ABCA4 and Stargardt disease: Biallelic variants in the ATP-binding cassette subfamily A member 4 (ABCA4, MIM 601691) gene give rise to ABCA4-associated retinopathies of which Stargardt disease (STGD1, MIM 248200) is the most common, with an estimated incidence between 1 in 8,000 and 1 in 10,000 [1,2,3,4,5].