ABCA4 and Stargardt disease: Stargardt's disease is caused by mutation in the phospholipid floppase gene ABCA4, which is required of removal of all-trans retinal-PE complexes (Molday et al., 2009; Tsybovsky et al., 2010); thus, loss of atp11a may result in the decreased availability of PE on the inner membrane leaflet, decreasing the ability to remove all-trans retinal through Abca4.