1
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Ekesten B, Mäkeläinen S, Ellis S, Kjellström U, Bergström TF. Abnormal Appearance of the Area Centralis in Labrador Retrievers With an ABCA4 Loss-of-function Mutation. Transl Vis Sci Technol 2022; 11:36. [PMID: 35201338 PMCID: PMC8883171 DOI: 10.1167/tvst.11.2.36] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
PURPOSE To study retinal appearance and morphology in Labrador retrievers (LRs) heterozygous and homozygous for an ABCA4 loss-of-function mutation. METHODS Ophthalmic examination, including ophthalmoscopy and simple testing of vision, was performed in five ABCA4wt/wt, four ABCA4wt/InsC, and six ABCA4InsC/InsC LRs. Retinas were also examined with confocal scanning laser ophthalmoscopy (cSLO) and optical coherence tomography (OCT). Infrared and fundus autofluorescence (FAF) images were studied, and outer nuclear layer (ONL) and neuroretinal thickness were measured in the central and peripheral area centralis. RESULTS Clinical signs in young ABCA4InsC/InsC LRs were subtle, whereas ophthalmoscopic findings and signs of visual impairment were obvious in old ABCA4InsC/InsC LRs. Retinal appearance and vision testing was unremarkable in heterozygous LRs regardless of age. The cSLO/OCT showed abnormal morphology including ONL thinning, abnormal outer retinal layer segmentation, and focal loss of retinal pigment epithelium in the fovea equivalent in juvenile ABCA4InsC/InsC LRs. The abnormal appearance extended into the area centralis and visual streak in middle-aged ABCA4InsC/InsC and then spread more peripherally. A mild phenotype was seen on cSLO/OCT and FAF in middle-aged to old ABCA4wt/InsC LRs. CONCLUSIONS Abnormal appearance and morphology in the fovea equivalent are present in juvenile ABCA4InsC/InsC. In the older affected LRs, the visual streak and then the peripheral retina also develop an abnormal appearance. Vision deteriorates slowly, but some vision is retained throughout life. Older heterozygotes may show a mild retinal phenotype but no obvious visual impairment. The ABCA4InsC/InsC LR is a potential model for ABCA4-mediated retinopathies/juvenile-onset Stargardt disease in a species with human-sized eyes. TRANSLATIONAL RELEVANCE The ABCA4InsC mutation causes juvenile-onset abnormal appearance of the fovea equivalent in affected dogs that slowly spreads in the retina, while only a mild phenotype is seen in older carriers. This is the first non-primate, large-animal model for ABCA4-related/STGD1 retinopathies in a species with a fovea equivalent.
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Affiliation(s)
- Björn Ekesten
- Department of Clinical Sciences, Swedish University of Agricultural Sciences, Uppsala, Sweden
| | - Suvi Mäkeläinen
- Department of Animal Breeding and Genetics, Swedish University of Agricultural Sciences, Uppsala, Sweden.,Department of Medical Biochemistry and Microbiology, Comparative Genetics and Functional Genomics, Uppsala University, Uppsala, Sweden
| | | | | | - Tomas F Bergström
- Department of Animal Breeding and Genetics, Swedish University of Agricultural Sciences, Uppsala, Sweden
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2
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Schneider N, Sundaresan Y, Gopalakrishnan P, Beryozkin A, Hanany M, Levanon EY, Banin E, Ben-Aroya S, Sharon D. Inherited retinal diseases: Linking genes, disease-causing variants, and relevant therapeutic modalities. Prog Retin Eye Res 2021; 89:101029. [PMID: 34839010 DOI: 10.1016/j.preteyeres.2021.101029] [Citation(s) in RCA: 44] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2021] [Revised: 11/11/2021] [Accepted: 11/16/2021] [Indexed: 12/11/2022]
Abstract
Inherited retinal diseases (IRDs) are a clinically complex and heterogenous group of visual impairment phenotypes caused by pathogenic variants in at least 277 nuclear and mitochondrial genes, affecting different retinal regions, and depleting the vision of affected individuals. Genes that cause IRDs when mutated are unique by possessing differing genotype-phenotype correlations, varying inheritance patterns, hypomorphic alleles, and modifier genes thus complicating genetic interpretation. Next-generation sequencing has greatly advanced the identification of novel IRD-related genes and pathogenic variants in the last decade. For this review, we performed an in-depth literature search which allowed for compilation of the Global Retinal Inherited Disease (GRID) dataset containing 4,798 discrete variants and 17,299 alleles published in 31 papers, showing a wide range of frequencies and complexities among the 194 genes reported in GRID, with 65% of pathogenic variants being unique to a single individual. A better understanding of IRD-related gene distribution, gene complexity, and variant types allow for improved genetic testing and therapies. Current genetic therapeutic methods are also quite diverse and rely on variant identification, and range from whole gene replacement to single nucleotide editing at the DNA or RNA levels. IRDs and their suitable therapies thus require a range of effective disease modelling in human cells, granting insight into disease mechanisms and testing of possible treatments. This review summarizes genetic and therapeutic modalities of IRDs, provides new analyses of IRD-related genes (GRID and complexity scores), and provides information to match genetic-based therapies such as gene-specific and variant-specific therapies to the appropriate individuals.
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Affiliation(s)
- Nina Schneider
- Department of Ophthalmology, Hadassah Medical Center, Faculty of Medicine, The Hebrew University of Jerusalem, 91120, Israel
| | - Yogapriya Sundaresan
- Department of Ophthalmology, Hadassah Medical Center, Faculty of Medicine, The Hebrew University of Jerusalem, 91120, Israel
| | - Prakadeeswari Gopalakrishnan
- Department of Ophthalmology, Hadassah Medical Center, Faculty of Medicine, The Hebrew University of Jerusalem, 91120, Israel
| | - Avigail Beryozkin
- Department of Ophthalmology, Hadassah Medical Center, Faculty of Medicine, The Hebrew University of Jerusalem, 91120, Israel
| | - Mor Hanany
- Department of Ophthalmology, Hadassah Medical Center, Faculty of Medicine, The Hebrew University of Jerusalem, 91120, Israel
| | - Erez Y Levanon
- The Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat Gan, 5290002, Israel
| | - Eyal Banin
- Department of Ophthalmology, Hadassah Medical Center, Faculty of Medicine, The Hebrew University of Jerusalem, 91120, Israel
| | - Shay Ben-Aroya
- The Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat Gan, 5290002, Israel
| | - Dror Sharon
- Department of Ophthalmology, Hadassah Medical Center, Faculty of Medicine, The Hebrew University of Jerusalem, 91120, Israel.
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3
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Cremers FPM, Lee W, Collin RWJ, Allikmets R. Clinical spectrum, genetic complexity and therapeutic approaches for retinal disease caused by ABCA4 mutations. Prog Retin Eye Res 2020; 79:100861. [PMID: 32278709 PMCID: PMC7544654 DOI: 10.1016/j.preteyeres.2020.100861] [Citation(s) in RCA: 162] [Impact Index Per Article: 40.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2019] [Revised: 03/13/2020] [Accepted: 03/18/2020] [Indexed: 12/18/2022]
Abstract
The ABCA4 protein (then called a “rim protein”) was first
identified in 1978 in the rims and incisures of rod photoreceptors. The
corresponding gene, ABCA4, was cloned in 1997, and variants
were identified as the cause of autosomal recessive Stargardt disease (STGD1).
Over the next two decades, variation in ABCA4 has been
attributed to phenotypes other than the classically defined STGD1 or fundus
flavimaculatus, ranging from early onset and fast progressing cone-rod dystrophy
and retinitis pigmentosa-like phenotypes to very late onset cases of mostly mild
disease sometimes resembling, and confused with, age-related macular
degeneration. Similarly, analysis of the ABCA4 locus uncovered
a trove of genetic information, including >1200 disease-causing mutations
of varying severity, and of all types – missense, nonsense, small
deletions/insertions, and splicing affecting variants, of which many are located
deep-intronic. Altogether, this has greatly expanded our understanding of
complexity not only of the diseases caused by ABCA4 mutations,
but of all Mendelian diseases in general. This review provides an in depth
assessment of the cumulative knowledge of ABCA4-associated retinopathy –
clinical manifestations, genetic complexity, pathophysiology as well as current
and proposed therapeutic approaches.
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Affiliation(s)
- Frans P M Cremers
- Department of Human Genetics, Radboud University Medical Center, PO Box 9101, 6500 HB, Nijmegen, the Netherlands; Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, PO Box 9104, 6500 HE, Nijmegen, the Netherlands.
| | - Winston Lee
- Department of Ophthalmology, Columbia University, New York, NY, 10032, USA; Department of Genetics & Development, Columbia University, New York, NY, 10032, USA
| | - Rob W J Collin
- Department of Human Genetics, Radboud University Medical Center, PO Box 9101, 6500 HB, Nijmegen, the Netherlands; Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, PO Box 9104, 6500 HE, Nijmegen, the Netherlands
| | - Rando Allikmets
- Department of Ophthalmology, Columbia University, New York, NY, 10032, USA; Department of Pathology & Cell Biology, Columbia University, New York, NY, 10032, USA.
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4
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Collison FT, Fishman GA, Nagasaki T, Zernant J, McAnany JJ, Park JC, Allikmets R. Characteristic Ocular Features in Cases of Autosomal Recessive PROM1 Cone-Rod Dystrophy. Invest Ophthalmol Vis Sci 2019; 60:2347-2356. [PMID: 31136651 PMCID: PMC6538366 DOI: 10.1167/iovs.19-26993] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Purpose To define characteristic ocular features in a group of patients with autosomal recessive (AR) PROM1 cone-rod dystrophy (CRD). Methods Three males and one female from three unrelated families were first seen at the ages of 15 to 22 years and diagnosed with CRD. Clinical testing available for review included full-field electroretinogram (ERG) in three patients, as well as near-infrared autofluorescence (NIR-AF), spectral-domain optical coherence tomography (SD-OCT), and color fundus photography in all four patients. Whole exome sequencing (WES) was performed on all cases, and whole genome sequencing (WGS) was performed in two families. Results WES found compound heterozygous PROM1 variants in one isolated male, plus heterozygous variants in the remaining patients. WGS uncovered deleterious PROM1 variants in these two families. ERG showed markedly reduced cone-isolated amplitudes and variably reduced rod-isolated amplitudes. The dark-adapted combined rod and cone responses demonstrated notably reduced a-wave amplitudes and moderately reduced b-waves, and the resultant waveform resembled the normal rod-isolated response. On fundus examination, oval-shaped macular lesions were observed, as were several small, circular hypoautofluorescent lesions within the posterior pole on NIR-AF. Three patients showed extramacular circular atrophic lesions. Conclusions The autofluorescence changes, peripheral retinal abnormalities, and ERG findings have not been emphasized in previous reports of AR PROM1, but they became a recognizable phenotype in this cohort of patients. A similar constellation of findings may be observed in CRD due to CDHR1, a functionally related gene. The pattern of abnormalities reported herein may help to focus genetic screening in patients with these findings.
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Affiliation(s)
- Frederick T Collison
- The Pangere Center for Inherited Retinal Diseases, The Chicago Lighthouse, Chicago, Illinois, United States
| | - Gerald A Fishman
- The Pangere Center for Inherited Retinal Diseases, The Chicago Lighthouse, Chicago, Illinois, United States.,Department of Ophthalmology and Visual Sciences, The University of Illinois at Chicago, Chicago, Illinois, United States
| | - Takayuki Nagasaki
- Department of Ophthalmology, Columbia University, New York, New York, United States
| | - Jana Zernant
- Department of Ophthalmology, Columbia University, New York, New York, United States
| | - J Jason McAnany
- Department of Ophthalmology and Visual Sciences, The University of Illinois at Chicago, Chicago, Illinois, United States
| | - Jason C Park
- Department of Ophthalmology and Visual Sciences, The University of Illinois at Chicago, Chicago, Illinois, United States
| | - Rando Allikmets
- Department of Ophthalmology, Columbia University, New York, New York, United States.,Department of Pathology and Cell Biology, Columbia University, New York, New York, United States
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5
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Bauwens M, Garanto A, Sangermano R, Naessens S, Weisschuh N, De Zaeytijd J, Khan M, Sadler F, Balikova I, Van Cauwenbergh C, Rosseel T, Bauwens J, De Leeneer K, De Jaegere S, Van Laethem T, De Vries M, Carss K, Arno G, Fakin A, Webster AR, de Ravel de l'Argentière TJL, Sznajer Y, Vuylsteke M, Kohl S, Wissinger B, Cherry T, Collin RWJ, Cremers FPM, Leroy BP, De Baere E. ABCA4-associated disease as a model for missing heritability in autosomal recessive disorders: novel noncoding splice, cis-regulatory, structural, and recurrent hypomorphic variants. Genet Med 2019; 21:1761-1771. [PMID: 30670881 PMCID: PMC6752479 DOI: 10.1038/s41436-018-0420-y] [Citation(s) in RCA: 92] [Impact Index Per Article: 18.4] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2018] [Accepted: 12/17/2018] [Indexed: 12/30/2022] Open
Abstract
Purpose ABCA4-associated disease, a recessive retinal dystrophy, is hallmarked by a large proportion of patients with only one pathogenic ABCA4 variant, suggestive for missing heritability. Methods By locus-specific analysis of ABCA4, combined with extensive functional studies, we aimed to unravel the missing alleles in a cohort of 67 patients (p), with one (p = 64) or no (p = 3) identified coding pathogenic variants of ABCA4. Results We identified eight pathogenic (deep-)intronic ABCA4 splice variants, of which five are novel and six structural variants, four of which are novel, including two duplications. Together, these variants account for the missing alleles in 40.3% of patients. Furthermore, two novel variants with a putative cis-regulatory effect were identified. The common hypomorphic variant c.5603A>T p.(Asn1868Ile) was found as a candidate second allele in 43.3% of patients. Overall, we have elucidated the missing heritability in 83.6% of our cohort. In addition, we successfully rescued three deep-intronic variants using antisense oligonucleotide (AON)-mediated treatment in HEK 293-T cells and in patient-derived fibroblast cells. Conclusion Noncoding pathogenic variants, novel structural variants, and a common hypomorphic allele of the ABCA4 gene explain the majority of unsolved cases with ABCA4-associated disease, rendering this retinopathy a model for missing heritability in autosomal recessive disorders.
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Affiliation(s)
- Miriam Bauwens
- Center for Medical Genetics Ghent, Ghent University and Ghent University Hospital, Ghent, Belgium
| | - Alejandro Garanto
- Department of Human Genetics, Radboud University Medical Center, Nijmegen, The Netherlands.,Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Riccardo Sangermano
- Department of Human Genetics, Radboud University Medical Center, Nijmegen, The Netherlands.,Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Sarah Naessens
- Center for Medical Genetics Ghent, Ghent University and Ghent University Hospital, Ghent, Belgium
| | - Nicole Weisschuh
- Molecular Genetics Laboratory, Institute for Ophthalmic Research, University of Tuebingen, Tuebingen, Germany
| | - Julie De Zaeytijd
- Department of Ophthalmology, Ghent University and Ghent University Hospital, Ghent, Belgium
| | - Mubeen Khan
- Department of Human Genetics, Radboud University Medical Center, Nijmegen, The Netherlands.,Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Françoise Sadler
- Molecular Genetics Laboratory, Institute for Ophthalmic Research, University of Tuebingen, Tuebingen, Germany
| | - Irina Balikova
- Department of Ophthalmology, Ghent University and Ghent University Hospital, Ghent, Belgium
| | - Caroline Van Cauwenbergh
- Center for Medical Genetics Ghent, Ghent University and Ghent University Hospital, Ghent, Belgium.,Department of Ophthalmology, Ghent University and Ghent University Hospital, Ghent, Belgium
| | - Toon Rosseel
- Center for Medical Genetics Ghent, Ghent University and Ghent University Hospital, Ghent, Belgium
| | - Jim Bauwens
- Department of Computer Science, Free University of Brussels, Brussels, Belgium
| | - Kim De Leeneer
- Center for Medical Genetics Ghent, Ghent University and Ghent University Hospital, Ghent, Belgium
| | - Sarah De Jaegere
- Center for Medical Genetics Ghent, Ghent University and Ghent University Hospital, Ghent, Belgium
| | - Thalia Van Laethem
- Center for Medical Genetics Ghent, Ghent University and Ghent University Hospital, Ghent, Belgium
| | - Meindert De Vries
- Department of Ophthalmology, Hôpital des Enfants Reine Fabiola, Brussels, Belgium
| | - Keren Carss
- Department of Haematology, University of Cambridge, NHS Blood and Transplant Centre, Cambridge, UK.,UK NIHR BioResource, Cambridge University Hospitals NHS Foundation Trust, Cambridge Biomedical Campus, Cambridge, UK
| | - Gavin Arno
- UCL Institute of Ophthalmology, London, UK
| | - Ana Fakin
- UCL Institute of Ophthalmology, London, UK.,Moorfields Eye Hospital NHS Foundation Trust, London, UK
| | - Andrew R Webster
- UCL Institute of Ophthalmology, London, UK.,Moorfields Eye Hospital NHS Foundation Trust, London, UK
| | | | - Yves Sznajer
- Centre de Génétique Humaine, Cliniques Universitaires St. Luc, Université Catholique de Louvain, Brussels, Belgium
| | | | - Susanne Kohl
- Molecular Genetics Laboratory, Institute for Ophthalmic Research, University of Tuebingen, Tuebingen, Germany
| | - Bernd Wissinger
- Molecular Genetics Laboratory, Institute for Ophthalmic Research, University of Tuebingen, Tuebingen, Germany
| | - Timothy Cherry
- Department of Pediatrics, University of Washington School of Medicine, Seattle, WA, USA.,Center for Developmental Biology and Regenerative Medicine, Seattle Children's Research Institute, Seattle, WA, USA
| | - Rob W J Collin
- Department of Human Genetics, Radboud University Medical Center, Nijmegen, The Netherlands.,Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Frans P M Cremers
- Department of Human Genetics, Radboud University Medical Center, Nijmegen, The Netherlands.,Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Bart P Leroy
- Center for Medical Genetics Ghent, Ghent University and Ghent University Hospital, Ghent, Belgium.,Department of Ophthalmology, Ghent University and Ghent University Hospital, Ghent, Belgium.,Division of Ophthalmology and Center for Cellular & Molecular Therapeutics, The Children's Hospital of Philadelphia, Philadelphia, PA, USA
| | - Elfride De Baere
- Center for Medical Genetics Ghent, Ghent University and Ghent University Hospital, Ghent, Belgium.
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6
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Nassisi M, Mohand-Saïd S, Dhaenens CM, Boyard F, Démontant V, Andrieu C, Antonio A, Condroyer C, Foussard M, Méjécase C, Eandi CM, Sahel JA, Zeitz C, Audo I. Expanding the Mutation Spectrum in ABCA4: Sixty Novel Disease Causing Variants and Their Associated Phenotype in a Large French Stargardt Cohort. Int J Mol Sci 2018; 19:E2196. [PMID: 30060493 PMCID: PMC6121640 DOI: 10.3390/ijms19082196] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2018] [Revised: 06/18/2018] [Accepted: 07/22/2018] [Indexed: 12/18/2022] Open
Abstract
Here we report novel mutations in ABCA4 with the underlying phenotype in a large French cohort with autosomal recessive Stargardt disease. The DNA samples of 397 index subjects were analyzed in exons and flanking intronic regions of ABCA4 (NM_000350.2) by microarray analysis and direct Sanger sequencing. At the end of the screening, at least two likely pathogenic mutations were found in 302 patients (76.1%) while 95 remained unsolved: 40 (10.1%) with no variants identified, 52 (13.1%) with one heterozygous mutation, and 3 (0.7%) with at least one variant of uncertain significance (VUS). Sixty-three novel variants were identified in the cohort. Three of them were variants of uncertain significance. The other 60 mutations were classified as likely pathogenic or pathogenic, and were identified in 61 patients (15.4%). The majority of those were missense (55%) followed by frameshift and nonsense (30%), intronic (11.7%) variants, and in-frame deletions (3.3%). Only patients with variants never reported in literature were further analyzed herein. Recruited subjects underwent complete ophthalmic examination including best corrected visual acuity, kinetic and static perimetry, color vision test, full-field and multifocal electroretinography, color fundus photography, short-wavelength and near-infrared fundus autofluorescence imaging, and spectral domain optical coherence tomography. Clinical evaluation of each subject confirms the tendency that truncating mutations lead to a more severe phenotype with electroretinogram (ERG) impairment (p = 0.002) and an earlier age of onset (p = 0.037). Our study further expands the mutation spectrum in the exonic and flanking regions of ABCA4 underlying Stargardt disease.
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Affiliation(s)
- Marco Nassisi
- Sorbonne Université, INSERM, CNRS, Institut de la Vision, F-75012 Paris, France.
- Department of Surgical Sciences, Eye Clinic, University of Turin, 10126 Turin, Italy.
| | - Saddek Mohand-Saïd
- Sorbonne Université, INSERM, CNRS, Institut de la Vision, F-75012 Paris, France.
- Centre Hospitalier National d'Ophtalmologie des Quinze-Vingts, DHU Sight Restore, INSERM-DHOS CIC 1423, F-75012 Paris, France.
| | - Claire-Marie Dhaenens
- Univ. Lille, Inserm UMR-S 1172, CHU Lille, Biochemistry and Molecular Biology Department-UF Génopathies, F-59000 Lille, France.
| | - Fiona Boyard
- Sorbonne Université, INSERM, CNRS, Institut de la Vision, F-75012 Paris, France.
| | - Vanessa Démontant
- Sorbonne Université, INSERM, CNRS, Institut de la Vision, F-75012 Paris, France.
| | - Camille Andrieu
- Centre Hospitalier National d'Ophtalmologie des Quinze-Vingts, DHU Sight Restore, INSERM-DHOS CIC 1423, F-75012 Paris, France.
| | - Aline Antonio
- Sorbonne Université, INSERM, CNRS, Institut de la Vision, F-75012 Paris, France.
| | - Christel Condroyer
- Sorbonne Université, INSERM, CNRS, Institut de la Vision, F-75012 Paris, France.
| | - Marine Foussard
- Sorbonne Université, INSERM, CNRS, Institut de la Vision, F-75012 Paris, France.
| | - Cécile Méjécase
- Sorbonne Université, INSERM, CNRS, Institut de la Vision, F-75012 Paris, France.
| | - Chiara Maria Eandi
- Department of Surgical Sciences, Eye Clinic, University of Turin, 10126 Turin, Italy.
| | - José-Alain Sahel
- Sorbonne Université, INSERM, CNRS, Institut de la Vision, F-75012 Paris, France.
- Centre Hospitalier National d'Ophtalmologie des Quinze-Vingts, DHU Sight Restore, INSERM-DHOS CIC 1423, F-75012 Paris, France.
- Fondation Ophtalmologique Adolphe de Rothschild, F-75019 Paris, France.
- Académie des Sciences-Institut de France, F-75006 Paris, France.
- Department of Ophthalmology, The University of Pittsburgh School of Medicine, Pittsburg, PA 15213, USA.
| | - Christina Zeitz
- Sorbonne Université, INSERM, CNRS, Institut de la Vision, F-75012 Paris, France.
| | - Isabelle Audo
- Sorbonne Université, INSERM, CNRS, Institut de la Vision, F-75012 Paris, France.
- Centre Hospitalier National d'Ophtalmologie des Quinze-Vingts, DHU Sight Restore, INSERM-DHOS CIC 1423, F-75012 Paris, France.
- Institute of Ophthalmology, University College of London, London EC1V 9EL, UK.
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7
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The Rapid-Onset Chorioretinopathy Phenotype of ABCA4 Disease. Ophthalmology 2017; 125:89-99. [PMID: 28947085 DOI: 10.1016/j.ophtha.2017.07.019] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2017] [Revised: 07/20/2017] [Accepted: 07/21/2017] [Indexed: 12/16/2022] Open
Abstract
PURPOSE To characterize patients affected by a uniquely severe, rapid-onset chorioretinopathy (ROC) phenotype of ABCA4 disease. DESIGN Comparative cohort study. PARTICIPANTS Sixteen patients were selected from a large clinically diagnosed and genetically confirmed cohort (n = 300) of patients diagnosed with ABCA4 disease. MAIN OUTCOME MEASURES Phenotypic characteristics were assessed on color fundus photographs, short-wavelength autofluorescence (488-nm), and near-infrared autofluorescence (NIR-AF, 787-nm) images. Subfoveal thickness measurements were obtained from enhanced-depth imaging OCT. Generalized retinal function was determined with full-field electroretinogram (ffERG) testing, and lipofuscin accumulation was assessed by quantitative autofluorescence (qAF). RESULTS All patients exhibited advanced disease features, including pigment migration in the macula and retinal vessel attenuation at an early age, and reported a symptomatic onset, on average, at 7.4 years (average for ABCA4 disease is 21.9 years, P < 0.0001). Deterioration of the macula was observed to begin with an intense, homogeneous signal on short-wavelength autofluorescence, which corresponds to an attenuated NIR-AF signal and progresses to a patchy, coalescing pattern of chorioretinal atrophy within the subsequent decade. Measurement of choroidal thickness revealed a more rapid thinning of choriocapillaris with age of Sattler's layer compared with the rate in most other patients with ABCA4 disease (P < 0.001). Levels of qAF in the macula before atrophy were above both the 95% confidence intervals for healthy individuals and patients with Stargardt disease (STGD1) (>1000 qAF units). Severe attenuation of cone responses and notable decreases in rod responses were detected by ffERG. Sequencing of the ABCA4 gene revealed exclusively deleterious, null mutations, including stop codons; frameshift deletions; variants in canonical splice sites, which completely abolish splicing; and known deleterious missense alleles. CONCLUSIONS The ROC phenotype is a unique classification of ABCA4 disease, which is caused by deleterious null biallelic ABCA4 mutations and is characterized by the rapid deterioration of retinal pigment epithelium and photoreceptor layers in the macula and significant choroidal thinning within the first 2 decades of life.
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8
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Strasser T, Langrova H, Sundermeier S, Hillerkuss D, Stingl K, Durst W, Kurtenbach A, Zrenner E, Zobor D. The Tuebingen Scotopic Threshold Test (TSTT). IEEE J Biomed Health Inform 2017; 22:607-610. [PMID: 28103197 DOI: 10.1109/jbhi.2017.2648891] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Measurement of the dark-adaptation threshold plays a key role in the diagnosis and estimation of disease progression of many retinal disorders. Determining the threshold is, however, difficult to perform in young children. We present here a prototype for a dark adaptometer, the Tuebingen Scotopic Threshold Test aimed to ease measurement of photoreceptor thresholds in young subjects. The device consists of two 7 cm ×10 cm fields with either blue or yellow LEDs, for testing rod or cone sensitivity, respectively. Presentation of homogenous field patterns or a flickering stimulus is also possible. The luminance threshold is measured by the method of ascending limits and the stimulus luminance, data recording and analysis are computer controlled. Preliminary results for six adults and two older children were ascertained and the influence of pupil dilation, binocular presentation, and a flickering stimulus examined. The method provides credible and consistent evaluations of the absolute threshold.
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9
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Shankar SP, Hughbanks-Wheaton DK, Birch DG, Sullivan LS, Conneely KN, Bowne SJ, Stone EM, Daiger SP. Autosomal Dominant Retinal Dystrophies Caused by a Founder Splice Site Mutation, c.828+3A>T, in PRPH2 and Protein Haplotypes in trans as Modifiers. Invest Ophthalmol Vis Sci 2016; 57:349-59. [PMID: 26842753 PMCID: PMC4736744 DOI: 10.1167/iovs.15-16965] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Purpose We determined the phenotypic variation, disease progression, and potential modifiers of autosomal dominant retinal dystrophies caused by a splice site founder mutation, c.828+3A>T, in the PRPH2 gene. Methods A total of 62 individuals (19 families) harboring the PRPH2 c.828+3A>T mutation, had phenotype analysis by fundus appearance, electrophysiology, and visual fields. The PRPH2 haplotypes in trans were sequenced for potential modifying variants and generalized estimating equations (GEE) used for statistical analysis. Results Several distinct phenotypes caused by the PRPH2 c.828+3A>T mutation were observed and fell into two clinical categories: Group I (N = 44) with mild pattern dystrophies (PD) and Group II (N = 18) with more severe cone-rod dystrophy (CRD), retinitis pigmentosa (RP), and central areolar chorioretinal dystrophy (CACD). The PRPH2 Gln304-Lys310-Asp338 protein haplotype in trans was found in Group I only (29.6% vs. 0%), whereas the Glu304-Lys310-Gly338 haplotype was predominant in Group II (94.4% vs. 70.4%). Generalized estimating equations analysis for PD versus the CRD/CACD/RP phenotypes in individuals over 43 years alone with the PRPH2 haplotypes in trans and age as predictors, adjusted for correlation within families, confirmed a significant effect of haplotype on severity (P = 0.03) with an estimated odds ratio of 7.16 (95% confidence interval [CI] = [2.8, 18.4]). Conclusions The PRPH2 c.828+3A>T mutation results in multiple distinct phenotypes likely modified by protein haplotypes in trans; the odds of having the CACD/RP-like phenotype (versus the PD phenotype) are 7.16 times greater with a Glu304-Lys310-Gly338 haplotype in trans. Further functional studies of the modifying haplotypes in trans and PRPH2 splice variants may offer therapeutic targets.
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Affiliation(s)
- Suma P Shankar
- Human Genetics Center, School of Public Health, University of Texas Health Science Center, Houston, Texas, United States 2Department of Ophthalmology and Visual Sciences, Carver College of Medicine, Stephen A. Wynn Institute for Vision Research, Universit
| | - Dianna K Hughbanks-Wheaton
- Retina Foundation of the Southwest and Department of Ophthalmology, University of Texas Southwestern Medical Center, Dallas, Texas, United States
| | - David G Birch
- Retina Foundation of the Southwest and Department of Ophthalmology, University of Texas Southwestern Medical Center, Dallas, Texas, United States
| | - Lori S Sullivan
- Human Genetics Center, School of Public Health, University of Texas Health Science Center, Houston, Texas, United States
| | - Karen N Conneely
- Department of Human Genetics, Emory University School of Medicine, Atlanta, Georgia, United States
| | - Sara J Bowne
- Human Genetics Center, School of Public Health, University of Texas Health Science Center, Houston, Texas, United States
| | - Edwin M Stone
- Department of Ophthalmology and Visual Sciences, Carver College of Medicine, Stephen A. Wynn Institute for Vision Research, University of Iowa, Iowa City, Iowa, United States
| | - Stephen P Daiger
- Human Genetics Center, School of Public Health, University of Texas Health Science Center, Houston, Texas, United States 5Ruiz Department of Ophthalmology and Visual Science, University of Texas Health Science Center, Houston, Texas, United States
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Kolesnikov AV, Maeda A, Tang PH, Imanishi Y, Palczewski K, Kefalov VJ. Retinol dehydrogenase 8 and ATP-binding cassette transporter 4 modulate dark adaptation of M-cones in mammalian retina. J Physiol 2015; 593:4923-41. [PMID: 26350353 DOI: 10.1113/jp271285] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2015] [Accepted: 09/02/2015] [Indexed: 12/13/2022] Open
Abstract
KEY POINTS This study explores the molecular mechanisms that regulate the recycling of chromophore required for pigment regeneration in mammalian cones. We report that two chromophore binding proteins, retinol dehydrogenase 8 (RDH8) and photoreceptor-specific ATP-binding cassette transporter (ABCA4) accelerate the dark adaptation of cones, first, directly, by facilitating the processing of chromophore in cones, and second, indirectly, by accelerating the turnover of chromophore in rods, which is then recycled and delivered to both rods and cones. Preventing competition with the rods by knocking out rhodopsin accelerated cone dark adaptation, demonstrating the interplay between rod and cone pigment regeneration driven by the retinal pigment epithelium (RPE). This novel interdependence of rod and cone pigment regeneration should be considered when developing therapies targeting the recycling of chromophore for rods, and evaluating residual cone function should be a critical test for such regimens targeting the RPE. ABSTRACT Rapid recycling of visual chromophore and regeneration of the visual pigment are critical for the continuous function of mammalian cone photoreceptors in daylight vision. However, the molecular mechanisms modulating the supply of visual chromophore to cones have remained unclear. Here we explored the roles of two chromophore-binding proteins, retinol dehydrogenase 8 (RDH8) and photoreceptor-specific ATP-binding cassette transporter 4 (ABCA4), in dark adaptation of mammalian cones. We report that young adult RDH8/ABCA4-deficient mice have normal M-cone morphology but reduced visual acuity and photoresponse amplitudes. Notably, the deletion of RDH8 and ABCA4 suppressed the dark adaptation of M-cones driven by both the intraretinal visual cycle and the retinal pigmented epithelium (RPE) visual cycle. This delay can be caused by two separate mechanisms: direct involvement of RDH8 and ABCA4 in cone chromophore processing, and an indirect effect from the delayed recycling of chromophore by the RPE due to its slow release from RDH8/ABCA4-deficient rods. Intriguingly, our data suggest that RDH8 could also contribute to the oxidation of cis-retinoids in cones, a key reaction of the retina visual cycle. Finally, we dissected the roles of rod photoreceptors and RPE for dark adaptation of M-cones. We found that rods suppress, whereas RPE promotes, cone dark adaptation. Thus, therapeutic approaches targeting the RPE visual cycle could have adverse effects on the function of cones, making the evaluation of residual cone function a critical test for regimens targeting the RPE.
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Affiliation(s)
- Alexander V Kolesnikov
- Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, Saint Louis, MO, 63110, USA
| | - Akiko Maeda
- Department of Ophthalmology and Visual Sciences, Case Western Reserve University, Cleveland, OH, 44106, USA.,Department of Pharmacology and Cleveland Center for Membrane and Structural Biology, Case Western Reserve University, Cleveland, OH, 44106, USA
| | - Peter H Tang
- Department of Neuroscience, Medical University of South Carolina, Charleston, SC, 29425, USA.,Department of Ophthalmology and Visual Neurosciences, University of Minnesota, Minneapolis, MN, 55455, USA
| | - Yoshikazu Imanishi
- Department of Pharmacology and Cleveland Center for Membrane and Structural Biology, Case Western Reserve University, Cleveland, OH, 44106, USA
| | - Krzysztof Palczewski
- Department of Pharmacology and Cleveland Center for Membrane and Structural Biology, Case Western Reserve University, Cleveland, OH, 44106, USA
| | - Vladimir J Kefalov
- Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, Saint Louis, MO, 63110, USA
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North V, Gelman R, Tsang SH. Juvenile-onset macular degeneration and allied disorders. DEVELOPMENTS IN OPHTHALMOLOGY 2014; 53:44-52. [PMID: 24732760 DOI: 10.1159/000357293] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
While age-related macular degeneration (AMD) is a leading cause of central vision loss among the elderly, many inherited diseases that present earlier in life share features of AMD. These diseases of juvenile-onset macular degeneration include Stargardt disease, Best disease, retinitis pigmentosa, X-linked retinoschisis, and other allied disorders. In particular, they can be accompanied by the appearance of drusen, geographic atrophy, macular hyperpigmentation, choroidal neovascularization, and disciform scarring just as in AMD, and often may be confused for the adult form of the disease. Diagnosis based on funduscopic findings alone can be challenging. However, the use of diagnostic studies such as electroretinography, electrooculography, optical coherence tomography, and fundus autofluorescence in conjunction with genetic testing can lead to an accurate diagnosis.
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Affiliation(s)
- Victoria North
- Department of Ophthalmology, University of Southern California Eye Institute, University of Southern California, Los Angeles, Calif., USA
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Zhou Y, Tao S, Chen H, Huang L, Zhu X, Li Y, Wang Z, Lin H, Hao F, Yang Z, Wang L, Zhu X. Exome sequencing analysis identifies compound heterozygous mutation in ABCA4 in a Chinese family with Stargardt disease. PLoS One 2014; 9:e91962. [PMID: 24632595 PMCID: PMC3954841 DOI: 10.1371/journal.pone.0091962] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2013] [Accepted: 02/17/2014] [Indexed: 01/17/2023] Open
Abstract
Stargardt disease is the most common cause of juvenile macular dystrophy. Five subjects from a two-generation Chinese family with Stargardt disease are reported in this study. All family members underwent complete ophthalmologic examinations. Patients of the family initiated the disease during childhood, developing progressively impaired central vision and bilateral atrophic macular lesions in the retinal pigmental epithelium (RPE) that resembled a “beaten-bronze” appearance. Peripheral venous blood was obtained from all patients and their family members for genetic analysis. Exome sequencing was used to analyze the exome of two patients II1, II2. A total of 50709 variations shared by the two patients were subjected to several filtering steps against existing variation databases. Identified variations were verified in all family members by PCR and Sanger sequencing. Compound heterozygous variants p.Y808X and p.G607R of the ATP-binding cassette, sub-family A (ABC1), member 4 (ABCA4) gene, which encodes the ABCA4 protein, a member of the ATP-binding cassette (ABC) transport superfamily, were identified as causative mutations for Stargardt disease of this family. Our findings provide one novel ABCA4 mutation in Chinese patients with Stargardt disease.
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Affiliation(s)
- Yu Zhou
- Sichuan Provincial Key Laboratory for Human Disease Gene Study and Institute of Laboratory Medicine, Sichuan Academy of Medical Sciences and Sichuan Provincial People's Hospital, Chengdu, Sichuan, China
- School of Medicine, University of Electronic Science and Technology of China, Chengdu, Sichuan, China
- Chengdu Institute of Biology, Chinese Academy of Sciences and Chinese Academy of Sciences Sichuan Translational Medicine Research Hospital, Chengdu, Sichuan, China
| | - Siyu Tao
- Henan Eye Hospital and Henan Eye Institute, People’s Hospital of Zhengzhou University, Zhengzhou, Henan, China
| | - Hui Chen
- Department of Ophthalmology, Sichuan Academy of Medical Sciences and Sichuan Provincial People’s Hospital, Chengdu, Sichuan, China
- Laboratory Animal Institute, Sichuan Academy of Medical Sciences and Sichuan Provincial People’s Hospital, Chengdu, Sichuan, China
| | - Lulin Huang
- Sichuan Provincial Key Laboratory for Human Disease Gene Study and Institute of Laboratory Medicine, Sichuan Academy of Medical Sciences and Sichuan Provincial People's Hospital, Chengdu, Sichuan, China
- School of Medicine, University of Electronic Science and Technology of China, Chengdu, Sichuan, China
- Chengdu Institute of Biology, Chinese Academy of Sciences and Chinese Academy of Sciences Sichuan Translational Medicine Research Hospital, Chengdu, Sichuan, China
| | - Xiong Zhu
- Sichuan Provincial Key Laboratory for Human Disease Gene Study and Institute of Laboratory Medicine, Sichuan Academy of Medical Sciences and Sichuan Provincial People's Hospital, Chengdu, Sichuan, China
- School of Medicine, University of Electronic Science and Technology of China, Chengdu, Sichuan, China
- Chengdu Institute of Biology, Chinese Academy of Sciences and Chinese Academy of Sciences Sichuan Translational Medicine Research Hospital, Chengdu, Sichuan, China
| | - Youping Li
- Sichuan Provincial Key Laboratory for Human Disease Gene Study and Institute of Laboratory Medicine, Sichuan Academy of Medical Sciences and Sichuan Provincial People's Hospital, Chengdu, Sichuan, China
- School of Medicine, University of Electronic Science and Technology of China, Chengdu, Sichuan, China
| | - Zhili Wang
- Henan Eye Hospital and Henan Eye Institute, People’s Hospital of Zhengzhou University, Zhengzhou, Henan, China
| | - He Lin
- Sichuan Provincial Key Laboratory for Human Disease Gene Study and Institute of Laboratory Medicine, Sichuan Academy of Medical Sciences and Sichuan Provincial People's Hospital, Chengdu, Sichuan, China
- School of Medicine, University of Electronic Science and Technology of China, Chengdu, Sichuan, China
| | - Fang Hao
- Sichuan Provincial Key Laboratory for Human Disease Gene Study and Institute of Laboratory Medicine, Sichuan Academy of Medical Sciences and Sichuan Provincial People's Hospital, Chengdu, Sichuan, China
- School of Medicine, University of Electronic Science and Technology of China, Chengdu, Sichuan, China
| | - Zhenglin Yang
- Sichuan Provincial Key Laboratory for Human Disease Gene Study and Institute of Laboratory Medicine, Sichuan Academy of Medical Sciences and Sichuan Provincial People's Hospital, Chengdu, Sichuan, China
- School of Medicine, University of Electronic Science and Technology of China, Chengdu, Sichuan, China
- Chengdu Institute of Biology, Chinese Academy of Sciences and Chinese Academy of Sciences Sichuan Translational Medicine Research Hospital, Chengdu, Sichuan, China
- Key Laboratory for NeuroInformation of Ministry of Education, University of Electronic Science and Technology of China, Chengdu, Sichuan, China
| | - Liya Wang
- Henan Eye Hospital and Henan Eye Institute, People’s Hospital of Zhengzhou University, Zhengzhou, Henan, China
- * E-mail: (XZ); (LW)
| | - Xianjun Zhu
- Sichuan Provincial Key Laboratory for Human Disease Gene Study and Institute of Laboratory Medicine, Sichuan Academy of Medical Sciences and Sichuan Provincial People's Hospital, Chengdu, Sichuan, China
- School of Medicine, University of Electronic Science and Technology of China, Chengdu, Sichuan, China
- Chengdu Institute of Biology, Chinese Academy of Sciences and Chinese Academy of Sciences Sichuan Translational Medicine Research Hospital, Chengdu, Sichuan, China
- Key Laboratory for NeuroInformation of Ministry of Education, University of Electronic Science and Technology of China, Chengdu, Sichuan, China
- College of Life Sciences and Engineering, Xinan Jiaotong University, Chengdu, Sichuan, China
- * E-mail: (XZ); (LW)
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Utz VM, Chappelow AV, Marino MJ, Beight CD, Sturgill-Short GM, Pauer GJT, Crowe S, Hagstrom SA, Traboulsi EI. Identification of three ABCA4 sequence variations exclusive to African American patients in a cohort of patients with Stargardt disease. Am J Ophthalmol 2013; 156:1220-1227.e2. [PMID: 24011517 DOI: 10.1016/j.ajo.2013.07.008] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2012] [Revised: 07/10/2013] [Accepted: 07/11/2013] [Indexed: 11/18/2022]
Abstract
PURPOSE To describe the clinical and molecular findings in ten unrelated African American patients with Stargardt disease. DESIGN Retrospective, observational case series. METHODS We reviewed the clinical histories, examinations, and genotypes of 85 patients with molecular diagnoses of Stargardt disease. Three ABCA4 sequence variations identified exclusively in African Americans were evaluated in 300 African American controls and by in silico analysis. RESULTS ABCA4 sequence changes were identified in 85 patients from 80 families, of which 11 patients identified themselves as African American. Of these 11 patients, 10 unrelated patients shared 1 of 3 ABCA4 sequence variations: c.3602T>G (p.L1201R); c.3899G>A (p.R1300Q); or c.6320G>A (p.R2107H). The minor allele frequencies in the African American control population for each variation were 7.5%, 6.3%, and 2%, respectively. This is comparable to the allele frequency in African Americans in the Exome Variant Server. In contrast, the allele frequency of all three of these variations was less than or equal to 0.05% in European Americans. Although both c.3602T>G and c.3899G>A have been reported as likely disease-causing variations, one of our control patients was homozygous for each variant, suggesting that these are nonpathogenic. In contrast, the absence of c.6320G>A in the control population in the homozygous state, combined with the results of bioinformatics analysis, support its pathogenicity. CONCLUSIONS Three ABCA4 sequence variations were identified exclusively in 10 unrelated African American patients: p.L1201R and p.R1300Q likely represent nonpathogenic sequence variants, whereas the p.R2107H substitution appears to be pathogenic. Characterization of population-specific disease alleles may have important implications for the development of genetic screening algorithms.
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Fujinami K, Zernant J, Chana RK, Wright GA, Tsunoda K, Ozawa Y, Tsubota K, Webster AR, Moore AT, Allikmets R, Michaelides M. ABCA4 gene screening by next-generation sequencing in a British cohort. Invest Ophthalmol Vis Sci 2013; 54:6662-74. [PMID: 23982839 DOI: 10.1167/iovs.13-12570] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
PURPOSE We applied a recently reported next-generation sequencing (NGS) strategy for screening the ABCA4 gene in a British cohort with ABCA4-associated disease and report novel mutations. METHODS We identified 79 patients with a clinical diagnosis of ABCA4-associated disease who had a single variant identified by the ABCA4 microarray. Comprehensive phenotypic data were obtained, and the NGS strategy was applied to identify the second allele by means of sequencing the entire coding region and adjacent intronic sequences of the ABCA4 gene. Identified variants were confirmed by Sanger sequencing and assessed for pathogenicity by in silico analysis. RESULTS Of the 42 variants detected by prescreening with the microarray, in silico analysis suggested that 34, found in 66 subjects, were disease-causing and 8, found in 13 subjects, were benign variants. We detected 42 variants by NGS, of which 39 were classified as disease-causing. Of these 39 variants, 31 were novel, including 16 missense, 7 splice-site-altering, 4 nonsense, 1 in-frame deletion, and 3 frameshift variants. Two or more disease-causing variants were confirmed in 37 (47%) of 79 patients, one disease-causing variant in 36 (46%) subjects, and no disease-causing variant in 6 (7%) individuals. CONCLUSIONS Application of the NGS platform for ABCA4 screening enabled detection of the second disease-associated allele in approximately half of the patients in a British cohort where one mutation had been detected with the arrayed primer extension (APEX) array. The time- and cost-efficient NGS strategy is useful in screening large cohorts, which will be increasingly valuable with the advent of ABCA4-directed therapies.
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Affiliation(s)
- Kaoru Fujinami
- Laboratory of Visual Physiology, National Institute of Sensory Organs, National Tokyo Medical Center, Tokyo, Japan
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Fujinami K, Sergouniotis PI, Davidson AE, Wright G, Chana RK, Tsunoda K, Tsubota K, Egan CA, Robson AG, Moore AT, Holder GE, Michaelides M, Webster AR. Clinical and molecular analysis of Stargardt disease with preserved foveal structure and function. Am J Ophthalmol 2013; 156:487-501.e1. [PMID: 23953153 DOI: 10.1016/j.ajo.2013.05.003] [Citation(s) in RCA: 84] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2013] [Revised: 05/06/2013] [Accepted: 05/06/2013] [Indexed: 12/25/2022]
Abstract
PURPOSE To describe a cohort of patients with Stargardt disease who show a foveal-sparing phenotype. DESIGN Retrospective case series. METHODS The foveal-sparing phenotype was defined as foveal preservation on autofluorescence imaging, despite a retinopathy otherwise consistent with Stargardt disease. Forty such individuals were ascertained and a full ophthalmic examination was undertaken. Following mutation screening of ABCA4, the molecular findings were compared with those of patients with Stargardt disease but no foveal sparing. RESULTS The median age of onset and age at examination of 40 patients with the foveal-sparing phenotype were 43.5 and 46.5 years. The median logMAR visual acuity was 0.18. Twenty-two patients (22/40, 55%) had patchy parafoveal atrophy and flecks; 8 (20%) had numerous flecks at the posterior pole without atrophy; 7 (17.5%) had mottled retinal pigment epithelial changes; 2 (5%) had multiple atrophic lesions, extending beyond the arcades; and 1 (2.5%) had a bull's-eye appearance. The median central foveal thickness assessed with spectral-domain optical coherence tomographic images was 183.0 μm (n = 33), with outer retinal tubulation observed in 15 (45%). Twenty-two of 33 subjects (67%) had electrophysiological evidence of macular dysfunction without generalized retinal dysfunction. Disease-causing variants were found in 31 patients (31/40, 78%). There was a higher prevalence of the variant p.Arg2030Gln in the cohort with foveal sparing compared to the group with foveal atrophy (6.45% vs 1.07%). CONCLUSIONS The distinct clinical and molecular characteristics of patients with the foveal-sparing phenotype are described. The presence of 2 distinct phenotypes of Stargardt disease (foveal sparing and foveal atrophy) suggests that there may be more than 1 disease mechanism in ABCA4 retinopathy.
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Affiliation(s)
- Kaoru Fujinami
- University College London, Institute of Ophthalmology, London, United Kingdom; Moorfields Eye Hospital, London, United Kingdom; Laboratory of Visual Physiology, National Institute of Sensory Organs, National Tokyo Medical Center, Tokyo, Japan; Department of Ophthalmology, Keio University, School of Medicine, Tokyo, Japan
| | - Panagiotis I Sergouniotis
- University College London, Institute of Ophthalmology, London, United Kingdom; Moorfields Eye Hospital, London, United Kingdom
| | - Alice E Davidson
- University College London, Institute of Ophthalmology, London, United Kingdom; Moorfields Eye Hospital, London, United Kingdom
| | - Genevieve Wright
- University College London, Institute of Ophthalmology, London, United Kingdom; Moorfields Eye Hospital, London, United Kingdom
| | - Ravinder K Chana
- University College London, Institute of Ophthalmology, London, United Kingdom; Moorfields Eye Hospital, London, United Kingdom
| | - Kazushige Tsunoda
- Laboratory of Visual Physiology, National Institute of Sensory Organs, National Tokyo Medical Center, Tokyo, Japan
| | - Kazuo Tsubota
- Department of Ophthalmology, Keio University, School of Medicine, Tokyo, Japan
| | - Catherine A Egan
- University College London, Institute of Ophthalmology, London, United Kingdom; Moorfields Eye Hospital, London, United Kingdom
| | - Anthony G Robson
- University College London, Institute of Ophthalmology, London, United Kingdom; Moorfields Eye Hospital, London, United Kingdom
| | - Anthony T Moore
- University College London, Institute of Ophthalmology, London, United Kingdom; Moorfields Eye Hospital, London, United Kingdom
| | - Graham E Holder
- University College London, Institute of Ophthalmology, London, United Kingdom; Moorfields Eye Hospital, London, United Kingdom
| | - Michel Michaelides
- University College London, Institute of Ophthalmology, London, United Kingdom; Moorfields Eye Hospital, London, United Kingdom
| | - Andrew R Webster
- University College London, Institute of Ophthalmology, London, United Kingdom; Moorfields Eye Hospital, London, United Kingdom.
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Miller JW. Age-related macular degeneration revisited--piecing the puzzle: the LXIX Edward Jackson memorial lecture. Am J Ophthalmol 2013; 155:1-35.e13. [PMID: 23245386 DOI: 10.1016/j.ajo.2012.10.018] [Citation(s) in RCA: 180] [Impact Index Per Article: 16.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2012] [Revised: 10/19/2012] [Accepted: 10/23/2012] [Indexed: 12/11/2022]
Abstract
PURPOSE To present the current understanding of age-related macular degeneration (AMD) pathogenesis, based on clinical evidence, epidemiologic data, histopathologic examination, and genetic data; to provide an update on current and emerging therapies; and to propose an integrated model of the pathogenesis of AMD. DESIGN Review of published clinical and experimental studies. METHODS Analysis and synthesis of clinical and experimental data. RESULTS We are closer to a complete understanding of the pathogenesis of AMD, having progressed from clinical observations to epidemiologic observations and clinical pathologic correlation. More recently, modern genetic and genomic studies have facilitated the exploration of molecular pathways. It seems that AMD is a complex disease that results from the interaction of genetic susceptibility with aging and environmental factors. Disease progression also seems to be driven by a combination of genetic and environmental factors. CONCLUSIONS Therapies based on pathophysiologic features have changed the paradigm for treating neovascular AMD. With improved understanding of the underlying genetic susceptibility, we can identify targets to halt early disease and to prevent progression and vision loss.
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Biswas-Fiss EE, Affet S, Ha M, Biswas SB. Retinoid binding properties of nucleotide binding domain 1 of the Stargardt disease-associated ATP binding cassette (ABC) transporter, ABCA4. J Biol Chem 2012; 287:44097-107. [PMID: 23144455 DOI: 10.1074/jbc.m112.409623] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
The retina-specific ATP binding cassette transporter, ABCA4 protein, is associated with a broad range of inherited macular degenerations, including Stargardt disease, autosomal recessive cone rod dystrophy, and fundus flavimaculatus. In order to understand its role in retinal transport in rod out segment discs, we have investigated the interactions of the soluble domains of ABCA4 with both 11-cis- and all-trans-retinal. Using fluorescence anisotropy-based binding analysis and recombinant polypeptides derived from the amino acid sequences of the four soluble domains of ABCA4, we demonstrated that the nucleotide binding domain 1 (NBD1) specifically bound 11-cis-retinal. Its affinity for all-trans-retinal was markedly reduced. Stargardt disease-associated mutations in this domain resulted in attenuation of 11-cis-retinal binding. Significant differences in 11-cis-retinal binding affinities were observed between NBD1 and other cytoplasmic and lumenal domains of ABCA4. The results suggest a possible role of ABCA4 and, in particular, the NBD1 domain in 11-cis-retinal binding. These results also correlate well with a recent report on the in vivo role of ABCA4 in 11-cis-retinal transport.
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Affiliation(s)
- Esther E Biswas-Fiss
- Department of Bioscience Technologies, Program in Biotechnology, Jefferson School of Health Professions, Thomas Jefferson University, Philadelphia, Pennsylvania 19107, USA.
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Burke TR, Fishman GA, Zernant J, Schubert C, Tsang SH, Smith RT, Ayyagari R, Koenekoop RK, Umfress A, Ciccarelli ML, Baldi A, Iannaccone A, Cremers FPM, Klaver CCW, Allikmets R. Retinal phenotypes in patients homozygous for the G1961E mutation in the ABCA4 gene. Invest Ophthalmol Vis Sci 2012; 53:4458-67. [PMID: 22661473 DOI: 10.1167/iovs.11-9166] [Citation(s) in RCA: 76] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
PURPOSE We evaluated the pathogenicity of the G1961E mutation in the ABCA4 gene, and present the range of retinal phenotypes associated with this mutation in homozygosity in a patient cohort with ABCA4-associated phenotypes. METHODS Patients were enrolled from the ABCA4 disease database at Columbia University or by inquiry from collaborating physicians. Only patients homozygous for the G1961E mutation were enrolled. The entire ABCA4 gene open reading frame, including all exons and flanking intronic sequences, was sequenced in all patients. Phenotype data were obtained from clinical history and examination, fundus photography, infrared imaging, fundus autofluorescence, fluorescein angiography, and spectral domain-optical coherence tomography. Additional functional data were obtained using the full-field electroretinogram, and static or kinetic perimetry. RESULTS We evaluated 12 patients homozygous for the G1961E mutation. All patients had evidence of retinal pathology consistent with the range of phenotypes observed in ABCA4 disease. The latest age of onset was recorded at 64 years, in a patient diagnosed initially with age-related macular degeneration (AMD). Of 6 patients in whom severe structural (with/without functional) fundus changes were detected, 5 had additional, heterozygous or homozygous, variants detected in the ABCA4 gene. CONCLUSIONS Homozygous G1961E mutation in ABCA4 results in a range of retinal pathology. The phenotype usually is at the milder end of the disease spectrum, with severe phenotypes linked to the presence of additional ABCA4 variants. Our report also highlights that milder, late-onset Stargardt disease may be confused with AMD.
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Affiliation(s)
- Tomas R Burke
- Department of Ophthalmology, Columbia University, New York, New York 10032, USA
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Hufnagel RB, Ahmed ZM, Corrêa ZM, Sisk RA. Gene therapy for Leber congenital amaurosis: advances and future directions. Graefes Arch Clin Exp Ophthalmol 2012; 250:1117-28. [PMID: 22644094 DOI: 10.1007/s00417-012-2028-2] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2011] [Revised: 03/25/2012] [Accepted: 04/03/2012] [Indexed: 01/03/2023] Open
Abstract
BACKGROUND Leber congenital amaurosis (LCA) is a congenital retinal dystrophy that results in significant and often severe vision loss at an early age. Comprehensive analysis of the genetic mutations and phenotypic correlations in LCA patients has allowed for significant improvements in understanding molecular pathways of photoreceptor degeneration and dysfunction. The purpose of this article is to review the literature on the subject of retinal gene therapy for LCA, including historical descriptions, preclinical animal studies, and human clinical trials. METHODS A literature search of peer-reviewed and indexed publications from 1996-2011 using the PubMed search engine was performed. Key terms included "Leber congenital amaurosis", LCA, RPE65, "cone-rod dystrophy", "gene therapy", and "human trials" in various combinations. Seminal articles prior to 1996 were selected from primary sources and reviews from the initial search. Articles were chosen based on pertinence to clinical, genetic, and therapeutic topics reviewed in this manuscript. Fundus photographs from LCA patients were obtained retrospectively from the clinical practice of one of the authors (R.A.S). RESULTS Herein, we reviewed the literature on LCA as a genetic disease, the results of human gene therapy trials to date, and possible future directions towards treating inherited retinal diseases at the genetic level. Original descriptions of LCA by Theodor Leber and subsequent research demonstrate the severity of this disease with early-onset blindness. Discoveries of the causative heritable mutations revealed genes and protein products involved in photoreceptor development and visual transduction. Animal models have provided a means to test novel therapeutic strategies, namely gene therapy. Stemming from these experiments, three independent clinical trials tested the safety of subretinal delivery of viral gene therapy to patients with mutations in the RPE65 gene. More recently, efficacy studies have been conducted with encouraging results. CONCLUSIONS Initial safety studies indicated promising results of subretinal delivery of viral vector with subclinical immunologic or surgical sequelae. Overall, these initial studies demonstrate that viral vector gene therapy results are very promising, safe, and effective. Future studies measuring potential improvement in photoreceptor function may rely on recent advances in retinal imaging and electrophysiologic testing.
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Affiliation(s)
- Robert B Hufnagel
- Department of Pediatrics, Division of Pediatric Ophthalmology, University of Cincinnati and Cincinnati Children's Hospital, College of Medicine, 3333 Burnet Ave, ML 7003, Cincinnati, OH 45229, USA.
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Zhang Y, Rubin GR, Fineberg N, Huisingh C, McGwin G, Pittler SJ, Kraft TW. Age-related changes in Cngb1-X1 knockout mice: prolonged cone survival. Doc Ophthalmol 2012; 124:163-75. [PMID: 22367173 DOI: 10.1007/s10633-012-9317-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2011] [Accepted: 02/06/2012] [Indexed: 11/30/2022]
Abstract
The rod photoreceptor cGMP-gated cation channel has an essential role in phototransduction functioning as the primary point for calcium and sodium entry into the rod outer segment. The channel consists of two subunits, α and β. The α-subunit can function in isolation as an ion channel, and the β-subunit modulates channel activity and has a structural role. We previously reported that a mouse knockout (KO) of the β-subunit and related glutamic acid-rich proteins (GARPs) attenuates rod function and causes structural alterations and slowly progressive retinal degeneration. Here, we have extended our functional analyses of the KO mice evaluating rod and cone function using the electroretinogram in mice up to 4 months of age. Retinal stratification is preserved in the knockout mice at 3 months, and a significant number of cones remain up to 7 months based on PNA staining of cone sheaths. Electroretinography of KO mice at 1 month old revealed a diminished dark-adapted b-wave and normal light-adapted b-wave compared to wild-type mice. Over the next 3 months, both dark- and light-adapted b-wave amplitudes declined, but the reduction was greater for dark-adapted b-wave amplitudes. In one-month-old mice, the critical flicker frequency (CFF) was substantially lower for the KO mice at scotopic intensities, but normal at photopic intensities. CFF values remained stable in the KO mice as the b-wave amplitudes decreased with age. Declining b-wave amplitudes confirm an RP phenotype of rod followed by cone degeneration. Flicker responses show that the cone circuits function normally at threshold despite significant losses in the maximum light-adapted b-wave amplitude. These results confirm that rods are marginally functional in the absence of the β-subunit and in addition show that CFF may be a more sensitive measure of remaining functional cone vision in animal models of RP undergoing progressive rod-cone degeneration.
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Affiliation(s)
- Youwen Zhang
- Department of Vision Sciences, University of Alabama at Birmingham, Birmingham, AL 35294-0019, USA
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Abstract
Since the discovery of the ABCA4 gene as the cause of autosomal recessive Stargardt disease/fundus flavimaculatus much has been written of the phenotypic variability in ABCA4 retinopathy. In this review the authors discuss the findings seen on examination and the disease features detected using various clinical tests. Important differential diagnoses are presented and unusual presentations of ABCA4 disease highlighted.
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Affiliation(s)
- Tomas R Burke
- Department of Ophthalmology, Edward S. Harkness Eye Institute, Columbia University, 160 Fort Washington Avenue, New York, NY, 10032, USA
| | - Stephen H Tsang
- Department of Ophthalmology, Edward S. Harkness Eye Institute, Columbia University, 160 Fort Washington Avenue, New York, NY, 10032, USA
- Department of Pathology and Cell Biology, Bernard and Shirlee Brown Glaucoma Laboratory, Edward S. Harkness Eye Institute, Columbia University, 160 Fort Washington Avenue, New York, NY, 10032, USA
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Sun H. Membrane receptors and transporters involved in the function and transport of vitamin A and its derivatives. Biochim Biophys Acta Mol Cell Biol Lipids 2011; 1821:99-112. [PMID: 21704730 DOI: 10.1016/j.bbalip.2011.06.010] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2011] [Revised: 06/01/2011] [Accepted: 06/10/2011] [Indexed: 12/12/2022]
Abstract
The eye is the human organ most sensitive to vitamin A deficiency because of vision's absolute and heavy dependence on vitamin A for light perception. Studies of the molecular basis of vision have provided important insights into the intricate mechanistic details of the function, transport and recycling of vitamin A and its derivatives (retinoid). This review focuses on retinoid-related membrane receptors and transporters. Three kinds of mammalian membrane receptors and transporters are discussed: opsins, best known as vitamin A-based light sensors in vision; ABCA4, an ATP-dependent transporter specializes in the transport of vitamin A derivative; and STRA6, a recently identified membrane receptor that mediates cellular uptake of vitamin A. The evolutionary driving forces for their existence and the wide spectrum of human diseases associated with these proteins are discussed. Lessons learned from the study of the visual system might be useful for understanding retinoid biology and retinoid-related diseases in other organ systems as well. This article is part of a Special Issue entitled Retinoid and Lipid Metabolism.
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Affiliation(s)
- Hui Sun
- Department of Physiology, Jules Stein Eye Institute, Brian Research Institute, and Howard Hughes Medical Institute, David Geffen School of Medicine, University of California, Los Angeles, CA, USA.
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Fishman GA. Historical evolution in the understanding of Stargardt macular dystrophy. Ophthalmic Genet 2010; 31:183-9. [DOI: 10.3109/13816810.2010.499887] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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Abstract
OBJECTIVE Retrospective analysis of the famous painter Edgar Degas' eye disease. DESIGN A historical review and analysis based on Degas' paintings and letters exchanged between the painter and his friends and family members, as well as on the chronicles of his associates. DeGas-Musson family papers at the Howard-Tilton Library of Tulane University are also reviewed. RESULTS Degas had an eye disease that was first noticed in 1870 and that progressed throughout his life. He suffered from progressive bilateral central visual loss and light sensitivity which was most acutely recognized while he was visiting his mother's side of the family in New Orleans where he could not paint outside because of the bright sun. Edgar's maternal first cousin, Estelle Musson, also suffered gradual bilateral visual loss, and was also known to have light sensitivity early in her life. Estelle became totally blind in her early 30s. Both Edgar and Estelle were otherwise healthy and lived long lives. CONCLUSION It is likely that Edgar Degas and his cousin Estelle Musson had a hereditary retinal degeneration primarily affecting their central vision. Degas' retinal disease undoubtedly affected his life and his art but did not prevent him from being one of the most admired painters of all times.
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Petzold A, Plant GT. Central and Paracentral Visual Field Defects and Driving Abilities. Ophthalmologica 2008; 219:191-201. [PMID: 16088237 DOI: 10.1159/000085727] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2004] [Accepted: 08/19/2004] [Indexed: 12/29/2022]
Abstract
The effect of central and paracentral visual field defects on driving abilities has until now received little attention. To date studies and surveys have concentrated on visual acuity and peripheral field loss. Here we summarise for the first time those diseases causing central visual field defects likely to be associated with binocular visual acuity adequate for driving.
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Affiliation(s)
- A Petzold
- Department of Neuroimmunology, Institute of Neurology, London, UK.
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ABCA4 gene analysis in patients with autosomal recessive cone and cone rod dystrophies. Eur J Hum Genet 2008; 16:812-9. [PMID: 18285826 DOI: 10.1038/ejhg.2008.23] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
The ATP-binding cassette (ABC) transporters constitute a family of large membrane proteins, which transport a variety of substrates across membranes. The ABCA4 protein is expressed in photoreceptors and possibly functions as a transporter for N-retinylidene-phosphatidylethanolamine (N-retinylidene-PE), the Schiff base adduct of all-trans-retinal with PE. Mutations in the ABCA4 gene have been initially associated with autosomal recessive Stargardt disease. Subsequent studies have shown that mutations in ABCA4 can also cause a variety of other retinal dystrophies including cone rod dystrophy and retinitis pigmentosa. To determine the prevalence and mutation spectrum of ABCA4 gene mutations in non-Stargardt phenotypes, we have screened 64 unrelated patients with autosomal recessive cone (arCD) and cone rod dystrophy (arCRD) applying the Asper Ophthalmics ABCR400 microarray followed by DNA sequencing of all coding exons of the ABCA4 gene in subjects with single heterozygous mutations. Disease-associated ABCA4 alleles were identified in 20 of 64 patients with arCD or arCRD. In four of 64 patients (6%) only one mutant ABCA4 allele was detected and in 16 patients (25%), mutations on both ABCA4 alleles were identified. Based on these data we estimate a prevalence of 31% for ABCA4 mutations in arCD and arCRD, supporting the concept that the ABCA4 gene is a major locus for various types of degenerative retinal diseases with abnormalities in cone or both cone and rod function.
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Pawar AS, Qtaishat NM, Little DM, Pepperberg DR. Recovery of rod photoresponses in ABCR-deficient mice. Invest Ophthalmol Vis Sci 2008; 49:2743-55. [PMID: 18263807 DOI: 10.1167/iovs.07-1499] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
PURPOSE The ABCR protein of the rod outer segment is thought to facilitate movement of the all-trans retinal photoproduct of rhodopsin bleaching out of the disc lumen. This study was undertaken to investigate the extent to which ABCR deficiency affects the post-bleach recovery of the rod photoresponse in ABCR-deficient (abcr-/-) mice. METHODS Electroretinographic (ERG) a-wave responses were recorded from abcr-/- mice and two control strains. A bright probe flash was used to examine the course of rod recovery after fractional rhodopsin bleaches of approximately 10(-6), approximately 3 x 10(-5), approximately 0.03, and approximately 0.30 to approximately 0.40. RESULTS Dark-adapted abcr-/- mice and control animals exhibited similar normalized near-peak amplitudes of the paired-flash-ERG-derived, weak-flash response. Response recovery after approximately 10(-6) bleaching exhibited an average exponential time constant of 319, 171, and 213 ms, respectively, in the abcr-/- and the two control strains. Recovery time constants determined for approximately 3 x 10(-5) bleaching did not differ significantly among strains. However, those determined for the approximately 0.03 bleach indicated significantly faster recovery in abcr-/- mice (2.34 +/- 0.74 minutes) than in the controls (5.36 +/- 2.20 and 5.92 +/- 2.44 minutes). After approximately 0.30 to approximately 0.40 bleaching, the initial recovery in the abcr-/- mice was, on average, faster than in control mice. CONCLUSIONS By comparison with control animals, abcr-/- mice exhibit faster rod recovery after a bleach of approximately 0.03. The data suggest that ABCR in normal rods may directly or indirectly prolong all-trans retinal clearance from the disc lumen over a significant bleaching range, and that the essential function of ABCR may be to promote the clearance of residual amounts of all-trans retinal that remain in the discs long after bleaching.
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Affiliation(s)
- Ambarish S Pawar
- Lions of Illinois Eye Research Institute, Department of Ophthalmology and Visual Sciences, University of Illinois at Chicago, Chicago, Illinois. 60612, USA
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Cideciyan AV, Swider M, Aleman TS, Sumaroka A, Schwartz SB, Roman MI, Milam AH, Bennett J, Stone EM, Jacobson SG. ABCA4-associated retinal degenerations spare structure and function of the human parapapillary retina. Invest Ophthalmol Vis Sci 2006; 46:4739-46. [PMID: 16303974 PMCID: PMC2579900 DOI: 10.1167/iovs.05-0805] [Citation(s) in RCA: 92] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
PURPOSE To study the parapapillary retinal region in patients with ABCA4-associated retinal degenerations. METHODS Patients with Stargardt disease or cone-rod dystrophy and disease-causing variants in the ABCA4 gene were included. Fixation location was determined under fundus visualization, and central cone-mediated vision was measured. Intensity and texture abnormalities of autofluorescence (AF) images were quantified. Parapapillary retina of an eye donor with ungenotyped Stargardt disease was examined microscopically. RESULTS AF images ranged from normal, to spatially homogenous abnormal increase of intensity, to a spatially heterogenous speckled pattern, to variably sized patches of low intensity. A parapapillary ring of normal-appearing AF was visible at all disease stages. Quantitative analysis of the intensity and texture properties of AF images showed the preserved region to be an annulus, at least 0.6 mm wide, surrounding the optic nerve head. A similar region of relatively preserved photoreceptor nuclei was apparent in the donor retina. In patients with foveal fixation, there was better cone sensitivity at a parapapillary locus in the nasal retina than at the same eccentricity in the temporal retina. In patients with eccentric fixation, approximately 30% had a preferred retinal locus in the parapapillary retina. CONCLUSIONS Human retinal degenerations caused by ABCA4 mutations spare the structure of retina and RPE in a circular parapapillary region that commonly serves as the preferred fixation locus when central vision is lost. The retina between fovea and optic nerve head could serve as a convenient, accessible, and informative region for structural and functional studies to determine natural history or outcome of therapy in ABCA4-associated disease.
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Affiliation(s)
- Artur V Cideciyan
- Scheie Eye Institute, Department of Ophthalmology, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA.
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Kozma P, Hughbanks-Wheaton DK, Locke KG, Fish GE, Gire AI, Spellicy CJ, Sullivan LS, Bowne SJ, Daiger SP, Birch DG. Phenotypic characterization of a large family with RP10 autosomal-dominant retinitis pigmentosa: an Asp226Asn mutation in the IMPDH1 gene. Am J Ophthalmol 2005; 140:858-867. [PMID: 16214101 PMCID: PMC2771559 DOI: 10.1016/j.ajo.2005.05.027] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2005] [Revised: 05/10/2005] [Accepted: 05/10/2005] [Indexed: 10/25/2022]
Abstract
PURPOSE To evaluate the clinical features associated with the RP10 form of autosomal-dominant retinitis pigmentosa in 11 affected members of various ages from one family with a defined IMPDH1 mutation (Asp226Asn). DESIGN Prospective, observational case series. METHODS Visual function assessment included visual acuity, color vision, visual field, dark adaptometry, full-field electroretinography (ffERG), and multifocal electroretinography (mfERG). Ophthalmologic examinations, fundus photography, and optical coherence tomographic scans were also performed. Blood samples were obtained to screen for basic immune function. RESULTS Visual acuity was slightly reduced in the teenage years and substantially reduced in association with cystoid macular edema (CME) at all ages. Color defects were observed in three patients (one teen, two adults). Dark-adapted thresholds were elevated. Visual fields were markedly constricted by age 40 (<or=20 degrees). Rod and cone a-wave and b-wave ffERG responses were small or nondetectable by age 20, with greater rod than cone loss at all ages. The normal to significantly delayed ffERG cone b-wave implicit times in different patients were explained by their mfERG implicit times from the central retina. The amplification factors (log S) and recovery kinetics derived from the full-field rod a-waves were normal. Optical coherence tomography revealed subretinal fluid accumulation in the majority of eyes. Cystoid macular edema was diagnosed in four patients. No unusual immunologic findings were noted. CONCLUSIONS The Asp226Asn mutation is associated with a severe, early-onset form of retinal degeneration in members of this family.
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Affiliation(s)
- Petra Kozma
- Retina Foundation of the Southwest, Dallas, Texas 75231, USA.
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Klevering BJ, Yzer S, Rohrschneider K, Zonneveld M, Allikmets R, van den Born LI, Maugeri A, Hoyng CB, Cremers FPM. Microarray-based mutation analysis of the ABCA4 (ABCR) gene in autosomal recessive cone-rod dystrophy and retinitis pigmentosa. Eur J Hum Genet 2005; 12:1024-32. [PMID: 15494742 DOI: 10.1038/sj.ejhg.5201258] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
Mutations in the ABCA4 gene have been associated with autosomal recessive Stargardt disease (STGD1), cone-rod dystrophy (CRD), and retinitis pigmentosa (RP). We employed a recently developed genotyping microarray, the ABCR400-chip, to search for known ABCA4 mutations in patients with isolated or autosomal recessive CRD (54 cases) or RP (90 cases). We performed detailed ophthalmologic examinations and identified at least one ABCA4 mutation in 18 patients (33%) with CRD and in five patients (5.6%) with RP. Single-strand conformation polymorphism (SSCP) analysis and subsequent DNA sequencing revealed four novel missense mutations (R24C, E161K, P597S, G618E) and a novel 1-bp deletion (5888delG). Ophthalmoscopic abnormalities in CRD patients ranged from minor granular pigmentary changes in the posterior pole to widespread atrophy. In 12 patients with recordable electroretinogram (ERG) tracings, a cone-rod pattern was detected. Three patients demonstrated progression from a retinal dystrophy resembling STGD1 to a more widespread degeneration, and were subsequently diagnosed as CRD. In addition to a variable degree of atrophy, all RP patients displayed ophthalmologic characteristics of classic RP. When detectable, ERG recordings in these patients demonstrated rod-cone patterns of photoreceptor degeneration. In conclusion, in this study, we show that the ABCA4 mutation chip is an efficient first screening tool for arCRD.
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Affiliation(s)
- B Jeroen Klevering
- Department of Ophthalmology, University Medical Centre Nijmegen, Nijmegen, The Netherlands
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Klevering BJ, Deutman AF, Maugeri A, Cremers FPM, Hoyng CB. The spectrum of retinal phenotypes caused by mutations in the ABCA4 gene. Graefes Arch Clin Exp Ophthalmol 2004; 243:90-100. [PMID: 15614537 DOI: 10.1007/s00417-004-1079-4] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2004] [Revised: 11/09/2004] [Accepted: 11/10/2004] [Indexed: 11/30/2022] Open
Abstract
BACKGROUND The majority of studies on the retina-specific ATP-binding cassette transporter (ABCA4) gene have focussed on molecular genetic analysis; comparatively few studies have described the clinical aspects of ABCA4-associated retinal disorders. In this study, we demonstrate the spectrum of retinal dystrophies associated with ABCA4 gene mutations. METHODS Nine well-documented patients representing distinct phenotypes in the continuum of ABCA4-related disorders were selected. All patients received an extensive ophthalmologic evaluation, including kinetic perimetry, fluorescein angiography, and electroretinography (ERG). Mutation analysis had been performed previously with the genotyping microarray (ABCR400 chip) and/or single-strand conformation polymorphism analysis in combination with direct DNA sequencing. RESULTS In all patients, at least one pathologic ABCA4 mutation was identified. Patient 10034 represented the mild end of the phenotypic spectrum, demonstrating exudative age-related macular degeneration (AMD). Patient 24481 received the diagnosis of late-onset fundus flavimaculatus (FFM), patient 15168 demonstrated the typical FFM phenotype, and patient 19504 had autosomal recessive Stargardt disease (STGD1). Patients 11302 and 7608 exhibited progression from FFM/STGD1 to cone-rod dystrophy (CRD). A more typical CRD phenotype was found in patients 15680 and 12608. Finally, the most severe ABCA4-associated phenotype was retinitis pigmentosa (RP) in patient 11366. This phenotype was characterised by extensive atrophy with almost complete loss of peripheral and central retinal functions. CONCLUSION We describe nine patients during different stages of disease progression; together, these patients form a continuum of ABCA4-associated phenotypes. Besides characteristic disorders such as FFM/STGD1, CRD and RP, intermediate phenotypes may be encountered. Moreover, as the disease progresses, marked differences may be observed between initially comparable phenotypes. In contrast, distinctly different phenotypes may converge to a similar final stage, characterised by extensive chorioretinal atrophy and very low visual functions. The identified ABCA4 mutations in most, but not all, patients were compatible with the resulting phenotypes, as predicted by the genotype-phenotype model for ABCA4-associated disorders. With the advent of therapeutic options, recognition by the general ophthalmologist of the various retinal phenotypes associated with ABCA4 mutations is becoming increasingly important.
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Affiliation(s)
- B Jeroen Klevering
- Department of Ophthalmology, University Medical Centre Nijmegen, P.O. Box 9101, 6500 HB, Nijmegen, The Netherlands.
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Cideciyan AV, Aleman TS, Swider M, Schwartz SB, Steinberg JD, Brucker AJ, Maguire AM, Bennett J, Stone EM, Jacobson SG. Mutations in ABCA4 result in accumulation of lipofuscin before slowing of the retinoid cycle: a reappraisal of the human disease sequence. Hum Mol Genet 2004; 13:525-34. [PMID: 14709597 DOI: 10.1093/hmg/ddh048] [Citation(s) in RCA: 192] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Mutations in ABCA4, which encodes a photoreceptor specific ATP-binding cassette transporter (ABCR), cause autosomal recessive forms of human blindness due to retinal degeneration (RD) including Stargardt disease. The exact disease sequence leading to photoreceptor and vision loss in ABCA4-RD is not known. Extrapolation from murine and in vitro studies predicts that two of the earliest pathophysiological features resulting from disturbed ABCR function in man would be slowed kinetics of the retinoid cycle and accelerated deposition of lipofuscin in the retinal pigment epithelium (RPE). To determine the human pathogenetic sequence, we studied surrogate measures of retinoid cycle kinetics, lipofuscin accumulation, and rod and cone photoreceptor and RPE loss in ABCA4-RD patients with a wide spectrum of disease severities. There were different extents of photoreceptor/RPE loss and lipofuscin accumulation in different regions of the retina. Slowing of retinoid cycle kinetics was not present in all patients; when present, it was not homogeneous across the retina; and the extent of slowing correlated well with the degree of degeneration. The orderly relationship between these phenotypic features permitted the development of a model of disease sequence in ABCA4-RD. The model predicted lipofuscin accumulation as a key and early component of the disease expression in man, as in mice. In man, however, abnormal slowing of the rod and cone retinoid cycle occurs at later stages of the disease sequence. Knowledge of the human ABCA4 disease sequence will be critical for defining rates of progression, selecting appropriate patients and retinal locations for future therapy, and choosing appropriate treatment outcomes.
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Affiliation(s)
- Artur V Cideciyan
- Scheie Eye Institute, Department of Ophthalmology, University of Pennsylvania, Philadelphia, PA 19104, USA.
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Simonelli F, Testa F, Zernant J, Nesti A, Rossi S, Rinaldi E, Allikmets R. Association of a Homozygous Nonsense Mutation in the ABCA4 (ABCR) Gene with Cone-Rod Dystrophy Phenotype in an Italian Family. Ophthalmic Res 2004; 36:82-8. [PMID: 15017103 DOI: 10.1159/000076886] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2003] [Accepted: 10/18/2003] [Indexed: 11/19/2022]
Abstract
Genetic variation in the <i>ABCA4 (ABCR)</i> gene has been associated with several distinct retinal phenotypes, including Stargardt disease/fundus flavimaculatus (STGD/FFM), cone-rod dystrophy (CRD), retinitis pigmentosa (RP) and age-related macular degeneration. The current model of genotype/phenotype association suggests that patients harboring deleterious mutations in both ABCR alleles would develop RP-like retinal pathology. Here we describe ABCA4-associated phenotypes, including a proband with a homozygous nonsense mutation in a family from Southern Italy. The proband had been originally diagnosed with STGD. Ophthalmologic examination included kinetic perimetry, electrophysiological studies and fluorescein angiography. DNA of the affected individual and family members was analyzed for variants in all 50 exons of the <i>ABCA4</i> gene by screening on the ABCR400 microarray. A homozygous nonsense mutation 2971G>T (G991X) was detected in a patient initially diagnosed with STGD based on funduscopic evidence, including bull’s eye depigmentation of the fovea and flecks at the posterior pole extending to the mid-peripheral retina. Since this novel nucleotide substitution results in a truncated, nonfunctional, ABCA4 protein, the patient was examined in-depth for the severity of the disease phenotype. Indeed, subsequent electrophysiological studies determined severely reduced cone amplitude as compared to the rod amplitude, suggesting the diagnosis of CRD. ABCR400 microarray is an efficient tool for determining causal genetic variation, including new mutations. A homozygous protein-truncating mutation in ABCA4 can cause a phenotype ranging from STGD to CRD as diagnosed at an early stage of the disease. Only a combination of comprehensive genotype/phenotype correlation studies will determine the proper diagnosis and prognosis of ABCA4-associated pathology.
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Besch D, Jägle H, Scholl HPN, Seeliger MW, Zrenner E. Inherited multifocal RPE-diseases: mechanisms for local dysfunction in global retinoid cycle gene defects. Vision Res 2003; 43:3095-108. [PMID: 14611947 DOI: 10.1016/j.visres.2003.09.020] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Alterations of retinoid cycle genes are known to cause retinal diseases characterized by focal white dot fundus lesions. Fundus appearances reveal circumscribed RPE-changes, although generalized metabolic defects and global functional abnormalities are present. As a possible explanation, topographic inhomogeneities of the human photoreceptor mosaic and the role of a cone specific visual cycle will be discussed. Due to particular characteristics of photoreceptor subtypes as well as different pathways for photopigment regeneration the metabolic demand of individual RPE cells might differ. In "flecked retina diseases" heterogeneity of metabolic demand in individual RPE cells could therefore be responsible for their multifocal appearance.
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Affiliation(s)
- Dorothea Besch
- University Eye Hospital, Schleichstr. 12-16, D-72076 Tübingen, Germany.
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Affiliation(s)
- Fred Gilbert
- Weill Medical College of Cornell University, New York, NY 10021, USA.
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