PNPLA6 and retinal degeneration: Loss of PNPLA6 activity, due to pathogenic variants, disrupts choline metabolism and triggers retinal degeneration via two key pathways: 1 Accumulation of PC and LPC in RPE cells, coupled with reduced choline, impairs proliferation, adhesion, phagocytosis, and mitochondrial dysfunction; 2 Disrupted choline secretion from RPE to photoreceptors leads to structural and functional impairment of photoreceptors due to choline deficiency.