Abstract
PurposeTo determine the reliability and repeatability of quantitative evaluation of areas of decreased autofluorescence (DAF) from fundus autofluorescence (FAF) images and track disease progression in children with Stargardt disease (STGD1), and to investigate clinical and genotype correlations, disease symmetry, and intrafamilial variability.DesignProspective cohort study.MethodsChildren and adults with molecularly confirmed STGD1 (n = 90) underwent longitudinal FAF imaging with subsequent semiautomated measurement of the area of DAF and calculation of the annual rate of progression. The age of disease onset was recorded for all subjects, as well as the electroretinography (ERG) group at baseline (n = 86). Patients were grouped for analysis based on the age at baseline and age of onset, into children (n = 56), adults with childhood-onset STGD1 (n = 15), and adults with adult-onset (n = 19). Fifty FAF images were selected randomly and analyzed by 2 observers to evaluate repeatability and reproducibility. Differences between groups, interocular symmetry, genotype–phenotype correlations, and intrafamilial variability were also investigated both for baseline measurements as well as progression rates. We measured visual acuity, molecular genetics, ERG group, FAF metrics, and their correlations.ResultsThe mean age of onset ± SD was 9.6 ± 3.4 years for childhood-onset (n = 71) and 28.3 ± 7.8 years for adult-onset STGD1 (n = 19). The intra- and interobserver reliability of DAF quantification was excellent (intraclass correlation coefficients 0.995 and 0.987, respectively). DAF area was symmetric between eyes and the mean rate of progression (SD) was 0.69 (0.72), 0.78 (0.48), and 0.40 (0.36) mm2/year for children, adults with childhood-onset, and adults with adult-onset disease, respectively. Patients belonging to a group 3 ERG phenotype (generalized cone and rod dysfunction) had a significantly greater progression rate. Limited intrafamilial variability was observed.ConclusionsThis is the first large prospective study of FAF in a cohort of molecularly confirmed children with STGD1. DAF area quantification was highly reliable and may thereby serve as a robust structural endpoint. A high rate of progression was observed in childhood-onset disease, making this subtype of STGD1 ideally suited to be considered for prioritization in clinical trials.
Highlights
The age of onset was documented in all subjects and was 9.6 6 3.4 years for childhood-onset (n 1⁄4 71) and 28.3 6 7.8 years for adult-onset STGD1 (n 1⁄4 19); with the presenting symptom in all patients being increased difficulty in seeing
GENETICS: In documented childhood-onset disease (n 1⁄4 71), >_2 likely disease-causing variants were identified in 69 patients; with 4 patients having 3 variants and 2 siblings having 4 variants
The genetic data are summarized in Supplemental Table
Summary
The purpose of this study was to investigate FAF imaging qualitatively and quantitatively over a clinically significant follow-up period in a large, well characterized cohort of children with genetically confirmed STGD1, and to explore potential correlations of progression rate with age of disease onset, disease duration, genotype, and baseline area of atrophy and electrophysiological group
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