ABCA4 and severe early-childhood-onset retinal dystrophy: ABCA4 pathogenic variants cause several retinal autosomal recessive disorders, including Stargardt disease (STGD1, OMIM #248200) [1,2,3,4,5,6,7], cone-rod dystrophy (CORD3, OMIM #604116) [8,9,10], and retinitis pigmentosa (RP19, OMIM #601718) [8,10,11].