JCI Insight (Jan 2022)

Photoreceptor degeneration in ABCA4-associated retinopathy and its genetic correlates

  • Maximilian Pfau,
  • Catherine A. Cukras,
  • Laryssa A. Huryn,
  • Wadih M. Zein,
  • Ehsan Ullah,
  • Marisa P. Boyle,
  • Amy Turriff,
  • Michelle A. Chen,
  • Aarti S. Hinduja,
  • Hermann E.A. Siebel,
  • Robert B. Hufnagel,
  • Brett G. Jeffrey,
  • Brian P. Brooks

Journal volume & issue
Vol. 7, no. 2

Abstract

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BACKGROUND Outcome measures sensitive to disease progression are needed for ATP-binding cassette, sub-family A, member 4–associated (ABCA4-associated) retinopathy. We aimed to quantify ellipsoid zone (EZ) loss and photoreceptor degeneration beyond EZ-loss in ABCA4-associated retinopathy and investigate associations between photoreceptor degeneration, genotype, and age.METHODS We analyzed 132 eyes from 66 patients (of 67 enrolled) with molecularly confirmed ABCA4-associated retinopathy from a prospective natural history study with a median [IQR] follow-up of 4.2 years [3.1, 5.1]. Longitudinal spectral-domain optical coherence tomography volume scans (37 B-scans, 30° × 15°) were segmented using a deep learning (DL) approach. For genotype-phenotype analysis, a model of ABCA4 variants was applied with the age of criterion EZ-loss (6.25 mm2) as the dependent variable.RESULTS Patients exhibited an average (square-root-transformed) EZ-loss progression rate of [95% CI] 0.09 mm/y [0.06, 0.11]. Outer nuclear layer (ONL) thinning extended beyond the area of EZ-loss. The average distance from the EZ-loss boundary to normalization of ONL thickness (to ±2 z score units) was 3.20° [2.53, 3.87]. Inner segment (IS) and outer segment (OS) thinning was less pronounced, with an average distance from the EZ-loss boundary to layer thickness normalization of 1.20° [0.91, 1.48] for the IS and 0.60° [0.49, 0.72] for the OS. An additive model of allele severity explained 52.7% of variability in the age of criterion EZ-loss.CONCLUSION Patients with ABCA4-associated retinopathy exhibited significant alterations of photoreceptors outside of EZ-loss. DL-based analysis of photoreceptor laminae may help monitor disease progression and estimate the severity of ABCA4 variants.TRIAL REGISTRATION ClinicalTrials.gov identifier: NCT01736293.FUNDING National Eye Institute Intramural Research Program and German Research Foundation grant PF950/1-1.

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