ABCA4 and severe early-childhood-onset retinal dystrophy: Stargardt macular dystrophy is the most common form of juvenile macular degeneration.1, 2 It is an autosomal recessively inherited disorder caused by disease-causing variants in the ABCA4 gene, encoding a photoreceptor-specific ATP-binding cassette transporter involved in active transport of all-trans-retinal across the disc membranes within photoreceptor outer segments.3