance stemming from a loss of cone function, LCA1 patients retain normal photoreceptor architecture, except for foveal cone outer segment abnormalities and, in some patients, foveal cone loss. These results point to the cone-rich central retina as a target for GUCY2D replacement. LCA1 gene replacement studies thus far have been conducted in rod-dominant models (mouse) or with vectors and organisms lacking clinical translatability. Here we investigate gene replacement in the Nrl(-/-) Gucy2e(-/-) mouse, an all-cone model deficient in retGC1. We show that AAV-retGC1 treatment fully restores cone function, cone-mediated visual behavior, and guanylate cyclase activity, and preserves cones in treated Nrl(-/-) Gucy2e(-/-) mice over the long-term. A novel finding was that retinal function could be restored to levels above that in Nrl(-/-) controls, contrasting results in other models of retGC1 deficiency. We attribute this to increased cyclase activity in treated Nrl(-/-) Gucy2e(-/-) mice relative to Nrl(-/-) controls. Thus, Nrl(-/-) Gucy2e(-/-) mice possess an expanded dynamic range in ERG response to gene replacement relative to other models. Lastly, we show that a candidate clinical vector, AAV5-GRK1-GUCY2D, when delivered to adult Nrl(-/-) Gucy2e(-/-) mice, restores retinal function that persists for at least 6 months. Our results provide strong support for clinical application of a gene therapy targeted to the cone-rich, central retina of LCA1 patients.
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Affiliation(s)
- Sanford L Boye
- 1 Department of Ophthalmology, College of Medicine, University of Florida , Gainesville, Florida
| | - James J Peterson
- 1 Department of Ophthalmology, College of Medicine, University of Florida , Gainesville, Florida
| | - Shreyasi Choudhury
- 1 Department of Ophthalmology, College of Medicine, University of Florida , Gainesville, Florida
| | - Seok Hong Min
- 1 Department of Ophthalmology, College of Medicine, University of Florida , Gainesville, Florida
| | - Qing Ruan
- 1 Department of Ophthalmology, College of Medicine, University of Florida , Gainesville, Florida
| | - K Tyler McCullough
- 1 Department of Ophthalmology, College of Medicine, University of Florida , Gainesville, Florida
| | - Zhonghong Zhang
- 1 Department of Ophthalmology, College of Medicine, University of Florida , Gainesville, Florida
| | - Elena V Olshevskaya
- 2 Department of Basic Sciences Research, Salus University , Elkins Park, Pennsylvania
| | - Igor V Peshenko
- 2 Department of Basic Sciences Research, Salus University , Elkins Park, Pennsylvania
| | - William W Hauswirth
- 1 Department of Ophthalmology, College of Medicine, University of Florida , Gainesville, Florida
| | - Xi-Qin Ding
- 3 Department of Cell Biology, College of Medicine, University of Oklahoma , Oklahoma City, Oklahoma
| | - Alexander M Dizhoor
- 2 Department of Basic Sciences Research, Salus University , Elkins Park, Pennsylvania
| | - Shannon E Boye
- 1 Department of Ophthalmology, College of Medicine, University of Florida , Gainesville, Florida
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Electrophysiological testing as a method of cone–rod and cone dystrophy diagnoses and prediction of disease progression. Doc Ophthalmol 2015; 130:103-9. [DOI: 10.1007/s10633-015-9479-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2014] [Accepted: 01/05/2015] [Indexed: 10/24/2022]
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Duncker T, Tsang SH, Lee W, Zernant J, Allikmets R, Delori FC, Sparrow JR. Quantitative fundus autofluorescence distinguishes ABCA4-associated and non-ABCA4-associated bull's-eye maculopathy. Ophthalmology 2014; 122:345-55. [PMID: 25283059 DOI: 10.1016/j.ophtha.2014.08.017] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2014] [Revised: 06/26/2014] [Accepted: 08/06/2014] [Indexed: 11/30/2022] Open
Abstract
PURPOSE Quantitative fundus autofluorescence (qAF) and spectral-domain optical coherence tomography (SD OCT) were performed in patients with bull's-eye maculopathy (BEM) to identify phenotypic markers that can aid in the differentiation of ABCA4-associated and non-ABCA4-associated disease. DESIGN Prospective cross-sectional study at an academic referral center. SUBJECTS Thirty-seven BEM patients (age range, 8-60 years) were studied. All patients exhibited a localized macular lesion exhibiting a smooth contour and qualitatively normal-appearing surrounding retina without flecks. Control values consisted of previously published data from 277 healthy subjects (374 eyes; age range, 5-60 years) without a family history of retinal dystrophy. METHODS Autofluorescence (AF) images (30°, 488-nm excitation) were acquired with a confocal scanning laser ophthalmoscope equipped with an internal fluorescent reference to account for variable laser power and detector sensitivity. The grey levels (GLs) from 8 circularly arranged segments positioned at an eccentricity of approximately 7° to 9° in each image were calibrated to the reference (0 GL), magnification, and normative optical media density to yield qAF. In addition, horizontal SD OCT images through the fovea were obtained. All patients were screened for ABCA4 mutations using the ABCR600 microarray, next-generation sequencing, or both. MAIN OUTCOME MEASURES Quantitative AF, correlations between AF and SD OCT, and genotyping for ABCA4 variants. RESULTS ABCA4 mutations were identified in 22 patients, who tended to be younger (mean age, 21.9±8.3 years) than patients without ABCA4 mutations (mean age, 42.1±14.9 years). Whereas phenotypic differences were not obvious on the basis of qualitative fundus AF and SD OCT imaging, with qAF, the 2 groups of patients were clearly distinguishable. In the ABCA4-positive group, 37 of 41 eyes (19 of 22 patients) had qAF8 of more than the 95% confidence interval for age. Conversely, in the ABCA4-negative group, 22 of 26 eyes (13 of 15 patients) had qAF8 within the normal range. CONCLUSIONS The qAF method can differentiate between ABCA4-associated and non-ABCA4-associated BEM and may guide clinical diagnosis and genetic testing.
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Affiliation(s)
- Tobias Duncker
- Department of Ophthalmology, Columbia University, New York, New York
| | - Stephen H Tsang
- Department of Ophthalmology, Columbia University, New York, New York; Department of Pathology and Cell Biology, Columbia University, New York, New York
| | - Winston Lee
- Department of Ophthalmology, Columbia University, New York, New York
| | - Jana Zernant
- Department of Ophthalmology, Columbia University, New York, New York
| | - Rando Allikmets
- Department of Ophthalmology, Columbia University, New York, New York; Department of Pathology and Cell Biology, Columbia University, New York, New York
| | - François C Delori
- Schepens Eye Research Institute and Department of Ophthalmology, Harvard Medical School, Boston, Massachusetts
| | - Janet R Sparrow
- Department of Ophthalmology, Columbia University, New York, New York; Department of Pathology and Cell Biology, Columbia University, New York, New York.
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Hoyo NLD, López-Begines S, Rosa JL, Chen J, Méndez A. Functional EF-hands in neuronal calcium sensor GCAP2 determine its phosphorylation state and subcellular distribution in vivo, and are essential for photoreceptor cell integrity. PLoS Genet 2014; 10:e1004480. [PMID: 25058152 PMCID: PMC4109901 DOI: 10.1371/journal.pgen.1004480] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2013] [Accepted: 05/17/2014] [Indexed: 11/18/2022] Open
Abstract
The neuronal calcium sensor proteins GCAPs (guanylate cyclase activating proteins) switch between Ca2+-free and Ca2+-bound conformational states and confer calcium sensitivity to guanylate cyclase at retinal photoreceptor cells. They play a fundamental role in light adaptation by coupling the rate of cGMP synthesis to the intracellular concentration of calcium. Mutations in GCAPs lead to blindness. The importance of functional EF-hands in GCAP1 for photoreceptor cell integrity has been well established. Mutations in GCAP1 that diminish its Ca2+ binding affinity lead to cell damage by causing unabated cGMP synthesis and accumulation of toxic levels of free cGMP and Ca2+. We here investigate the relevance of GCAP2 functional EF-hands for photoreceptor cell integrity. By characterizing transgenic mice expressing a mutant form of GCAP2 with all EF-hands inactivated (EF−GCAP2), we show that GCAP2 locked in its Ca2+-free conformation leads to a rapid retinal degeneration that is not due to unabated cGMP synthesis. We unveil that when locked in its Ca2+-free conformation in vivo, GCAP2 is phosphorylated at Ser201 and results in phospho-dependent binding to the chaperone 14-3-3 and retention at the inner segment and proximal cell compartments. Accumulation of phosphorylated EF−GCAP2 at the inner segment results in severe toxicity. We show that in wildtype mice under physiological conditions, 50% of GCAP2 is phosphorylated correlating with the 50% of the protein being retained at the inner segment. Raising mice under constant light exposure, however, drastically increases the retention of GCAP2 in its Ca2+-free form at the inner segment. This study identifies a new mechanism governing GCAP2 subcellular distribution in vivo, closely related to disease. It also identifies a pathway by which a sustained reduction in intracellular free Ca2+ could result in photoreceptor damage, relevant for light damage and for those genetic disorders resulting in “equivalent-light” scenarios. Visual perception is initiated at retinal photoreceptor cells, where light activates an enzymatic cascade that reduces free cGMP. As cGMP drops, cGMP-channels close and reduce the inward current –including Ca2+ influx– so that photoreceptors hyperpolarize and emit a signal. As the light extinguishes, cGMP levels are restored to reestablish sensitivity. cGMP synthesis relies on guanylate cyclase/guanylate cyclase activating protein (RetGC/GCAP) complexes. GCAPs link the rate of cGMP synthesis to intracellular Ca2+ levels, by switching between a Ca2+-free state that activates cGMP synthesis during light exposure, and a Ca2+-bound state that arrests cGMP synthesis in the dark. It is established that GCAP1 mutations linked to adCORD disrupt this tight Ca2+ control of the cGMP levels. We here show that a GCAP2 functional transition from the Ca2+-free to the Ca2+-loaded form is essential for photoreceptor cell integrity, by a non-related mechanism. We show that GCAP2 locked in its Ca2+-free form is retained by phosphorylation and 14-3-3 binding to the proximal rod compartments, causing severe cell damage. This study identifies a pathway by which a sustained reduction in intracellular free Ca2+ could result in photoreceptor damage, relevant for light damage and for those genetic disorders resulting in “equivalent-light” scenarios.
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Affiliation(s)
| | | | - Jose Luis Rosa
- Department of Physiological Sciences II, University of Barcelona-Bellvitge Health Science Campus, Barcelona, Spain
| | - Jeannie Chen
- Department of Cell and Neurobiology, Zilkha Neurogenetic Institute, Keck School of Medicine, University of Southern California, Los Angeles, California, United States of America
| | - Ana Méndez
- Bellvitge Biomedical Research Institute (IDIBELL), Barcelona, Spain
- Department of Pathology and Experimental Therapeutics, University of Barcelona-Bellvitge Health Science Campus, Barcelona, Spain
- * E-mail:
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Jiang L, Frederick JM, Baehr W. RNA interference gene therapy in dominant retinitis pigmentosa and cone-rod dystrophy mouse models caused by GCAP1 mutations. Front Mol Neurosci 2014; 7:25. [PMID: 24778606 PMCID: PMC3985072 DOI: 10.3389/fnmol.2014.00025] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2014] [Accepted: 03/19/2014] [Indexed: 12/26/2022] Open
Abstract
RNA interference (RNAi) knockdown is an efficacious therapeutic strategy for silencing genes causative for dominant retinal dystrophies. To test this, we used self-complementary (sc) AAV2/8 vector to develop an RNAi-based therapy in two dominant retinal degeneration mouse models. The allele-specific model expresses transgenic bovine GCAP1(Y99C) establishing a rapid RP-like phenotype, whereas the nonallele-specific model expresses mouse GCAP1(L151F) producing a slowly progressing cone-rod dystrophy (CORD). The late onset GCAP1(L151F)-CORD mimics the dystrophy observed in human GCAP1-CORD patients. Subretinal injection of scAAV2/8 carrying shRNA expression cassettes specific for bovine or mouse guanylate cyclase-activating protein 1 (GCAP1) showed strong expression at 1 week post-injection. In both allele-specific [GCAP1(Y99C)-RP] and nonallele-specific [GCAP1(L151F)-CORD] models of dominant retinal dystrophy, RNAi-mediated gene silencing enhanced photoreceptor survival, delayed onset of degeneration and improved visual function. Such results provide a "proof of concept" toward effective RNAi-based gene therapy mediated by scAAV2/8 for dominant retinal disease based on GCAP1 mutation. Further, nonallele-specific RNAi knockdown of GCAP1 may prove generally applicable toward the rescue of any human GCAP1-based dominant cone-rod dystrophy.
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Affiliation(s)
- Li Jiang
- Department of Ophthalmology and Visual Sciences, John A. Moran Eye Center, University of Utah Health Science Center Salt Lake City, UT, USA
| | - Jeanne M Frederick
- Department of Ophthalmology and Visual Sciences, John A. Moran Eye Center, University of Utah Health Science Center Salt Lake City, UT, USA
| | - Wolfgang Baehr
- Department of Ophthalmology and Visual Sciences, John A. Moran Eye Center, University of Utah Health Science Center Salt Lake City, UT, USA ; Department of Biology, University of Utah Salt Lake City, UT, USA ; Department of Neurobiology and Anatomy, University of Utah Health Science Center Salt Lake City, UT, USA
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Nong E, Lee W, Merriam JE, Allikmets R, Tsang SH. Disease progression in autosomal dominant cone-rod dystrophy caused by a novel mutation (D100G) in the GUCA1A gene. Doc Ophthalmol 2013; 128:59-67. [PMID: 24352742 DOI: 10.1007/s10633-013-9420-z] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2013] [Accepted: 12/05/2013] [Indexed: 11/30/2022]
Abstract
PURPOSE To document longitudinal fundus autofluorescence (FAF) and electroretinogram (ERG) findings in a family with cone-rod dystrophy (CRD) caused by a novel missense mutation (D100G) in the GUCA1A gene. METHODS Observational case series. RESULTS Three family members 26-49 years old underwent complete clinical examinations. In all patients, funduscopic findings showed intraretinal pigment migration, loss of neurosensory retinal pigment epithelium, and macular atrophy. FAF imaging revealed the presence of a progressive hyperautofluorescent ring around a hypoautofluorescent center corresponding to macular atrophy. Full-field ERGs showed a more severe loss of cone than rod function in each patient. Thirty-hertz flicker responses fell far below normal limits. Longitudinal FAF and ERG findings in one patient suggested progressive CRD. Two more advanced patients exhibited reduced rod response consistent with disease stage. Direct sequencing of the GUCA1A gene revealed a new missense mutation, p.Asp100Gly (D100G), in each patient. CONCLUSION Patients with autosomal dominant CRD caused by a D100G mutation in GUCA1A exhibit progressive vision loss early within the first decade of life identifiable by distinct ERG characteristics and subsequent genetic testing.
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Affiliation(s)
- Eva Nong
- Department of Ophthalmology, Columbia University, New York, NY, USA
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Novel GUCA1A mutations suggesting possible mechanisms of pathogenesis in cone, cone-rod, and macular dystrophy patients. BIOMED RESEARCH INTERNATIONAL 2013; 2013:517570. [PMID: 24024198 PMCID: PMC3759255 DOI: 10.1155/2013/517570] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/18/2013] [Accepted: 06/19/2013] [Indexed: 01/06/2023]
Abstract
Here, we report two novel GUCA1A (the gene for guanylate cyclase activating protein 1) mutations identified in unrelated Spanish families affected by autosomal dominant retinal degeneration (adRD) with cone and rod involvement. All patients from a three-generation adRD pedigree underwent detailed ophthalmic evaluation. Total genome scan using single-nucleotide polymorphisms and then the linkage analysis were undertaken on the pedigree. Haplotype analysis revealed a 55.37 Mb genomic interval cosegregating with the disease phenotype on chromosome 6p21.31-q15. Mutation screening of positional candidate genes found a heterozygous transition c.250C>T in exon 4 of GUCA1A, corresponding to a novel mutation p.L84F. A second missense mutation, c.320T>C (p.I107T), was detected by screening of the gene in a Spanish patients cohort. Using bioinformatics approach, we predicted that either haploinsufficiency or dominant-negative effect accompanied by creation of a novel function for the mutant protein is a possible mechanism of the disease due to c.250C>T and c.320T>C. Although additional functional studies are required, our data in relation to the c.250C>T mutation open the possibility that transacting factors binding to de novo created recognition site resulting in formation of aberrant splicing variant is a disease model which may be more widespread than previously recognized as a mechanism causing inherited RD.
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Zahlava J, Lestak J, Karel I. Optical coherence tomography in progressive cone dystrophy. Biomed Pap Med Fac Univ Palacky Olomouc Czech Repub 2013; 158:628-34. [PMID: 23549508 DOI: 10.5507/bp.2013.017] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2012] [Accepted: 02/27/2013] [Indexed: 11/23/2022] Open
Abstract
AIM The aim of the study was to analyse different clinical pictures in patients with progressive cone dystrophy (PCD), to compare these with the results of optical coherence tomography (OCT) and to evaluate the benefits of this method for diagnosis. METHODS The group consisted of 16 patients (32 eyes) with PCD. All patients were examined for visual acuity, colour sense and visual field. We performed biomicroscopic examination, photo-documentation, fluorescein angiography, electrophysiological tests and OCT. RESULTS Using biomicroscopy and fluorescein angiography, we found changes in the retinal pigment epithelium ranging from barely detectable changes up to the typical bull's eye appearance. In all the eyes, OCT established statistically significant reduction in the thickness and structural changes in the neuroretina of the macula. Atrophy was evident especially in the outer nuclear layer, in the photoreceptor inner segment/outer segment junction and in the retinal pigment epithelium. Visual acuity was mainly dependent on the degree to which the continuity of the photoreceptor inner segment/outer segment junction layer was maintained. Eyes with better preserved neuroretinal structure in the fovea centralis had generally less reduced thickness of the retina and a better visual acuity. CONCLUSION OCT specifies the quantitative and qualitative changes in the macula and may contribute significantly to the diagnosis of the progressive cone dystrophy, particularly in the early stages of the disease which is difficult to diagnose.
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Affiliation(s)
- Jiri Zahlava
- Eye department of the Clinic JL, V Hurkach 1296, 158 00 Prague 5, Czech Republic
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Zhang X, Greenlee MHW, Serb JM. EnRICH: Extraction and Ranking using Integration and Criteria Heuristics. BMC SYSTEMS BIOLOGY 2013; 7:4. [PMID: 23320748 PMCID: PMC3564850 DOI: 10.1186/1752-0509-7-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/11/2012] [Accepted: 01/07/2013] [Indexed: 11/10/2022]
Abstract
Background High throughput screening technologies enable biologists to generate candidate genes at a rate that, due to time and cost constraints, cannot be studied by experimental approaches in the laboratory. Thus, it has become increasingly important to prioritize candidate genes for experiments. To accomplish this, researchers need to apply selection requirements based on their knowledge, which necessitates qualitative integration of heterogeneous data sources and filtration using multiple criteria. A similar approach can also be applied to putative candidate gene relationships. While automation can assist in this routine and imperative procedure, flexibility of data sources and criteria must not be sacrificed. A tool that can optimize the trade-off between automation and flexibility to simultaneously filter and qualitatively integrate data is needed to prioritize candidate genes and generate composite networks from heterogeneous data sources. Results We developed the java application, EnRICH (Extraction and Ranking using Integration and Criteria Heuristics), in order to alleviate this need. Here we present a case study in which we used EnRICH to integrate and filter multiple candidate gene lists in order to identify potential retinal disease genes. As a result of this procedure, a candidate pool of several hundred genes was narrowed down to five candidate genes, of which four are confirmed retinal disease genes and one is associated with a retinal disease state. Conclusions We developed a platform-independent tool that is able to qualitatively integrate multiple heterogeneous datasets and use different selection criteria to filter each of them, provided the datasets are tables that have distinct identifiers (required) and attributes (optional). With the flexibility to specify data sources and filtering criteria, EnRICH automatically prioritizes candidate genes or gene relationships for biologists based on their specific requirements. Here, we also demonstrate that this tool can be effectively and easily used to apply highly specific user-defined criteria and can efficiently identify high quality candidate genes from relatively sparse datasets.
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Affiliation(s)
- Xia Zhang
- Department of Biomedical Sciences, 2008 Veterinary Medicine, Iowa State University, Ames, IA 50010, USA
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Retinal guanylyl cyclase isozyme 1 is the preferential in vivo target for constitutively active GCAP1 mutants causing congenital degeneration of photoreceptors. J Neurosci 2012; 32:7208-17. [PMID: 22623665 DOI: 10.1523/jneurosci.0976-12.2012] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Two calcium-sensitive guanylyl cyclase activating proteins (GCAP1 and GCAP2) activate cGMP synthesis in photoreceptor by retinal membrane guanylyl cyclase isozymes (RetGC1 and RetGC2) to expedite recovery, but calcium-insensitive constitutively active GCAP1 mutants cause photoreceptor degeneration in human patients and transgenic mice. Although GCAP1 and GCAP2 can both activate RetGC1 and RetGC2 in vitro, we find that GCAP1 selectively regulates RetGC1 in vivo. Furthermore, elimination of RetGC1 but not RetGC2 isozyme reverses abnormal calcium sensitivity of cGMP synthesis and rescues mouse rods in transgenic mice expressing GCAP1 mutants causing photoreceptor disease. Rods expressing mutant GCAP1 not only survive in the absence of RetGC1 but also remain functional, albeit with reduced electroretinography (ERG) amplitudes typical of RetGC1-/- genotype. The rod ERG recovery from a strong flash, only slightly affected in both RetGC1-/- and RetGC2-/- mice, becomes very slow in RetGC1-/- but not RetGC2-/- mice when GCAP2 is not available to provide Ca²⁺ feedback to the remaining RetGC isozyme. The intrinsic biochemical properties of RetGC and GCAP determined in vitro do not explain the observed phenomena. Instead, our results argue that there must be a cellular mechanism that limits GCAP1 access to RetGC2 and makes RetGC1 isozyme a preferential target for the disease-causing GCAP1 mutants. A more general conclusion from our findings is that nondiscriminatory interactions between homologous effector enzymes and their regulatory proteins permitted by their intrinsic biochemical properties can be effectively restricted in a living photoreceptor.
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Thiadens AAHJ, Phan TML, Zekveld-Vroon RC, Leroy BP, van den Born LI, Hoyng CB, Klaver CCW, Roosing S, Pott JWR, van Schooneveld MJ, van Moll-Ramirez N, van Genderen MM, Boon CJF, den Hollander AI, Bergen AAB, De Baere E, Cremers FPM, Lotery AJ. Clinical course, genetic etiology, and visual outcome in cone and cone-rod dystrophy. Ophthalmology 2012; 119:819-26. [PMID: 22264887 DOI: 10.1016/j.ophtha.2011.10.011] [Citation(s) in RCA: 80] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2011] [Revised: 10/07/2011] [Accepted: 10/07/2011] [Indexed: 10/14/2022] Open
Abstract
OBJECTIVE To evaluate the clinical course, genetic etiology, and visual prognosis in patients with cone dystrophy (CD) and cone-rod dystrophy (CRD). DESIGN Clinic-based, longitudinal, multicenter study. PARTICIPANTS Consecutive probands with CD (N = 98), CRD (N = 83), and affected relatives (N = 41 and N = 17, respectively) from various ophthalmogenetic clinics in The Netherlands, Belgium, and the United Kingdom. METHODS Data on best-corrected Snellen visual acuity, color vision, ophthalmoscopy, fundus photography, Goldmann perimetry, and full-field standard electroretinogram (ERG) from all patients were registered from medical charts over a mean follow-up of 19 years. The ABCA4, CNGB3, KCNV2, PDE6C, and RPGR genes were analyzed by direct sequencing in autosomal recessive (AR) and X-linked (XL), respectively. Genotyping was not undertaken for autosomal-dominant cases. MAIN OUTCOME MEASURES The 10-year progression of all clinical parameters and cumulative lifetime risk of low vision and legal blindness were assessed. RESULTS The mean age onset for CD was 16 years (standard deviation, 11), and of CRD 12 years (standard deviation, 11; P = 0.02). The pattern of inheritance was AR in 92% of CD and 90% of CRD. Ten years after diagnosis, 35% of CD and 51% of CRD had a bull's eye maculopathy; 70% of CRD showed absolute peripheral visual field defects and 37% of CD developed rod involvement on ERG. The mean age of legal blindness was 48 (standard error [SE], 3.1) years in CD, and 35 (SE, 1.1; P<0.001) years in CRD. ABCA4 mutations were found in 8 of 90 (9%) of AR-CD, and in 17 of 65 (26%) of AR-CRD. Other mutations were detected in CNGB3 (3/90; 3%), KCNV2 (4/90; 4%), and in PDE6C (1/90; 1%). The RPGR gene was mutated in the 2 XL-CD and in 4 of 5 (80%) of XL-CRD. ABCA4 mutations as well as age of onset <20 years were significantly associated with a faster progression to legal blindness (P<0.001). CONCLUSIONS Although CD had a slightly more favorable clinical course than CRD, both disorders progressed to legal blindness in the majority of patients. Mutations in the ABCA4 gene and early onset of disease were independent prognostic parameters for visual loss. Our data may serve as an aid in counseling patients with progressive cone disorders.
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Long-term RNA interference gene therapy in a dominant retinitis pigmentosa mouse model. Proc Natl Acad Sci U S A 2011; 108:18476-81. [PMID: 22042849 DOI: 10.1073/pnas.1112758108] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
RNA interference (RNAi) gene silencing is a potential therapeutic strategy for dominant retinal degeneration disorders. We used self-complementary (sc) AAV2/8 vector to develop an RNAi-based gene therapy in a dominant retinal degeneration mouse model expressing bovine GCAP1(Y99C). We established an in vitro shRNA screening assay based on EGFP-tagged bovine GCAP1, and identified a shRNA that effectively silenced the bovine GCAP1 transgene with ∼80% efficiency. Subretinal injection of scAAV2/8 carrying shRNA expression cassette showed robust expression as early as 1 wk after injection. The gene silencing significantly improved photoreceptor survival, delayed disease onset, and increased visual function. Our results provide a promising strategy toward effective RNAi-based gene therapy by scAAV2/8 delivery for dominant retinal diseases.
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Buch PK, Mihelec M, Cottrill P, Wilkie SE, Pearson RA, Duran Y, West EL, Michaelides M, Ali RR, Hunt DM. Dominant cone-rod dystrophy: a mouse model generated by gene targeting of the GCAP1/Guca1a gene. PLoS One 2011; 6:e18089. [PMID: 21464903 PMCID: PMC3065489 DOI: 10.1371/journal.pone.0018089] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2010] [Accepted: 02/20/2011] [Indexed: 11/30/2022] Open
Abstract
Cone dystrophy 3 (COD3) is a severe dominantly inherited retinal degeneration caused by missense mutations in GUCA1A, the gene encoding Guanylate Cyclase Activating Protein 1 (GCAP1). The role of GCAP1 in controlling cyclic nucleotide levels in photoreceptors has largely been elucidated using knock-out mice, but the disease pathology in these mice cannot be extrapolated directly to COD3 as this involves altered, rather than loss of, GCAP1 function. Therefore, in order to evaluate the pathology of this dominant disorder, we have introduced a point mutation into the murine Guca1a gene that causes an E155G amino acid substitution; this is one of the disease-causing mutations found in COD3 patients. Disease progression in this novel mouse model of cone dystrophy was determined by a variety of techniques including electroretinography (ERG), retinal histology, immunohistochemistry and measurement of cGMP levels. It was established that although retinal development was normal up to 3 months of age, there was a subsequent progressive decline in retinal function, with a far greater alteration in cone than rod responses, associated with a corresponding loss of photoreceptors. In addition, we have demonstrated that accumulation of cyclic GMP precedes the observed retinal degeneration and is likely to contribute to the disease mechanism. Importantly, this knock-in mutant mouse has many features in common with the human disease, thereby making it an excellent model to further probe disease pathogenesis and investigate therapeutic interventions.
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Affiliation(s)
- Prateek K. Buch
- University College London Institute of Ophthalmology, London, United Kingdom
| | - Marija Mihelec
- University College London Institute of Ophthalmology, London, United Kingdom
| | - Phillippa Cottrill
- University College London Institute of Ophthalmology, London, United Kingdom
| | - Susan E. Wilkie
- University College London Institute of Ophthalmology, London, United Kingdom
| | - Rachael A. Pearson
- University College London Institute of Ophthalmology, London, United Kingdom
| | - Yanai Duran
- University College London Institute of Ophthalmology, London, United Kingdom
| | - Emma L. West
- University College London Institute of Ophthalmology, London, United Kingdom
| | - Michel Michaelides
- University College London Institute of Ophthalmology, London, United Kingdom
| | - Robin R. Ali
- University College London Institute of Ophthalmology, London, United Kingdom
| | - David M. Hunt
- University College London Institute of Ophthalmology, London, United Kingdom
- School of Animal Biology, University of Western Australia, Perth, Western Australia, Australia
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Kitiratschky VBD, Glöckner CJ, Kohl S. Mutation screening of the GUCA1B gene in patients with autosomal dominant cone and cone rod dystrophy. Ophthalmic Genet 2011; 32:151-5. [PMID: 21405999 DOI: 10.3109/13816810.2011.559650] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
BACKGROUND Heterozygous mutations in GUCA1A (MIM # 600364) have been identified to cause autosomal dominantly inherited cone dystrophy, cone rod dystrophy and macular dystrophy. However, the role of GUCA1B gene mutations in inherited retinal disease has been controversial. We therefore performed a mutation analysis of the GUCA1B gene in a clinically well characterized group of patients of European and North-American geographical origin with autosomal dominantly inherited cone dystrophy and cone rod dystrophy. MATERIAL AND METHODS Twenty-four unrelated patients diagnosed with cone dystrophy or cone rod dystrophy according to standard diagnostic criteria and a family history consistent with an autosomal dominant mode of inheritance were included in the study. Mutation analysis of all coding exons of the GUCA1B gene was performed by polymerase chain reaction amplification of genomic DNA and subsequent DNA sequencing. RESULTS Three different sequence variants, c.-17T>C, c.171T>C, c.465G>T were identified. The sequence variant c.465G>T encodes a conservative amino acid substitution, p.Glu155Asp, located in EF-hand 4, the calcium binding site of GCAP2 protein. All sequence variants were previously reported in healthy subjects. CONCLUSION The absence of clearly pathogenic mutations in the selected patient group suggests that the GUCA1B gene is a minor cause for retinal degenerations in Europeans or North-Americans.
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Affiliation(s)
- Veronique B D Kitiratschky
- Molecular Genetics Laboratory, Institute for Ophthalmic Research, Centre for Ophthalmology, University of Tübingen, Tübingen, Germany.
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Langwińska-Wośko E, Szulborski K, Broniek-Kowalik K. Late onset cone dystrophy. Doc Ophthalmol 2010; 120:215-8. [DOI: 10.1007/s10633-010-9214-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2009] [Accepted: 01/07/2010] [Indexed: 10/20/2022]
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Hunt DM, Buch P, Michaelides M. Guanylate cyclases and associated activator proteins in retinal disease. Mol Cell Biochem 2009; 334:157-68. [PMID: 19941038 DOI: 10.1007/s11010-009-0331-y] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2009] [Accepted: 11/04/2009] [Indexed: 01/15/2023]
Abstract
Two isoforms of guanylate cyclase, GC1 and GC2 encoded by GUCY2D and GUCY2F, are responsible for the replenishment of cGMP in photoreceptors after exposure to light. Both are required for the normal kinetics of photoreceptor sensitivity and recovery, although disease mutations are restricted to GUCY2D. Recessive mutations in this gene cause the severe early-onset blinding disorder Leber congenital amaurosis whereas dominant mutations result in a later onset less severe cone-rod dystrophy. Cyclase activity is regulated by Ca(2+) which binds to the GC-associated proteins, GCAP1 and GCAP2 encoded by GUCA1A and GUCA1B, respectively. No recessive mutations in either of these genes have been reported. Dominant missense mutations are largely confined to the Ca(2+)-binding EF hands of the proteins. In a similar fashion to the disease mechanism for the dominant GUCY2D mutations, these mutations generally alter the sensitivity of the cyclase to inhibition as Ca(2+) levels rise following a light flash.
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Affiliation(s)
- David M Hunt
- UCL Institute of Ophthalmology, 11-43 Bath Street, London EC1V 9EL, UK.
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Abstract
BACKGROUND Cone dystrophies present with highly variable clinical findings and often limited retinal changes, which may lead to misdiagnosis. The purpose of the present review of the clinical presentation and diagnosis of cone dystrophies is to provide guidelines for improved patient care. METHODS A literature search and evaluation of the clinical findings were carried out in 450 patients with cone dystrophy examined between 1986 and 2008. RESULTS Characteristic signs are loss of visual acuity, photophobia and central scotoma. The diagnosis of cone dystrophy is determined by a full-field electroretinogram (ERG). Fundus and near-infrared autofluorescence as well as optical coherence tomography allow detection of retinal structural abnormalities even when findings from ophthalmoscopy are normal. CONCLUSION The diagnosis of cone dystrophy is difficult due to unspecific subjective symptoms and absence of characteristic ophthalmoscopic findings. The differential diagnosis of unexplained visual loss should include cone dystrophy and requires either a full-field or multifocal ERG.
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Abstract
Detailed biochemical, structural and physiological studies of the role of Ca2(+)-binding proteins in mammalian retinal neurons have yielded new insights into the function of these proteins in normal and pathological states. In phototransduction, a biochemical process that is responsible for the conversion of light into an electrical impulse, guanylate cyclases (GCs) are regulated by GC-activating proteins (GCAPs). These regulatory proteins respond to changes in cytoplasmic Ca2+ concentrations. Disruption of Ca2+ homeostasis in photoreceptor cells by genetic and environmental factors can result ultimately in degeneration of these cells. Pathogenic mutations in GC1 and GCAP1 cause autosomal recessive Leber congenital amaurosis and autosomal dominant cone dystrophy, respectively. This report provides a recent account of the advances, challenges, and possible future prospects of studying this important step in visual transduction that transcends to other neuronal Ca2+ homeostasis processes.
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Michaelides M, Hardcastle AJ, Hunt DM, Moore AT. Progressive cone and cone-rod dystrophies: phenotypes and underlying molecular genetic basis. Surv Ophthalmol 2006; 51:232-58. [PMID: 16644365 DOI: 10.1016/j.survophthal.2006.02.007] [Citation(s) in RCA: 148] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
The cone and cone-rod dystrophies form part of a heterogeneous group of retinal disorders that are an important cause of visual impairment in children and adults. There have been considerable advances made in recent years in our understanding of the pathogenesis of these retinal dystrophies, with many of the chromosomal loci and causative genes having now been identified. Mutations in 12 genes, including GUCA1A, peripherin/RDS, ABCA4 and RPGR, have been described to date; and in many cases detailed functional assessment of the effects of the encoded mutant proteins has been undertaken. This improved knowledge of disease mechanisms has raised the possibility of future treatments for these disorders, for which there are no specific therapies available at the present time.
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