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Du X, Butler AG, Chen HY. Cell-cell interaction in the pathogenesis of inherited retinal diseases. Front Cell Dev Biol 2024; 12:1332944. [PMID: 38500685 PMCID: PMC10944940 DOI: 10.3389/fcell.2024.1332944] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2023] [Accepted: 02/06/2024] [Indexed: 03/20/2024] Open
Abstract
The retina is part of the central nervous system specialized for vision. Inherited retinal diseases (IRD) are a group of clinically and genetically heterogenous disorders that lead to progressive vision impairment or blindness. Although each disorder is rare, IRD accumulatively cause blindness in up to 5.5 million individuals worldwide. Currently, the pathophysiological mechanisms of IRD are not fully understood and there are limited treatment options available. Most IRD are caused by degeneration of light-sensitive photoreceptors. Genetic mutations that abrogate the structure and/or function of photoreceptors lead to visual impairment followed by blindness caused by loss of photoreceptors. In healthy retina, photoreceptors structurally and functionally interact with retinal pigment epithelium (RPE) and Müller glia (MG) to maintain retinal homeostasis. Multiple IRD with photoreceptor degeneration as a major phenotype are caused by mutations of RPE- and/or MG-associated genes. Recent studies also reveal compromised MG and RPE caused by mutations in ubiquitously expressed ciliary genes. Therefore, photoreceptor degeneration could be a direct consequence of gene mutations and/or could be secondary to the dysfunction of their interaction partners in the retina. This review summarizes the mechanisms of photoreceptor-RPE/MG interaction in supporting retinal functions and discusses how the disruption of these processes could lead to photoreceptor degeneration, with an aim to provide a unique perspective of IRD pathogenesis and treatment paradigm. We will first describe the biology of retina and IRD and then discuss the interaction between photoreceptors and MG/RPE as well as their implications in disease pathogenesis. Finally, we will summarize the recent advances in IRD therapeutics targeting MG and/or RPE.
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Affiliation(s)
| | | | - Holly Y. Chen
- Department of Cell, Developmental and Integrative Biology, Heersink School of Medicine, University of Alabama at Birmingham, Birmingham, AL, United States
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Clinical and Genetic Re-Evaluation of Inherited Retinal Degeneration Pedigrees following Initial Negative Findings on Panel-Based Next Generation Sequencing. Int J Mol Sci 2022; 23:ijms23020995. [PMID: 35055178 PMCID: PMC8780304 DOI: 10.3390/ijms23020995] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2021] [Revised: 01/03/2022] [Accepted: 01/12/2022] [Indexed: 02/06/2023] Open
Abstract
Although rare, inherited retinal degenerations (IRDs) are the most common reason for blind registration in the working age population. They are highly genetically heterogeneous (>300 known genetic loci), and confirmation of a molecular diagnosis is a prerequisite for many therapeutic clinical trials and approved treatments. First-tier genetic testing of IRDs with panel-based next-generation sequencing (pNGS) has a diagnostic yield of ≈70-80%, leaving the remaining more challenging cases to be resolved by second-tier testing methods. This study describes the phenotypic reassessment of patients with a negative result from first-tier pNGS and the rationale, outcomes, and cost of second-tier genetic testing approaches. Removing non-IRD cases from consideration and utilizing case-appropriate second-tier genetic testing techniques, we genetically resolved 56% of previously unresolved pedigrees, bringing the overall resolve rate to 92% (388/423). At present, pNGS remains the most cost-effective first-tier approach for the molecular assessment of diverse IRD populations Second-tier genetic testing should be guided by clinical (i.e., reassessment, multimodal imaging, electrophysiology), and genetic (i.e., single alleles in autosomal recessive disease) indications to achieve a genetic diagnosis in the most cost-effective manner.
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3
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High-Throughput Analysis of Retinal Cis-Regulatory Networks by Massively Parallel Reporter Assays. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2020; 1185:359-364. [PMID: 31884638 DOI: 10.1007/978-3-030-27378-1_59] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Inherited retinal degenerations are diverse and debilitating blinding diseases. Genetic tests and exome sequencing have identified mutations in many protein-coding genes associated with such diseases, but causal sequence variants remain to be found in many retinopathy cases. Since 99% of our genome does not code for protein but contains cis-regulatory elements (CREs) that regulate the expression of essential genes, CRE variants might hold the answer for some of these cases. However, identifying functional CREs within the noncoding genome and predicting the pathogenicity of CRE variants pose a significant challenge. Here, we review the development of massively parallel reporter assays in the mouse retina, its use in dissecting retinal cis-regulatory networks, and its potential application for developing therapies.
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Khan M, Fadaie Z, Cornelis SS, Cremers FPM, Roosing S. Identification and Analysis of Genes Associated with Inherited Retinal Diseases. Methods Mol Biol 2019; 1834:3-27. [PMID: 30324433 DOI: 10.1007/978-1-4939-8669-9_1] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Inherited retinal diseases (IRDs) display a very high degree of clinical and genetic heterogeneity, which poses challenges in finding the underlying defects in known IRD-associated genes and in identifying novel IRD-associated genes. Knowledge on the molecular and clinical aspects of IRDs has increased tremendously in the last decade. Here, we outline the state-of-the-art techniques to find the causative genetic variants, with special attention for next-generation sequencing which can combine molecular diagnostics and retinal disease gene identification. An important aspect is the functional assessment of rare variants with RNA and protein effects which can only be predicted in silico. We therefore describe the in vitro assessment of putative splice defects in human embryonic kidney cells. In addition, we outline the use of stem cell technology to generate photoreceptor precursor cells from patients' somatic cells which can subsequently be used for RNA and protein studies. Finally, we outline the in silico methods to interpret the causality of variants associated with inherited retinal disease and the registry of these variants.
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Affiliation(s)
- Mubeen Khan
- Department of Human Genetics, Donders Institute for Brain Cognition and Behaviour, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Zeinab Fadaie
- Department of Human Genetics, Donders Institute for Brain Cognition and Behaviour, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Stéphanie S Cornelis
- Department of Human Genetics, Donders Institute for Brain Cognition and Behaviour, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Frans P M Cremers
- Department of Human Genetics, Donders Institute for Brain Cognition and Behaviour, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Susanne Roosing
- Department of Human Genetics, Donders Institute for Brain Cognition and Behaviour, Radboud University Medical Center, Nijmegen, The Netherlands.
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Farrar GJ, Carrigan M, Dockery A, Millington-Ward S, Palfi A, Chadderton N, Humphries M, Kiang AS, Kenna PF, Humphries P. Toward an elucidation of the molecular genetics of inherited retinal degenerations. Hum Mol Genet 2017; 26:R2-R11. [PMID: 28510639 PMCID: PMC5886474 DOI: 10.1093/hmg/ddx185] [Citation(s) in RCA: 55] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2017] [Accepted: 05/08/2017] [Indexed: 02/06/2023] Open
Abstract
While individually classed as rare diseases, hereditary retinal degenerations (IRDs) are the major cause of registered visual handicap in the developed world. Given their hereditary nature, some degree of intergenic heterogeneity was expected, with genes segregating in autosomal dominant, recessive, X-linked recessive, and more rarely in digenic or mitochondrial modes. Today, it is recognized that IRDs, as a group, represent one of the most genetically diverse of hereditary conditions - at least 260 genes having been implicated, with 70 genes identified in the most common IRD, retinitis pigmentosa (RP). However, targeted sequencing studies of exons from known IRD genes have resulted in the identification of candidate mutations in only approximately 60% of IRD cases. Given recent advances in the development of gene-based medicines, characterization of IRD patient cohorts for known IRD genes and elucidation of the molecular pathologies of disease in those remaining unresolved cases has become an endeavor of the highest priority. Here, we provide an outline of progress in this area.
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Affiliation(s)
- G Jane Farrar
- Institute of Genetics, School of Genetics and Microbiology, University of Dublin, Trinity College, Dublin 2, Ireland
| | - Matthew Carrigan
- Institute of Genetics, School of Genetics and Microbiology, University of Dublin, Trinity College, Dublin 2, Ireland
| | - Adrian Dockery
- Institute of Genetics, School of Genetics and Microbiology, University of Dublin, Trinity College, Dublin 2, Ireland
| | - Sophia Millington-Ward
- Institute of Genetics, School of Genetics and Microbiology, University of Dublin, Trinity College, Dublin 2, Ireland
| | - Arpad Palfi
- Institute of Genetics, School of Genetics and Microbiology, University of Dublin, Trinity College, Dublin 2, Ireland
| | - Naomi Chadderton
- Institute of Genetics, School of Genetics and Microbiology, University of Dublin, Trinity College, Dublin 2, Ireland
| | - Marian Humphries
- Institute of Genetics, School of Genetics and Microbiology, University of Dublin, Trinity College, Dublin 2, Ireland
| | - Anna Sophia Kiang
- Institute of Genetics, School of Genetics and Microbiology, University of Dublin, Trinity College, Dublin 2, Ireland
| | - Paul F Kenna
- Research Foundation, Royal Victoria Eye and Ear Hospital, Dublin 2, Ireland
| | - Pete Humphries
- Institute of Genetics, School of Genetics and Microbiology, University of Dublin, Trinity College, Dublin 2, Ireland
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Wensel TG, Zhang Z, Anastassov IA, Gilliam JC, He F, Schmid MF, Robichaux MA. Structural and molecular bases of rod photoreceptor morphogenesis and disease. Prog Retin Eye Res 2016; 55:32-51. [PMID: 27352937 PMCID: PMC5112133 DOI: 10.1016/j.preteyeres.2016.06.002] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2015] [Revised: 06/14/2016] [Accepted: 06/20/2016] [Indexed: 12/15/2022]
Abstract
The rod cell has an extraordinarily specialized structure that allows it to carry out its unique function of detecting individual photons of light. Both the structural features of the rod and the metabolic processes required for highly amplified light detection seem to have rendered the rod especially sensitive to structural and metabolic defects, so that a large number of gene defects are primarily associated with rod cell death and give rise to blinding retinal dystrophies. The structures of the rod, especially those of the sensory cilium known as the outer segment, have been the subject of structural, biochemical, and genetic analysis for many years, but the molecular bases for rod morphogenesis and for cell death in rod dystrophies are still poorly understood. Recent developments in imaging technology, such as cryo-electron tomography and super-resolution fluorescence microscopy, in gene sequencing technology, and in gene editing technology are rapidly leading to new breakthroughs in our understanding of these questions. A summary is presented of our current understanding of selected aspects of these questions, highlighting areas of uncertainty and contention as well as recent discoveries that provide new insights. Examples of structural data from emerging imaging technologies are presented.
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Affiliation(s)
- Theodore G Wensel
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX 77030, USA.
| | - Zhixian Zhang
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX 77030, USA
| | - Ivan A Anastassov
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX 77030, USA
| | - Jared C Gilliam
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX 77030, USA
| | - Feng He
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX 77030, USA
| | - Michael F Schmid
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX 77030, USA
| | - Michael A Robichaux
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX 77030, USA
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Carrigan M, Duignan E, Malone CPG, Stephenson K, Saad T, McDermott C, Green A, Keegan D, Humphries P, Kenna PF, Farrar GJ. Panel-Based Population Next-Generation Sequencing for Inherited Retinal Degenerations. Sci Rep 2016; 6:33248. [PMID: 27624628 PMCID: PMC5021935 DOI: 10.1038/srep33248] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2016] [Accepted: 08/23/2016] [Indexed: 12/15/2022] Open
Abstract
Inherited retinopathies affect approximately two and a half million people globally, yet the majority of affected patients lack clear genetic diagnoses given the diverse range of genes and mutations implicated in these conditions. We present results from a next-generation sequencing study of a large inherited retinal disease patient population, with the goal of providing clear and actionable genetic diagnoses. Targeted sequencing was performed on 539 individuals from 309 inherited retinal disease pedigrees. Causative mutations were identified in the majority (57%, 176/309) of pedigrees. We report the association of many previously unreported variants with retinal disease, as well as new disease phenotypes associated with known genes, including the first association of the SLC24A1 gene with retinitis pigmentosa. Population statistics reporting the genes most commonly implicated in retinal disease in the cohort are presented, as are some diagnostic conundrums that can arise during such studies. Inherited retinal diseases represent an exemplar group of disorders for the application of panel-based next-generation sequencing as an effective tool for detection of causative mutations.
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Affiliation(s)
- Matthew Carrigan
- School of Genetics and Microbiology, Trinity College Dublin, Dublin, Ireland
| | - Emma Duignan
- Research Foundation, Royal Victoria Eye and Ear Hospital, Dublin, Ireland
| | - Conor P G Malone
- Research Foundation, Royal Victoria Eye and Ear Hospital, Dublin, Ireland
| | | | - Tahira Saad
- Mater Misericordiae University Hospital, Dublin, Ireland
| | - Ciara McDermott
- School of Genetics and Microbiology, Trinity College Dublin, Dublin, Ireland
| | - Andrew Green
- Our Lady's Children's Hospital, Crumlin, Dublin, Ireland
| | - David Keegan
- Mater Misericordiae University Hospital, Dublin, Ireland
| | - Peter Humphries
- School of Genetics and Microbiology, Trinity College Dublin, Dublin, Ireland
| | - Paul F Kenna
- School of Genetics and Microbiology, Trinity College Dublin, Dublin, Ireland.,Research Foundation, Royal Victoria Eye and Ear Hospital, Dublin, Ireland
| | - G Jane Farrar
- School of Genetics and Microbiology, Trinity College Dublin, Dublin, Ireland
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