Abstract
Purpose: :
To describe the phenotype and genotype of patients with late-onset Stargardt disease (STGD1).
Methods: :
Ophthalmologic examination, including best-corrected visual acuity (VA), Amsler grid testing, fundus photography, fluorescein angiography (FA), spectral-domain optical coherence tomography (OCT), fundus autofluorescence imaging (FAF), full field electroretinography (ERG), multifocal ERG and Humphrey 30-2 central visual field testing. Microarray analysis, full sequencing and Multiplex Ligation-dependent Probe Amplification (MLPA) were used for ABCA4 gene analysis. In addition, mutations in the PRPH2 (RDS) gene and the CFH gene were excluded.
Results: :
The mean age at onset was 55 years (range: 45 - 72 years). A preserved visual acuity of ≥ 20/25 OU was found in 16 eyes (42%). Vision loss at presentation was a predictor for poor visual outcome. A "dark choroid" on fluorescein angiography was observed in 14 patients (74%). Choroidal neovascularization occurred in one patient. A fundus flavimaculatus phenotype was seen in 16 patients (84%), and three patients had a central Stargardt disease phenotype without flavimaculatus flecks. Eight patients (42%) carried two ABCA4 gene mutations, whereas only one ABCA4 mutation was found in the other patients.
Conclusions: :
Late-onset STGD1 is a mild phenotype associated with mutations in the ABCA4 gene. Confusion with other macular phenotypes such as age-related macular degeneration is possible, due to the late age at onset and overlapping phenotypic characteristics. Based on studies on abca4 knockout mice, present counseling should advice patients to avoid excessive light exposure and excessive dietary intake of vitamin A.
Keywords: macula/fovea • retina • genetics