The pooled OR indicated that IL-4 C33T polymorphism increase risk of asthma across all genotype models including dominant model (OR = 1.15, 95% CI = 1.04–1.26, P = ≤0.001, FEM), recessive model (OR = 1.16, 95% CI = 1.06–1.28, P = ≤0.001, FEM), allelic model (OR = 1.14, 95% CI = 1.07–1.21, P = ≤0.001, FEM), CC vs. TT model (OR = 1.21, 95% CI = 1.02–1.43, P = 0.02, FEM) and CT vs. TT model (OR = 1.10, 95% CI = 1–1.22, P = 0.05, FEM) Fig.2. Here, IL4 is linked to asthma.