Overall, the frequency of T allele of IL-13 +1923C/T polymorphism was found to be a little higher in asthma patients than that in controls (27.9% compared with 26.2%), and the statistical analysis demonstrated that this allele was significantly related with increased asthma susceptibility (T compared with C: OR=1.44, 95% CI= 1.30–1.60, P<0.00001) as shown in Figure 2. Here, IL13 is linked to asthma.