[Correlation of interleukin-13 gene - 1112c/T polymorphism with asthma and total plasma IgE levels]

To investigate the correlation of - 1112C/T polymorphism of Interleukin-13 (IL-13) gene promoter with asthma and its effect on total plasma IgE levels.

One hundred asthmatic patients (the asthma group) and 100 healthy controls (the control group) were recruited. Polymerase chain reaction/restriction fragment length polymorphism (PCR/RFLP) techniques were used to determine the - 1112 locus polymorphism, and the total plasma IgE levels were determined by ELISA.

There were significant differences in C and T allele frequencies at -1112 locus (chi2 =9.01, P< 0.01), and in the genotype distribution such as CC, CT and TT between the two groups [chi2 =7.19, P < 0.05; OR(TT/CC) =2.99, 95%CI=1.06-8.41 (P<0.05); OR (CT/CC) =2.04, 95%CI=1.09-3.81 (P <0.05); OR(TT/CT) =1.46, 95% CI =0.49-4.37, P >0.05]. Allele T was associated with asthma, OR(T/C) = 2. 03, 95% CI =1.27-3.23 (P <0. 01). In the asthma group, the total plasma IgE levels of the patients with CC, CT and TT genotypes were (204 +/- 89)kU/L, (320 +/- 108)kU/L and (376 +/- 147) kU/L, respectively. While in the control group, the total plasma IgE levels of the subjects with CC, CT and TT genotypes were (96 +/- 34) kU/L, (122 +/- 42) kU/L and (150 +/- 36) kU/L, respectively. In both groups, the total plasma IgE levels in allele T carriers were higher than those in non- allele T carriers, and the total plasma IgE levels in the asthma group were higher than those in the control group with the same genotype.

The - 1112 locus polymorphism of IL-13 gene promoter may be an important candidate gene for asthma Allele T is associated with asthma and increases the total plasma IgE level via enhanced (enhancing) IL-13 gene expression.