ABCA4 and blindness (disorder): The bisretinoids of RPE lipofuscin are considered to lead to retinal degeneration in early onset blinding disorders associated with mutations in the genes encoding ATP-binding cassette sub-family A member 4 (ABCA4) [23,24], and have been implicated in retinal disease caused by mutations in elongation of very long chain fatty acids-4 (ELOVL4) [25].