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RP2-associated X-linked Retinopathy: Clinical Findings, Molecular Genetics, and Natural History

Georgiou, Michalis; Robson, Anthony G; Jovanovic, Katarina; Cabral de Guimarães, Thales Antônio; Ali, Naser; Pontikos, Nikolas; Uwaydat, Sami H; ... Michaelides, Michel; + view all (2022) RP2-associated X-linked Retinopathy: Clinical Findings, Molecular Genetics, and Natural History. Ophthalmology 10.1016/j.ophtha.2022.11.015. (In press). Green open access

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Abstract

PURPOSE: To review and describe in detail the clinical course, functional and anatomical characteristics of RP2-associated retinal degeneration. DESIGN: Retrospective case series. PARTICIPANTS: Males with disease-causing variants in the RP2 gene. METHODS: Review of all case notes and results of molecular genetic testing, retinal imaging (fundus autofluorescence (FAF) imaging, optical coherence tomography (OCT)) and electrophysiology assessment. MAIN OUTCOME MEASURES: Molecular genetic testing, clinical findings including best-corrected visual acuity (BCVA), qualitative and quantitative retinal imaging analysis, and electrophysiology parameters. RESULTS: Fifty-four molecularly confirmed patients were identified, from 38 pedigrees. Twenty-eight disease-causing variants were identified; with 20 not previously clinically characterized. Fifty-three patients (98.1%) presented with retinitis pigmentosa. The mean age of onset (range, ±SD) was 9.6 years of age (1-57 years, ± 9.2 years). Forty-four patients (91.7%) had childhood-onset disease, with mean age of onset of 7.6 years. The commonest first symptom was night blindness (68.8%). Mean BCVA (range, ±SD) was 0.91 LogMAR (0-2.7, ±0.80) and 0.94 LogMAR (0-2.7, ±0.78) for right and left eyes respectively. Based on the WHO visual impairment criteria, 18 patients (34%) had low vision. The majority (17/22) showed ERG evidence of a rod-cone dystrophy. Pattern ERG P50 was undetectable in all but 2 patients. A range of FAF findings was observed, from normal to advanced atrophy. There were no statistically significant differences between right and left eyes for ellipsoid zone (EZ) width and outer nuclear layer (ONL) thickness. The mean annual rate of EZ width loss was 219 μm/year and the mean annual decrease in ONL thickness was 4.93 μm/year. No patient with childhood-onset disease had identifiable EZ after the age of 26 years at baseline or follow-up. Four patients had adulthood-onset disease and a less severe phenotype. CONCLUSIONS: This study details the clinical phenotype of RP2 retinopathy in a large cohort. The majority presented with early-onset severe retinal degeneration, with early macular involvement and complete loss of the foveal photoreceptor layer by the third decade of life. Full-field ERGs revealed rod-cone dystrophy in the vast majority, but with generalised (peripheral) cone system involvement of widely varying severity in the first two decades of life.

Type: Article
Title: RP2-associated X-linked Retinopathy: Clinical Findings, Molecular Genetics, and Natural History
Location: United States
Open access status: An open access version is available from UCL Discovery
DOI: 10.1016/j.ophtha.2022.11.015
Publisher version: https://doi.org/10.1016/j.ophtha.2022.11.015
Language: English
Additional information: Copyright 2022 by the American Academy of Ophthalmology This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).
Keywords: Genetics, Genotyping, Inherited Retinal Diseases, Phenotyping, RP2, Retinitis Pigmentosa, Retinopathy
UCL classification: UCL
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Brain Sciences
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Brain Sciences > Institute of Ophthalmology
URI: https://discovery.ucl.ac.uk/id/eprint/10160797
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