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Poli FE, Yusuf IH, Clouston P, Shanks M, Whitfield J, Charbel Issa P, MacLaren RE. MERTK missense variants in three patients with retinitis pigmentosa. Ophthalmic Genet 2023; 44:74-82. [PMID: 36036427 PMCID: PMC9615558 DOI: 10.1080/13816810.2022.2113541] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2021] [Revised: 07/27/2022] [Accepted: 08/01/2022] [Indexed: 10/15/2022]
Abstract
BACKGROUND MERTK (MER proto-oncogene, tyrosine kinase) is a transmembrane protein essential in regulating photoreceptor outer segment phagocytosis. Biallelic mutations in MERTK cause retinal degeneration. Here we present the retinal phenotype of three patients with missense variants in MERTK. MATERIALS AND METHODS All patients underwent a full clinical examination, fundus photography, short-wavelength fundus autofluorescence and optical coherence tomography imaging. Two patients also underwent Goldmann visual field testing and electroretinography was undertaken for the third patient. Molecular genetic testing was undertaken using next generation or whole-exome sequencing with all variants confirmed by Sanger sequencing. RESULTS The first patient was a 29-year-old female heterozygous for a missense variant (c.1133C>T, p.Thr378 Met) and a nonsense variant (c.1744_1751delinsT, p.Ile582Ter) in MERTK. The second patient was a 26-year-old male homozygous for a c.2163T>A, p.His721Gln variant in MERTK. The third patient was an 11-year-old female heterozygous for a deletion of exons 5-19 and a missense variant (c.1866 G>C, p.Lys622Asn) in MERTK. Reduced night vision was the initial symptom in all patients. Fundoscopy revealed typical signs of retinitis pigmentosa (RP) with early-onset macular atrophy. All three MERTK missense variants affect highly conserved residues within functional domains, have low population frequencies and are predicted to be pathogenic in silico. CONCLUSIONS We report three missense variants in MERTK and present the associated phenotypic data, which are supportive of non-syndromic RP. MERTK is a promising candidate for viral-mediated gene replacement therapy. Moreover, one variant represents a single nucleotide transition, which is theoretically targetable with CRISPR-Cas9 base-editing.
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Affiliation(s)
- Federica E. Poli
- Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, UK
- Oxford Eye Hospital, Oxford University Hospitals NHS Foundation Trust, Oxford, UK
| | - Imran H. Yusuf
- Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, UK
- Oxford Eye Hospital, Oxford University Hospitals NHS Foundation Trust, Oxford, UK
| | - Penny Clouston
- Oxford Regional Genetics Laboratories, Oxford University Hospitals NHS Foundation Trust, Oxford, UK
| | - Morag Shanks
- Oxford Regional Genetics Laboratories, Oxford University Hospitals NHS Foundation Trust, Oxford, UK
| | - Jennifer Whitfield
- Oxford Regional Genetics Laboratories, Oxford University Hospitals NHS Foundation Trust, Oxford, UK
| | - Peter Charbel Issa
- Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, UK
- Oxford Eye Hospital, Oxford University Hospitals NHS Foundation Trust, Oxford, UK
| | - Robert E. MacLaren
- Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, UK
- Oxford Eye Hospital, Oxford University Hospitals NHS Foundation Trust, Oxford, UK
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2
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Challenges and Opportunities in the Genetic Analysis of Inherited Retinal Dystrophies in Africa, a Literature Review. J Pers Med 2023; 13:jpm13020239. [PMID: 36836473 PMCID: PMC9964248 DOI: 10.3390/jpm13020239] [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] [Received: 12/26/2022] [Revised: 01/20/2023] [Accepted: 01/26/2023] [Indexed: 01/31/2023] Open
Abstract
Inherited retinal dystrophies (IRDs) are a global problem that is largely unaddressed, especially in Africa. Black indigenous Africans are rarely represented in research that develops genetic tests and genetic therapies for IRDs, yet their genomes are more diverse. The aim of this literature review is to synthesize information on the IRD genetic research conducted among indigenous black Africans to identify challenges and opportunities for progress. PubMed was searched to identify empirical publications reporting the genetic analysis of IRDs among indigenous Africans. A total of 11 articles were selected for the review. Based on the information in the articles, the main genetic testing methods in use include next-generation, whole exome, and Sanger sequencing. The main IRDs characterized by the genetic tests include retinitis pigmentosa, Leber Congenital Amaurosis, Stagardt disease, and cone dystrophy. Examples of implicated genes include MERTK, GUCY2D, ABCA4, and KCNV2 for the four IRDs, respectively. Research activities on the genetics of IRDs are generally scanty in Africa. Even in South Africa and North Africa where some research activities were noted, only a few indigenous black Africans were included in the study cohorts. There is an urgent need for genetic research on IRDs, especially in East, Central, and West Africa.
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3
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Martínez-Vacas A, Di Pierdomenico J, Gallego-Ortega A, Valiente-Soriano FJ, Vidal-Sanz M, Picaud S, Villegas-Pérez MP, García-Ayuso D. Systemic taurine treatment affords functional and morphological neuroprotection of photoreceptors and restores retinal pigment epithelium function in RCS rats. Redox Biol 2022; 57:102506. [PMID: 36270186 PMCID: PMC9583577 DOI: 10.1016/j.redox.2022.102506] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2022] [Revised: 09/21/2022] [Accepted: 10/09/2022] [Indexed: 11/23/2022] Open
Abstract
The aim of our work was to study whether taurine administration has neuroprotective effects in dystrophic Royal College of Surgeons (RCS) rats, suffering retinal degeneration secondary to impaired retinal pigment epithelium phagocytosis caused by a MERTK mutation. Dystrophic RCS-p + female rats (n = 36) were divided into a non-treated group (n = 16) and a treated group (n = 20) that received taurine (0.2 M) in drinking water from postnatal day (P)21 to P45, when they were processed. Retinal function was assessed with electroretinogram. Retinal morphology was assessed in cross-sections using immunohistochemical techniques to label photoreceptors, retinal microglial and macroglial cells, active zones of conventional and ribbon synaptic connections, and oxidative stress. Retinal pigment epithelium function was examined using intraocular fluorogold injections. Our results document that taurine treatment increases taurine plasma levels and photoreceptor survival in dystrophic rats. The number of photoreceptor nuclei rows at P45 was 3-5 and 6-11 in untreated and treated animals, respectively. Electroretinograms showed increases of 70% in the rod response, 400% in the a-wave amplitude, 30% in the b-wave amplitude and 75% in the photopic b-wave response in treated animals. Treated animals also showed decreased numbers of microglial cells in the outer retinal layers, decreased glial fibrillary acidic protein (GFAP) expression in Müller cells, decreased oxidative stress in the outer and inner nuclear layers and improved maintenance of synaptic connections. Treated animals showed increased FG phagocytosis in the retinal pigment epithelium cells. In conclusion, systemic taurine treatment decreases photoreceptor degeneration and increases electroretinographic responses in dystrophic RCS rats and these effects may be mediated through various neuroprotective mechanisms.
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Affiliation(s)
- Ana Martínez-Vacas
- Departamento de Oftalmología, Facultad de Medicina, Universidad de Murcia, Instituto Murciano de Investigación Biosanitaria Hospital Virgen de la Arrixaca (IMIB-Virgen de la Arrixaca), Murcia, Spain
| | - Johnny Di Pierdomenico
- Departamento de Oftalmología, Facultad de Medicina, Universidad de Murcia, Instituto Murciano de Investigación Biosanitaria Hospital Virgen de la Arrixaca (IMIB-Virgen de la Arrixaca), Murcia, Spain
| | - Alejandro Gallego-Ortega
- Departamento de Oftalmología, Facultad de Medicina, Universidad de Murcia, Instituto Murciano de Investigación Biosanitaria Hospital Virgen de la Arrixaca (IMIB-Virgen de la Arrixaca), Murcia, Spain
| | - Francisco J Valiente-Soriano
- Departamento de Oftalmología, Facultad de Medicina, Universidad de Murcia, Instituto Murciano de Investigación Biosanitaria Hospital Virgen de la Arrixaca (IMIB-Virgen de la Arrixaca), Murcia, Spain
| | - Manuel Vidal-Sanz
- Departamento de Oftalmología, Facultad de Medicina, Universidad de Murcia, Instituto Murciano de Investigación Biosanitaria Hospital Virgen de la Arrixaca (IMIB-Virgen de la Arrixaca), Murcia, Spain
| | - Serge Picaud
- Sorbonne Universités, INSERM, CNRS, Institut de la Vision, Paris, France
| | - María Paz Villegas-Pérez
- Departamento de Oftalmología, Facultad de Medicina, Universidad de Murcia, Instituto Murciano de Investigación Biosanitaria Hospital Virgen de la Arrixaca (IMIB-Virgen de la Arrixaca), Murcia, Spain
| | - Diego García-Ayuso
- Departamento de Oftalmología, Facultad de Medicina, Universidad de Murcia, Instituto Murciano de Investigación Biosanitaria Hospital Virgen de la Arrixaca (IMIB-Virgen de la Arrixaca), Murcia, Spain.
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4
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Bhardwaj A, Yadav A, Yadav M, Tanwar M. Genetic dissection of non-syndromic retinitis pigmentosa. Indian J Ophthalmol 2022; 70:2355-2385. [PMID: 35791117 PMCID: PMC9426071 DOI: 10.4103/ijo.ijo_46_22] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
Retinitis pigmentosa (RP) belongs to a group of pigmentary retinopathies. It is the most common form of inherited retinal dystrophy, characterized by progressive degradation of photoreceptors that leads to nyctalopia, and ultimately, complete vision loss. RP is distinguished by the continuous retinal degeneration that progresses from the mid-periphery to the central and peripheral retina. RP was first described and named by Franciscus Cornelius Donders in the year 1857. It is one of the leading causes of bilateral blindness in adults, with an incidence of 1 in 3000 people worldwide. In this review, we are going to focus on the genetic heterogeneity of this disease, which is provided by various inheritance patterns, numerosity of variations and inter-/intra-familial variations based upon penetrance and expressivity. Although over 90 genes have been identified in RP patients, the genetic cause of approximately 50% of RP cases remains unknown. Heterogeneity of RP makes it an extremely complicated ocular impairment. It is so complicated that it is known as “fever of unknown origin”. For prognosis and proper management of the disease, it is necessary to understand its genetic heterogeneity so that each phenotype related to the various genetic variations could be treated.
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Affiliation(s)
- Aarti Bhardwaj
- Department of Genetics, M. D. University, Rohtak, Haryana, India
| | - Anshu Yadav
- Department of Genetics, M. D. University, Rohtak, Haryana, India
| | - Manoj Yadav
- Department of Genetics, M. D. University, Rohtak, Haryana, India
| | - Mukesh Tanwar
- Department of Genetics, M. D. University, Rohtak, Haryana, India
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5
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Francia S, Shmal D, Di Marco S, Chiaravalli G, Maya-Vetencourt JF, Mantero G, Michetti C, Cupini S, Manfredi G, DiFrancesco ML, Rocchi A, Perotto S, Attanasio M, Sacco R, Bisti S, Mete M, Pertile G, Lanzani G, Colombo E, Benfenati F. Light-induced charge generation in polymeric nanoparticles restores vision in advanced-stage retinitis pigmentosa rats. Nat Commun 2022; 13:3677. [PMID: 35760799 PMCID: PMC9237035 DOI: 10.1038/s41467-022-31368-3] [Citation(s) in RCA: 23] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2021] [Accepted: 06/14/2022] [Indexed: 12/16/2022] Open
Abstract
Retinal dystrophies such as Retinitis pigmentosa are among the most prevalent causes of inherited legal blindness, for which treatments are in demand. Retinal prostheses have been developed to stimulate the inner retinal network that, initially spared by degeneration, deteriorates in the late stages of the disease. We recently reported that conjugated polymer nanoparticles persistently rescue visual activities after a single subretinal injection in the Royal College of Surgeons rat model of Retinitis pigmentosa. Here we demonstrate that conjugated polymer nanoparticles can reinstate physiological signals at the cortical level and visually driven activities when microinjected in 10-months-old Royal College of Surgeons rats bearing fully light-insensitive retinas. The extent of visual restoration positively correlates with the nanoparticle density and hybrid contacts with second-order retinal neurons. The results establish the functional role of organic photovoltaic nanoparticles in restoring visual activities in fully degenerate retinas with intense inner retina rewiring, a stage of the disease in which patients are subjected to prosthetic interventions. Retinal dystrophies such as Retinitis pigmentosa are among the most prevalent causes of inherited incurable legal blindness. Here the authors demonstrate that conjugated polymer nanoparticles reinstate visual functions in aged rats with fully degenerated and rewired retinas.
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Affiliation(s)
- S Francia
- Center for Synaptic Neuroscience and Technology, Istituto Italiano di Tecnologia, Genova, Italy.,IRCCS Ospedale Policlinico San Martino, Genova, Italy
| | - D Shmal
- Center for Synaptic Neuroscience and Technology, Istituto Italiano di Tecnologia, Genova, Italy.,Department of Experimental Medicine, University of Genova, Genova, Italy
| | - S Di Marco
- Center for Synaptic Neuroscience and Technology, Istituto Italiano di Tecnologia, Genova, Italy.,IRCCS Ospedale Policlinico San Martino, Genova, Italy
| | - G Chiaravalli
- Center for Nanoscience and Technology, Istituto Italiano di Tecnologia, Milano, Italy
| | - J F Maya-Vetencourt
- Center for Synaptic Neuroscience and Technology, Istituto Italiano di Tecnologia, Genova, Italy.,Department of Biology, University of Pisa, Pisa, Italy
| | - G Mantero
- Center for Synaptic Neuroscience and Technology, Istituto Italiano di Tecnologia, Genova, Italy.,Department of Experimental Medicine, University of Genova, Genova, Italy
| | - C Michetti
- Center for Synaptic Neuroscience and Technology, Istituto Italiano di Tecnologia, Genova, Italy.,Department of Experimental Medicine, University of Genova, Genova, Italy
| | - S Cupini
- Center for Synaptic Neuroscience and Technology, Istituto Italiano di Tecnologia, Genova, Italy.,Department of Experimental Medicine, University of Genova, Genova, Italy
| | - G Manfredi
- Center for Nanoscience and Technology, Istituto Italiano di Tecnologia, Milano, Italy.,Novavido s.r.l., Bologna, Italy
| | - M L DiFrancesco
- Center for Synaptic Neuroscience and Technology, Istituto Italiano di Tecnologia, Genova, Italy.,IRCCS Ospedale Policlinico San Martino, Genova, Italy
| | - A Rocchi
- Center for Synaptic Neuroscience and Technology, Istituto Italiano di Tecnologia, Genova, Italy
| | - S Perotto
- Center for Nanoscience and Technology, Istituto Italiano di Tecnologia, Milano, Italy
| | - M Attanasio
- Department of Ophthalmology, IRCCS Sacrocuore Don Calabria Hospital, Negrar, Verona, Italy
| | - R Sacco
- Department of Mathematics, Politecnico di Milano, Milano, Italy
| | - S Bisti
- Center for Synaptic Neuroscience and Technology, Istituto Italiano di Tecnologia, Genova, Italy
| | - M Mete
- Department of Ophthalmology, IRCCS Sacrocuore Don Calabria Hospital, Negrar, Verona, Italy
| | - G Pertile
- Department of Ophthalmology, IRCCS Sacrocuore Don Calabria Hospital, Negrar, Verona, Italy
| | - G Lanzani
- Center for Nanoscience and Technology, Istituto Italiano di Tecnologia, Milano, Italy. .,Department of Physics, Politecnico di Milano, Milan, Italy.
| | - E Colombo
- Center for Synaptic Neuroscience and Technology, Istituto Italiano di Tecnologia, Genova, Italy.,IRCCS Ospedale Policlinico San Martino, Genova, Italy
| | - F Benfenati
- Center for Synaptic Neuroscience and Technology, Istituto Italiano di Tecnologia, Genova, Italy. .,IRCCS Ospedale Policlinico San Martino, Genova, Italy.
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6
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Shen-Sampas JH, Duret S, Duncan JL. Retinal Degeneration Secondary to MERTK Mutations: Potential Candidate for Gene Therapy. Int Ophthalmol Clin 2021; 61:143-148. [PMID: 34584051 PMCID: PMC8486302 DOI: 10.1097/iio.0000000000000374] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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7
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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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