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Marwan M, Dawood M, Ullah M, Shah IU, Khan N, Hassan MT, Karam M, Rawlins LE, Baple EL, Crosby AH, Saleha S. Unravelling the genetic basis of retinal dystrophies in Pakistani consanguineous families. BMC Ophthalmol 2023; 23:205. [PMID: 37165311 PMCID: PMC10170854 DOI: 10.1186/s12886-023-02948-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2022] [Accepted: 04/26/2023] [Indexed: 05/12/2023] Open
Abstract
BACKGROUND Retinitis Pigmentosa (RP) is a clinically and genetically progressive retinal dystrophy associated with severe visual impairments and sometimes blindness, the most common syndromic form of which is Usher syndrome (USH). This study aimed to further increase understanding of the spectrum of RP in the Khyber Pakhtunkhwa region of Pakistan. METHODOLOGY Four consanguineous families of Pashtun ethnic group were investigated which were referred by the local collaborating ophthalmologists. In total 42 individuals in four families were recruited and investigated using whole exome and dideoxy sequencing. Among them, 20 were affected individuals including 6 in both family 1 and 2, 5 in family 3 and 3 in family 4. RESULT Pathogenic gene variants were identified in all four families, including two in cone dystrophy and RP genes in the same family (PDE6C; c.480delG, p.Asn161ThrfsTer33 and TULP1; c.238 C > T, p.Gln80Ter) with double-homozygous individuals presenting with more severe disease. Other pathogenic variants were identified in MERTK (c.2194C > T, p.Arg732Ter), RHO (c.448G > A, p.Glu150Lys) associated with non-syndromic RP, and MYO7A (c.487G > A, p.Gly163Arg) associated with USH. In addition, the reported variants were of clinical significance as the PDE6C variant was detected novel, whereas TULP1, MERTK, and MYO7A variants were detected rare and first time found segregating with retinal dystrophies in Pakistani consanguineous families. CONCLUSIONS This study increases knowledge of the genetic basis of retinal dystrophies in families from Pakistan providing information important for genetic testing and diagnostic provision particularly from the Khyber Pakhtunkhwa region.
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Affiliation(s)
- Muhammad Marwan
- Department of Biotechnology and Genetic Engineering, Kohat University of Science and Technology, Kohat, Khyber Pakhtunkhwa, 26000, Pakistan
| | - Muhammad Dawood
- Department of Biotechnology and Genetic Engineering, Kohat University of Science and Technology, Kohat, Khyber Pakhtunkhwa, 26000, Pakistan
| | - Mukhtar Ullah
- Institute of Molecular and Clinical Ophthalmology Basel, Basel, 4031, Switzerland
- Department of Ophthalmology, University of Basel, Basel, 4056, Switzerland
| | - Irfan Ullah Shah
- Department of Ophthalmology, KMU Institute of Medical Sciences KIMS, Kohat, Khyber Pakhtunkhwa, 26000, Pakistan
| | - Niamat Khan
- Department of Biotechnology and Genetic Engineering, Kohat University of Science and Technology, Kohat, Khyber Pakhtunkhwa, 26000, Pakistan
| | - Muhammad Taimur Hassan
- Department of Biotechnology and Genetic Engineering, Kohat University of Science and Technology, Kohat, Khyber Pakhtunkhwa, 26000, Pakistan
| | - Muhammad Karam
- Department of Biotechnology and Genetic Engineering, Kohat University of Science and Technology, Kohat, Khyber Pakhtunkhwa, 26000, Pakistan
| | - Lettie E Rawlins
- Medical Research, RILD Wellcome Wolfson Centre (Level 4), Royal Devon and Exeter NHS Foundation Trust, Exeter, Devon, EX2 5DW, UK
- Peninsula Clinical Genetics Service, Royal Devon & Exeter Hospital (Heavitree), Exeter, UK
| | - Emma L Baple
- Medical Research, RILD Wellcome Wolfson Centre (Level 4), Royal Devon and Exeter NHS Foundation Trust, Exeter, Devon, EX2 5DW, UK
| | - Andrew H Crosby
- Medical Research, RILD Wellcome Wolfson Centre (Level 4), Royal Devon and Exeter NHS Foundation Trust, Exeter, Devon, EX2 5DW, UK
| | - Shamim Saleha
- Department of Biotechnology and Genetic Engineering, Kohat University of Science and Technology, Kohat, Khyber Pakhtunkhwa, 26000, Pakistan.
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Habib F, Yasin M, Nasir A, Hussain A, Ndubuisi C, Azam H, Sajid M, Rasheed A. Molecular Genetic Analysis of the Autosomal Recessive Non-Syndromic Inherited Retinitis Pigmentosa. Cureus 2023; 15:e37933. [PMID: 37267051 PMCID: PMC10200129 DOI: 10.7759/cureus.37933] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/21/2023] [Indexed: 06/04/2023] Open
Abstract
INTRODUCTION 90% of visually impaired people live in developing countries. There are various types of vision impairment, but the focus of the current study is retinitis pigmentosa (RP). Up to now, 150 mutations have been reported that are linked with RP. METHODOLOGY Healthy and affected members from two Pakistani families (RP01 and RP02) segregating autosomal recessive RP were selected for DNA extraction. PCR was conducted, and the amplified PCR products were analyzed using Polyacrylamide Gel Electrophoresis (PAGE) and visualized in the Gel Doc system for linkage analysis. The Gene Hunter 2.1r5 tool in the Simple Linkage v5.052 beta software suite was used to conduct multipoint parametric linkage analysis on the two consanguineous families examined on the 6K Illumina array. Exons and intron-exon borders of all known arRP genes found in homozygous areas were sequenced in the matching probands using a 3130 automated sequencer and the Big Dye Terminator Cycle Sequencing Kit v3.1. The mutation study was carried out using the AlaMut 1.5 program. RESULTS In both families, linkage analysis was performed using microsatellite marker DIS422 for gene crumbs homolog 1 (CRB1) and microsatellite marker D8S2332 for gene Retinitis Pigmentosa 1 (RP1). Multipoint linkage analysis identifies genomic regions that could potentially contain the genetic defect. In family RP01, only a single peak with a maximal multipoint LOD score of 3.00 was identified on chromosome 1, whereas in family RP02, multiple peaks with multipoint LOD scores of 1.80 were identified on chromosome 8. Analysis of the CRB1 gene revealed a homozygous substitution of glycine for valine (c.1152T>G; p.V243G), whereas the RP1 gene demonstrated that leucine was substituted for proline as a result of cytosine to thymine transfer (c.3419C>T; p. P1035L). Conclusion: Homozygosity mapping is a powerful method for finding genetic abnormalities that are both precise and comprehensive for identifying harmful variations in consanguineous families. This method is invaluable for providing accurate clinical diagnostic and genetic advice in remote regions of Pakistan while also increasing knowledge about autosomal recessive diseases and the dangers of mixing.
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Affiliation(s)
- Faiza Habib
- Department of Molecular Biology and Genetics, Institute of Basic Medical Sciences, Khyber Medical University, Peshawar, PAK
| | - Muhammad Yasin
- Department of Biotechnology and Genetic Engineering, Kohat University of Science and Technology, Kohat, PAK
| | - Areej Nasir
- Medicine, Quaid-e-Azam Medical College, Bahawalpur, PAK
| | - Abrar Hussain
- Department of Biological Sciences, International Islamic University, Islamabad, PAK
| | | | - Hiba Azam
- Surgery, University College of Medicine and Dentistry, Lahore, PAK
| | - Muhammad Sajid
- Department of Biotechnology and Genetic Engineering, International Islamic University, Islamabad, PAK
| | - Arsalan Rasheed
- Department of Zoology, Faculty of Life and Chemical Sciences, Abdul Wali Khan University Mardan, Mardan, PAK
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Sakti DH, Cornish EE, Mustafic N, Zaheer A, Retsas S, Rajagopalan S, Chung CW, Ewans L, McCluskey P, Nash BM, Jamieson RV, Grigg JR. MERTK retinopathy: biomarkers assessing vision loss. Ophthalmic Genet 2021; 42:706-716. [PMID: 34289798 DOI: 10.1080/13816810.2021.1955278] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
PURPOSE Mer tyrosine kinase-retinitis pigmentosa (MERTK-RP) causes a primary defect in the retinal pigment epithelium, which subsequently affects rod and cone photoreceptors. The study aims to identify the most appropriate MERTK-RP biomarkers to measure disease progression for deciding the optimum therapeutic trial intervention time. MATERIALS AND METHODS Patients' data from baseline (BL) and last follow-up (LFU) were reviewed. Best corrected visual acuity (BCVA), spectral domain-optical coherence tomography (SD-OCT), ultra-widefield fundus autofluorescence (UWF-FAF) patterns, kinetic perimetry (KP), and electroretinography (ERG) parameters were analyzed. RESULTS Five patients were included with the mean age of 17.7 ± 14.4 years old (6.7-42.3) at BL and mean BCVA follow-up of 8.4 ± 5.1 years. Mean BCVA at BL and LFU were 0.84 ± 0.86 LogMAR and 1.14 ± 0.86 LogMAR, respectively. The BCVA decline rate was 0.05 ± 0.03 LogMAR units/year. Ellipzoid zones (EZ) were measurable in eight eyes with mean BL length of 1293.75 ± 421.07 µm and reduction of 140.95 ± 69.28 µm/year and mean BL CMT of 174.2 ± 37.52 µm with the rate of 11.2 ± 12.77 µm declining/year. Full-field ERG (ffERG) and pattern ERG (pERG) were barely recordable. UWF-FAF showed central macular hyper-autofluorescence (hyperAF). KP (III4e and V4e) was normal in two eyes, restricted nasally in four eyes, superior wedge defect in two eyes and undetectable in two eyes. The four restricted nasally KPs became worse, while the others stayed almost unchanged. CONCLUSIONS This cohort showed early visual loss, moderately rapid EZ reduction and macular hyperAF. EZ, CMT, and BCVA were consistently reduced. Relative rapid decline in these biomarkers reflecting visual function suggests an early and narrow timespan for intervention.
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Affiliation(s)
- Dhimas H Sakti
- Save Sight Institute, Faculty of Medicine and Health, The University of Sydney, Sydney, NSW, Australia.,Department of Ophthalmology, Faculty of Medicine, Public Health and Nursing; Universitas Gadjah Mada, Yogyakarta, Indonesia
| | - Elisa E Cornish
- Save Sight Institute, Faculty of Medicine and Health, The University of Sydney, Sydney, NSW, Australia.,Eye Genetics Research Unit, Children's Medical Research Institute, the Children's Hospital at Westmead, Save Sight Institute, University of Sydney, Sydney, NSW, Australia
| | - Nina Mustafic
- Save Sight Institute, Faculty of Medicine and Health, The University of Sydney, Sydney, NSW, Australia
| | - Afsah Zaheer
- Save Sight Institute, Faculty of Medicine and Health, The University of Sydney, Sydney, NSW, Australia
| | - Stephanie Retsas
- Save Sight Institute, Faculty of Medicine and Health, The University of Sydney, Sydney, NSW, Australia
| | - Sulekha Rajagopalan
- Department of Clinical Genetics, Liverpool Hospital, Liverpool BC, NSW, Australia
| | - Clara Wt Chung
- Department of Clinical Genetics, Liverpool Hospital, Liverpool BC, NSW, Australia.,School of Women's & Children's Health, University of NSW, Sydney, NSW, Australia
| | - Lisa Ewans
- Department of Clinical Genetics, Royal Prince Alfred Hospital, Camperdown, NSW, Australia.,Faculty of Medicine and Health Central Clinical School, Sydney Medical School, University of Sydney, Sydney, NSW, Australia
| | - Peter McCluskey
- Save Sight Institute, Faculty of Medicine and Health, The University of Sydney, Sydney, NSW, Australia
| | - Benjamin M Nash
- Eye Genetics Research Unit, Children's Medical Research Institute, the Children's Hospital at Westmead, Save Sight Institute, University of Sydney, Sydney, NSW, Australia.,Disciplines of Genomic Medicine & Child and Adolescent Health, Sydney Medical School, University of Sydney, Sydney, NSW, Australia.,Sydney Genome Diagnostics, Western Sydney Genetics Program, the Children's Hospital at Westmead, Sydney, NSW, Australia
| | - Robyn V Jamieson
- Save Sight Institute, Faculty of Medicine and Health, The University of Sydney, Sydney, NSW, Australia.,Eye Genetics Research Unit, Children's Medical Research Institute, the Children's Hospital at Westmead, Save Sight Institute, University of Sydney, Sydney, NSW, Australia.,Disciplines of Genomic Medicine & Child and Adolescent Health, Sydney Medical School, University of Sydney, Sydney, NSW, Australia.,Department of Clinical Genetics, Western Sydney Genetics Program, the Children's Hospital at Westmead, Sydney, NSW, Australia
| | - John R Grigg
- Save Sight Institute, Faculty of Medicine and Health, The University of Sydney, Sydney, NSW, Australia.,Eye Genetics Research Unit, Children's Medical Research Institute, the Children's Hospital at Westmead, Save Sight Institute, University of Sydney, Sydney, NSW, Australia
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Biswas P, Borooah S, Matsui H, Voronchikhina M, Zhou J, Zawaydeh Q, Raghavendra PB, Ferreyra H, Riazuddin SA, Wahlin K, Frazer KA, Ayyagari R. Detection and validation of novel mutations in MERTK in a simplex case of retinal degeneration using WGS and hiPSC-RPEs model. Hum Mutat 2020; 42:189-199. [PMID: 33252167 DOI: 10.1002/humu.24146] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Revised: 11/03/2020] [Accepted: 11/24/2020] [Indexed: 12/30/2022]
Abstract
Inherited retinal degenerations (IRDs) are a group of genetically heterogeneous conditions with a broad phenotypic heterogeneity. Here, we report detection and validation of the underlying cause of progressive retinal degeneration in a nuclear family of European descent with a single affected individual. Whole genome sequencing of the proband and her unaffected sibling identified a novel intron 8 donor splice site variant (c.1296 + 1G>A) and a novel 731 base pair deletion encompassing exon 9 (Chr2:g.112751488_112752218 del) resulting in c.1297_1451del; p.K433_G484fsTer3 in the Mer tyrosine kinase protooncogene (MERTK), which is highly expressed in the retinal pigment epithelium (RPE). The proband carried both variants in the heterozygous state, which segregated with disease in the pedigree. These MERTK variants are predicted to result in the defective splicing of exon 8 and loss of exon 9 respectively. To evaluate the impact of these novel variants, peripheral blood mononuclear cells of the proband and her parents were reprogrammed to humaninduced pluripotent stem cell (hiPSC) lines, which were subsequently differentiated to hiPSC-RPE. Analysis of the proband's hiPSC-RPE revealed the absence of both MERTK transcript and its respective protein as well as abnormal phagocytosis when compared with the parental hiPSC-RPE. In summary, whole genome sequencing identified novel compound heterozygous variants in MERTK as the underlying cause of progressive retinal degeneration in a simplex case. Further, analysis using an hiPSC-RPE model established the functional impact of novel MERTK mutations and revealed the potential mechanism underlying pathology in the proband.
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Affiliation(s)
- Pooja Biswas
- Shiley Eye Institute, University of California San Diego, La Jolla, California, USA.,REVA University, Bengaluru, Karnataka, India
| | - Shyamanga Borooah
- Shiley Eye Institute, University of California San Diego, La Jolla, California, USA
| | - Hiroko Matsui
- Institute for Genomic Medicine, University of California, San Diego, La Jolla, California, USA
| | - Marina Voronchikhina
- Shiley Eye Institute, University of California San Diego, La Jolla, California, USA
| | - Jason Zhou
- Shiley Eye Institute, University of California San Diego, La Jolla, California, USA
| | - Qais Zawaydeh
- Shiley Eye Institute, University of California San Diego, La Jolla, California, USA
| | - Pongali B Raghavendra
- REVA University, Bengaluru, Karnataka, India.,School of Regenerative Medicine, Manipal University-MAHE, Bangalore, India
| | - Henry Ferreyra
- Shiley Eye Institute, University of California San Diego, La Jolla, California, USA
| | - S Amer Riazuddin
- Wilmer Eye Institute, Johns Hopkins Univesity School of Medicine, Baltimore, Maryland, USA
| | - Karl Wahlin
- Shiley Eye Institute, University of California San Diego, La Jolla, California, USA
| | - Kelly A Frazer
- Institute for Genomic Medicine, University of California, San Diego, La Jolla, California, USA.,Department of Pediatrics, Rady Children's Hospital, Division of Genome Information Sciences, San Diego, California, USA
| | - Radha Ayyagari
- Shiley Eye Institute, University of California San Diego, La Jolla, California, USA
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5
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Kanzaki Y, Fujita H, Sato K, Hosokawa M, Matsumae H, Shiraga F, Morizane Y, Ohuchi H. KCNJ13 Gene Deletion Impairs Cell Alignment and Phagocytosis in Retinal Pigment Epithelium Derived from Human-Induced Pluripotent Stem Cells. Invest Ophthalmol Vis Sci 2020; 61:38. [PMID: 32437550 PMCID: PMC7405706 DOI: 10.1167/iovs.61.5.38] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Purpose The purpose of this study was to establish and analyze a cell model of Leber congenital amaurosis type 16 (LCA16), which is caused by mutations in the KCNJ13 gene encoding Kir7.1, an inward-rectifying potassium ion channel. Methods The two guide RNAs specific to the target sites in the KCNJ13 gene were designed and KCNJ13 knock-out (KO) human-induced pluripotent stem cells (hiPSCs) were generated using the CRISPR/Cas9 system. The KCNJ13-KO hiPSCs were differentiated into retinal pigment epithelial cells (hiPSC-RPEs). The KCNJ13-KO in hiPSC-RPEs was confirmed by immunostaining. Phagocytic activity of hiPSC-RPEs was assessed using the uptake of fluorescently labeled porcine photoreceptor outer segments (POSs). Phagocytosis-related genes in RPE cells were assessed by quantitative polymerase chain reaction. Results Most of the translated region of the KCNJ13 gene was deleted in the KCNJ13-KO hiPSCs by the CRISPR/Cas9 system, and this confirmed that the Kir7.1 protein was not present in RPE cells induced from the hiPSCs. Expression of RPE marker genes such as BEST1 and CRALBP was retained in the wild-type (WT) and in the KCNJ13-KO hiPSC-RPE cells. However, phagocytic activity and expression of phagocytosis-related genes in the KCNJ13-null hiPSC-RPE cells were significantly reduced compared to those of WT. Conclusions We succeeded in generating an RPE model of LCA16 using hiPSCs. We suggest that Kir7.1 is required for phagocytosis of POSs by RPE cells and that impaired phagocytosis in the absence of Kir7.1 would be involved in the retinal degeneration found in LCA16.
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Ludwig PE, Freeman SC, Janot AC. Novel stem cell and gene therapy in diabetic retinopathy, age related macular degeneration, and retinitis pigmentosa. Int J Retina Vitreous 2019; 5:7. [PMID: 30805203 PMCID: PMC6373096 DOI: 10.1186/s40942-019-0158-y] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2018] [Accepted: 01/28/2019] [Indexed: 02/07/2023] Open
Abstract
Degenerative retinal disease leads to significant visual morbidity worldwide. Diabetic retinopathy and macular degeneration are leading causes of blindness in the developed world. While current therapies for these diseases slow disease progression, stem cell and gene therapy may also reverse the effects of these, and other, degenerative retinal conditions. Novel therapies being investigated include the use of various types of stem cells in the regeneration of atrophic or damaged retinal tissue, the prolonged administration of neurotrophic factors and/or drug delivery, immunomodulation, as well as the replacement of mutant genes, and immunomodulation through viral vector delivery. This review will update the reader on aspects of stem cell and gene therapy in diabetic retinopathy, age-related macular degeneration, retinitis pigmentosa and other less common inherited retinal dystrophies. These therapies include the use of adeno-associated viral vector-based therapies for treatment of various types of retinitis pigmentosa and dry age-related macular degeneration. Other potential therapies reviewed include the use of mesenchymal stem cells in local immunomodulation, and the use of stem cells in generating structures like three-dimensional retinal sheets for transplantation into degenerative retinas. Finally, aspects of stem cell and gene therapy in diabetic retinopathy, age-related macular degeneration, retinitis pigmentosa, and other less common inherited retinal dystrophies will be reviewed.
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Affiliation(s)
- Parker E Ludwig
- 1Creighton University School of Medicine, 2500 California Plaza, Omaha, NE 68178 USA
| | - S Caleb Freeman
- 1Creighton University School of Medicine, 2500 California Plaza, Omaha, NE 68178 USA
| | - Adam C Janot
- Vitreoretinal Institute, 7698 Goodwood Blvd, Baton Rouge, LA 70806 USA.,3Department of Ophthalmology, Louisiana State University Health Sciences Center, New Orleans, LA USA
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7
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Fu X, Huu VAN, Duan Y, Kermany DS, Valentim CCS, Zhang R, Zhu J, Zhang CL, Sun X, Zhang K. Clinical applications of retinal gene therapies. PRECISION CLINICAL MEDICINE 2018; 1:5-20. [PMID: 35694125 PMCID: PMC8982485 DOI: 10.1093/pcmedi/pby004] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2018] [Revised: 03/27/2018] [Accepted: 04/03/2018] [Indexed: 02/05/2023] Open
Abstract
Retinal degenerative diseases are a major cause of blindness. Retinal gene therapy is a
trail-blazer in the human gene therapy field, leading to the first FDA approved gene
therapy product for a human genetic disease. The application of Clustered Regularly
Interspaced Short Palindromic Repeat/Cas9 (CRISPR/Cas9)-mediated gene editing technology
is transforming the delivery of gene therapy. We review the history, present, and future
prospects of retinal gene therapy.
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Affiliation(s)
- Xin Fu
- Guangzhou Women and Children’s Medical Center, Guangzhou Medical University, Guangzhou, China
- Shiley Eye Institute, Institute for Engineering in Medicine, Institute for Genomic Medicine, University of California, San Diego, La Jolla, California, USA
| | - Viet Anh Nguyen Huu
- Guangzhou Women and Children’s Medical Center, Guangzhou Medical University, Guangzhou, China
- Shiley Eye Institute, Institute for Engineering in Medicine, Institute for Genomic Medicine, University of California, San Diego, La Jolla, California, USA
| | - Yaou Duan
- Shiley Eye Institute, Institute for Engineering in Medicine, Institute for Genomic Medicine, University of California, San Diego, La Jolla, California, USA
| | - Daniel S Kermany
- Guangzhou Women and Children’s Medical Center, Guangzhou Medical University, Guangzhou, China
- Shiley Eye Institute, Institute for Engineering in Medicine, Institute for Genomic Medicine, University of California, San Diego, La Jolla, California, USA
| | - Carolina C S Valentim
- Shiley Eye Institute, Institute for Engineering in Medicine, Institute for Genomic Medicine, University of California, San Diego, La Jolla, California, USA
| | - Runze Zhang
- Shiley Eye Institute, Institute for Engineering in Medicine, Institute for Genomic Medicine, University of California, San Diego, La Jolla, California, USA
| | - Jie Zhu
- Shiley Eye Institute, Institute for Engineering in Medicine, Institute for Genomic Medicine, University of California, San Diego, La Jolla, California, USA
| | - Charlotte L Zhang
- Shiley Eye Institute, Institute for Engineering in Medicine, Institute for Genomic Medicine, University of California, San Diego, La Jolla, California, USA
| | - Xiaodong Sun
- Shanghai Key Laboratory of Ocular Fundus Diseases, Shanghai General Hospital, Shanghai Jiaodong University, Shanghai, China
| | - Kang Zhang
- Guangzhou Women and Children’s Medical Center, Guangzhou Medical University, Guangzhou, China
- Shiley Eye Institute, Institute for Engineering in Medicine, Institute for Genomic Medicine, University of California, San Diego, La Jolla, California, USA
- Molecular Medicine Research Center, West China Hospital, Sichuan University, Chengdu, China
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8
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Audo I, Mohand-Said S, Boulanger-Scemama E, Zanlonghi X, Condroyer C, Démontant V, Boyard F, Antonio A, Méjécase C, El Shamieh S, Sahel JA, Zeitz C. MERTK
mutation update in inherited retinal diseases. Hum Mutat 2018; 39:887-913. [DOI: 10.1002/humu.23431] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2017] [Revised: 03/22/2018] [Accepted: 03/29/2018] [Indexed: 11/08/2022]
Affiliation(s)
- Isabelle Audo
- Sorbonne Université; INSERM; CNRS; Institut de la Vision; Paris France
- CHNO des Quinze-Vingts; DHU Sight Restore; INSERM-DGOS CIC1423 Paris France
- University College London Institute of Ophthalmology; London UK
| | - Saddek Mohand-Said
- Sorbonne Université; INSERM; CNRS; Institut de la Vision; Paris France
- CHNO des Quinze-Vingts; DHU Sight Restore; INSERM-DGOS CIC1423 Paris France
| | - Elise Boulanger-Scemama
- Sorbonne Université; INSERM; CNRS; Institut de la Vision; Paris France
- Fondation Ophtalmologique Adolphe de Rothschild; Paris France
| | | | | | - Vanessa Démontant
- Sorbonne Université; INSERM; CNRS; Institut de la Vision; Paris France
| | - Fiona Boyard
- Sorbonne Université; INSERM; CNRS; Institut de la Vision; Paris France
| | - Aline Antonio
- Sorbonne Université; INSERM; CNRS; Institut de la Vision; Paris France
| | - Cécile Méjécase
- Sorbonne Université; INSERM; CNRS; Institut de la Vision; Paris France
| | - Said El Shamieh
- Sorbonne Université; INSERM; CNRS; Institut de la Vision; Paris France
- Department of Medical Laboratory Technology; Faculty of Health Sciences; Beirut Arab University; Beirut Lebanon
| | - José-Alain Sahel
- Sorbonne Université; INSERM; CNRS; Institut de la Vision; Paris France
- CHNO des Quinze-Vingts; DHU Sight Restore; INSERM-DGOS CIC1423 Paris France
- University College London Institute of Ophthalmology; London UK
- Fondation Ophtalmologique Adolphe de Rothschild; Paris France
- Académie des Sciences-Institut de France; Paris France. Department of Ophthalmology; University of Pittsburgh Medical School; Pittsburgh Pennsylvania
| | - Christina Zeitz
- Sorbonne Université; INSERM; CNRS; Institut de la Vision; Paris France
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9
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Bhatia S, Kaur N, Singh IR, Vanita V. A novel mutation in MERTK for rod-cone dystrophy in a North Indian family. CANADIAN JOURNAL OF OPHTHALMOLOGY 2018; 54:40-50. [PMID: 30851773 DOI: 10.1016/j.jcjo.2018.02.008] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/11/2017] [Revised: 02/12/2018] [Accepted: 02/14/2018] [Indexed: 11/29/2022]
Abstract
OBJECTIVE To identify the underlying genetic defect of childhood-onset severe rod-cone dystrophy (RCD) in a consanguineous family from North India with autosomal recessive retinitis pigmentosa. METHODS A detailed family history, clinical data, and blood samples were collected from 11 members of the family, including 4 affected by an autosomal recessive rod-cone dystrophy (arRCD), and DNA was extracted. Whole-exome sequencing (WES) was performed on DNA samples of proband and her unaffected maternal uncle. Ion Reporter software (ver. 4.4) was used for the annotation of variants obtained by WES. The variants detected in proband were tested for validation in all other affected and unaffected family members using Sanger sequencing technique. RESULTS We have identified a novel nonsense mutation-c.1647T>G (p.Tyr549Ter)-in the exon 11 of MERTK that co-segregated completely with the disease phenotype in all the 4 affected members and was not observed in the 7 unaffected members of the family. This mutation was also not detected in 120 ethnically matched controls (240 chromosomes), hence excluding it as a polymorphism. CONCLUSIONS MERTK has a role in retinal pigment epithelium as a regulator of rod outer segments' phagocytosis. Due to c.1647T > G substitution, the stop codon (p.Tyr549Ter) appears early in the transcript. It seems that either the altered transcript would degenerate through nonsense-mediated decay (NMD) or potentially form truncated protein lacking a functionally important domain (i.e., tyrosine kinase domain). These findings thus further expand the mutation spectrum in MERTK and substantiate its role in the pathogenesis of retinal dystrophy.
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Affiliation(s)
- Sofia Bhatia
- Department of Human Genetics, Guru Nanak Dev University, Amritsar, India
| | - Navdeep Kaur
- Department of Human Genetics, Guru Nanak Dev University, Amritsar, India
| | | | - Vanita Vanita
- Department of Human Genetics, Guru Nanak Dev University, Amritsar, India.
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10
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Moore NA, Morral N, Ciulla TA, Bracha P. Gene therapy for inherited retinal and optic nerve degenerations. Expert Opin Biol Ther 2017; 18:37-49. [DOI: 10.1080/14712598.2018.1389886] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Affiliation(s)
- Nicholas A. Moore
- Department of Ophthalmology, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Nuria Morral
- Department of Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Thomas A. Ciulla
- Department of Ophthalmology, Indiana University School of Medicine, Indianapolis, IN, USA
- Retina Service, Midwest Eye Institute, Indianapolis, IN, USA
| | - Peter Bracha
- Department of Ophthalmology, Indiana University School of Medicine, Indianapolis, IN, USA
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11
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Kim DY, Yu J, Mui RK, Niibori R, Taufique HB, Aslam R, Semple JW, Cordes SP. The tyrosine kinase receptor Tyro3 enhances lifespan and neuropeptide Y (Npy) neuron survival in the mouse anorexia ( anx) mutation. Dis Model Mech 2017; 10:581-595. [PMID: 28093506 PMCID: PMC5451163 DOI: 10.1242/dmm.027433] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2016] [Accepted: 12/12/2016] [Indexed: 01/01/2023] Open
Abstract
Severe appetite and weight loss define the eating disorder anorexia nervosa, and can also accompany the progression of some neurodegenerative disorders such as amyotrophic lateral sclerosis (ALS). Although acute loss of hypothalamic neurons that produce appetite-stimulating neuropeptide Y (Npy) and agouti-related peptide (Agrp) in adult mice or in mice homozygous for the anorexia (anx) mutation causes aphagia, our understanding of the factors that help maintain appetite regulatory circuitry is limited. Here we identify a mutation (C19T) that converts an arginine to a tryptophan (R7W) in the TYRO3 protein tyrosine kinase 3 (Tyro3) gene, which resides within the anx critical interval, as contributing to the severity of anx phenotypes. Our observation that, like Tyro3-/- mice, anx/anx mice exhibit abnormal secondary platelet aggregation suggested that the C19T Tyro3 variant might have functional consequences. Tyro3 is expressed in the hypothalamus and other brain regions affected by the anx mutation, and its mRNA localization appeared abnormal in anx/anx brains by postnatal day 19 (P19). The presence of wild-type Tyro3 transgenes, but not an R7W-Tyro3 transgene, doubled the weight and lifespans of anx/anx mice and near-normal numbers of hypothalamic Npy-expressing neurons were present in Tyro3-transgenic anx/anx mice at P19. Although no differences in R7W-Tyro3 signal sequence function or protein localization were discernible in vitro, distribution of R7W-Tyro3 protein differed from that of Tyro3 protein in the cerebellum of transgenic wild-type mice. Thus, R7W-Tyro3 protein localization deficits are only detectable in vivo Further analyses revealed that the C19T Tyro3 mutation is present in a few other mouse strains, and hence is not the causative anx mutation, but rather an anx modifier. Our work shows that Tyro3 has prosurvival roles in the appetite regulatory circuitry and could also provide useful insights towards the development of interventions targeting detrimental weight loss.
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Affiliation(s)
- Dennis Y Kim
- Lunenfeld-Tanenbaum Research Institute, Room 876, Mount Sinai Hospital, 600 University Avenue, Toronto, ON M5G 1X5, Canada
- Department of Molecular Genetics, University of Toronto, 1 King's Crescent, Toronto, ON M5S 1A8, Canada
| | - Joanna Yu
- Lunenfeld-Tanenbaum Research Institute, Room 876, Mount Sinai Hospital, 600 University Avenue, Toronto, ON M5G 1X5, Canada
- Department of Molecular Genetics, University of Toronto, 1 King's Crescent, Toronto, ON M5S 1A8, Canada
| | - Ryan K Mui
- Lunenfeld-Tanenbaum Research Institute, Room 876, Mount Sinai Hospital, 600 University Avenue, Toronto, ON M5G 1X5, Canada
- Department of Molecular Genetics, University of Toronto, 1 King's Crescent, Toronto, ON M5S 1A8, Canada
| | - Rieko Niibori
- Lunenfeld-Tanenbaum Research Institute, Room 876, Mount Sinai Hospital, 600 University Avenue, Toronto, ON M5G 1X5, Canada
| | - Hamza Bin Taufique
- Lunenfeld-Tanenbaum Research Institute, Room 876, Mount Sinai Hospital, 600 University Avenue, Toronto, ON M5G 1X5, Canada
- Department of Molecular Genetics, University of Toronto, 1 King's Crescent, Toronto, ON M5S 1A8, Canada
| | - Rukhsana Aslam
- Keenan Research Centre for Biomedical Science, St. Michaels Hospital, Toronto, ON M5B 1W8, Canada
- Canadian Blood Services, 67 College Street, Toronto, ON M5G 2M1, Canada
| | - John W Semple
- Keenan Research Centre for Biomedical Science, St. Michaels Hospital, Toronto, ON M5B 1W8, Canada
- Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, ON M5S 1A1, Canada
- Canadian Blood Services, 67 College Street, Toronto, ON M5G 2M1, Canada
| | - Sabine P Cordes
- Lunenfeld-Tanenbaum Research Institute, Room 876, Mount Sinai Hospital, 600 University Avenue, Toronto, ON M5G 1X5, Canada
- Department of Molecular Genetics, University of Toronto, 1 King's Crescent, Toronto, ON M5S 1A8, Canada
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12
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Li L, Chen Y, Jiao X, Jin C, Jiang D, Tanwar M, Ma Z, Huang L, Ma X, Sun W, Chen J, Ma Y, M'hamdi O, Govindarajan G, Cabrera PE, Li J, Gupta N, Naeem MA, Khan SN, Riazuddin S, Akram J, Ayyagari R, Sieving PA, Riazuddin SA, Hejtmancik JF. Homozygosity Mapping and Genetic Analysis of Autosomal Recessive Retinal Dystrophies in 144 Consanguineous Pakistani Families. Invest Ophthalmol Vis Sci 2017; 58:2218-2238. [PMID: 28418496 PMCID: PMC5397137 DOI: 10.1167/iovs.17-21424] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Purpose The Pakistan Punjab population has been a rich source for identifying genes causing or contributing to autosomal recessive retinal degenerations (arRD). This study was carried out to delineate the genetic architecture of arRD in the Pakistani population. Methods The genetic origin of arRD in a total of 144 families selected only for having consanguineous marriages and multiple members affected with arRD was examined. Of these, causative mutations had been identified in 62 families while only the locus had been identified for an additional 15. The remaining 67 families were subjected to homozygosity exclusion mapping by screening of closely flanking microsatellite markers at 180 known candidate genes/loci followed by sequencing of the candidate gene for pathogenic changes. Results Of these 67 families subjected to homozygosity mapping, 38 showed homozygosity for at least one of the 180 regions, and sequencing of the corresponding genes showed homozygous cosegregating mutations in 27 families. Overall, mutations were detected in approximately 61.8 % (89/144) of arRD families tested, with another 10.4% (15/144) being mapped to a locus but without a gene identified. Conclusions These results suggest the involvement of unmapped novel genes in the remaining 27.8% (40/144) of families. In addition, this study demonstrates that homozygosity mapping remains a powerful tool for identifying the genetic defect underlying genetically heterogeneous arRD disorders in consanguineous marriages for both research and clinical applications.
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Affiliation(s)
- Lin Li
- Department of Ophthalmology, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China 2Ophthalmic Genetics and Visual Function Branch, National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States
| | - Yabin Chen
- Ophthalmic Genetics and Visual Function Branch, National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States
| | - Xiaodong Jiao
- Ophthalmic Genetics and Visual Function Branch, National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States
| | - Chongfei Jin
- Ophthalmic Genetics and Visual Function Branch, National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States 3Department of Medicine, Brookdale University Hospital and Medical Center, New York, New York, United States
| | - Dan Jiang
- Ophthalmic Genetics and Visual Function Branch, National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States
| | - Mukesh Tanwar
- Ophthalmic Genetics and Visual Function Branch, National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States 4Department of Genetics, Maharshi Dayanand University Rohtak, Haryana, India
| | - Zhiwei Ma
- Ophthalmic Genetics and Visual Function Branch, National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States
| | - Li Huang
- Ophthalmic Genetics and Visual Function Branch, National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States 5State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-Sen University, Guangzhou, Guangdong, China
| | - Xiaoyin Ma
- Ophthalmic Genetics and Visual Function Branch, National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States 6Laboratory of Developmental Cell Biology and Disease, School of Ophthalmology and Optometry and Eye Hospital, Wenzhou Medical University, Wenzhou, China
| | - Wenmin Sun
- Ophthalmic Genetics and Visual Function Branch, National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States 5State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-Sen University, Guangzhou, Guangdong, China
| | - Jianjun Chen
- Ophthalmic Genetics and Visual Function Branch, National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States 7Department of Ophthalmology, Shanghai Tenth People's Hospital, and Tongji Eye Institute, Tongji University School of Medicine, Shanghai, China
| | - Yan Ma
- Ophthalmic Genetics and Visual Function Branch, National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States
| | - Oussama M'hamdi
- Ophthalmic Genetics and Visual Function Branch, National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States
| | - Gowthaman Govindarajan
- Ophthalmic Genetics and Visual Function Branch, National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States
| | - Patricia E Cabrera
- Ophthalmic Genetics and Visual Function Branch, National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States
| | - Jiali Li
- Ophthalmic Genetics and Visual Function Branch, National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States 5State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-Sen University, Guangzhou, Guangdong, China
| | - Nikhil Gupta
- Ophthalmic Genetics and Visual Function Branch, National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States
| | - Muhammad Asif Naeem
- National Centre of Excellence in Molecular Biology, University of the Punjab, Lahore, Pakistan
| | - Shaheen N Khan
- National Centre of Excellence in Molecular Biology, University of the Punjab, Lahore, Pakistan
| | - Sheikh Riazuddin
- National Centre of Excellence in Molecular Biology, University of the Punjab, Lahore, Pakistan 9Allama Iqbal Medical College, University of Health Sciences, Lahore, Pakistan 10National Centre for Genetic Diseases, Shaheed Zulfiqar Ali Bhutto Medical University, Islamabad, Pakistan
| | - Javed Akram
- Allama Iqbal Medical College, University of Health Sciences, Lahore, Pakistan 10National Centre for Genetic Diseases, Shaheed Zulfiqar Ali Bhutto Medical University, Islamabad, Pakistan
| | - Radha Ayyagari
- Shiley Eye Institute, University of California-San Diego, La Jolla, California, United States
| | - Paul A Sieving
- National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States
| | - S Amer Riazuddin
- The Wilmer Eye Institute, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States 14McKusick-Nathans Institute of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States
| | - J Fielding Hejtmancik
- Ophthalmic Genetics and Visual Function Branch, National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States
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13
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Ramsden CM, Nommiste B, R Lane A, Carr AJF, Powner MB, J K Smart M, Chen LL, Muthiah MN, Webster AR, Moore AT, Cheetham ME, da Cruz L, Coffey PJ. Rescue of the MERTK phagocytic defect in a human iPSC disease model using translational read-through inducing drugs. Sci Rep 2017; 7:51. [PMID: 28246391 PMCID: PMC5427915 DOI: 10.1038/s41598-017-00142-7] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2016] [Accepted: 02/07/2017] [Indexed: 01/22/2023] Open
Abstract
Inherited retinal dystrophies are an important cause of blindness, for which currently there are no effective treatments. In order to study this heterogeneous group of diseases, adequate disease models are required in order to better understand pathology and to test potential therapies. Induced pluripotent stem cells offer a new way to recapitulate patient specific diseases in vitro, providing an almost limitless amount of material to study. We used fibroblast-derived induced pluripotent stem cells to generate retinal pigment epithelium (RPE) from an individual suffering from retinitis pigmentosa associated with biallelic variants in MERTK. MERTK has an essential role in phagocytosis, one of the major functions of the RPE. The MERTK deficiency in this individual results from a nonsense variant and so the MERTK-RPE cells were subsequently treated with two translational readthrough inducing drugs (G418 & PTC124) to investigate potential restoration of expression of the affected gene and production of a full-length protein. The data show that PTC124 was able to reinstate phagocytosis of labeled photoreceptor outer segments at a reduced, but significant level. These findings represent a confirmation of the usefulness of iPSC derived disease specific models in investigating the pathogenesis and screening potential treatments for these rare blinding disorders.
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Affiliation(s)
- Conor M Ramsden
- Department of Ocular Biology and Therapeutics (ORBIT), Institute of Ophthalmology, University College London, 11-43 Bath Street, London, EC1V 9EL, UK.,NIHR Biomedical Research Centre at Moorfields Eye Hospital NHS Foundation Trust and UCL Institute of Ophthalmology, London, EC1V 2PD, UK.,Moorfields Eye Hospital NHS Foundation Trust, 162 City Road, London, EC1V 2PD, UK
| | - Britta Nommiste
- Department of Ocular Biology and Therapeutics (ORBIT), Institute of Ophthalmology, University College London, 11-43 Bath Street, London, EC1V 9EL, UK
| | - Amelia R Lane
- Department of Ocular Biology and Therapeutics (ORBIT), Institute of Ophthalmology, University College London, 11-43 Bath Street, London, EC1V 9EL, UK
| | - Amanda-Jayne F Carr
- Department of Ocular Biology and Therapeutics (ORBIT), Institute of Ophthalmology, University College London, 11-43 Bath Street, London, EC1V 9EL, UK
| | - Michael B Powner
- Department of Ocular Biology and Therapeutics (ORBIT), Institute of Ophthalmology, University College London, 11-43 Bath Street, London, EC1V 9EL, UK.,Division of Optometry and Visual Sciences, City University London, Northampton Square, London, EC1V 0HB, UK
| | - Matthew J K Smart
- Department of Ocular Biology and Therapeutics (ORBIT), Institute of Ophthalmology, University College London, 11-43 Bath Street, London, EC1V 9EL, UK
| | - Li Li Chen
- Department of Ocular Biology and Therapeutics (ORBIT), Institute of Ophthalmology, University College London, 11-43 Bath Street, London, EC1V 9EL, UK
| | - Manickam N Muthiah
- NIHR Biomedical Research Centre at Moorfields Eye Hospital NHS Foundation Trust and UCL Institute of Ophthalmology, London, EC1V 2PD, UK.,Moorfields Eye Hospital NHS Foundation Trust, 162 City Road, London, EC1V 2PD, UK
| | - Andrew R Webster
- Department of Ocular Biology and Therapeutics (ORBIT), Institute of Ophthalmology, University College London, 11-43 Bath Street, London, EC1V 9EL, UK.,NIHR Biomedical Research Centre at Moorfields Eye Hospital NHS Foundation Trust and UCL Institute of Ophthalmology, London, EC1V 2PD, UK
| | - Anthony T Moore
- Department of Ocular Biology and Therapeutics (ORBIT), Institute of Ophthalmology, University College London, 11-43 Bath Street, London, EC1V 9EL, UK.,NIHR Biomedical Research Centre at Moorfields Eye Hospital NHS Foundation Trust and UCL Institute of Ophthalmology, London, EC1V 2PD, UK.,UCSF School of Medicine, Koret Vision Center, 10 Koret Way, San Francisco, CA 94143, USA
| | - Michael E Cheetham
- Department of Ocular Biology and Therapeutics (ORBIT), Institute of Ophthalmology, University College London, 11-43 Bath Street, London, EC1V 9EL, UK
| | - Lyndon da Cruz
- Department of Ocular Biology and Therapeutics (ORBIT), Institute of Ophthalmology, University College London, 11-43 Bath Street, London, EC1V 9EL, UK.,NIHR Biomedical Research Centre at Moorfields Eye Hospital NHS Foundation Trust and UCL Institute of Ophthalmology, London, EC1V 2PD, UK.,Moorfields Eye Hospital NHS Foundation Trust, 162 City Road, London, EC1V 2PD, UK
| | - Peter J Coffey
- Department of Ocular Biology and Therapeutics (ORBIT), Institute of Ophthalmology, University College London, 11-43 Bath Street, London, EC1V 9EL, UK. .,NIHR Biomedical Research Centre at Moorfields Eye Hospital NHS Foundation Trust and UCL Institute of Ophthalmology, London, EC1V 2PD, UK. .,Center for Stem Cell Biology and Engineering, NRI, UC Santa Barbara, USA.
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14
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Jinda W, Poungvarin N, Taylor TD, Suzuki Y, Thongnoppakhun W, Limwongse C, Lertrit P, Suriyaphol P, Atchaneeyasakul LO. A novel start codon mutation of the MERTK gene in a patient with retinitis pigmentosa. Mol Vis 2016; 22:342-51. [PMID: 27122965 PMCID: PMC4842005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2016] [Accepted: 04/19/2016] [Indexed: 11/03/2022] Open
Abstract
PURPOSE Retinitis pigmentosa (RP) is a clinically and genetically heterogeneous group of inherited retinal degenerations characterized by progressive loss of photoreceptor cells and RPE functions. More than 70 causative genes are known to be responsible for RP. This study aimed to identify the causative gene in a patient from a consanguineous family with childhood-onset severe retinal dystrophy. METHODS To identify the defective gene, whole exome sequencing was performed. Candidate causative variants were selected and validated using Sanger sequencing. Segregation analysis of the causative gene was performed in additional family members. To verify that the mutation has an effect on protein synthesis, an expression vector containing the first ten amino acids of the mutant protein fused with the DsRed2 fluorescent protein was constructed and transfected into HEK293T cells. Expression of the fusion protein in the transfected cells was measured using fluorescence microscopy. RESULTS By filtering against public variant databases, a novel homozygous missense mutation (c.3G>A) localized in the start codon of the MERTK gene was detected as a potentially pathogenic mutation for autosomal recessive RP. The c.3G>A mutation cosegregated with the disease phenotype in the family. No expression of the first ten amino acids of the MerTK mutant fused with the DsRed2 fluorescent protein was detected in HEK293T cells, indicating that the mutation affects the translation initiation site of the gene that may lead to loss of function of the MerTK signaling pathway. CONCLUSIONS We report a novel missense mutation (c.3G>A, p.0?) in the MERTK gene that causes severe vision impairment in a patient. Taken together with previous reports, our results expand the spectrum of MERTK mutations and extend our understanding of the role of the MerTK protein in the pathogenesis of retinitis pigmentosa.
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Affiliation(s)
- Worapoj Jinda
- Department of Biochemistry, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand
| | - Naravat Poungvarin
- Clinical Molecular Pathology Laboratory, Department of Clinical Pathology, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand
| | - Todd D. Taylor
- Laboratory for Integrated Bioinformatics, Core for Precise Measuring and Modeling, RIKEN Center for Integrative Medical Sciences, 1-7-22 Suehiro-cho, Tsurumi-ku, Yokohama, Kanagawa, Japan
| | - Yutaka Suzuki
- Department of Medical Genome Sciences, The University of Tokyo, Kashiwa, Chiba, Japan
| | - Wanna Thongnoppakhun
- Division of Molecular Genetics, Department of Research and Development, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand
| | - Chanin Limwongse
- Division of Molecular Genetics, Department of Research and Development, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand,Division of Medical Genetics, Department of Medicine, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand
| | - Patcharee Lertrit
- Department of Biochemistry, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand
| | - Prapat Suriyaphol
- Bioinformatics and Data Management for Research Unit, Office for Research and Development, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand
| | - La-ongsri Atchaneeyasakul
- Department of Biochemistry, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand,Department of Ophthalmology, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand
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15
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Parinot C, Nandrot EF. A Comprehensive Review of Mutations in the MERTK Proto-Oncogene. RETINAL DEGENERATIVE DISEASES 2016; 854:259-65. [DOI: 10.1007/978-3-319-17121-0_35] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
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16
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Gene Therapy for MERTK-Associated Retinal Degenerations. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2016; 854:487-93. [PMID: 26427450 DOI: 10.1007/978-3-319-17121-0_65] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
MERTK-associated retinal degenerations are thought to have defects in phagocytosis of shed outer segment membranes by the retinal pigment epithelium (RPE), as do the rodent models of these diseases. We have subretinally injected an RPE-specific AAV2 vector, AAV2-VMD2-hMERTK, to determine whether this would provide long-term photoreceptor rescue in the RCS rat, which it did for up to 6.5 months, the longest time point examined. Moreover, we found phagosomes in the RPE in the rescued regions of RCS retinas soon after the onset of light. The same vector also had a major protective effect in Mertk-null mice, with a concomitant increase in ERG response amplitudes in the vector-injected eyes. These findings suggest that planned clinical trials with this vector will have a favorable outcome.
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17
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Ahonen SJ, Arumilli M, Seppälä E, Hakosalo O, Kaukonen MK, Komáromy AM, Lohi H. Increased expression of MERTK is associated with a unique form of canine retinopathy. PLoS One 2014; 9:e114552. [PMID: 25517981 PMCID: PMC4269413 DOI: 10.1371/journal.pone.0114552] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2014] [Accepted: 11/10/2014] [Indexed: 01/25/2023] Open
Abstract
Progressive retinal degenerations are among the most common causes of blindness both in human and in dogs. Canine progressive retinal atrophy (PRA) resembles human retinitis pigmentosa (RP) and is typically characterized by a progressive loss of rod photoreceptors followed by a loss of cone function. The disease gradually progress from the loss of night and day vision to a complete blindness. We have recently described a unique form of retinopathy characterized by the multifocal gray/brown discoloration and thinning of the retina in the Swedish Vallhund (SV) breed. We aimed to identify the genetic cause by performing a genome wide association analysis in a cohort of 18 affected and 10 healthy control dogs using Illumina's canine 22k SNP array. We mapped the disease to canine chromosome 17 (p = 7.7×10−5) and found a 6.1 Mb shared homozygous region in the affected dogs. A combined analysis of the GWAS and replication data with additional 60 dogs confirmed the association (p = 4.3×10−8, OR = 11.2 for homozygosity). A targeted resequencing of the entire associated region in four cases and four controls with opposite risk haplotypes identified several variants in the coding region of functional candidate genes, such as a known retinopathy gene, MERTK. However, none of the identified coding variants followed a compelling case- or breed-specific segregation pattern. The expression analyses of four candidate genes in the region, MERTK, NPHP1, ANAPC1 and KRCC1, revealed specific upregulation of MERTK in the retina of the affected dogs. Collectively, these results indicate that the retinopathy is associated with overexpression of MERTK, however further investigation is needed to discover the regulatory mutation for the better understanding of the disease pathogenesis. Our study establishes a novel gain-of-function model for the MERTK biology and provides a therapy model for retinopathy MERTK inhibitors. Meanwhile, a marker-based genetic counseling can be developed to revise breeding programs.
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Affiliation(s)
- Saija J. Ahonen
- Department of Veterinary Biosciences and Research Programs Unit, Molecular Neurology, University of Helsinki, Helsinki, Finland
- The Folkhälsan Institute of Genetics, Helsinki, Finland
| | - Meharji Arumilli
- Department of Veterinary Biosciences and Research Programs Unit, Molecular Neurology, University of Helsinki, Helsinki, Finland
- The Folkhälsan Institute of Genetics, Helsinki, Finland
| | - Eija Seppälä
- Department of Veterinary Biosciences and Research Programs Unit, Molecular Neurology, University of Helsinki, Helsinki, Finland
- The Folkhälsan Institute of Genetics, Helsinki, Finland
| | - Osmo Hakosalo
- Department of Veterinary Biosciences and Research Programs Unit, Molecular Neurology, University of Helsinki, Helsinki, Finland
- The Folkhälsan Institute of Genetics, Helsinki, Finland
| | - Maria K. Kaukonen
- Department of Veterinary Biosciences and Research Programs Unit, Molecular Neurology, University of Helsinki, Helsinki, Finland
- The Folkhälsan Institute of Genetics, Helsinki, Finland
| | - András M. Komáromy
- Department of Small Animal Clinical Sciences, College of Veterinary Medicine, Michigan State University, East Lansing, Michigan, United States of America
- Department of Clinical Studies, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Hannes Lohi
- Department of Veterinary Biosciences and Research Programs Unit, Molecular Neurology, University of Helsinki, Helsinki, Finland
- The Folkhälsan Institute of Genetics, Helsinki, Finland
- * E-mail:
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18
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Khan MI, Azam M, Ajmal M, Collin RWJ, den Hollander AI, Cremers FPM, Qamar R. The molecular basis of retinal dystrophies in pakistan. Genes (Basel) 2014; 5:176-95. [PMID: 24705292 PMCID: PMC3978518 DOI: 10.3390/genes5010176] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2014] [Revised: 02/14/2014] [Accepted: 02/14/2014] [Indexed: 12/23/2022] Open
Abstract
The customary consanguineous nuptials in Pakistan underlie the frequent occurrence of autosomal recessive inherited disorders, including retinal dystrophy (RD). In many studies, homozygosity mapping has been shown to be successful in mapping susceptibility loci for autosomal recessive inherited disease. RDs are the most frequent cause of inherited blindness worldwide. To date there is no comprehensive genetic overview of different RDs in Pakistan. In this review, genetic data of syndromic and non-syndromic RD families from Pakistan has been collected. Out of the 132 genes known to be involved in non-syndromic RD, 35 different genes have been reported to be mutated in families of Pakistani origin. In the Pakistani RD families 90% of the mutations causing non-syndromic RD and all mutations causing syndromic forms of the disease have not been reported in other populations. Based on the current inventory of all Pakistani RD-associated gene defects, a cost-efficient allele-specific analysis of 11 RD-associated variants is proposed, which may capture up to 35% of the genetic causes of retinal dystrophy in Pakistan.
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Affiliation(s)
- Muhammad Imran Khan
- Department of Biosciences, Faculty of Science, COMSATS Institute of Information Technology, Islamabad 45600, Pakistan.
| | - Maleeha Azam
- Department of Biosciences, Faculty of Science, COMSATS Institute of Information Technology, Islamabad 45600, Pakistan.
| | - Muhammad Ajmal
- Department of Biosciences, Faculty of Science, COMSATS Institute of Information Technology, Islamabad 45600, Pakistan.
| | - Rob W J Collin
- Department of Human Genetics, Radboud University Medical Center, Nijmegen 6500 HB, The Netherlands.
| | - Anneke I den Hollander
- Department of Human Genetics, Radboud University Medical Center, Nijmegen 6500 HB, The Netherlands.
| | - Frans P M Cremers
- Department of Biosciences, Faculty of Science, COMSATS Institute of Information Technology, Islamabad 45600, Pakistan.
| | - Raheel Qamar
- Department of Biosciences, Faculty of Science, COMSATS Institute of Information Technology, Islamabad 45600, Pakistan.
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19
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Conlon TJ, Deng WT, Erger K, Cossette T, Pang JJ, Ryals R, Clément N, Cleaver B, McDoom I, Boye SE, Peden MC, Sherwood MB, Abernathy CR, Alkuraya FS, Boye SL, Hauswirth WW. Preclinical potency and safety studies of an AAV2-mediated gene therapy vector for the treatment of MERTK associated retinitis pigmentosa. HUM GENE THER CL DEV 2013; 24:23-8. [PMID: 23692380 DOI: 10.1089/humc.2013.037] [Citation(s) in RCA: 72] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Abstract Proof of concept for MERTK gene replacement therapy has been demonstrated using different viral vectors in the Royal College of Surgeon (RCS) rat, a well characterized model of recessive retinitis pigmentosa that contains a mutation in the Mertk gene. MERTK plays a key role in renewal of photoreceptor outer segments (OS) by phagocytosis of shed OS tips. Mutations in MERTK cause impaired phagocytic activity and accumulation of OS debris in the interphotoreceptor space that ultimately leads to photoreceptor cell death. In the present study, we conducted a series of preclinical potency and GLP-compliant safety evaluations of an adeno-associated virus type 2 (AAV2) vector expressing human MERTK cDNA driven by the retinal pigment epithelium-specific, VMD2 promoter. We demonstrate the potency of the vector in RCS rats by improved electroretinogram (ERG) responses in treated eyes compared with contralateral untreated controls. Toxicology and biodistribution studies were performed in Sprague-Dawley (SD) rats injected with two different doses of AAV vectors and buffer control. Delivery of vector in SD rats did not result in a change in ERG amplitudes of rod and cone responses relative to balanced salt solution control-injected eyes, indicating that administration of AAV vector did not adversely affect normal retinal function. In vivo fundoscopic analysis and postmortem retinal morphology of the vector-injected eyes were normal compared with controls. Evaluation of blood smears showed the lack of transformed cells in the treated eyes. All injected eyes and day 1 blood samples were positive for vector genomes, and all peripheral tissues were negative. Our results demonstrate the potency and safety of the AAV2-VMD2-hMERTK vector in animal models tested. A GMP vector has been manufactured and is presently in clinical trial.
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Affiliation(s)
- Thomas J Conlon
- Powell Gene Therapy Center, Department of Pediatrics, University of Florida, Gainesville, FL 32610, USA.
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Boye SE, Boye SL, Lewin AS, Hauswirth WW. A comprehensive review of retinal gene therapy. Mol Ther 2013; 21:509-19. [PMID: 23358189 DOI: 10.1038/mt.2012.280] [Citation(s) in RCA: 204] [Impact Index Per Article: 18.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Blindness, although not life threatening, is a debilitating disorder for which few, if any treatments exist. Ocular gene therapies have the potential to profoundly improve the quality of life in patients with inherited retinal disease. As such, tremendous focus has been given to develop such therapies. Several factors make the eye an ideal organ for gene-replacement therapy including its accessibility, immune privilege, small size, compartmentalization, and the existence of a contralateral control. This review will provide a comprehensive summary of (i) existing gene therapy clinical trials for several genetic forms of blindness and (ii) preclinical efficacy and safety studies in a variety of animal models of retinal disease which demonstrate strong potential for clinical application. To be as comprehensive as possible, we include additional proof of concept studies using gene replacement, neurotrophic/neuroprotective, optogenetic, antiangiogenic, or antioxidative stress strategies as well as a description of the current challenges and future directions in the ocular gene therapy field to this review as a supplement.
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Affiliation(s)
- Shannon E Boye
- Department of Ophthalmology, University of Florida, Gainesville, FL, USA.
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Homozygous mutation in MERTK causes severe autosomal recessive retinitis pigmentosa. Eur J Ophthalmol 2012; 22:647-53. [PMID: 22180149 DOI: 10.5301/ejo.5000096] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/17/2011] [Indexed: 11/20/2022]
Abstract
PURPOSE Gene identification in retinitis pigmentosa is a prerequisite to future therapies. Accordingly, autosomal recessive retinitis pigmentosa families were genotyped to search for causative mutations. METHODS Members of a consanguineous Moroccan family had standard ophthalmologic examination, optical coherence tomography-3 scan, autofluorescence testing, and electroretinogram. Their DNA was genotyped with the 250K SNP microchip (Affymetrix) and homozygosity mapping was done. MERTK exons were polymerase chain reaction amplified and sequenced. RESULTS Two sisters and one brother out of 6 siblings had rod cone dystrophy type of retinitis pigmentosa. Salient features were night blindness starting in early infancy, dot-like whitish deposits in fovea and macula with corresponding autofluorescent dots in youngest patients, decreased visual acuity, and cone responses higher than rod responses at electroretinogram. The patients were homozygous in regions from chromosomes 2 and 8, but only that of chromosome 2 was inherited from a common ancestor. Sequencing of the MERTK gene belonging to the chromosome 2 region showed that the 3 affected patients carried a novel homozygous mutation in exon 17, c.2323C>T, leading to p.Arg775X, while their unaffected brothers and sister, parents, and paternal grandfather were heterozygous. CONCLUSIONS MERTK mutations lead to severe retinitis pigmentosa with discrete dot-like autofluorescent deposits at early stages, which are a hallmark of this MERTK-specific dystrophy.
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Deng WT, Dinculescu A, Li Q, Boye SL, Li J, Gorbatyuk MS, Pang J, Chiodo VA, Matthes MT, Yasumura D, Liu L, Alkuraya FS, Zhang K, Vollrath D, LaVail MM, Hauswirth WW. Tyrosine-mutant AAV8 delivery of human MERTK provides long-term retinal preservation in RCS rats. Invest Ophthalmol Vis Sci 2012; 53:1895-904. [PMID: 22408006 DOI: 10.1167/iovs.11-8831] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
PURPOSE The absence of Mertk in RCS rats results in defective RPE phagocytosis, accumulation of outer segment (OS) debris in the subretinal space, and subsequent death of photoreceptors. Previous research utilizing Mertk gene replacement therapy in RCS rats provided proof of concept for treatment of this form of recessive retinitis pigmentosa (RP); however, the beneficial effects on retinal function were transient. In the present study, we evaluated whether delivery of a MERTK transgene using a tyrosine-mutant AAV8 capsid could lead to more robust and longer-term therapeutic outcomes than previously reported. METHODS An AAV8 Y733F vector expressing a human MERTK cDNA driven by a RPE-selective promoter was administrated subretinally at postnatal day 2. Functional and morphological analyses were performed at 4 months and 8 months post-treatment. Retinal vasculature and Müller cell activation were analyzed by quantifying acellular capillaries and glial fibrillary acidic protein immunostaining, respectively. RESULTS Electroretinographic responses from treated eyes were more than one-third of wild-type levels and OS were well preserved in the injection area even at 8 months. Rescue of RPE phagocytosis, prevention of retinal vasculature degeneration, and inhibition of Müller cell activation were demonstrated in the treated eyes for at least 8 months. CONCLUSIONS This research describes a longer and much more robust functional and morphological rescue than previous studies. We also demonstrate for the first time that an AAV8 mutant capsid serotype vector has a substantial therapeutic potential for RPE-specific gene delivery. These results suggest that tyrosine-mutant AAV8 vectors hold promise for the treatment of individuals with MERTK-associated RP.
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Affiliation(s)
- Wen-Tao Deng
- Department of Ophthalmology, College of Medicine, University of Florida, 1600 SW Archer Road, Gainesville, FL 32610, USA.
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Naz S, Ali S, Riazuddin SA, Farooq T, Butt NH, Zafar AU, Khan SN, Husnain T, MacDonald IM, Sieving PA, Hejtmancik JF, Riazuddin S. Mutations in RLBP1 associated with fundus albipunctatus in consanguineous Pakistani families. Br J Ophthalmol 2011; 95:1019-24. [PMID: 21447491 PMCID: PMC3459316 DOI: 10.1136/bjo.2010.189076] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
OBJECTIVE To identify disease-causing mutations in two consanguineous Pakistani families with fundus albipunctatus. METHODS Affected individuals in both families underwent a thorough clinical examination including funduscopy and electroretinography. Blood samples were collected from all participating members and genomic DNA was extracted. Exclusion analysis was completed with microsatellite short tandem repeat markers that span all reported loci for fundus albipunctatus. Two-point logarithm of odds (LOD) scores were calculated, and coding exons and exon-intron boundaries of RLBP1 were sequenced bi-directionally. RESULTS The ophthalmic examination of affected patients in both families was consistent with fundus albipunctatus. The alleles of markers on chromosome 15q flanking RLBP1 segregated with the disease phenotype in both families and linkage was further confirmed by two-point LOD scores. Bi-directional sequencing of RLBP1 identified a nonsense mutation (R156X) and a missense mutation (G116R) that segregated with the disease phenotype in their respective families. CONCLUSIONS These results strongly suggest that mutations in RLBP1 are responsible for fundus albipunctatus in the affected individuals of these consanguineous Pakistani families.
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Affiliation(s)
- Shagufta Naz
- National Centre of Excellence in Molecular Biology, University of the Punjab, Lahore, Pakistan
| | - Shahbaz Ali
- National Centre of Excellence in Molecular Biology, University of the Punjab, Lahore, Pakistan
| | - S Amer Riazuddin
- National Centre of Excellence in Molecular Biology, University of the Punjab, Lahore, Pakistan
- The Wilmer Eye Institute, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Tahir Farooq
- Layton Rahmatulla Benevolent Trust Hospital, Lahore, Pakistan
| | - Nadeem H Butt
- Allama Iqbal Medical College, University of Health Sciences, Lahore, Pakistan
| | - Ahmad U Zafar
- National Centre of Excellence in Molecular Biology, University of the Punjab, Lahore, Pakistan
| | - Shaheen N Khan
- National Centre of Excellence in Molecular Biology, University of the Punjab, Lahore, Pakistan
| | - Tayyab Husnain
- National Centre of Excellence in Molecular Biology, University of the Punjab, Lahore, Pakistan
| | - Ian M MacDonald
- Department of Ophthalmology, The University of Alberta, Edmonton, Alberta, Canada
- Ophthalmic Genetics and Visual Function Branch, National Eye Institute, National Institutes of Health, Bethesda, Maryland, USA
| | - Paul A Sieving
- Ophthalmic Genetics and Visual Function Branch, National Eye Institute, National Institutes of Health, Bethesda, Maryland, USA
| | - J Fielding Hejtmancik
- Ophthalmic Genetics and Visual Function Branch, National Eye Institute, National Institutes of Health, Bethesda, Maryland, USA
| | - Sheikh Riazuddin
- National Centre of Excellence in Molecular Biology, University of the Punjab, Lahore, Pakistan
- Allama Iqbal Medical College, University of Health Sciences, Lahore, Pakistan
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Ostergaard E, Duno M, Batbayli M, Vilhelmsen K, Rosenberg T. A novel MERTK deletion is a common founder mutation in the Faroe Islands and is responsible for a high proportion of retinitis pigmentosa cases. Mol Vis 2011; 17:1485-92. [PMID: 21677792 PMCID: PMC3110495] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2010] [Accepted: 06/01/2011] [Indexed: 11/21/2022] Open
Abstract
PURPOSE The aim of the study was to elucidate the genetic background of retinitis pigmentosa (RP) in a Faroe Islands population, a genetic isolate in the North Atlantic Ocean. METHODS Blood samples were collected from subjects diagnosed with RP and their families. DNA from affected individuals underwent single nucleotide polymorphism microarray analysis and homozygosity mapping followed by sequence analysis of candidate genes. RESULTS We identified 25 cases of nonsyndromic RP corresponding to a prevalence of 1 in 1,900. Single nucleotide polymorphism analysis revealed a homozygous region on chromosome 2q, common to patients in four families, which harbored the RP gene MER tyrosine kinase protooncogene (MERTK). A deletion of 91 kb was identified in seven patients, representing 30% of the analyzed Faroese cases of nonsyndromic RP. The clinical course of six patients who were homozygous for the deletion showed onset in the first decade followed by a rapid deterioration of both rod and cone photoreceptor function. Early macular involvement was present, in accordance with that of other reported patients with MERTK mutations. CONCLUSIONS Previous studies have shown a frequency of less than 1% of MERTK mutations in RP patients. The 91-kb deletion encompassing exons 1-7 of MERTK is a common founder mutation in the Faroe Islands, responsible for around 30% of RP, and together with mutations in protocadherin 21 (PCDH21) accounts for more than half of the retinal dystrophy cases.
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Affiliation(s)
- Elsebet Ostergaard
- Department of Clinical Genetics 4062, Copenhagen University Hospital Rigshospitalet, Copenhagen, Denmark
| | - Morten Duno
- Department of Clinical Genetics 4062, Copenhagen University Hospital Rigshospitalet, Copenhagen, Denmark
| | - Mustafa Batbayli
- Department of Clinical Genetics 4062, Copenhagen University Hospital Rigshospitalet, Copenhagen, Denmark
| | - Kaj Vilhelmsen
- Department of Ophthalmology, National Hospital of the Faroe Islands, Tórshavn, Faroe Islands
| | - Thomas Rosenberg
- Gordon Norrie Center for Genetic Eye Diseases, National Eye Clinic, Kennedy Center, Glostrup, Denmark
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Rothlin CV, Lemke G. TAM receptor signaling and autoimmune disease. Curr Opin Immunol 2010; 22:740-6. [PMID: 21030229 DOI: 10.1016/j.coi.2010.10.001] [Citation(s) in RCA: 145] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2010] [Revised: 09/09/2010] [Accepted: 10/01/2010] [Indexed: 11/26/2022]
Abstract
The TAM receptor tyrosine kinases Tyro3, Axl, and Mer and their ligands Gas6 and Protein S are essential for the phagocytosis of apoptotic cells and membranes in the adult immune, nervous, and reproductive systems. Genetic studies indicate that this receptor-ligand system is central to apoptotic cell engulfment that is triggered by the 'eat-me' signal phosphatidylserine (PtdSer). At the same time, TAM signaling is normally activated by Toll-like receptor (TLR) and type I interferon signaling, as part of the innate inflammatory response in dendritic cells (DCs) and macrophages, where it inhibits this response. Deficiencies in TAM signaling result in human retinal dystrophies and may contribute to lupus and other human autoimmune diseases.
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Affiliation(s)
- Carla V Rothlin
- Department of Immunobiology, Yale University School of Medicine, New Haven, CT 06520, United States.
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