Stargardt Disease: Clinical Features and Genotypes in an Indian Cohort

In this report, we describe the clinical features and spectrum of gene variants of an Indian cohort with Stargardt disease (STGD). We reviewed the medical records of 98 eyes of 49 patients with STGD who underwent colour fundus photography, fundus autofluorescence imaging (FAF), optical coherence tomography (OCT), full-field electroretinography (FFERG) and genetic testing using an NGS panel. Demographic data, clinical features, FAF, OCT, FFERG characteristics, and genotype analysis were the main outcome measures. The median age at onset and presentation was when the patients were 14 years (Range: 5-49 years) and 22 years (Range: 6-55 years) old, respectively. Median BCVA was 0.7 logMAR (Range: 0-1.8 logMAR). Lower BCVA was associated with the presence of flecks outside the arcade, significantly lower central foveal thickness (CFT), reduced scotopic and photopic FFERG response (Type III) and multiple areas of low FAF signal at the posterior pole with a heterogeneous background (Type III). Longer disease duration was associated with Type III FAF signal and Type III ERG response. ABCA4 gene mutation was seen in 44 (> 80%) patients; 1 each had PROM1, CNGB3, and PDE6A/TULP1 variants, and 2 had no known variants. Later onset of the disease was noted in patients with 2 recurrent variants (c.5882G>A and c.859-9T>C) detected in 8 patients each. Most patients reported at a younger age compared to other populations. FAF categories, CFT, and FFERG patterns correlated with disease duration and BCVA.