IL-4 gene polymorphisms and their association with atopic asthma and allergic rhinitis in Pakistani patients.

BACKGROUND AND OBJECTIVE Interleukin (IL) 4 is a cytokine that mediates allergic responses. Different single nucleotide polymorphisms (SNPs) can influence the immune response mediated by cytokines. The aim of the present study was to investigate the possible association between IL-4 polymorphisms and allergic rhinitis and atopic asthma. METHODS A total of 214 atopic patients (108 with asthma and 106 with allergic rhinitis) and 120 healthy controls from Pakistan were genotyped for IL-4 SNPs C-589T (rs2243250), T+2979G (rs2227284), and C-33T (rs2070874) using restriction fragment length polymorphism-polymerase chain reaction. Statistical analysis was performed using the statistical software package StatCalc, Epilnfo v.6. RESULTS The SNP rs2243250 was significantly associated with both asthma (P = .004, chi2 = 11.0) and allergic rhinitis (P < .001, chi2 = 20.2), as was T-2979G (P < .001, chi2 = 22.51 for asthma and P < .001, chi2 = 57.6 for allergic rhinitis). The most frequent genotypes in the asthma and allergic rhinitis groups were TT for SNP rs2243250, and GG for SNP rs2227284. rs2070874 was not found to be associated with either of the 2 atopic respiratory diseases analyzed in the Pakistani cohort. CONCLUSIONS rs2243250 and rs2227284 are significantly associated with asthma and allergic rhinitis. The results of this study indicate that in addition to environmental factors, genetic risk factors also play an important role in the development of atopic respiratory diseases.