Eyes Shut Homolog-Associated Retinal Degeneration: Natural History, Genetic Landscape, and Phenotypic Spectrum

Abstract

To describe the natural history, genetic landscape and phenotypic spectrum of EYS- associated retinal degeneration (EYS-RD). Retrospective, single-center cohort study complemented by a cross-sectional examination. Patients with biallelic EYS variants recruited at an inherited retinal degeneration referral center in Portugal. Every patient underwent a cross-sectional examination comprising a comprehensive ophthalmologic examination including best-corrected visual acuity (BCVA), dilated slit-lamp anterior segment and fundus biomicroscopy; ultra-widefield color fundus photography and fundus autofluorescence imaging; and spectral-domain optical coherence tomography (SD-OCT). In the setting of a retinitis pigmentosa (RP) diagnosis, every patient was classified as typical or atypical RP according to imaging criteria. Baseline demographics, age at onset of symptoms, family history, history of consanguinity, symptoms, age at diagnosis, BCVA at baseline and throughout follow-up, and EYS variants were collected from each individual patient file. Clinical/demographic, genetic, multimodal imaging data (ellipsoid zone widths) and BCVA variation were compared between typical and atypical RP. Additionally, BCVA variation during follow-up was used as an endpoint to describe EYS-RD natural history. Fifty-eight patients (59% males; mean age 52±14 years) from 48 Caucasian families of Portuguese ancestry were included. Twenty distinct EYS variants were identified, eight of which are novel. In 32.8% patients, onset of symptoms was in early adulthood (21-30 years). A clinical diagnosis of RP was established in 57 patients and cone-rod dystrophy in one patient. Regarding RP, 75.0% of the patients were graded as typical and 25.0% as atypical. Atypical EYS-RP commonly presents with inferior crescent-shaped macular atrophy with superior mid-peripheral sparing. In EYS-RD, a negative correlation was found between age and BCVA (r=-0.50; p<0.001), with an average loss of 1.45 letters per year. When stratifying for RP phenotype, lower average loss of letters per year (p<0.001), higher BCVA (p<0.001) and larger ellipsoid zone (EZ) widths (p<0.001) were found in atypical RP. This study expands the genetic spectrum of EYS-RD by reporting 8 novel variants. A high frequency of atypical phenotypes was identified. These patients have better BCVA and larger EZ widths, thus presenting an overall better prognosis.