Naive CD4+ T cells are activated after interaction with antigen–major histocompatibility complex to differentiate into specific subtypes, such as Th1, Th2, Th17, and regulatory T (Treg) cells during T cell receptor (TCR) activation in a particular cytokine milieu, which are involved in autoimmunity and produce proinflammatory cytokines such as IFN-γ, IL-4, IL-17, and TGF-β, respectively [30, 31]. The gene discussed is IL4; the disease is Autoimmunity.