IL-10, TGF-beta, IL-2, IL-12, and IFN-gamma cytokine gene polymorphisms in asthma.

Asthma is a complex respiratory disease, characterized by airway inflammation and reversible airway obstruction. Both genetic and environmental factors are important in the development and expression of the disease. In order to analyze the genetic profile of Th1 and Th2 cytokines in Iranian asthmatic patients, this study was performed. The allele and genotype frequencies of a number of polymorphic genes coding for IL-10, TGF-beta, IL-2, IL-12, and IFN-gamma were investigated in 60 patients with asthma in comparison with 140 controls. The most frequent genotypes in our patients were IL-10 GA at position-1082 (p = 0.001), IL-10 CT at position -819 (p = 0.001), IL-10 CA at position -592 (p = 0.0001), IL-12 CA at position -1188 (p = 0.003), TGF-beta CG at codon 25 (p = 0.002), IL-2 GT at position -330 (p = 0.004). In contrast, the frequencies of the genotypes IL-10 AA at position -1082 (p = 0.0001) and GG at position -1082 (p = 0.01), IL-10 CC at position -819 (p = 0.001) and TT at position -819 (p = 0.01), TGF-beta TT at codon 10 (p = 0.001), TGF-beta GG at codon 25 (p = 0.005), IL-12 AA at position -1188 (p = 0.004), IL-2 TT at position -330 (p = 0.01) were significantly lower in the patient group. The most frequent haplotypes in the patients were IL-10 GCC (p = 0.008) and ATA (p = 0.0001) at position -1082, -819, -592, and TGF-beta CC (p = 0.036) at codon 10 and codon 25. In contrast, the frequencies of the IL-10 ACC (p = 0.001), TGF-beta TG (p = 0.024), and IL-2 TT (p = 0.001) and GT (p= 0.0001) in the patients were significantly lower than controls. Considering the high frequency of presence of IL-10 ATA haplotype and the IL-2 GT genotype, it seems that the production of IL-10 and IL-2 in the asthmatic patients could be lower than normal subjects.