ABCA4 and retinal degeneration: Moreover, they have an accelerated deposition of lipofuscin and A2E in the RPE, supporting ABCA4's role as a transporter of N-ret-PE across disc membranes.68 The finding that the retinal degeneration in the knockout mouse was accelerated with exposure to significantly bright (ultraviolet) light69, 70 and ingestion of large doses of vitamin A43, 71 has led to patients with STGD1 being advised to avoid excessive exposure to bright sunlight and wear good-quality sunglasses with UVA/UVB blocking properties, and to also avoid vitamin A supplementation.