Microglia is one of the major cell types involved in the inflammatory responses in the central nervous system (CNS) that appear to contribute to neuroinflammation, evident from the expression of tumor necrosis factor-α (TNF-α; TNFa), interleukin-1β (IL-1β), and interferon-gamma (IFN-γ) in the midbrain of PD patients which strongly suggest the involvement of immune components in PD pathogenesis. This evidence concerns the gene IFNG and Parkinson disease.