NPC1 and lysosomal storage disease: Moreover, npc acts as a transport protein on the lysosome membrane, and down-regulation of the gene can cause a gradual accumulation of cholesterol triglycerides, non-metabolic substrates such as proteins, and can result in lysosomal storage disorders; the continuous and vast accumulation of undegraded substrates in the lysosome will eventually lead to cell dysfunction and even death [55].