ABCA4 and cone dystrophy: Interestingly, virtually all these variants occurred as single alleles, indicating that they are an uncommon cause of ABCA4R in our population.While ABCA4R are associated with extensive phenotypic variability, the most common clinical categories are STGD1, cone dystrophy, and retinitis pigmentosa (Del Pozo-Valero et al. 2020; Sheffield and Stone 2011; Tracewska et al. 2019).