ABCA4 and severe early-childhood-onset retinal dystrophy: Stargardt disease (STGD1; MIM 248200) is the most common inherited macular dystrophy in both adults and children with a prevalence of 1 in 8000–10 000.1–7 STGD1 has an autosomal recessive mode of inheritance associated with disease-causing mutations in the ABCA4 gene.8–11 It is both clinically and genetically highly heterogeneous.5–7, 12–17