NPC1 and neurodegenerative disease: In Niemann–Pick type C, in addition to the dysregulation of proteins involved in NPC1 and NPC2 disease, the accumulation of some proteins upregulated in various neurodegenerative diseases, such as hyperphosphorylated tau protein, α-synuclein, and TDP-43, has also been noted, which is why it is called a proteinopathy [11,12,13,14].