Author: Dinah Zur (Israel)
Co-authors: Eran Pras, Tamar Ben-Yosef, Claudio Iovino, Ygal Rotenstreich, Francesca Simonelli, Matias Iglicki
Purpose
Retinol dehydrogenase (RDH)5 related fundus albipunctatus (FAP) can present with phenotypic variability. Our purpose was to investigate new clinical characteristics and multimodal imaging findings in patients from different ethnic origins, carrying different mutations.
Setting/Venue
This international multicenter retrospective case series included five centers (Tel Aviv Medical Center, Israel; Shamir Medical Center, Israel; Sheba Medical Center, Israel; Schneider Children's Medical Center, Israel; University of Campania Luigi Vanvitelli, Naples, Italy). Patient records from January 1, 2016 to August 1, 2020 were reviewed for consecutive cases of FAP which had a genetically confirmed diagnosis and OCT imaging.
Methods
Eighteen patients who were diagnosed with FAP and had pathogenic bi-allelic RDH5 mutations (GeneBank Accession Number NM_001199771) were studied. Patients’ files were reviewed for fundus images, visual acuity, macular optical coherence tomography (OCT) scans, near-infrared images, fundus autofluorescence (FAF), electroretinogram (ERG), and genetic mutations. Main Outcome Measures: Imaging and ERG findings.
Results
All eyes (n=36, 100%) showed small circular findings seen on near infrared images, termed as the “target sign”, correlating to the yellowish dots seen clinically and to the distinct hyperreflective linear lesions on OCT at the level between ELM and RPE. Perifoveal atrophy with foveal sparing was seen in 4 eyes of 2 patients (both RDH5 - c.160C>T, p.R54X mutation). FAF revealed small hyperautofluorescent dots (n=16, 44.4%). Scotopic ERGs were significantly reduced in all cases with an electronegative pattern, 66.7% displayed cone dysfunction.
Conlusions
Our results show distinct imaging findings present in all FAP patients independent of ethnicity or genetic mutation. Using the imaging findings described in this paper, we showed that the diagnosis can be made with more proficiency. Our results might facilitate the current algorithm to diagnose RDH5-related FAP. Using the imaging features described here, we can accurately target the genetic testing for RDH5 mutations. This finding may also guide the genetic counselling given in the scenario of a patient with night blindnesss towards a stationary nature of the disease rather than a deteriorating one, thereby alleviating the anxiety and stress of the patients and their family.
Financial Disclosure
Bayer, Allergan, Novartis, Roche - Consultant. No financial disclosures related to this study
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