ABCA4 and severe early-childhood-onset retinal dystrophy: Entities discussed in this manuscript include ABCA4-associated IRDs, such as cone-rod dystrophy (CORD3), Stargardt disease type 1 (STGD1) and retinitis pigmentosa (RP; RP19), as well as CACNA1F-associated incomplete congenital stationary night blindness (iCSNB; CSNB2A), IMPG1-associated vitelliform macular dystrophy (VMD4) and RP (RP91), HK1-associated RP (RP79) and MYO7A-associated Usher syndrome (USH1B).