A quantitative proteomic study has revealed dysregulation of a number of proteins in Niemann–Pick disease, type C1 (NPC1). An initial analysis in mouse cerebellar tissue identified 77 proteins that were differentially expressed between Npc1 mutants and controls. Altered expression of three of these proteins—glutathione S-transferase α, superoxide dismutase and FABP3—was confirmed in cerebrospinal fluid from patients with NPC1.