Increased pro-inflammatory cytokines (including IL-1β, IL-6, TNF, and IFN-γ) have been observed in postmortem brains and cerebrospinal fluid from PD patients (Mogi et al., 1994a, b), moreover, the blood serum of PD patients also showed increased concentration of inflammatory cytokines (including IL-2, IL-6, TNF-α, and IFN-γ; Reale et al., 2009). Here, IFNG is linked to Parkinson disease.