Our data here also explains the striking phenotypic difference between deletion of NCKX1 (and nonsense mutation in the SLC24A1 gene encoding NCKX1 that cause night blindness in humans) leading to 100-fold reduction of rod response amplitudes and severely compromised dim light vision (Vinberg et al., 2015), as compared to deletion of either NCKX2 or NCKX4 in cones leading only to altered kinetics of light responses and light adaptation without affecting cone dark current. The gene discussed is SLC24A4; the disease is night blindness.