But, following brain injury or the beginning of a variety of neurodegenerative diseases such as, trauma, stroke, Alzheimer’s disease, Parkinson’s disease, and multiple sclerosis, microglial cells become stimulated and produce proinflammatory cytokines and neurotoxic materials, including tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), IL-6, IL-12, nitric oxide (NO) [21]. The gene discussed is TNF; the disease is Parkinson disease.