ABCA4 Versus PRPH2 -Associated Retinopathy: Clinical and Electrophysiological Findings

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Purpose: The purpose of this study was to characterize the clinical features, electrophysiology, and variant spectrum in ABCA4- and PRPH2-retinopathies and to identify novel electrodiagnostic biomarkers to differentiate between these two genotypes. Methods: We conducted an international multicenter case-control study of patients with a clinical and genetic diagnosis of ABCA4- or PRPH2-retinopathy. Age at symptom onset, best-corrected visual acuity (BCVA), electroretinography (ERG) components, and fundus autofluorescence (FAF) imaging were compared. Subgroup exploratory analysis was performed on those patients with a phenotype similar to central areolar choroidal dystrophy ("CACD-like"), those with flecks distributed throughout the posterior pole ("fleck-like") and a healthy control group. Receiver operating characteristic (ROC) analysis was performed to determine the optimal cutoff for ERG parameters to distinguish PRPH2- from ABCA4-retinopathy. Results: This study included 155 patients with ABCA4-retinopathy, 133 patients with PRPH2-retinopathy, and 52 healthy controls. Significant electrophysiological biomarkers included the light-adapted (LA)30 hertz (Hz) flicker and LA3.0 single flash b-wave peak time (P < 0.001) for the "CACD-like" group with an area under the ROC curve (AUROC) of 0.78 and 0.76 and cutoff thresholds of 27.8 ms or 31.7 ms providing 77% and 85% sensitivity, respectively. Conversely, in the "fleck-like" group, the dark-adapted (DA)0.01 b-wave amplitude and DA3 a-wave amplitude (P < 0.001) had the highest AUROC, namely 0.88 and 0.88, respectively, with cutoff thresholds of 85 µV and 109 µV providing 93% and 88% sensitivity, respectively. Conclusions: Unique ERG profiles can distinguish PRPH2- from ABCA4-retinopathy. The LA30 Hz peak time and DA0.01 b-wave amplitude may have clinical utility in predicting and interpreting the genotype in patients with overlapping retinal phenotypes.

Ce résumé expose les affirmations des auteurs. BNTIC ne l’interprète pas comme une validation indépendante des résultats.