TLR9 is overexpressed in brain regions such as substantia nigra and putamen from PD patients (Ros-Bernal et al., 2011), in striatum of a PD mouse model (Ros-Bernal et al., 2011), and in the spinal cord in an ALS mouse model (Letiembre et al., 2009). This evidence concerns the gene TLR9 and Parkinson disease.