Overall, the results rejected significant association between IL-4 C33T polymorphism and risk of asthma in different age group except for allelic model [adults (OR = 1.14, 95% CI = 1.02–1.26, P = 0.02, FEM), mixed (OR = 1.14, 95% CI = 1.01–1.29, P = 0.03, REM), children (OR = 1.13, 95% CI = 1.04–1.24, P = ≤0.001, FEM)] and recessive model (just in children (OR = 1.18, 95% CI = 1.03–1.35, P = 0.01, REM)) Fig. 3. This evidence concerns the gene IL4 and asthma.