Interestingly, the phenotypic variability among TRPM1 patients seems to be lower than that observed in association with other genes causing hereditary retinal disease, including many RP-causing genes, such as ABCA4 (causing variable phenotypes including Stargardt, cone-rod degeneration, and retinitis pigmentosa) as well as CACNA1F which may cause CSNB but also rod-cone and cone-rod degeneration phenotypes29–31. This evidence concerns the gene ABCA4 and retinitis pigmentosa.