DRD2 and Parkinson disease: Knockout mice lacking DRD2 have been found to have remarkable inflammatory responses in multiple central nervous system regions as well as increased neurotoxicity.37 C-reactive protein (CRP) which is a biomarker of inflammation is associated with the risk of death and predicted prognosis of patients with PD, also suggesting the possibility that chronic inflammation is associated with a neurodegenerative process in PD.38 Inflammation may play an important role of PD.