The serum levels of IL-4 in patients with moderate (1.66±0.06 pg/mL) and severe asthma (1.66 ± 0.10 pg/mL) were significantly higher than that of the healthy controls (1.42 ± 0.04 pg/mL; P <0.004 and P <0.02, respectively). The gene discussed is IL4; the disease is asthma.