For the purpose of clearing the insult, pro-inflammatory cytokines, including interleukin (IL)-1β, IL-6 and tumor necrosis factor (TNF)-α, are locally produced and is linked to connective tissue destruction resulting from host matrix metalloproteinase activation; however, cytokines including IL-1β, IL-6 and TNF-α, in addition to the arachidonic acid metabolite prostaglandin E2, are strongly related to periodontal diseases’ onset and progression (31). The gene discussed is TNF; the disease is periodontal disorder.