The previous nonsense mutation is present in the population database (GnomAD exomes, number of homozygous alleles = 0) at an exceedingly low frequency (8:627,570 alleles, 0.00001275), the variant affecting the KCNV2 gene, which is associated with retinal cone dystrophy type 3B (610,356; AR). Here, KCNV2 is linked to cone dystrophy with supernormal rod response.