RPGR-Associated Dystrophies: Clinical, Genetic, and Histopathological Features.

Robert M. Verdijk,Xuan-Thanh-An Nguyen,Mary J. van Schooneveld,Jan Wijnholds,Mays Talib,Camiel J.F. Boon,Ralph J. Florijn,Jacoline ten Brink,Joost Brinks,Arthur A. Bergen

doi:10.3390/ijms21030835

Abstract

This study describes the clinical, genetic, and histopathological features in patients with RPGR-associated retinal dystrophies. Nine male patients from eight unrelated families underwent a comprehensive ophthalmic examination. Additionally, the histopathology of the right eye from a patient with an end-stage cone-rod-dystrophy (CRD)/sector retinitis pigmentosa (RP) phenotype was examined. All RPGR mutations causing a CRD phenotype were situated in exon ORF15. The mean best-corrected visual acuity (BCVA, decimals) was 0.58 (standard deviation (SD)): 0.34; range: 0.05–1.13); and the mean spherical refractive error was −4.1 D (SD: 2.11; range: −1.38 to −8.19). Hyperautofluorescent rings were observed in six patients. Full-field electroretinography responses were absent in all patients. The visual field defects ranged from peripheral constriction to central islands. The mean macular sensitivity on microperimetry was 11.6 dB (SD: 7.8; range: 1.6–24.4) and correlated significantly with BCVA (r = 0.907; p = 0.001). A histological examination of the donor eye showed disruption of retinal topology and stratification, with a more severe loss found in the peripheral regions. Reactive gliosis was seen in the inner layers of all regions. Our study demonstrates the highly variable phenotype found in RPGR-associated retinal dystrophies. Therapies should be applied at the earliest signs of photoreceptor degeneration, prior to the remodeling of the inner retina.

Highlights

Retinitis pigmentosa (RP) is the most common inherited retinal dystrophy, affecting approximately 1 in 3000 individuals [1]
We describe the clinical and genetic characteristics of Retinitis Pigmentosa GTPase Regulator (RPGR) patients at different stages of disease based on extensive prospective structural and functional phenotyping
An early onset of symptoms was present in patients with RP, with initial symptoms being night blindness or peripheral visual field loss

Summary

Introduction

Retinitis pigmentosa (RP) is the most common inherited retinal dystrophy, affecting approximately 1 in 3000 individuals [1]. Its predominant feature is the irreversible loss of rod photoreceptors, with secondary loss of cone photoreceptors. X-linked RP (XLRP) accounts for 5%–15% of all RP cases and is recognized as one of the most severe forms of RP [2,3]. Mutations in the RPGR gene are responsible for 70%–90% of all XLRP cases [4,5,6]. Symptom onset in affected males starts in childhood years and is described to reach blindness within the 4th decade of life [2,7,8]. Despite the X-linked inheritance of RPGR, female carriers may be affected by XLRP [9,10]

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Conclusion