Association of Interleukin 13 +2044G/A Polymorphism with Bronchial Asthma Development, Severity and Immunoglobulin E levels in an Egyptian Population

Background : Asthma is a chronic, inflammatory disease of the respiratory tract, which is characterized by bronchial hyperreactivity and respiratory obstruction in which many cells and cellular elements play a role. Interleukin 13 (IL-13) is a type 2 helper T cells (Th2) cytokine that has been shown to be pivotal in the induction of allergic inflammation of the airways. Moreover, Several IL-13 genetic polymorphisms have been linked with susceptibility to bronchial asthma. Aim : The aim of this study was to evaluate the association of IL-13 + 2044G/A polymorphism with bronchial asthma development, severity and total serum immunoglobulin E (IgE) levels in Egyptian patients with bronchial asthma. Subjects and methods : This study included 50 asthmatic patients and 30 controls. Restriction Fragment Length Polymorphism (RFLP) PCR was used for the analysis of the studied polymorphism. Also, the serum was analyzed for total IgE levels by enzyme-linked immunosorbent assay (ELISA). Results : The frequency of the A allele was significantly higher in asthmatic patients as compared to control subjects. On the contrary, the G allele was less frequent in the asthmatic patients as compared to control subjects. In addition the A allele was more frequent in severe asthmatic patients and on the other hand the G allele was less frequent in severe asthmatic patients. Moreover, the presence of the A allele was significantly associated with higher total serum IgE levels whether in homozygous or heterozygous state. Conclusions : The results showed that the IL-13 +2044 A allele is a risk factor for bronchial asthma. There is a significant association between the A allele and more severe asthma, however the G allele is significantly associated with less severe asthma. In addition, the A allele is significantly associated with higher total serum IgE levels.