(A) Plasma sGpnmb levels were assayed by ELISA in plasma of Npc1+/+ (WT), Npc1+/nih (HET) and Npc1nih/nih (KO) mice at the age of 20–23, 40–43, 60–63 and 84–90 days. Data (n = 3–6, mean ± S.E.M.) were analysed using a two-way ANOVA: * P < 0.05, ** P < 0.01 and *** P < 0.001 from Npc1+/+. (B) Plasma levels of sGpnmb in Npc1+/+ (WT) and Npc1nmf164 mice at 110 days of age. Data (n = 3–5, mean ± S.E.M.) were analysed using an unpaired t-test: ** P < 0.01. (C) Plasma levels of sGpnmb in healthy volunteers (n = 9), carriers of one known mutation on the Npc1 gene (n = 8) and confirmed NPC patients (n = 17) detected by ELISA, were analysed using the Matt-Whitney u test: * P < 0.05.