DJ-I is an antioxidant protein whose loss of function by gene mutations has been linked to familial Parkinson's disease (PD). The main objective of the present study was to determine if this molecule was also involved in the pathogenesis of sporadic PD. For this purpose, quantitative immunoblot assays were performed to evaluate DJ-1 in cerebrospinal fluids (CSF) collected from sporadic PD patients (n = 40) and non-PD controls (n = 38). The results showed that the CSF DJ-1 levels in PD were significantly higher than those in non-PD controls. Especially, upregulation of CSF DJ-1 in the early stage of PD (Yahr I-II) were distinct compared to those in the advanced stage of PD (Yahr III-IV) and non-PD controls (p < 0.001 by ANOVA with post hoc Bonferroni's test), suggesting a protective role of DJ-1 against oxidative stress during the early stage. Thus, we propose that CSF DJ-1 could be a possible biomarker for early sporadic PD. (c) 2006 Elsevier Inc. All rights reserved.