A previous study demonstrated that the physical and functional interactions between CAIV and NBC maximize transmembrane HCO3− transport in HEK239 cells transfected with NBC1b and CAIV [8], renal proximal tubules [9] and a retinal photoreceptor, which has been detected in an autosomal dominant form of retinitis pigmentosa (the R14W mutation of CAIV) [10]. This evidence concerns the gene CA4 and retinitis pigmentosa.