Parkinson's disease (PD) is a slowly progressive neurodegenerative disorder 
characterized clinically by bradykinesia, rigidity, tremor, gait dysfunction, 
and postural instability. Several genes have been identified for monogenic 
disorders that variably resemble Parkinson's disease. Here, we focus on PARK7, a 
gene relates to an autosomal recessive form of early-onset Parkinsonism and 
encodes a protein named DJ-1. Though the exact role of DJ-1 needs to be 
elucidated, it is generally thought to be functioned as a molecular chaperone 
and an oxidative sensor (or antioxidative factor). We will review the protective 
role of DJ-1 to prevent dopaminergic neurons in the substantia nigra pars 
compacta (SNpc) from degeneration and how its dysfunction would lead to 
neurodegeneration.