IL4 and asthma: Moreover, there was a significant association between IL-4 C33T polymorphism and risk of asthma in American population under dominant model (OR = 1.26, 95% CI = 1.05–1.51, P = ≤0.001, FEM), allelic model (OR = 1.17, 95% CI = 1.03–1.33, P = 0.01, FEM), and CT vs. TT model (OR = 1.23, 95% CI = 1.02–1.49, P = 0.03, FEM).