PDE6D and retinitis pigmentosa 1: RPGRIP, RANBP2, NPM1, PDE6D, and NPHP5 were selected on the basis of protein interaction with RPGR or RPGRIP1 as these two proteins independently cause photoreceptor degeneration when mutated; ABCA4 was selected as a control gene, and because of its association with macular degeneration and RP [36,37].