Different Th cell subtypes secrete various inflammatory cytokines: Th1 cells secrete interferon-γ (IFN-γ), interleukin-2 (IL-2), and tumour necrosis factor-alpha (TNF-α); Th2 cells secrete IL-4 and IL-5; and Th17 cells (present in the autoimmune disease pathophysiology) secrete IL-17 and IL-23 [10]. The gene discussed is IL2; the disease is autoimmune disease.