Polymorphisms in the IL-4 and IL-4R [α] genes and allergic asthma

Allergic asthma is caused by genetic and environmental factors that interact to determine disease susceptibility and severity. Several lines of evidence suggest that the interleukin (IL)-4 gene and the IL-4-receptor alpha (IL-4Ralpha) gene are involved in the development of atopic diseases. We sought to determine whether two polymorphism sites in IL-4 and IL-4Ralpha chain were associated with allergic asthma in a Chinese population. We obtained DNA and clinical data from allergic asthma patients, which were compared with those of a group of healthy control subjects. The subjects were genotyped for the IL-4 C-590T promoter polymorphism and the IL-4R alpha chain Q576R by polymerase chain reaction-restriction fragment length polymorphism. The results showed that the IL-4 C-590T was not associated with allergic asthma in a Chinese population. However, the IL-4R alpha chain 576R/R was significantly increased in allergic asthma patients compared with control subjects (chi(2)=21.16; p<0.01), and also total plasma immunoglobulin E (IgE) level was increased in allergic asthma patients. These data suggest that the IL-4R alpha chain 576R/R genotypes confer genetic susceptibility to allergic asthma in Chinese.