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Feathers KL, Jia L, Khan NW, Smith AJ, Ma JX, Ali RR, Thompson DA. Gene Supplementation in Mice Heterozygous for the D477G RPE65 Variant Implicated in Autosomal Dominant Retinitis Pigmentosa. Hum Gene Ther 2023; 34:639-648. [PMID: 37014074 PMCID: PMC10354729 DOI: 10.1089/hum.2022.240] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2022] [Accepted: 03/20/2023] [Indexed: 04/05/2023] Open
Abstract
The use of AAV-RPE65 vectors for gene supplementation has achieved spectacular success as a treatment for individuals with autosomal recessive retinal disease caused by biallelic mutations in the visual cycle gene RPE65. However, the efficacy of this approach in treating autosomal dominant retinitis pigmentosa (adRP) associated with a monoallelic mutation encoding a rare D477G RPE65 variant has not been studied. Although lacking a severe phenotype, we now find that knock-in mice heterozygous for D477G RPE65 (D477G KI mice) can be used to evaluate outcomes of AAV-RPE65 gene supplementation. Total RPE65 protein levels, which are decreased in heterozygous D477G KI mice, were doubled following subretinal delivery of rAAV2/5.hRPE65p.hRPE65. In addition, rates of recovery of the chromophore 11-cis retinal after bleaching were significantly increased in eyes that received AAV-RPE65, consistent with increased RPE65 isomerase activity. While dark-adapted chromophore levels and a-wave amplitudes were not affected, b-wave recovery rates were modestly improved. The present findings establish that gene supplementation enhances 11-cis retinal synthesis in heterozygous D477G KI mice and complement previous studies showing that chromophore therapy results in improved vision in individuals with adRP associated with D477G RPE65.
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Affiliation(s)
- Kecia L. Feathers
- Department of Ophthalmology and Visual Sciences, University of Michigan Medical School, Ann Arbor, Michigan, USA
| | - Lin Jia
- Department of Ophthalmology and Visual Sciences, University of Michigan Medical School, Ann Arbor, Michigan, USA
| | - Naheed W. Khan
- Department of Ophthalmology and Visual Sciences, University of Michigan Medical School, Ann Arbor, Michigan, USA
| | - Alexander J. Smith
- Centre for Stem Cells & Regenerative Medicine, King's College London, London, United Kingdom
| | - Jian-Xing Ma
- Department of Biochemistry, Wake Forest School of Medicine, Winston-Salem, North Carolina, USA
| | - Robin R. Ali
- Centre for Stem Cells & Regenerative Medicine, King's College London, London, United Kingdom
| | - Debra A. Thompson
- Department of Biological Chemistry, University of Michigan Medical School, Ann Arbor, Michigan, USA
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Amato A, Arrigo A, Aragona E, Manitto MP, Saladino A, Bandello F, Battaglia Parodi M. Gene Therapy in Inherited Retinal Diseases: An Update on Current State of the Art. Front Med (Lausanne) 2021; 8:750586. [PMID: 34722588 PMCID: PMC8553993 DOI: 10.3389/fmed.2021.750586] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2021] [Accepted: 09/20/2021] [Indexed: 12/11/2022] Open
Abstract
Background: Gene therapy cannot be yet considered a far perspective, but a tangible therapeutic option in the field of retinal diseases. Although still confined in experimental settings, the preliminary results are promising and provide an overall scenario suggesting that we are not so far from the application of gene therapy in clinical settings. The main aim of this review is to provide a complete and updated overview of the current state of the art and of the future perspectives of gene therapy applied on retinal diseases. Methods: We carefully revised the entire literature to report all the relevant findings related to the experimental procedures and the future scenarios of gene therapy applied in retinal diseases. A clinical background and a detailed description of the genetic features of each retinal disease included are also reported. Results: The current literature strongly support the hope of gene therapy options developed for retinal diseases. Although being considered in advanced stages of investigation for some retinal diseases, such as choroideremia (CHM), retinitis pigmentosa (RP), and Leber's congenital amaurosis (LCA), gene therapy is still quite far from a tangible application in clinical practice for other retinal diseases. Conclusions: Gene therapy is an extremely promising therapeutic tool for retinal diseases. The experimental data reported in this review offer a strong hope that gene therapy will be effectively available in clinical practice in the next years.
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Affiliation(s)
- Alessia Amato
- Department of Ophthalmology, Scientific Institute San Raffaele Hospital, Milan, Italy
| | - Alessandro Arrigo
- Department of Ophthalmology, Scientific Institute San Raffaele Hospital, Milan, Italy
| | - Emanuela Aragona
- Department of Ophthalmology, Scientific Institute San Raffaele Hospital, Milan, Italy
| | - Maria Pia Manitto
- Department of Ophthalmology, Scientific Institute San Raffaele Hospital, Milan, Italy
| | - Andrea Saladino
- Department of Ophthalmology, Scientific Institute San Raffaele Hospital, Milan, Italy
| | - Francesco Bandello
- Department of Ophthalmology, Scientific Institute San Raffaele Hospital, Milan, Italy
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Chiu W, Lin TY, Chang YC, Isahwan-Ahmad Mulyadi Lai H, Lin SC, Ma C, Yarmishyn AA, Lin SC, Chang KJ, Chou YB, Hsu CC, Lin TC, Chen SJ, Chien Y, Yang YP, Hwang DK. An Update on Gene Therapy for Inherited Retinal Dystrophy: Experience in Leber Congenital Amaurosis Clinical Trials. Int J Mol Sci 2021; 22:ijms22094534. [PMID: 33926102 PMCID: PMC8123696 DOI: 10.3390/ijms22094534] [Citation(s) in RCA: 37] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2021] [Revised: 04/22/2021] [Accepted: 04/22/2021] [Indexed: 12/20/2022] Open
Abstract
Inherited retinal dystrophies (IRDs) are a group of rare eye diseases caused by gene mutations that result in the degradation of cone and rod photoreceptors or the retinal pigment epithelium. Retinal degradation progress is often irreversible, with clinical manifestations including color or night blindness, peripheral visual defects and subsequent vision loss. Thus, gene therapies that restore functional retinal proteins by either replenishing unmutated genes or truncating mutated genes are needed. Coincidentally, the eye’s accessibility and immune-privileged status along with major advances in gene identification and gene delivery systems heralded gene therapies for IRDs. Among these clinical trials, voretigene neparvovec-rzyl (Luxturna), an adeno-associated virus vector-based gene therapy drug, was approved by the FDA for treating patients with confirmed biallelic RPE65 mutation-associated Leber Congenital Amaurosis (LCA) in 2017. This review includes current IRD gene therapy clinical trials and further summarizes preclinical studies and therapeutic strategies for LCA, including adeno-associated virus-based gene augmentation therapy, 11-cis-retinal replacement, RNA-based antisense oligonucleotide therapy and CRISPR-Cas9 gene-editing therapy. Understanding the gene therapy development for LCA may accelerate and predict the potential hurdles of future therapeutics translation. It may also serve as the template for the research and development of treatment for other IRDs.
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Affiliation(s)
- Wei Chiu
- School of Medicine, National Yang Ming Chiao Tung University, Taipei 11221, Taiwan; (W.C.); (S.-C.L.); (S.-C.L.); (K.-J.C.); (Y.-B.C.); (C.-C.H.)
- Department of Medical Research, Taipei Veterans General Hospital, Taipei 11217, Taiwan; (T.-Y.L.); (H.I.-A.M.L.); (C.M.); (A.A.Y.); (T.-C.L.); (S.-J.C.)
| | - Ting-Yi Lin
- Department of Medical Research, Taipei Veterans General Hospital, Taipei 11217, Taiwan; (T.-Y.L.); (H.I.-A.M.L.); (C.M.); (A.A.Y.); (T.-C.L.); (S.-J.C.)
- School of Medicine, Kaohsiung Medical University, Kaohsiung 80708, Taiwan
| | - Yun-Chia Chang
- Department of Ophthalmology, Taipei Veterans General Hospital, Taipei 11217, Taiwan;
| | - Henkie Isahwan-Ahmad Mulyadi Lai
- Department of Medical Research, Taipei Veterans General Hospital, Taipei 11217, Taiwan; (T.-Y.L.); (H.I.-A.M.L.); (C.M.); (A.A.Y.); (T.-C.L.); (S.-J.C.)
- Institute of Pharmacology, College of Medicine, National Yang Ming Chiao Tung University, Taipei 11221, Taiwan
| | - Shen-Che Lin
- School of Medicine, National Yang Ming Chiao Tung University, Taipei 11221, Taiwan; (W.C.); (S.-C.L.); (S.-C.L.); (K.-J.C.); (Y.-B.C.); (C.-C.H.)
| | - Chun Ma
- Department of Medical Research, Taipei Veterans General Hospital, Taipei 11217, Taiwan; (T.-Y.L.); (H.I.-A.M.L.); (C.M.); (A.A.Y.); (T.-C.L.); (S.-J.C.)
- Department of Medicine, National Taiwan University, Taipei 10617, Taiwan
| | - Aliaksandr A. Yarmishyn
- Department of Medical Research, Taipei Veterans General Hospital, Taipei 11217, Taiwan; (T.-Y.L.); (H.I.-A.M.L.); (C.M.); (A.A.Y.); (T.-C.L.); (S.-J.C.)
| | - Shiuan-Chen Lin
- School of Medicine, National Yang Ming Chiao Tung University, Taipei 11221, Taiwan; (W.C.); (S.-C.L.); (S.-C.L.); (K.-J.C.); (Y.-B.C.); (C.-C.H.)
- Department of Medical Research, Taipei Veterans General Hospital, Taipei 11217, Taiwan; (T.-Y.L.); (H.I.-A.M.L.); (C.M.); (A.A.Y.); (T.-C.L.); (S.-J.C.)
| | - Kao-Jung Chang
- School of Medicine, National Yang Ming Chiao Tung University, Taipei 11221, Taiwan; (W.C.); (S.-C.L.); (S.-C.L.); (K.-J.C.); (Y.-B.C.); (C.-C.H.)
- Department of Medical Research, Taipei Veterans General Hospital, Taipei 11217, Taiwan; (T.-Y.L.); (H.I.-A.M.L.); (C.M.); (A.A.Y.); (T.-C.L.); (S.-J.C.)
- Institute of Clinical Medicine, National Yang Ming Chiao Tung University, Taipei 11221, Taiwan
| | - Yu-Bai Chou
- School of Medicine, National Yang Ming Chiao Tung University, Taipei 11221, Taiwan; (W.C.); (S.-C.L.); (S.-C.L.); (K.-J.C.); (Y.-B.C.); (C.-C.H.)
- Department of Ophthalmology, Taipei Veterans General Hospital, Taipei 11217, Taiwan;
| | - Chih-Chien Hsu
- School of Medicine, National Yang Ming Chiao Tung University, Taipei 11221, Taiwan; (W.C.); (S.-C.L.); (S.-C.L.); (K.-J.C.); (Y.-B.C.); (C.-C.H.)
- Department of Ophthalmology, Taipei Veterans General Hospital, Taipei 11217, Taiwan;
| | - Tai-Chi Lin
- Department of Medical Research, Taipei Veterans General Hospital, Taipei 11217, Taiwan; (T.-Y.L.); (H.I.-A.M.L.); (C.M.); (A.A.Y.); (T.-C.L.); (S.-J.C.)
- Department of Ophthalmology, Taipei Veterans General Hospital, Taipei 11217, Taiwan;
| | - Shih-Jen Chen
- Department of Medical Research, Taipei Veterans General Hospital, Taipei 11217, Taiwan; (T.-Y.L.); (H.I.-A.M.L.); (C.M.); (A.A.Y.); (T.-C.L.); (S.-J.C.)
- Department of Ophthalmology, Taipei Veterans General Hospital, Taipei 11217, Taiwan;
| | - Yueh Chien
- Department of Medical Research, Taipei Veterans General Hospital, Taipei 11217, Taiwan; (T.-Y.L.); (H.I.-A.M.L.); (C.M.); (A.A.Y.); (T.-C.L.); (S.-J.C.)
- Division of Basic Research, Department of Medical Research, Taipei Veterans General Hospital, Taipei 11217, Taiwan
- Correspondence: (Y.C.); (Y.-P.Y.); (D.-K.H.)
| | - Yi-Ping Yang
- Department of Medical Research, Taipei Veterans General Hospital, Taipei 11217, Taiwan; (T.-Y.L.); (H.I.-A.M.L.); (C.M.); (A.A.Y.); (T.-C.L.); (S.-J.C.)
- Division of Basic Research, Department of Medical Research, Taipei Veterans General Hospital, Taipei 11217, Taiwan
- Institute of Food Safety and Health Risk Assessment, National Yang Ming Chiao Tung University, Taipei 11221, Taiwan
- Correspondence: (Y.C.); (Y.-P.Y.); (D.-K.H.)
| | - De-Kuang Hwang
- Department of Medical Research, Taipei Veterans General Hospital, Taipei 11217, Taiwan; (T.-Y.L.); (H.I.-A.M.L.); (C.M.); (A.A.Y.); (T.-C.L.); (S.-J.C.)
- Department of Ophthalmology, Taipei Veterans General Hospital, Taipei 11217, Taiwan;
- Correspondence: (Y.C.); (Y.-P.Y.); (D.-K.H.)
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Maguire AM, Bennett J, Aleman EM, Leroy BP, Aleman TS. Clinical Perspective: Treating RPE65-Associated Retinal Dystrophy. Mol Ther 2021; 29:442-463. [PMID: 33278565 PMCID: PMC7854308 DOI: 10.1016/j.ymthe.2020.11.029] [Citation(s) in RCA: 77] [Impact Index Per Article: 25.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2020] [Revised: 11/16/2020] [Accepted: 11/25/2020] [Indexed: 12/25/2022] Open
Abstract
Until recently, there was no approved treatment for a retinal degenerative disease. Subretinal injection of a recombinant adeno-associated virus (AAV) delivering the normal copy of the human RPE65 cDNA led to reversal of blindness first in animal models and then in humans. This led to the first US Food and Drug Administration (FDA)-approved gene therapy product for a genetic disease, voretigene neparvovec-rzyl (Luxturna). Luxturna was then approved by the European Medicines Association and is now available in the US through Spark Therapeutics and worldwide through Novartis. Not only has treatment with Luxturna changed the lives of people previously destined to live a life of blindness, but it has fueled interest in developing additional gene therapy reagents targeting numerous other genetic forms of inherited retinal disease. This review describes many of the considerations for administration of Luxturna and describes how lessons from experience with Luxturna could lead to additional gene-based treatments of blindness.
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Affiliation(s)
- Albert M Maguire
- Center for Advanced Retinal and Ocular Therapeutics (CAROT), Department of Ophthalmology, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, USA; The Children's Hospital of Philadelphia (CHOP), Philadelphia, PA, USA
| | - Jean Bennett
- Center for Advanced Retinal and Ocular Therapeutics (CAROT), Department of Ophthalmology, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, USA; The Children's Hospital of Philadelphia (CHOP), Philadelphia, PA, USA
| | - Elena M Aleman
- Center for Advanced Retinal and Ocular Therapeutics (CAROT), Department of Ophthalmology, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, USA
| | - Bart P Leroy
- Center for Advanced Retinal and Ocular Therapeutics (CAROT), Department of Ophthalmology, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, USA; Department of Ophthalmology and Center for Medical Genetics Ghent, Ghent University Hospital, Ghent, Belgium
| | - Tomas S Aleman
- Center for Advanced Retinal and Ocular Therapeutics (CAROT), Department of Ophthalmology, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, USA; The Children's Hospital of Philadelphia (CHOP), Philadelphia, PA, USA.
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Leber congenital amaurosis: Current genetic basis, scope for genetic testing and personalized medicine. Exp Eye Res 2019; 189:107834. [PMID: 31639339 DOI: 10.1016/j.exer.2019.107834] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2019] [Revised: 10/06/2019] [Accepted: 10/10/2019] [Indexed: 02/07/2023]
Abstract
Retinal dystrophies are one of the leading causes of pediatric congenital blindness. Leber's congenital amaurosis (LCA) encompasses one of the most severe forms of inherited retinal dystrophy responsible for early-onset childhood blindness in infancy. These are clinically characterized by nystagmus, amaurotic pupil response and markedly reduced or in most instances completely absent full-field electroretinogram. LCA exhibits immense genetic heterogeneity. With advances in next-generation genetic technologies, tremendous progress has been achieved over the last two decades in discovering genes and genetic defects leading to retinal dystrophies. Currently, 28 genes have been implicated in the pathogenesis of LCA and with initial reports of success in management with targeted gene therapy the disease has attracted a lot of research attention in the recent time. The review provides an update on genetic basis of LCA, scope for genetic testing and pharmacogenetic medicine in diagnosis and treatment of these diseases.
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Wiegering A, Rüther U, Gerhardt C. The ciliary protein Rpgrip1l in development and disease. Dev Biol 2018; 442:60-68. [DOI: 10.1016/j.ydbio.2018.07.024] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2018] [Revised: 07/13/2018] [Accepted: 07/28/2018] [Indexed: 12/28/2022]
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Sharon D, Wimberg H, Kinarty Y, Koch KW. Genotype-functional-phenotype correlations in photoreceptor guanylate cyclase (GC-E) encoded by GUCY2D. Prog Retin Eye Res 2018; 63:69-91. [DOI: 10.1016/j.preteyeres.2017.10.003] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2017] [Revised: 10/16/2017] [Accepted: 10/16/2017] [Indexed: 01/09/2023]
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Wang S, Zhang Q, Zhang X, Wang Z, Zhao P. Clinical and genetic characteristics of Leber congenital amaurosis with novel mutations in known genes based on a Chinese eastern coast Han population. Graefes Arch Clin Exp Ophthalmol 2016; 254:2227-2238. [PMID: 27422788 DOI: 10.1007/s00417-016-3428-5] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2016] [Revised: 05/31/2016] [Accepted: 06/22/2016] [Indexed: 11/26/2022] Open
Abstract
PURPOSE To study the genotype-phenotype characteristics of Leber congenital amaurosis (LCA) in the Chinese eastern coast Han population. METHODS Children with strictly defined LCA with novel mutations of known LCA genes identified by targeted next-generation sequencing (NGS) and a prediction of pathogenicity (in silico) were included in this study (2013-2015). Mutations were confirmed using Sanger sequencing and segregation analysis. The clinical findings were recorded, including visual function, refractive error, fundus changes, and electroretinograms (ERGs). Spectral-domain optical coherence tomography (SD-OCT) examination, fundus fluorescein angiography (FFA), and ultra-wide field scanning laser ophthalmoscopy (UWF SLO) were performed on children when available. RESULTS A total of 65 patients underwent NGS for mutation screening and 45 patients were identified as carrying known LCA genes. Of these, 36(80 %) children harbored novel mutations, and they were all from the eastern coast of China. A total of 50 novel variants were identified, which covered 15 known LCA genes. GUCY2D (17 %), CEP290 (14 %), NMNAT1 (14 %), AIPL1 (11 %) and RPGRIP1 (11 %) were the five most frequently mutated genes with novel mutations. A total of four (11 %) patients with AIPL1 mutations harbored the same novel mutated allele (c.C241T p.Q81X), which was homozygous in patients 1 and 2. Unusual manifestations were detected in patient 16 who had novel mutations in CRB1 with a dense proliferative membrane adhering to the posterior retina of the right eye with numerous fine glistening crystals spreading over the retina of both eyes. Ten (40 %) of the 25 available patients who underwent SD-OCT showed a normal macular appearance using fundus photography but an abnormal macular structure using OCT imaging, most of whom presented with a thickened fovea with maldevelopment of the inner and outer retinal laminae. CONCLUSIONS There may be a high frequency of AIPL1 novel mutations and a founder mutation of p.Q81X in the Chinese eastern coast Han population. Our findings of specific features in this population broaden the spectrum of novel mutations and the phenotype of LCA with ethnic and regional variations. Fundus multimodality imaging may help guide comprehensive assessments for patients with LCA.
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Affiliation(s)
- Shiyuan Wang
- Department of Ophthalmology, Xin Hua Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, 1665 Kong Jiang Road, Shanghai, 200092, China
| | - Qi Zhang
- Department of Ophthalmology, Xin Hua Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, 1665 Kong Jiang Road, Shanghai, 200092, China
| | - Xiang Zhang
- Department of Ophthalmology, Xin Hua Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, 1665 Kong Jiang Road, Shanghai, 200092, China
| | - Zhaoyang Wang
- Department of Ophthalmology, Xin Hua Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, 1665 Kong Jiang Road, Shanghai, 200092, China
| | - Peiquan Zhao
- Department of Ophthalmology, Xin Hua Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, 1665 Kong Jiang Road, Shanghai, 200092, China.
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Xu Y, Xiao X, Li S, Jia X, Xin W, Wang P, Sun W, Huang L, Guo X, Zhang Q. Molecular genetics of Leber congenital amaurosis in Chinese: New data from 66 probands and mutation overview of 159 probands. Exp Eye Res 2016; 149:93-99. [PMID: 27375279 DOI: 10.1016/j.exer.2016.06.019] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2015] [Revised: 04/28/2016] [Accepted: 06/27/2016] [Indexed: 10/21/2022]
Abstract
Leber congenital amaurosis (LCA) is the most severe form of inherited retinal dystrophy. We have previously performed a mutational analysis of the known LCA-associated genes in probands with LCA by both Sanger and whole exome sequencing. In this study, whole exome sequencing was carried out on 66 new probabds with LCA. In conjunction with these data, the present study provides a comprehensive analysis of the spectrum and frequency of all known genes associated with retinal dystrophy in a total of 159 Chinese probands with LCA. The known genes responsible for all forms hereditary retinal dystrophy were included based on information from RetNet. The candidate variants were filtered by bioinformatics analysis and confirmed by Sanger sequencing. Potentially causative mutations were further validated in available family members. Overall, a total of 118 putative pathogenic mutations from 23 genes were identified in 56.6% (90/159) of probands. These mutations were harbored in 13 LCA-associated genes and in ten genes related to other forms of retinal dystrophy. The most frequently mutated gene in probands with LCA was GUCY2D (10.7%, 17/159). A series of mutational analyses suggests that all known genes associated with retinal dystrophy account for 56.6% of Chinese patients with LCA. A comprehensive molecular genetic analysis of Chinese patients with LCA provides an overview of the spectrum and frequency of ethno-specific mutations of all known genes, as well as indications about other unknown genes in the remaining probands who lacked identified mutations.
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Affiliation(s)
- Yan Xu
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou 510060, China
| | - Xueshan Xiao
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou 510060, China
| | - Shiqiang Li
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou 510060, China
| | - Xiaoyun Jia
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou 510060, China
| | - Wei Xin
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou 510060, China
| | - Panfeng Wang
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou 510060, China
| | - Wenmin Sun
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou 510060, China
| | - Li Huang
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou 510060, China
| | - Xiangming Guo
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou 510060, China
| | - Qingjiong Zhang
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou 510060, China.
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Wang H, Wang X, Zou X, Xu S, Li H, Soens ZT, Wang K, Li Y, Dong F, Chen R, Sui R. Comprehensive Molecular Diagnosis of a Large Chinese Leber Congenital Amaurosis Cohort. Invest Ophthalmol Vis Sci 2015; 56:3642-55. [PMID: 26047050 DOI: 10.1167/iovs.14-15972] [Citation(s) in RCA: 69] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
PURPOSE Leber congenital amaurosis (LCA) is an inherited retinal disease that causes early-onset severe visual impairment. To evaluate the mutation spectrum in the Chinese population, we performed a mutation screen in 145 Chinese LCA families. METHODS First, we performed direct Sanger sequencing of 7 LCA disease genes in 81 LCA families. Next, we developed a capture panel that enriches the entire coding exons and splicing sites of 163 known retinal disease genes and other candidate retinal disease genes. The capture panel allowed us to quickly identify disease-causing mutations in a large number of genes at a relatively low cost. Thus, this method was applied to the 53 LCA families that were unsolved by direct Sanger sequencing of 7 LCA disease genes and an additional 64 LCA families. Systematic next-generation sequencing (NGS) data analysis, Sanger sequencing validation, and segregation analysis were used to identify pathogenic mutations. RESULTS Homozygous or compound heterozygous mutations were identified in 107 families, heterozygous autosomal dominant mutations were identified in 3 families and an X-linked mutation was found in 1 family, for a combined solving rate of 76.6%. In total, 136 novel pathogenic mutations were found in this study. In combination with two previous studies carried out in Chinese LCA patients, we concluded that the mutation spectrum in the Chinese population is distinct compared to that in the European population. After revisiting, we also refined the clinical diagnosis of 10 families based on their molecular diagnosis. CONCLUSIONS Our results highlight the importance of a molecular diagnosis as an integral part of the clinical diagnostic process.
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Affiliation(s)
- Hui Wang
- Institute of Developmental and Regenerative Biology Hangzhou Normal University, Jianggan, Hangzhou, Zhejiang, China
| | - Xia Wang
- Human Genome Sequencing Center, Baylor College of Medicine, Houston, Texas, United States 3Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States
| | - Xuan Zou
- Department of Ophthalmology, Peking Union Medical College Hospital, Peking Union Medical College, Dongcheng, Beijing, China
| | - Shan Xu
- Human Genome Sequencing Center, Baylor College of Medicine, Houston, Texas, United States
| | - Hui Li
- Department of Ophthalmology, Peking Union Medical College Hospital, Peking Union Medical College, Dongcheng, Beijing, China
| | - Zachry Tore Soens
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States
| | - Keqing Wang
- Human Genome Sequencing Center, Baylor College of Medicine, Houston, Texas, United States 3Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States
| | - Yumei Li
- Human Genome Sequencing Center, Baylor College of Medicine, Houston, Texas, United States 3Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States
| | - Fangtian Dong
- Department of Ophthalmology, Peking Union Medical College Hospital, Peking Union Medical College, Dongcheng, Beijing, China
| | - Rui Chen
- Human Genome Sequencing Center, Baylor College of Medicine, Houston, Texas, United States 3Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States 5Structural and Computational Biology & Molecular Biophysics
| | - Ruifang Sui
- Department of Ophthalmology, Peking Union Medical College Hospital, Peking Union Medical College, Dongcheng, Beijing, China
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Li T. Leber congenital amaurosis caused by mutations in RPGRIP1. Cold Spring Harb Perspect Med 2014; 5:cshperspect.a017384. [PMID: 25414380 DOI: 10.1101/cshperspect.a017384] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Recessive null mutations in retinitis pigmentosa GTPase regulator interacting protein 1 (RPGRIP1) gene are the cause of LCA6 and account for 5% to 6% of the total patient population. RPGRIP1 has an essential role in the photoreceptor connecting cilia, and photoreceptors lacking RPGRIP1 are unable to maintain the light sensing outer segments. As a result, patients lose retinal functions at an early age but retain photoreceptors in the central retina well into adulthood thus holding out the prospect for gene augmentation therapies. Laboratory studies in animal models have demonstrated efficacy of gene therapy in slowing disease progression. With further refinement in the design of the replacement gene construct, clinical trials for Leber congenital amaurosis (LCA) caused by RPGRIP1 mutations could be in the offing in the near future.
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Affiliation(s)
- Tiansen Li
- Retinal Cell Biology and Degeneration Section, Neurobiology-Neurodegeneration & Repair Laboratory, National Eye Institute, Bethesda, Maryland 20892
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Khan AO, Abu-Safieh L, Eisenberger T, Bolz HJ, Alkuraya FS. TheRPGRIP1-related retinal phenotype in children. Br J Ophthalmol 2013; 97:760-4. [DOI: 10.1136/bjophthalmol-2012-303050] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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Asai-Coakwell M, March L, Dai XH, Duval M, Lopez I, French CR, Famulski J, De Baere E, Francis PJ, Sundaresan P, Sauvé Y, Koenekoop RK, Berry FB, Allison WT, Waskiewicz AJ, Lehmann OJ. Contribution of growth differentiation factor 6-dependent cell survival to early-onset retinal dystrophies. Hum Mol Genet 2013; 22:1432-42. [PMID: 23307924 DOI: 10.1093/hmg/dds560] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Retinal dystrophies are predominantly caused by mutations affecting the visual phototransduction system and cilia, with few genes identified that function to maintain photoreceptor survival. We reasoned that growth factors involved with early embryonic retinal development would represent excellent candidates for such diseases. Here we show that mutations in the transforming growth factor-β (TGF-β) ligand Growth Differentiation Factor 6, which specifies the dorso-ventral retinal axis, contribute to Leber congenital amaurosis. Furthermore, deficiency of gdf6 results in photoreceptor degeneration, so demonstrating a connection between Gdf6 signaling and photoreceptor survival. In addition, in both murine and zebrafish mutant models, we observe retinal apoptosis, a characteristic feature of human retinal dystrophies. Treatment of gdf6-deficient zebrafish embryos with a novel aminopropyl carbazole, P7C3, rescued the retinal apoptosis without evidence of toxicity. These findings implicate for the first time perturbed TGF-β signaling in the genesis of retinal dystrophies, support the study of related morphogenetic genes for comparable roles in retinal disease and may offer additional therapeutic opportunities for genetically heterogeneous disorders presently only treatable with gene therapy.
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Affiliation(s)
- Mika Asai-Coakwell
- Department of Ophthalmology, University of Alberta, Edmonton, AB, Canada
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Petrukhin K. Pharmacological inhibition of lipofuscin accumulation in the retina as a therapeutic strategy for dry AMD treatment. ACTA ACUST UNITED AC 2013; 10:e11-e20. [PMID: 25152755 DOI: 10.1016/j.ddstr.2013.05.004] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Age-related macular degeneration (AMD) is the leading cause of blindness in the western world. There is no FDA-approved treatment for the most prevalent dry (atrophic) form of AMD. Photoreceptor degeneration in dry AMD is triggered by abnormalities in the retinal pigment epithelium (RPE). It has been suggested that excessive accumulation of fluorescent lipofuscin pigment in the RPE represents an important pathogenic factor in etiology and progression of dry AMD. Cytotoxic lipofuscin bisretinoids, such as A2E, are formed in the retina in a non-enzymatic way from visual cycle retinoids. Inhibition of toxic bisretinoid production in the retina seems to be a sound treatment strategy for dry AMD. In this review we discuss the following classes of pharmacological treatments inhibiting lipofuscin bisretinoid formation in the retina: direct inhibitors of key visual cycle enzymes, RBP4 antagonists, primary amine-containing aldehyde traps, and deuterated analogs of vitamin A.
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Métrailler S, Schorderet DF, Cottet S. Early apoptosis of rod photoreceptors in Rpe65(-/-) mice is associated with the upregulated expression of lysosomal-mediated autophagic genes. Exp Eye Res 2011; 96:70-81. [PMID: 22227450 DOI: 10.1016/j.exer.2011.12.019] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2011] [Revised: 12/07/2011] [Accepted: 12/23/2011] [Indexed: 01/05/2023]
Abstract
RPE65-related Leber's congenital amaurosis (LCA) is a rod-cone dystrophy whose clinical outcome is mainly attributed to the loss of rod photoreceptors followed by cone degeneration. Pathogenesis in Rpe65(-/-) mice is characterized by a slow and progressive degeneration of rods dependent on the constitutive activation of unliganded opsin. We previously reported that this opsin-mediated apoptosis of rods was dependent on Bcl-2-apoptotic pathway and Bax-induced pro-death activity. In this study, we report early initial apoptosis in the newly differentiated retina of Rpe65(-/-) mice. Apoptotic photoreceptors were identified as rods and resulted from pathological phototransduction signaling. This wave of early apoptosis triggered Bcl-2-related pathway and Bax apoptotic activity, while activation of the caspases was not induced. Following cellular stress, multiple signaling pathways are initiated which either commit cells to death or trigger pro-survival responses including autophagy. We report that Bcl-2-related early rod apoptosis was associated with the upregulation of autophagy markers including chaperone-mediated autophagy (CMA) substrate receptor LAMP-2 and lysosomal hydrolases Cathepsin S and Lysozyme. This suggests that lysosomal-mediated autophagy may be triggered in response to early rod apoptosis in Rpe65-LCA disease. These results highlight that Rpe65-related primary stress induces early signaling events, which trigger Bax-induced-apoptotic pathway and autophagy-mediated cellular response. These events may determine retinal cell fate, progression and severity of the disease.
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Abstract
Glaucoma is a genetically heterogeneous disorder and is the second cause of blindness worldwide owing to the progressive degeneration of retinal ganglion neurons. Very few genes causing glaucoma were identified to this date. In this study, we screened 10 candidate genes of glaucoma between the D14S261 and D14S121 markers of chromosome 14q11, a critical region previously linked to primary open-angle glaucoma (POAG). Mutation analyses of two large cohorts of patients with POAG, normal tension glaucoma (NTG) and juvenile open-angle glaucoma (JOAG), and control subjects, found only association of non-synonymous heterozygous variants of the retinitis pigmentosa GTPase regulator-interacting protein 1 (RPGRIP1) with POAG, NTG and JOAG. The 20 non-synonymous variants identified in RPGRIP1 were all distinct from variants causing photoreceptor dystrophies and were found throughout all but one domain (RPGR-interacting domain) of RPGRIP1. Among them, 14 missense variants clustered within or around the C2 domains of RPGRIP1. Yeast two-hybrid analyses of a subset of the missense mutations within the C2 domains of RPGRIP1 shows that five of them (p.R598Q, p.A635G, p.T806I, p.A837G and p.I838V) decrease the association of the C2 domains with nephrocystin-4 (NPHPH). When considering only these five confirmed C2-domain mutations, the association remains statistically significant (P=0.001). Altogether, the data support that heterozygous non-synonymous variants of RPGRIP1 may cause or increase the susceptibility to various forms of glaucoma and that among other factors, physical impairment of the interaction of RPGRIP1with different proteins may contribute to the pathogenesis of forms of glaucoma.
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Bax-induced apoptosis in Leber's congenital amaurosis: a dual role in rod and cone degeneration. PLoS One 2009; 4:e6616. [PMID: 19672311 PMCID: PMC2720534 DOI: 10.1371/journal.pone.0006616] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2009] [Accepted: 07/07/2009] [Indexed: 01/13/2023] Open
Abstract
Pathogenesis in the Rpe65(-/-) mouse model of Leber's congenital amaurosis (LCA) is characterized by a slow and progressive degeneration of the rod photoreceptors. On the opposite, cones degenerate rapidly at early ages. Retinal degeneration in Rpe65(-/-) mice, showing a null mutation in the gene encoding the retinal pigment epithelium 65-kDa protein (Rpe65), was previously reported to depend on continuous activation of a residual transduction cascade by unliganded opsin. However, the mechanisms of apoptotic signals triggered by abnormal phototransduction remain elusive. We previously reported that activation of a Bcl-2-dependent pathway was associated with apoptosis of rod photoreceptors in Rpe65(-/-) mice during the course of the disease. In this study we first assessed whether activation of Bcl-2-mediated apoptotic pathway was dependent on constitutive activation of the visual cascade through opsin apoprotein. We then challenged the direct role of pro-apoptotic Bax protein in triggering apoptosis of rod and cone photoreceptors.Quantitative PCR analysis showed that increased expression of pro-apoptotic Bax and decreased level of anti-apoptotic Bcl-2 were restored in Rpe65(-/-)/Gnat1(-/-) mice lacking the Gnat1 gene encoding rod transducin. Moreover, photoreceptor apoptosis was prevented as assessed by TUNEL assay. These data indicate that abnormal activity of opsin apoprotein induces retinal cell apoptosis through the Bcl-2-mediated pathway. Following immunohistological and real-time PCR analyses, we further observed that decreased expression of rod genes in Rpe65-deficient mice was rescued in Rpe65(-/-)/Bax(-/-) mice. Histological and TUNEL studies confirmed that rod cell demise and apoptosis in diseased Rpe65(-/-) mice were dependent on Bax-induced pathway. Surprisingly, early loss of cones was not prevented in Rpe65(-/-)/Bax(-/-) mice, indicating that pro-apoptotic Bax was not involved in the pathogenesis of cone cell death in Rpe65-deficient mice.This is the first report, to our knowledge, that a single genetic mutation can trigger two independent apoptotic pathways in rod and cone photoreceptors in Rpe65-dependent LCA disease. These results highlight the necessity to investigate and understand the specific death signaling pathways committed in rods and cones to develop effective therapeutic approaches to treat RP diseases.
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Benayoun L, Spiegel R, Auslender N, Abbasi AH, Rizel L, Hujeirat Y, Salama I, Garzozi HJ, Allon-Shalev S, Ben-Yosef T. Genetic heterogeneity in two consanguineous families segregating early onset retinal degeneration: the pitfalls of homozygosity mapping. Am J Med Genet A 2009; 149A:650-6. [PMID: 19140180 DOI: 10.1002/ajmg.a.32634] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Retinitis pigmentosa is the most common form of hereditary retinal degeneration, with a worldwide prevalence of 1 in 4,000. At least 28 genes and loci have been implicated in nonsyndromic autosomal recessive retinitis pigmentosa. Here we report two extended and highly consanguineous families segregating early onset retinitis pigmentosa. Despite the consanguinity in both families, we found allelic heterogeneity in one of them, in which affected individuals were compound heterozygotes for two different mutations of the CRB1 gene. In the second family we found evidence for locus heterogeneity. A novel homozygous mutation of RDH12 was found in only 14 of 17 affected individuals in this family. Our data indicate that in the other affected individuals the disease is caused by a different gene/s. These findings demonstrate that while homozygosity mapping is an efficient tool for identification of the underlying mutated genes in inbred families, both locus and allelic heterogeneity may occur even within the same consanguineous family. These observations should be taken into account, especially when studying common and heterogeneous recessive genetic conditions.
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Bereta G, Kiser PD, Golczak M, Sun W, Heon E, Saperstein DA, Palczewski K. Impact of retinal disease-associated RPE65 mutations on retinoid isomerization. Biochemistry 2008; 47:9856-65. [PMID: 18722466 DOI: 10.1021/bi800905v] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Pathogenic mutations in the RPE65 gene are associated with a spectrum of congenital blinding diseases in humans. We evaluated changes in the promoter region, coding regions, and exon/intron junctions of the RPE65 gene by direct sequencing of DNA from 36 patients affected with Leber's congenital amaurosis (LCA), 62 with autosomal recessive retinitis pigmentosa (arRP), and 21 with autosomal dominant/recessive cone-rod dystrophies (CORD). Fifteen different variants were found, of which 6 were novel. Interesting was Gly244Val, a novel mutation close to the catalytic center. To assess the role of this mutation in RPE65 inactivation, we performed detailed biochemical studies of the mutant along with a structural analysis of the 244 amino acid position with respect to amino acids known to be important for RPE65-dependent retinoid isomerization. Bicistronic plasmid expression of the RPE65 Gly244Val mutant and enhanced green fluorescent protein (EGFP) allowed us to document both its instability in cultured cells by cell sorting and immunoblotting methodology and its loss of RPE65-dependent isomerase activity by enzymatic assays. Further insights into the structural requirements for retinoid isomerization by RPE65 were obtained by using the carotenoid oxygenase (ACO) from Synechocystis (PDB accession code 2BIW ) as a structural template to construct a RPE65 homology model and locating all known inactivating mutations including Gly244Val within this model.
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Affiliation(s)
- Grzegorz Bereta
- Department of Pharmacology, School of Medicine, Case Western Reserve University, Cleveland, Ohio 44106-4965, USA
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Cottet S, Schorderet DF. Triggering of Bcl-2-related pathway is associated with apoptosis of photoreceptors in Rpe65-/- mouse model of Leber's congenital amaurosis. Apoptosis 2008; 13:329-42. [PMID: 18274907 DOI: 10.1007/s10495-008-0180-2] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Mutations in RPE65 protein is characterized by the loss of photoreceptors, although the molecular pathways triggering retinal cell death remain largely unresolved. The role of the Bcl-2 family of proteins in retinal degeneration is still controversial. However, alteration in Bcl-2-related proteins has been observed in several models of retinal injury. In particular, Bax has been suggested to play a crucial role in apoptotic pathways in murine glaucoma model as well as in retinal detachment-associated cell death. We demonstrated that Bcl-2-related signaling pathway is involved in Rpe65-dependent apoptosis of photoreceptors during development of the disease. Pro-apoptotic Bax alpha and beta isoforms were upregulated in diseased retina. This was associated with a progressive reduction of anti-apoptotic Bcl-2, reflecting imbalanced Bcl-2/Bax ratio as the disease progresses. Moreover, specific translocation of Bax beta from cytosol to mitochondria was observed in Rpe65-deficient retina. This correlated with the initiation of photoreceptor cell loss at 4 months of age, and further increased during disease development. Altogether, these data suggest that Bcl-2-apoptotic pathway plays a crucial role in Leber's congenital amaurosis disease. They further highlight a new regulatory mechanism of Bax-dependent apoptosis based on regulated expression and activation of specific isoforms of this protein.
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Affiliation(s)
- Sandra Cottet
- Institute for Research in Ophthalmology (IRO), Avenue Grand-Champsec 64, 1950, Sion 4, Switzerland.
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Abstract
Over the last decade there have been major advances in our understanding of the molecular pathology of inherited retinal dystrophies. This paper reviews recent advances in the identification of genetic mutations underlying infantile-onset inherited retinal disorders and considers how this knowledge may lead to novel therapeutic approaches.
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Affiliation(s)
- P Moradi
- Institute of Ophthalmology UCL, London, UK
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Yang HK, Yu YS, Hwang JM. Joubert Syndrome Associated with Leber's Congenital Amaurosis. JOURNAL OF THE KOREAN OPHTHALMOLOGICAL SOCIETY 2008. [DOI: 10.3341/jkos.2008.49.8.1360] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Affiliation(s)
- Hee Kyung Yang
- Department of Ophthalmology, Seoul National University College of Medicine, Seoul, Korea
- Seoul National University Hospital Clinical Research Institute, Seoul, Korea
| | - Young Suk Yu
- Department of Ophthalmology, Seoul National University College of Medicine, Seoul, Korea
- Seoul National University Hospital Clinical Research Institute, Seoul, Korea
| | - Jeong-Min Hwang
- Department of Ophthalmology, Seoul National University College of Medicine, Seoul, Korea
- Department of Ophthalmology, Seoul National University Bundang Hospital, Seongnam, Korea
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Koenekoop RK, Lopez I, den Hollander AI, Allikmets R, Cremers FPM. Genetic testing for retinal dystrophies and dysfunctions: benefits, dilemmas and solutions. Clin Exp Ophthalmol 2007; 35:473-85. [PMID: 17651254 DOI: 10.1111/j.1442-9071.2007.01534.x] [Citation(s) in RCA: 87] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Human retinal dystrophies have unparalleled genetic and clinical diversity and are currently linked to more than 185 genetic loci. Genotyping is a crucial exercise, as human gene-specific clinical trials to study photoreceptor rescue are on their way. Testing confirms the diagnosis at the molecular level and allows for a more precise prognosis of the possible future clinical evolution. As treatments are gene-specific and the 'window of opportunity' is time-sensitive; accurate, rapid and cost-effective genetic testing will play an ever-increasing crucial role. The gold standard is sequencing but is fraught with excessive costs, time, manpower issues and finding non-pathogenic variants. Therefore, no centre offers testing of all currently 132 known genes. Several new micro-array technologies have emerged recently, that offer rapid, cost-effective and accurate genotyping. The new disease chips from Asper Ophthalmics (for Stargardt dystrophy, Leber congenital amaurosis [LCA], Usher syndromes and retinitis pigmentosa) offer an excellent first pass opportunity. All known mutations are placed on the chip and in 4 h a patient's DNA is screened. Identification rates (identifying at least one disease-associated mutation) are currently approximately 70% (Stargardt), approximately 60-70% (LCA) and approximately 45% (Usher syndrome subtype 1). This may be combined with genotype-phenotype correlations that suggest the causal gene from the clinical appearance (e.g. preserved para-arteriolar retinal pigment epithelium suggests the involvement of the CRB1 gene in LCA). As approximately 50% of the retinal dystrophy genes still await discovery, these technologies will improve dramatically as additional novel mutations are added. Genetic testing will then become standard practice to complement the ophthalmic evaluation.
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Affiliation(s)
- Robert K Koenekoop
- McGill Ocular Genetics Center, McGill University Health Center, Montreal, Quebec, Canada.
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Cottet S, Michaut L, Boisset G, Schlecht U, Gehring W, Schorderet DF. Biological characterization of gene response in Rpe65-/- mouse model of Leber's congenital amaurosis during progression of the disease. FASEB J 2006; 20:2036-49. [PMID: 17012256 DOI: 10.1096/fj.06-6211com] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
RPE65 is the retinal isomerase essential for conversion of all-trans-retinyl ester to 11-cis-retinol in the visual cycle. Leber's congenital amaurosis (LCA), an autosomal recessive form of RP resulting in blindness, is commonly caused by mutations in the Rpe65 gene. Whereas the molecular mechanisms by which these mutations contribute to retinal disease remain largely unresolved, affected patients show marked RPE damage and photoreceptor degeneration. We evaluated gene expression in Rpe65-/- mouse model of LCA before and at the onset of photoreceptor cell death in 2, 4, and 6 month old animals. Microarray analysis demonstrates altered expression of genes involved in phototransduction, apoptosis regulation, cytoskeleton organization, and extracellular matrix (ECM) constituents. Cone-specific phototransduction genes are strongly decreased, reflecting early loss of cones. In addition, remaining rods show modified expression of genes encoding components of the cytoskeleton and ECM. This may affect rod physiology and interaction with the adjacent RPE and lead to loss of survival signals, as reflected by the alteration of apoptosis-related genes Together, these results suggest that RPE65 defect triggers an overall remodeling of the neurosensitive retina that may, in turn, disrupt photoreceptor homeostasis and induce apoptosis signaling cascade toward retinal cell death.
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Affiliation(s)
- Sandra Cottet
- Institute of Research in Ophthalmology, Sion, Switzerland.
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Richard M, Roepman R, Aartsen WM, van Rossum AGSH, den Hollander AI, Knust E, Wijnholds J, Cremers FPM. Towards understanding CRUMBS function in retinal dystrophies. Hum Mol Genet 2006; 15 Spec No 2:R235-43. [PMID: 16987889 DOI: 10.1093/hmg/ddl195] [Citation(s) in RCA: 103] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Mutations in the Crumbs homologue 1 (CRB1) gene cause autosomal recessive retinitis pigmentosa (arRP) and autosomal Leber congenital amaurosis (arLCA). The crumbs (crb) gene was originally identified in Drosophila and encodes a large transmembrane protein required for maintenance of apico-basal cell polarity and adherens junction in embryonic epithelia. Human CRB1 and its two paralogues, CRB2 and CRB3, are highly conserved throughout the animal kingdom. Both in Drosophila and in vertebrates, the short intracellular domain of Crb/CRB organizes an evolutionary conserved protein scaffold. Several lines of evidence, obtained both in Drosophila and in mouse, show that loss-of-function of crb/CRB1 or some of its intracellular interactors lead to morphological defects and light-induced degeneration of photoreceptor cells, features comparable to those observed in patients lacking CRB1 function. In this review, we describe how understanding Crb complex function in fly and vertebrate retina enhances our knowledge of basic cell biological processes and might lead to new therapeutic approaches for patients affected with retinal dystrophies caused by mutations in the CRB1 gene.
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Affiliation(s)
- Mélisande Richard
- Institut für Genetik, Heinrich Heine Universität Düsseldorf, Universitätsstrasse 1, 40225 Düsseldorf, Germany.
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