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Xu J, Zhao C, Kang Y. The Formation and Renewal of Photoreceptor Outer Segments. Cells 2024; 13:1357. [PMID: 39195247 DOI: 10.3390/cells13161357] [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: 06/30/2024] [Revised: 08/12/2024] [Accepted: 08/13/2024] [Indexed: 08/29/2024] Open
Abstract
The visual system is essential for humans to perceive the environment. In the retina, rod and cone photoreceptor neurons are the initial sites where vision forms. The apical region of both cone and rod photoreceptors contains a light-sensing organelle known as the outer segment (OS), which houses tens of thousands of light-sensitive opsins. The OSs of photoreceptors are not static; they require rhythmic renewal to maintain normal physiological functions. Disruptions in OS renewal can lead to various genetic disorders, such as retinitis pigmentosa (RP). Understanding the patterns and molecular mechanisms of photoreceptor OS renewal remains one of the most intriguing topics in visual biology. This review aims to elucidate the structure of photoreceptor OSs, the molecular mechanisms underlying photoreceptor OS renewal, and the retinal diseases resulting from defects in this renewal process. Additionally, we will explore retinal diseases related to photoreceptor OS renewal and potential therapeutic strategies, concluding with a discussion on future research directions for OS renewal.
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Affiliation(s)
- Jingjin Xu
- College of Marine Life Sciences, Ocean University of China, Qingdao 266003, China
- MoE Key Laboratory of Evolution and Marine Biodiversity, Institute of Evolution and Marine Biodiversity, Ocean University of China, Qingdao 266003, China
| | - Chengtian Zhao
- College of Marine Life Sciences, Ocean University of China, Qingdao 266003, China
- MoE Key Laboratory of Evolution and Marine Biodiversity, Institute of Evolution and Marine Biodiversity, Ocean University of China, Qingdao 266003, China
| | - Yunsi Kang
- College of Marine Life Sciences, Ocean University of China, Qingdao 266003, China
- MoE Key Laboratory of Evolution and Marine Biodiversity, Institute of Evolution and Marine Biodiversity, Ocean University of China, Qingdao 266003, China
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2
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Reeves MJ, Goetz KE, Guan B, Ullah E, Blain D, Zein WM, Tumminia SJ, Hufnagel RB. Genotype-phenotype associations in a large PRPH2-related retinopathy cohort. Hum Mutat 2020; 41:1528-1539. [PMID: 32531846 DOI: 10.1002/humu.24065] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2020] [Revised: 04/17/2020] [Accepted: 05/04/2020] [Indexed: 12/26/2022]
Abstract
Molecular variant interpretation lacks disease gene-specific cohorts for determining variant enrichment in disease versus healthy populations. To address the molecular etiology of retinal degeneration, specifically the PRPH2-related retinopathies, we reviewed genotype and phenotype information obtained from 187 eyeGENE® participants from 161 families. Clinical details were provided by referring clinicians participating in the eyeGENE® Network. The cohort was sequenced for variants in PRPH2. Variant complementary DNA clusters and cohort frequency were compared to variants in public databases to help us to determine pathogenicity by current American College of Medical Genetics and Genomics/Association for Molecular Pathology interpretation criteria. The most frequent variant was c.828+3A>T, which affected 28 families (17.4%), and 25 of 79 (31.64%) variants were novel. The majority of missense variants clustered in the D2 intracellular loop of the peripherin-2 protein, constituting a hotspot. Disease enrichment was noted for 23 (29.1%) of the variants. Hotspot and disease-enrichment evidence modified variant classification for 16.5% of variants. The missense allele p.Arg172Trp was associated with a younger age of onset. To the best of our knowledge, this is the largest patient cohort review of PRPH2-related retinopathy. Large disease gene-specific cohorts permit gene modeling for hotspot and disease-enrichment analysis, providing novel variant classification evidence, including for novel missense variants.
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Affiliation(s)
- Melissa J Reeves
- Ophthalmic Genetics and Visual Function Branch, National Eye Institute/National Institutes of Health, Bethesda, Maryland
| | - Kerry E Goetz
- Office of the Director, National Eye Institute/National Institutes of Health, Bethesda, Maryland
| | - Bin Guan
- Ophthalmic Genetics and Visual Function Branch, National Eye Institute/National Institutes of Health, Bethesda, Maryland
| | - Ehsan Ullah
- Ophthalmic Genetics and Visual Function Branch, National Eye Institute/National Institutes of Health, Bethesda, Maryland
| | - Delphine Blain
- Ophthalmic Genetics and Visual Function Branch, National Eye Institute/National Institutes of Health, Bethesda, Maryland
| | - Wadih M Zein
- Ophthalmic Genetics and Visual Function Branch, National Eye Institute/National Institutes of Health, Bethesda, Maryland
| | - Santa J Tumminia
- Office of the Director, National Eye Institute/National Institutes of Health, Bethesda, Maryland
| | - Robert B Hufnagel
- Ophthalmic Genetics and Visual Function Branch, National Eye Institute/National Institutes of Health, Bethesda, Maryland
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Chen X, Jiang C, Yang D, Sun R, Wang M, Sun H, Xu M, Zhou L, Chen M, Xie P, Yan B, Liu Q, Zhao C. CRB2 mutation causes autosomal recessive retinitis pigmentosa. Exp Eye Res 2018; 180:164-173. [PMID: 30593785 DOI: 10.1016/j.exer.2018.12.018] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2018] [Revised: 12/21/2018] [Accepted: 12/21/2018] [Indexed: 01/29/2023]
Abstract
Retinitis pigmentosa (RP), the most common form of inherited retinal dystrophies, exhibits significant genetic heterogeneity. The crumbs homolog 2 (CRB2) protein, together with CRB1 and CRB3, belongs to the Crumbs family. Given that CRB1 mutations account for 4% of RP cases, the role of CRB2 mutations in RP etiology has long been hypothesized but never confirmed. Herein, we report the identification of CRB2 as a novel RP causative gene in a Chinese consanguineous family and have analyzed its pathogenic effects. Comprehensive ophthalmic and systemic evaluations confirmed the clinical diagnosis of the two patients in this family as RP. WES revealed a homozygous missense mutation, CRB2 p.R1249G, to segregate the RP phenotype, which was highly conserved among multiple species. In vitro cellular study revealed that this mutation not only interrupted the stability of the transcribed CRB2 mRNA and the encoded CRB2 protein, but also interfered with the wild type CRB2 mRNA/protein and decreased their expression. This mutation was also shown to trigger epithelial-mesenchymal transition (EMT) in retinal pigment epithelium (RPE) cells, thus impairing regular RPE phagocytosis and induce RPE degeneration and apoptosis. Thus, we conclude that CRB2 p.R1249G mutation causes RP via accelerating EMT, dysfunction and loss of RPE cells, and establish CRB2 as a novel Crumbs family member associated with non-syndromic RP. We provide important hints for understanding of CRB2 defects and retinopathy, and for the involvement of EMT of RPE cells in RP pathogenesis.
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Affiliation(s)
- Xue Chen
- Department of Ophthalmology, The First Affiliated Hospital of Nanjing Medical University, Nanjing, 210029, China; Department of Ophthalmology and Vision Science, Eye & ENT Hospital, Shanghai Medical College, Fudan University, Shanghai, 200023, China; Key Laboratory of Myopia of State Health Ministry (Fudan University) and Shanghai Key Laboratory of Visual Impairment and Restoration, Shanghai, 200023, China
| | - Chao Jiang
- Department of Ophthalmology, The First Affiliated Hospital of Nanjing Medical University, Nanjing, 210029, China
| | - Daidi Yang
- Department of Ophthalmology, The First Affiliated Hospital of Nanjing Medical University, Nanjing, 210029, China
| | - Ruxu Sun
- Department of Ophthalmology, The First Affiliated Hospital of Nanjing Medical University, Nanjing, 210029, China
| | - Min Wang
- Department of Ophthalmology and Vision Science, Eye & ENT Hospital, Shanghai Medical College, Fudan University, Shanghai, 200023, China; Key Laboratory of Myopia of State Health Ministry (Fudan University) and Shanghai Key Laboratory of Visual Impairment and Restoration, Shanghai, 200023, China
| | - Hong Sun
- Department of Ophthalmology, The First Affiliated Hospital of Nanjing Medical University, Nanjing, 210029, China
| | - Min Xu
- Department of Ophthalmology, Northern Jiangsu People's Hospital, Yangzhou, 211406, China
| | - Luyin Zhou
- Department of Ophthalmology, The First Affiliated Hospital of Nanjing Medical University, Nanjing, 210029, China
| | - Mingkang Chen
- Department of Ophthalmology, The First Affiliated Hospital of Nanjing Medical University, Nanjing, 210029, China
| | - Ping Xie
- Department of Ophthalmology, The First Affiliated Hospital of Nanjing Medical University, Nanjing, 210029, China
| | - Biao Yan
- Department of Ophthalmology and Vision Science, Eye & ENT Hospital, Shanghai Medical College, Fudan University, Shanghai, 200023, China; Key Laboratory of Myopia of State Health Ministry (Fudan University) and Shanghai Key Laboratory of Visual Impairment and Restoration, Shanghai, 200023, China
| | - Qinghuai Liu
- Department of Ophthalmology, The First Affiliated Hospital of Nanjing Medical University, Nanjing, 210029, China.
| | - Chen Zhao
- Department of Ophthalmology, The First Affiliated Hospital of Nanjing Medical University, Nanjing, 210029, China; Department of Ophthalmology and Vision Science, Eye & ENT Hospital, Shanghai Medical College, Fudan University, Shanghai, 200023, China; Key Laboratory of Myopia of State Health Ministry (Fudan University) and Shanghai Key Laboratory of Visual Impairment and Restoration, Shanghai, 200023, China.
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Identification of a Disease-Causing Mutation in a Chinese Patient with Retinitis Pigmentosa by Targeted Next-Generation Sequencing. Eur J Ophthalmol 2018; 27:791-796. [PMID: 28430325 DOI: 10.5301/ejo.5000971] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
PURPOSE To identify disease-causing mutations in a Chinese patient with retinitis pigmentosa (RP). METHODS A detailed clinical examination was performed on the proband. Targeted next-generation sequencing (NGS) combined with bioinformatics analysis was performed on the proband to detect candidate disease-causing mutations. Sanger sequencing was performed on all subjects to confirm the candidate mutations and assess cosegregation within the family. RESULTS Clinical examinations of the proband showed typical characteristics of RP. Three candidate heterozygous mutations in 3 genes associated with RP were detected in the proband by targeted NGS. The 3 mutations were confirmed by Sanger sequencing and the deletion (c.357_358delAA) in PRPF31 was shown to cosegregate with RP phenotype in 7 affected family members, but not in 3 unaffected family members. CONCLUSIONS The deletion (c.357_358delAA) in PRPF31 was the disease-causing mutation for the proband and his affected family members with RP. To our knowledge, this is the second report of the deletion and the first report of the other 2 mutations in the Chinese population. Targeted NGS combined with bioinformatics analysis proved to be an effective molecular diagnostic tool for RP.
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Abstract
Retinitis pigmentosa is the most common form of inherited blindness in humans. A well-studied model of the disease is the rd1 mouse, characterized by a loss of function mutation in the catalytic β subunit of the phosphodiesterase 6 (Pde6) holoenzyme involved in phototransduction within rods and cones. The period of photoreceptor degeneration in the rd1 mouse occurs during postnatal days 10-21. In previous work, only Pde6β and vesicular-trafficking protein Prenylated Rab Acceptor 1 (PRA1) have been found to be consistently downregulated during the first ten days following birth. In a yeast-two-hybrid assay conducted by our lab, PRA1 was shown to interact with Charged Multivesicular Body Protein 2B (CHMP2B), an endosomal sorting protein that has been implicated in several neurodegenerative diseases, such as frontotemporal dementia and amyotrophic lateral sclerosis. We investigated whether CHMP2B is mislocalized in the rd1 mouse. Immunohistochemical labeling of CHMP2B was done in both postnatal wild type and rd1 mouse retinas. Prior to the onset of degeneration, CHMP2B immunolabeling was weaker in rd1 retinas, particularly in the developing photoreceptor synaptic layer, compared to wild type. Furthermore, staining of CHMP2B in wild type photoreceptors peaked at postnatal day 12, while CHMP2B staining in rd1 retinas was diffuse and disorganized. In conclusion, these findings show that proper localization of CHMP2B is disrupted in rd1 photoreceptors. Further studies are needed to investigate possible roles for CHMP2B in endocytic activity that is vital to photoreceptor maintenance, as well as differentiation, and development in mouse photoreceptors.
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Affiliation(s)
- Fadi Assaf
- Department of Biology, Saint Louis University, St. Louis, Missouri 63103
| | - Ameair Abu Irqeba
- Department of Biology, Saint Louis University, St. Louis, Missouri 63103
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Costa KA, Salles MV, Whitebirch C, Chiang J, Sallum JMF. Gene panel sequencing in Brazilian patients with retinitis pigmentosa. Int J Retina Vitreous 2017; 3:33. [PMID: 28912962 PMCID: PMC5592712 DOI: 10.1186/s40942-017-0087-6] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2017] [Accepted: 07/31/2017] [Indexed: 12/17/2022] Open
Abstract
Background Retinal dystrophies constitute a group of diseases characterized by clinical variability and pronounced genetic heterogeneity. Retinitis pigmentosa is the most common subtype of hereditary retinal dystrophy and is characterized by a progressive loss of peripheral field vision (Tunnel Vision), eventual loss of central vision, and progressive night blindness. The characteristics of the fundus changes include bone-spicule formations, attenuated blood vessels, reduced and/or abnormal electroretinograms, changes in structure imaged by optical coherence tomography, and subjective changes in visual function. The different syndromic and nonsyndromic forms of retinal dystrophies can be attributed to mutations in more than 250 genes. Molecular diagnosis for patients with retinitis pigmentosa has been hampered by extreme genetic and clinical heterogeneity between retinitis pigmentosa and other forms of retinal dystrophies. Next generation sequencing (NGS) technologies are among the most promising techniques to identify pathogenic variations in retinal dystrophies. Purpose The purpose of this study was to discover the molecular diagnosis for Brazilian patients clinically diagnosed with a retinitis pigmentosa pattern of inheritance by using NGS technologies. Materials and methods Sixteen patients with the clinical diagnosis of retinitis pigmentosa were included in the study. Their DNA was sequenced in a panel with 132 genes related to retinal dystrophies using the Illumina® platform. Sequence analysis and variation calling was performed using Soft Genetics®, NextGene, and Geneticist Assistant software. The criteria for pathogenicity analysis were established according to the results of prediction programs (Polyphen 2, Mutation taster and MetaCore™) and comparison of pathogenic variations found with databases. Results The identified potentially pathogenic variations were all confirmed by Sanger sequencing. There were 89 variations predicted as pathogenic, but only 10 of them supported the conclusion of the molecular diagnosis. Five of the nine patients were autosomal dominant RP (56%), two (22%) were autosomal recessive RP, and two (22%) were X-linked RP. Nine of the 16 patients (56%) had probably positive or positive results. Conclusion The Next Generation Sequencing used in this study allowed the molecular diagnosis to be confirmed in 56% of the patients and clarified the inheritance pattern of the patient’s retinal dystrophies. Electronic supplementary material The online version of this article (doi:10.1186/s40942-017-0087-6) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Kárita Antunes Costa
- Department of Ophthalmology and Visual Sciences, Federal University of São Paulo (UNIFESP), São Paulo, Brazil
| | - Mariana Vallim Salles
- Department of Ophthalmology and Visual Sciences, Federal University of São Paulo (UNIFESP), São Paulo, Brazil
| | - Chris Whitebirch
- Casey Eye Institute Molecular Diagnostic Laboratory, Oregon Health and Science University (OHSU), Portland, OR USA
| | - John Chiang
- Casey Eye Institute Molecular Diagnostic Laboratory, Oregon Health and Science University (OHSU), Portland, OR USA
| | - Juliana Maria Ferraz Sallum
- Department of Ophthalmology and Visual Sciences, Federal University of São Paulo (UNIFESP), São Paulo, Brazil
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Zhang L, Du J, Justus S, Hsu CW, Bonet-Ponce L, Wu WH, Tsai YT, Wu WP, Jia Y, Duong JK, Mahajan VB, Lin CS, Wang S, Hurley JB, Tsang SH. Reprogramming metabolism by targeting sirtuin 6 attenuates retinal degeneration. J Clin Invest 2016; 126:4659-4673. [PMID: 27841758 DOI: 10.1172/jci86905] [Citation(s) in RCA: 68] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2016] [Accepted: 10/06/2016] [Indexed: 12/16/2022] Open
Abstract
Retinitis pigmentosa (RP) encompasses a diverse group of Mendelian disorders leading to progressive degeneration of rods and then cones. For reasons that remain unclear, diseased RP photoreceptors begin to deteriorate, eventually leading to cell death and, consequently, loss of vision. Here, we have hypothesized that RP associated with mutations in phosphodiesterase-6 (PDE6) provokes a metabolic aberration in rod cells that promotes the pathological consequences of elevated cGMP and Ca2+, which are induced by the Pde6 mutation. Inhibition of sirtuin 6 (SIRT6), a histone deacetylase repressor of glycolytic flux, reprogrammed rods into perpetual glycolysis, thereby driving the accumulation of biosynthetic intermediates, improving outer segment (OS) length, enhancing photoreceptor survival, and preserving vision. In mouse retinae lacking Sirt6, effectors of glycolytic flux were dramatically increased, leading to upregulation of key intermediates in glycolysis, TCA cycle, and glutaminolysis. Both transgenic and AAV2/8 gene therapy-mediated ablation of Sirt6 in rods provided electrophysiological and anatomic rescue of both rod and cone photoreceptors in a preclinical model of RP. Due to the extensive network of downstream effectors of Sirt6, this study motivates further research into the role that these pathways play in retinal degeneration. Because reprogramming metabolism by enhancing glycolysis is not gene specific, this strategy may be applicable to a wide range of neurodegenerative disorders.
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Zhang L, Justus S, Xu Y, Pluchenik T, Hsu CW, Yang J, Duong JK, Lin CS, Jia Y, Bassuk AG, Mahajan VB, Tsang SH. Reprogramming towards anabolism impedes degeneration in a preclinical model of retinitis pigmentosa. Hum Mol Genet 2016; 25:4244-4255. [PMID: 27516389 DOI: 10.1093/hmg/ddw256] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2016] [Revised: 06/25/2016] [Accepted: 07/22/2016] [Indexed: 11/14/2022] Open
Abstract
Retinitis pigmentosa (RP) is an incurable neurodegenerative condition featuring photoreceptor death that leads to blindness. Currently, there is no approved therapeutic for photoreceptor degenerative conditions like RP and atrophic age-related macular degeneration (AMD). Although there are promising results in human gene therapy, RP is a genetically diverse disorder, such that gene-specific therapies would be practical in a small fraction of patients with RP. Here, we explore a non-gene-specific strategy that entails reprogramming photoreceptors towards anabolism by upregulating the mechanistic target of rapamycin (mTOR) pathway. We conditionally ablated the tuberous sclerosis complex 1 (Tsc1) gene, an mTOR inhibitor, in the rods of the Pde6bH620Q/H620Q preclinical RP mouse model and observed, functionally and morphologically, an improvement in the survival of rods and cones at early and late disease stages. These results elucidate the ability of reprogramming the metabolome to slow photoreceptor degeneration. This strategy may also be applicable to a wider range of neurodegenerative diseases, as enhancement of nutrient uptake is not gene-specific and is implicated in multiple pathologies. Enhancing anabolism promoted neuronal survival and function and could potentially benefit a number of photoreceptor and other degenerative conditions.
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Affiliation(s)
- Lijuan Zhang
- Barbara & Donald Jonas Stem Cell & Regenerative Medicine Laboratory, and Bernard & Shirlee Brown Glaucoma Laboratory, Departments of Ophthalmology and Pathology & Cell Biology, Institute of Human Nutrition, Herbert Irving Comprehensive Cancer Center, Columbia University, New York, NY, USA.,Edward S. Harkness Eye Institute, New York-Presbyterian Hospital, New York, NY, USA.,Shanxi Eye Hospital, affiliated with Shanxi Medical University, Xinghualing, Taiyuan, Shanxi, China
| | - Sally Justus
- Barbara & Donald Jonas Stem Cell & Regenerative Medicine Laboratory, and Bernard & Shirlee Brown Glaucoma Laboratory, Departments of Ophthalmology and Pathology & Cell Biology, Institute of Human Nutrition, Herbert Irving Comprehensive Cancer Center, Columbia University, New York, NY, USA.,Edward S. Harkness Eye Institute, New York-Presbyterian Hospital, New York, NY, USA
| | - Yu Xu
- Barbara & Donald Jonas Stem Cell & Regenerative Medicine Laboratory, and Bernard & Shirlee Brown Glaucoma Laboratory, Departments of Ophthalmology and Pathology & Cell Biology, Institute of Human Nutrition, Herbert Irving Comprehensive Cancer Center, Columbia University, New York, NY, USA.,Edward S. Harkness Eye Institute, New York-Presbyterian Hospital, New York, NY, USA.,Department of Ophthalmology, Xinhua Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Tamara Pluchenik
- Barbara & Donald Jonas Stem Cell & Regenerative Medicine Laboratory, and Bernard & Shirlee Brown Glaucoma Laboratory, Departments of Ophthalmology and Pathology & Cell Biology, Institute of Human Nutrition, Herbert Irving Comprehensive Cancer Center, Columbia University, New York, NY, USA.,Edward S. Harkness Eye Institute, New York-Presbyterian Hospital, New York, NY, USA
| | - Chun-Wei Hsu
- Barbara & Donald Jonas Stem Cell & Regenerative Medicine Laboratory, and Bernard & Shirlee Brown Glaucoma Laboratory, Departments of Ophthalmology and Pathology & Cell Biology, Institute of Human Nutrition, Herbert Irving Comprehensive Cancer Center, Columbia University, New York, NY, USA.,Edward S. Harkness Eye Institute, New York-Presbyterian Hospital, New York, NY, USA
| | - Jin Yang
- Barbara & Donald Jonas Stem Cell & Regenerative Medicine Laboratory, and Bernard & Shirlee Brown Glaucoma Laboratory, Departments of Ophthalmology and Pathology & Cell Biology, Institute of Human Nutrition, Herbert Irving Comprehensive Cancer Center, Columbia University, New York, NY, USA.,Edward S. Harkness Eye Institute, New York-Presbyterian Hospital, New York, NY, USA.,Tianjin Medical University Eye Hospital, Tianjin, China
| | - Jimmy K Duong
- Department of Biostatistics, Mailman School of Public Health, Columbia University Medical Center, New York, USA
| | - Chyuan-Sheng Lin
- Department of Pathology and Cell Biology, Transgenic Animal Facility, Herbert Irving Comprehensive Cancer Center, College of Physicians and Surgeons of Columbia University, New York, NY, USA
| | - Yading Jia
- Shanxi Eye Hospital, affiliated with Shanxi Medical University, Xinghualing, Taiyuan, Shanxi, China
| | - Alexander G Bassuk
- Department of Pediatrics and Neurology, University of Iowa, Iowa City, IA
| | - Vinit B Mahajan
- Omics Laboratory, University of Iowa, Iowa City, IA, USA.,Department of Ophthalmology and Visual Sciences, University of Iowa, Iowa City, IA, USA
| | - Stephen H Tsang
- Barbara & Donald Jonas Stem Cell & Regenerative Medicine Laboratory, and Bernard & Shirlee Brown Glaucoma Laboratory, Departments of Ophthalmology and Pathology & Cell Biology, Institute of Human Nutrition, Herbert Irving Comprehensive Cancer Center, Columbia University, New York, NY, USA .,Edward S. Harkness Eye Institute, New York-Presbyterian Hospital, New York, NY, USA
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Goldberg AFX, Moritz OL, Williams DS. Molecular basis for photoreceptor outer segment architecture. Prog Retin Eye Res 2016; 55:52-81. [PMID: 27260426 DOI: 10.1016/j.preteyeres.2016.05.003] [Citation(s) in RCA: 122] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2016] [Revised: 05/27/2016] [Accepted: 05/29/2016] [Indexed: 01/11/2023]
Abstract
To serve vision, vertebrate rod and cone photoreceptors must detect photons, convert the light stimuli into cellular signals, and then convey the encoded information to downstream neurons. Rods and cones are sensory neurons that each rely on specialized ciliary organelles to detect light. These organelles, called outer segments, possess elaborate architectures that include many hundreds of light-sensitive membranous disks arrayed one atop another in precise register. These stacked disks capture light and initiate the chain of molecular and cellular events that underlie normal vision. Outer segment organization is challenged by an inherently dynamic nature; these organelles are subject to a renewal process that replaces a significant fraction of their disks (up to ∼10%) on a daily basis. In addition, a broad range of environmental and genetic insults can disrupt outer segment morphology to impair photoreceptor function and viability. In this chapter, we survey the major progress that has been made for understanding the molecular basis of outer segment architecture. We also discuss key aspects of organelle lipid and protein composition, and highlight distributions, interactions, and potential structural functions of key OS-resident molecules, including: kinesin-2, actin, RP1, prominin-1, protocadherin 21, peripherin-2/rds, rom-1, glutamic acid-rich proteins, and rhodopsin. Finally, we identify key knowledge gaps and challenges that remain for understanding how normal outer segment architecture is established and maintained.
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Affiliation(s)
- Andrew F X Goldberg
- Eye Research Institute, Oakland University, 417 Dodge Hall, Rochester, MI, 48309, USA.
| | - Orson L Moritz
- Department of Ophthalmology & Visual Sciences, University of British Columbia, Vancouver, BC, Canada
| | - David S Williams
- Department of Ophthalmology and Jules Stein Eye Institute, Department of Neurobiology, David Geffen School of Medicine at UCLA, University of California, Los Angeles, CA, USA
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10
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Liu Y, Chen X, Xu Q, Gao X, Tam POS, Zhao K, Zhang X, Chen LJ, Jia W, Zhao Q, Vollrath D, Pang CP, Zhao C. SPP2 Mutations Cause Autosomal Dominant Retinitis Pigmentosa. Sci Rep 2015; 5:14867. [PMID: 26459573 PMCID: PMC4602186 DOI: 10.1038/srep14867] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2014] [Accepted: 09/08/2015] [Indexed: 01/12/2023] Open
Abstract
Retinitis pigmentosa (RP) shows progressive loss of photoreceptors involved with heterogeneous genetic background. Here, by exome sequencing and linkage analysis on a Chinese family with autosomal dominant RP, we identified a putative pathogenic variant, p.Gly97Arg, in the gene SPP2, of which expression was detected in multiple tissues including retina. The p.Gly97Arg was absent in 800 ethnically matched chromosomes and 1400 in-house exome dataset, and was located in the first of the two highly conserved disulfide bonded loop of secreted phosphoprotein 2 (Spp-24) encoded by SPP2. Overexpression of p.Gly97Arg and another signal peptide mutation, p.Gly29Asp, caused cellular retention of both endogenous wild type and exogenous mutants in vitro, and primarily affected rod photoreceptors in zebrafish mimicking cardinal feature of RP. Taken together, our data indicate that the two mutations of SPP2 have dominant negative effects and cellular accumulation of Spp-24 might be particularly toxic to photoreceptors and/or retinal pigment epithelium. SPP2 has a new role in retinal degeneration.
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Affiliation(s)
- Yuan Liu
- Department of Ophthalmology, The First Affiliated Hospital of Nanjing Medical University and State Key Laboratory of Reproductive Medicine, Nanjing Medical University, Nanjing 210029, China
| | - Xue Chen
- Department of Ophthalmology, The First Affiliated Hospital of Nanjing Medical University and State Key Laboratory of Reproductive Medicine, Nanjing Medical University, Nanjing 210029, China
| | - Qihua Xu
- Department of Ophthalmology, The First Affiliated Hospital of Nanjing Medical University and State Key Laboratory of Reproductive Medicine, Nanjing Medical University, Nanjing 210029, China.,Department of Ophthalmology, The Affiliated Jiangyin Hospital of Southeast University Medical College, Jiangyin, China
| | - Xiang Gao
- Department of Ophthalmology, School of Medicine, Henan Polytechnic University, Henan 454150, China
| | - Pancy O S Tam
- Department of Ophthalmology &Visual Sciences, The Chinese University of Hong Kong, Hong Kong
| | - Kanxing Zhao
- Tianjin Medical University, Tianjin Eye Hospital, Tianjin Key Laboratory of Ophthalmology and Visual Science, Tianjin 300040, China
| | - Xiumei Zhang
- Department of Ophthalmology, School of Medicine, Henan Polytechnic University, Henan 454150, China
| | - Li Jia Chen
- Department of Ophthalmology &Visual Sciences, The Chinese University of Hong Kong, Hong Kong
| | - Wenshuang Jia
- Model Animal Research Center, MOE Key Laboratory of Model Animal for Disease Study, Nanjing University, Nanjing 210061, China
| | - Qingshun Zhao
- Model Animal Research Center, MOE Key Laboratory of Model Animal for Disease Study, Nanjing University, Nanjing 210061, China
| | - Douglas Vollrath
- Department of Genetics, Stanford University School of Medicine, CA 94305, USA
| | - Chi Pui Pang
- Department of Ophthalmology &Visual Sciences, The Chinese University of Hong Kong, Hong Kong
| | - Chen Zhao
- Department of Ophthalmology, The First Affiliated Hospital of Nanjing Medical University and State Key Laboratory of Reproductive Medicine, Nanjing Medical University, Nanjing 210029, China.,State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat Sen University, Guangzhou, China
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11
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Application of Whole Exome Sequencing in Six Families with an Initial Diagnosis of Autosomal Dominant Retinitis Pigmentosa: Lessons Learned. PLoS One 2015. [PMID: 26197217 PMCID: PMC4509755 DOI: 10.1371/journal.pone.0133624] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
This study aimed to identify the genetics underlying dominant forms of inherited retinal dystrophies using whole exome sequencing (WES) in six families extensively screened for known mutations or genes. Thirty-eight individuals were subjected to WES. Causative variants were searched among single nucleotide variants (SNVs) and insertion/deletion variants (indels) and whenever no potential candidate emerged, copy number variant (CNV) analysis was performed. Variants or regions harboring a candidate variant were prioritized and segregation of the variant with the disease was further assessed using Sanger sequencing in case of SNVs and indels, and quantitative PCR (qPCR) for CNVs. SNV and indel analysis led to the identification of a previously reported mutation in PRPH2. Two additional mutations linked to different forms of retinal dystrophies were identified in two families: a known frameshift deletion in RPGR, a gene responsible for X-linked retinitis pigmentosa and p.Ser163Arg in C1QTNF5 associated with Late-Onset Retinal Degeneration. A novel heterozygous deletion spanning the entire region of PRPF31 was also identified in the affected members of a fourth family, which was confirmed with qPCR. This study allowed the identification of the genetic cause of the retinal dystrophy and the establishment of a correct diagnosis in four families, including a large heterozygous deletion in PRPF31, typically considered one of the pitfalls of this method. Since all findings in this study are restricted to known genes, we propose that targeted sequencing using gene-panel is an optimal first approach for the genetic screening and that once known genetic causes are ruled out, WES might be used to uncover new genes involved in inherited retinal dystrophies.
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Presentation of Complex Homozygous Allele in ABCA4 Gene in a Patient with Retinitis Pigmentosa. Case Rep Ophthalmol Med 2015; 2015:452068. [PMID: 26229699 PMCID: PMC4503555 DOI: 10.1155/2015/452068] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2015] [Revised: 06/08/2015] [Accepted: 06/17/2015] [Indexed: 11/17/2022] Open
Abstract
Retinitis pigmentosa is a degenerative retinal disease characterized by progressive photoreceptor damage, which causes loss of peripheral and night vision and the development of tunnel vision and may result in loss of central vision. This study describes a patient with retinitis pigmentosa caused by a mutation in the ABCA4 gene with complex allele c.1622T>C, p.L541P; c.3113C>T, p.A1038V in homozygous state.
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Lee K, Garg S. Navigating the current landscape of clinical genetic testing for inherited retinal dystrophies. Genet Med 2015; 17:245-52. [PMID: 25790163 DOI: 10.1038/gim.2015.15] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2014] [Accepted: 01/19/2015] [Indexed: 12/18/2022] Open
Abstract
Inherited eye disorders are a significant cause of vision loss. Genetic testing can be particularly helpful for patients with inherited retinal dystrophies because of genetic heterogeneity and overlapping phenotypes. The need to identify a molecular diagnosis for retinal dystrophies is particularly important in the era of developing novel gene therapy-based treatments, such as the RPE65 gene-based clinical trials and others on the horizon, as well as recent advances in reproductive options. The introduction of massively parallel sequencing technologies has significantly advanced the identification of novel gene candidates and has expanded the landscape of genetic testing. In a relatively short time clinical medicine has progressed from limited testing options to a plethora of choices ranging from single-gene testing to whole-exome sequencing. This article outlines currently available genetic testing and factors to consider when selecting appropriate testing for patients with inherited retinal dystrophies.
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Affiliation(s)
- Kristy Lee
- Department of Genetics, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - Seema Garg
- Department of Ophthalmology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
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Sullivan LS, Koboldt DC, Bowne SJ, Lang S, Blanton SH, Cadena E, Avery CE, Lewis RA, Webb-Jones K, Wheaton DH, Birch DG, Coussa R, Ren H, Lopez I, Chakarova C, Koenekoop RK, Garcia CA, Fulton RS, Wilson RK, Weinstock GM, Daiger SP. A dominant mutation in hexokinase 1 (HK1) causes retinitis pigmentosa. Invest Ophthalmol Vis Sci 2014; 55:7147-58. [PMID: 25190649 DOI: 10.1167/iovs.14-15419] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
PURPOSE To identify the cause of retinitis pigmentosa (RP) in UTAD003, a large, six-generation Louisiana family with autosomal dominant retinitis pigmentosa (adRP). METHODS A series of strategies, including candidate gene screening, linkage exclusion, genome-wide linkage mapping, and whole-exome next-generation sequencing, was used to identify a mutation in a novel disease gene on chromosome 10q22.1. Probands from an additional 404 retinal degeneration families were subsequently screened for mutations in this gene. RESULTS Exome sequencing in UTAD003 led to identification of a single, novel coding variant (c.2539G>A, p.Glu847Lys) in hexokinase 1 (HK1) present in all affected individuals and absent from normal controls. One affected family member carries two copies of the mutation and has an unusually severe form of disease, consistent with homozygosity for this mutation. Screening of additional adRP probands identified four other families (American, Canadian, and Sicilian) with the same mutation and a similar range of phenotypes. The families share a rare 450-kilobase haplotype containing the mutation, suggesting a founder mutation among otherwise unrelated families. CONCLUSIONS We identified an HK1 mutation in five adRP families. Hexokinase 1 catalyzes phosphorylation of glucose to glucose-6-phosphate. HK1 is expressed in retina, with two abundant isoforms expressed at similar levels. The Glu847Lys mutation is located at a highly conserved position in the protein, outside the catalytic domains. We hypothesize that the effect of this mutation is limited to the retina, as no systemic abnormalities in glycolysis were detected. Prevalence of the HK1 mutation in our cohort of RP families is 1%.
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Affiliation(s)
- Lori S Sullivan
- Human Genetics Center, University of Texas Health Science Center, Houston, Texas, United States
| | - Daniel C Koboldt
- The Genome Institute at Washington University, St. Louis, Missouri, United States
| | - Sara J Bowne
- Human Genetics Center, University of Texas Health Science Center, Houston, Texas, United States
| | - Steven Lang
- John P. Hussman Institute for Human Genomics, University of Miami, Miami, Florida, United States
| | - Susan H Blanton
- John P. Hussman Institute for Human Genomics, University of Miami, Miami, Florida, United States
| | - Elizabeth Cadena
- Human Genetics Center, University of Texas Health Science Center, Houston, Texas, United States
| | - Cheryl E Avery
- Human Genetics Center, University of Texas Health Science Center, Houston, Texas, United States
| | - Richard A Lewis
- Departments of Ophthalmology, Medicine, Pediatrics, and Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States
| | - Kaylie Webb-Jones
- The Retina Foundation of the Southwest, Dallas, Texas, United States
| | - Dianna H Wheaton
- The Retina Foundation of the Southwest, Dallas, Texas, United States
| | - David G Birch
- The Retina Foundation of the Southwest, Dallas, Texas, United States
| | - Razck Coussa
- McGill Ocular Genetics Laboratory, Departments of Paediatric Surgery, Human Genetics, and Ophthalmology, McGill University Health Center, Montreal, Quebec, Canada
| | - Huanan Ren
- McGill Ocular Genetics Laboratory, Departments of Paediatric Surgery, Human Genetics, and Ophthalmology, McGill University Health Center, Montreal, Quebec, Canada
| | - Irma Lopez
- McGill Ocular Genetics Laboratory, Departments of Paediatric Surgery, Human Genetics, and Ophthalmology, McGill University Health Center, Montreal, Quebec, Canada
| | - Christina Chakarova
- Institute of Ophthalmology, University College London, London, United Kingdom
| | - Robert K Koenekoop
- McGill Ocular Genetics Laboratory, Departments of Paediatric Surgery, Human Genetics, and Ophthalmology, McGill University Health Center, Montreal, Quebec, Canada
| | - Charles A Garcia
- Department of Ophthalmology and Visual Sciences, University of Texas Health Science Center, Houston, Texas, United States
| | - Robert S Fulton
- The Genome Institute at Washington University, St. Louis, Missouri, United States
| | - Richard K Wilson
- The Genome Institute at Washington University, St. Louis, Missouri, United States
| | - George M Weinstock
- The Genome Institute at Washington University, St. Louis, Missouri, United States
| | - Stephen P Daiger
- Human Genetics Center, University of Texas Health Science Center, Houston, Texas, United States Department of Ophthalmology and Visual Sciences, University of Texas Health Science Center, Houston, Texas, United States
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Siemiatkowska AM, Collin RWJ, den Hollander AI, Cremers FPM. Genomic approaches for the discovery of genes mutated in inherited retinal degeneration. Cold Spring Harb Perspect Med 2014; 4:a017137. [PMID: 24939053 PMCID: PMC4109577 DOI: 10.1101/cshperspect.a017137] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
In view of their high degree of genetic heterogeneity, inherited retinal diseases (IRDs) pose a significant challenge for identifying novel genetic causes. Thus far, more than 200 genes have been found to be mutated in IRDs, which together contain causal variants in >80% of the cases. Accurate genetic diagnostics is particularly important for isolated cases, in which X-linked and de novo autosomal dominant variants are not uncommon. In addition, new gene- or mutation-specific therapies are emerging, underlining the importance of identifying causative mutations in each individual. Sanger sequencing of selected genes followed by cost-effective targeted next-generation sequencing (NGS) can identify defects in known IRD-associated genes in the majority of the cases. Exome NGS in combination with genetic linkage or homozygosity mapping studies can aid the identification of the remaining causal genes. As these are thought to be mutated in <1% of the cases, validation through functional modeling in, for example, zebrafish and/or replication through the genotyping of large patient cohorts is required. In the near future, whole genome NGS in combination with transcriptome NGS may reveal mutations that are currently hidden in the noncoding regions of the human genome.
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Affiliation(s)
- Anna M Siemiatkowska
- Department of Human Genetics, Radboud University Medical Center, Nijmegen, The Netherlands Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Rob W J Collin
- Department of Human Genetics, Radboud University Medical Center, Nijmegen, The Netherlands Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Anneke I den Hollander
- Department of Human Genetics, Radboud University Medical Center, Nijmegen, The Netherlands Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, The Netherlands Department of Ophthalmology, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Frans P M Cremers
- Department of Human Genetics, Radboud University Medical Center, Nijmegen, The Netherlands Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
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Daiger SP, Bowne SJ, Sullivan LS, Blanton SH, Weinstock GM, Koboldt DC, Fulton RS, Larsen D, Humphries P, Humphries MM, Pierce EA, Chen R, Li Y. Application of next-generation sequencing to identify genes and mutations causing autosomal dominant retinitis pigmentosa (adRP). ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2014; 801:123-9. [PMID: 24664689 DOI: 10.1007/978-1-4614-3209-8_16] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
The goal of our research is to identify genes and mutations causing autosomal dominant retinitis pigmentosa (adRP). For this purpose we established a cohort of more than 250 independently ascertained families with adRP in the Houston Laboratory for Molecular Diagnosis of Inherited Eye Diseases. Affected members of each family were screened for disease-causing mutations in genes and gene regions that are commonly associated with adRP. By this approach, we detected mutations in 65 % of the families, leaving 85 families that are likely to harbor mutations outside of the "common" regions or in novel genes. Of these, 32 families were tested by several types of next-generation sequencing (NGS), including (a) targeted polymerase chain reaction (PCR) NGS, (b) whole exome NGS, and (c) targeted retinal-capture NGS. We detected mutations in 11 of these families (31 %) bringing the total detected in the adRP cohort to 70 %. Several large families have also been tested for linkage using Afymetrix single nucleotide polymorphism (SNP) arrays.
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Affiliation(s)
- Stephen P Daiger
- Human Genetics Center, School of Public Health, Univ. of Texas HSC, 1200 Herman Pressler Dr., 77030, Houston, TX, USA,
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Sullivan LS, Bowne SJ, Reeves MJ, Blain D, Goetz K, Ndifor V, Vitez S, Wang X, Tumminia SJ, Daiger SP. Prevalence of mutations in eyeGENE probands with a diagnosis of autosomal dominant retinitis pigmentosa. Invest Ophthalmol Vis Sci 2013; 54:6255-61. [PMID: 23950152 DOI: 10.1167/iovs.13-12605] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
PURPOSE To screen samples from patients with presumed autosomal dominant retinitis pigmentosa (adRP) for mutations in 12 disease genes as a contribution to the research and treatment goals of the National Ophthalmic Disease Genotyping and Phenotyping Network (eyeGENE). METHODS DNA samples were obtained from eyeGENE. A total of 170 probands with an intake diagnosis of adRP were tested through enrollment in eyeGENE. The 10 most common genes causing adRP (IMPDH1, KLHL7, NR2E3, PRPF3/RP18, PRPF31/RP11, PRPF8/RP13, PRPH2/RDS, RHO, RP1, and TOPORS) were chosen for PCR-based dideoxy sequencing, along with the two X-linked RP genes, RPGR and RP2. RHO, PRPH2, PRPF31, RPGR, and RP2 were completely sequenced, while only mutation hotspots in the other genes were analyzed. RESULTS Disease-causing mutations were identified in 52% of the probands. The frequencies of disease-causing mutations in the 12 genes were consistent with previous studies. CONCLUSIONS The Laboratory for Molecular Diagnosis of Inherited Eye Disease at the University of Texas in Houston has thus far received DNA samples from 170 families with a diagnosis of adRP from the eyeGENE Network. Disease-causing mutations in autosomal genes were identified in 48% (81/170) of these families while mutations in X-linked genes accounted for an additional 4% (7/170). Of the 55 distinct mutations detected, 19 (33%) have not been previously reported. All diagnostic results were returned by eyeGENE to participating patients via their referring clinician. These genotyped samples along with their corresponding phenotypic information are also available to researchers who may request access to them for further study of these ophthalmic disorders. (ClinicalTrials.gov number, NCT00378742.).
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Affiliation(s)
- Lori S Sullivan
- Human Genetics Center, University of Texas Health Science Center at Houston, Houston, Texas
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Churchill JD, Bowne SJ, Sullivan LS, Lewis RA, Wheaton DK, Birch DG, Branham KE, Heckenlively JR, Daiger SP. Mutations in the X-linked retinitis pigmentosa genes RPGR and RP2 found in 8.5% of families with a provisional diagnosis of autosomal dominant retinitis pigmentosa. Invest Ophthalmol Vis Sci 2013; 54:1411-6. [PMID: 23372056 DOI: 10.1167/iovs.12-11541] [Citation(s) in RCA: 98] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
PURPOSE We determined the fraction of families in a well-characterized cohort with a provisional diagnosis of autosomal dominant retinitis pigmentosa (adRP) that have disease-causing mutations in the X-linked retinitis pigmentosa GTPase regulator (RPGR) gene or the retinitis pigmentosa 2 (RP2) gene. METHODS Families with a provisional clinical diagnosis of adRP, and a pedigree consistent with adRP but no male-to-male transmission were selected from a cohort of 258 families, and tested for mutations in the RPGR and RP2 genes with di-deoxy sequencing. To facilitate testing of RPGR in "adRP" families that had no male members available for testing, the repetitive and purine-rich ORF15 of RPGR was subcloned and sequenced in heterozygous female subjects from 16 unrelated families. RESULTS Direct sequencing of RPGR and RP2 allowed for identification of a disease-causing mutation in 21 families. Of these "adRP" families 19 had RPGR mutations, and two had RP2 mutations. Subcloning and sequencing of ORF15 of RPGR in female subjects identified one additional RPGR mutation. Of the 22 mutations identified, 15 have been reported previously. CONCLUSIONS These data show that 8.5% (22 in 258) of families thought to have adRP truly have X-linked retinitis pigmentosa (XLRP). These results have substantive implications for calculation of recurrence risk, genetic counseling, and potential treatment options, and illustrate the importance of screening families with a provisional diagnosis of autosomal inheritance and no male-to-male transmission for mutations in X-linked genes. Mutations in RPGR are one of the most common causes of all forms of retinitis pigmentosa.
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Affiliation(s)
- Jennifer D Churchill
- Human Genetics Center, University of Texas Health Science Center at Houston, Houston, Texas 77030, USA
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Blanco-Kelly F, García-Hoyos M, Cortón M, Ávila-Fernández A, Riveiro-Álvarez R, Giménez A, Hernan I, Carballo M, Ayuso C. Genotyping microarray: mutation screening in Spanish families with autosomal dominant retinitis pigmentosa. Mol Vis 2012; 18:1478-83. [PMID: 22736939 PMCID: PMC3380913] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2011] [Accepted: 05/31/2012] [Indexed: 11/26/2022] Open
Abstract
PURPOSE Presently, 22 genes have been described in association with autosomal dominant retinitis pigmentosa (adRP); however, they explain only 50% of all cases, making genetic diagnosis of this disease difficult and costly. The aim of this study was to evaluate a specific genotyping microarray for its application to the molecular diagnosis of adRP in Spanish patients. METHODS We analyzed 139 unrelated Spanish families with adRP. Samples were studied by using a genotyping microarray (adRP). All mutations found were further confirmed with automatic sequencing. Rhodopsin (RHO) sequencing was performed in all negative samples for the genotyping microarray. RESULTS The adRP genotyping microarray detected the mutation associated with the disease in 20 of the 139 families with adRP. As in other populations, RHO was found to be the most frequently mutated gene in these families (7.9% of the microarray genotyped families). The rate of false positives (microarray results not confirmed with sequencing) and false negatives (mutations in RHO detected with sequencing but not with the genotyping microarray) were established, and high levels of analytical sensitivity (95%) and specificity (100%) were found. Diagnostic accuracy was 15.1%. CONCLUSIONS The adRP genotyping microarray is a quick, cost-efficient first step in the molecular diagnosis of Spanish patients with adRP.
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Affiliation(s)
- Fiona Blanco-Kelly
- Servicio de Genética, IIS Fundación Jiménez Díaz, Madrid. Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), ISCIII, Madrid, Spain
| | - María García-Hoyos
- Servicio de Genética, IIS Fundación Jiménez Díaz, Madrid. Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), ISCIII, Madrid, Spain
| | - Marta Cortón
- Servicio de Genética, IIS Fundación Jiménez Díaz, Madrid. Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), ISCIII, Madrid, Spain
| | - Almudena Ávila-Fernández
- Servicio de Genética, IIS Fundación Jiménez Díaz, Madrid. Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), ISCIII, Madrid, Spain
| | - Rosa Riveiro-Álvarez
- Servicio de Genética, IIS Fundación Jiménez Díaz, Madrid. Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), ISCIII, Madrid, Spain
| | - Ascensión Giménez
- Servicio de Genética, IIS Fundación Jiménez Díaz, Madrid. Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), ISCIII, Madrid, Spain
| | - Inma Hernan
- Unidad de Genética Molecular, Hospital de Terrassa, Terrassa, Barcelona, Spain
| | - Miguel Carballo
- Unidad de Genética Molecular, Hospital de Terrassa, Terrassa, Barcelona, Spain
| | - Carmen Ayuso
- Servicio de Genética, IIS Fundación Jiménez Díaz, Madrid. Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), ISCIII, Madrid, Spain
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Neveling K, Collin RWJ, Gilissen C, van Huet RAC, Visser L, Kwint MP, Gijsen SJ, Zonneveld MN, Wieskamp N, de Ligt J, Siemiatkowska AM, Hoefsloot LH, Buckley MF, Kellner U, Branham KE, den Hollander AI, Hoischen A, Hoyng C, Klevering BJ, van den Born LI, Veltman JA, Cremers FPM, Scheffer H. Next-generation genetic testing for retinitis pigmentosa. Hum Mutat 2012; 33:963-72. [PMID: 22334370 PMCID: PMC3490376 DOI: 10.1002/humu.22045] [Citation(s) in RCA: 213] [Impact Index Per Article: 17.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2011] [Accepted: 01/18/2012] [Indexed: 01/07/2023]
Abstract
Molecular diagnostics for patients with retinitis pigmentosa (RP) has been hampered by extreme genetic and clinical heterogeneity, with 52 causative genes known to date. Here, we developed a comprehensive next-generation sequencing (NGS) approach for the clinical molecular diagnostics of RP. All known inherited retinal disease genes (n = 111) were captured and simultaneously analyzed using NGS in 100 RP patients without a molecular diagnosis. A systematic data analysis pipeline was developed and validated to prioritize and predict the pathogenicity of all genetic variants identified in each patient, which enabled us to reduce the number of potential pathogenic variants from approximately 1,200 to zero to nine per patient. Subsequent segregation analysis and in silico predictions of pathogenicity resulted in a molecular diagnosis in 36 RP patients, comprising 27 recessive, six dominant, and three X-linked cases. Intriguingly, De novo mutations were present in at least three out of 28 isolated cases with causative mutations. This study demonstrates the enormous potential and clinical utility of NGS in molecular diagnosis of genetically heterogeneous diseases such as RP. De novo dominant mutations appear to play a significant role in patients with isolated RP, having major implications for genetic counselling.
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Affiliation(s)
- Kornelia Neveling
- Department of Human Genetics, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands
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Kannabiran C, Singh HP, Jalali S. Mapping of locus for autosomal dominant retinitis pigmentosa on chromosome 6q23. Hum Genet 2011; 131:717-23. [PMID: 22083234 DOI: 10.1007/s00439-011-1115-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2011] [Accepted: 11/03/2011] [Indexed: 11/26/2022]
Abstract
Retinitis pigmentosa (RP) is a genetically heterogeneous group of retinal degenerative disorders resulting in severe visual loss and blindness that have remained incurable till date. We report the mapping of the disease locus in a 3-generation family of Indian origin with autosomal dominant RP (ADRP). Diagnosis of RP and recruitment was made after a complete clinical evaluation of all members. Manifestations of the disease included night blindness with blurred central vision in some cases, loss of peripheral vision, and diffuse degeneration of the retinal pigment epithelium. Linkage analysis using microsatellite markers was carried out on 34 members (14 affected). After testing for linkage to known retinal dystrophy loci as well as a subsequent genome-wide analysis, we detected linkage to markers on chromosome 6q23: D6S262 at 130 cM, D6S457 (130 cM) and D6S1656 (131 cM) gave significant 2-point LOD scores of 3.0-3.8. Multipoint LOD scores of ≥3.0 were obtained for markers between 121 and 130 cM. Haplotype analysis with several markers in the same region on chromosome 6 shows a disease-cosegregating region of about 25 Mb between 109 and 135 Mb. There are no known RP genes in this interval, which contains >100 genes. This study provides evidence for a novel ADRP locus on chromosome 6q23.
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Affiliation(s)
- Chitra Kannabiran
- Kallam Anji Reddy Molecular Genetics Laboratory, Hyderabad Eye Research Foundation, LV Prasad Eye Institute, LV Prasad Marg, Banjara Hills, Hyderabad 500034, Andhra Pradesh, India.
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Lanier KT, Joy JT, Morris RW. Nonclassic retinitis pigmentosa: A challenging clinical diagnosis solved by pedigree analysis and electrodiagnostic testing. OPTOMETRY (ST. LOUIS, MO.) 2010; 81:181-187. [PMID: 20346889 DOI: 10.1016/j.optm.2009.09.022] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/10/2008] [Revised: 01/20/2009] [Accepted: 09/16/2009] [Indexed: 05/29/2023]
Abstract
PURPOSE The aim of this study was to describe a case of nonclassic retinitis pigmentosa, to highlight ancillary testing tools for proper diagnosis, and to differentiate between common hereditary fundus dystrophies. METHODS Methods used in this study included complete ophthalmologic evaluation, optical coherence tomography, visual field testing, pedigree analysis, and electrodiagnostic testing. RESULTS Reduced vision and photopsia were the initial complaints of a patient who had an overall normal ocular appearance. However, a strong family history of retinitis pigmentosa and depressed scotopic and photopic electroretinograms confirmed the diagnosis of autosomal dominant retinitis pigmentosa. CONCLUSION In cases of atypical-appearing retinitis pigmentosa, both pedigree analysis and electrodiagnostic testing are fundamental in correct diagnosis of this multifaceted hereditary fundus disorder.
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Affiliation(s)
- Kate T Lanier
- W.G. Bill Hefner Veterans Affairs Medical Center, Salisbury, North Carolina, USA.
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