ABCA4 and Stargardt disease: Stargardt disease (STGD1, OMIM# 248200), also known as fundus flavimaculatus or ABCA4-retinopathy, is the most frequent retinal dystrophy caused by a single gene, characterized by a progressive degeneration of the retinal pigment epithelium (RPE) and photoreceptors [1,2,3].