Contrary to the beneficial housekeeping role of resting and slightly activated microglia, activated microglia located in the SNpc are involved in PD pathogenesis [17] and are a chronic source of various pro-inflammatory cytokines such as interleukin (IL)-1β, tumor necrosis factor (TNF)-α, IL-6, and reactive oxygen species (ROS) [19,20], which induce progressive neuronal damage. The gene discussed is TNF; the disease is Parkinson disease.