ABCA4 and retinitis pigmentosa: The biallelic ABCA4 variants cause a group of ABCA4-related retinopathies, including Stargardt disease (STGD1) [5], cone–rod dystrophy (CRD) [6], retinitis pigmentosa [7], generalized choriocapillaris dystrophy [8], and rapid onset chorioretinopathy [9].