Various studies have shown that Th type 1 (Th1)-related cytokines (interleukin [IL]-12 and IFN-γ), Th type 2 (Th2)-related cytokines (IL-4, IL-5, and IL-13), and proinflammatory cytokines (IL-1β, IL-6, and TNF-α) are associated with asthma. This evidence concerns the gene IL4 and asthma.