Niemann-Pick type C (NPC) disease is a fatal neurodegenerative disorder characterized by the accumulation of unesterified cholesterol in the late endosomal/lysosomal compartments. Mutations in the NPC1 protein are implicated in 95% of patients with NPC disease. The most prevalent mutation is the missense mutation I1061T that occurs in approximately 15–20% of disease alleles. In this study, we have performed an isobaric labeling based quantitative analysis of proteome of NPC1-I1061T versus wild-type primary fibroblasts.