Association of Promoter Polymorphisms of Interleukin-10 and Interferon-Gamma Genes with Tuberculosis in Azeri Population of Iran

Abstract

Promoter polymorphism of cytokine genes may lead to inter-individual differences in cytokine levels, therefore, polymorphisms may associate with susceptibility to infectious diseases. In this study, we investigated a possible association between interleukin-10 (IL-10) 1082A/G (rs1800896) and interferon (IFN)-gamma +874T/A (rs2430561) promoter polymorphisms and tuberculosis (TB) in the Azeri population of Iran. IL-10 -1082G/A and IFN-gamma +874T/A single nucleotide polymorphisms (SNPs) were genotyped by amplification refractory mutation system (ARMS)-PCR in 200 healthy controls and 124 tuberculosis patients. IL-10 -1082 A allele was more frequent in the control group than in the patient group (p=0.001, odds ratio [OR]=2.183). On the other hand, the AA genotype was significantly more frequent in the control group (p=0.0001). The frequency of IFN-gamma +874 T allele was significantly higher in the controls (p=0.013, OR=1.56). There was no significant association between IFN-gamma +874 T/A genotypes and susceptibility to tuberculosis (p=0.078), but TT genotype was more frequent in the control group. Our findings suggest that interleukin-10 -1082G/A polymorphism may play an important role in susceptibility to tuberculosis in our population. On the other hand, the +874T allele, which has been suggested to be associated with high IFN-gamma levels, was significantly higher in the controls and TT genotype was also more frequent in the control group. Thus, +874 T allele may be associated with resistance to tuberculosis in this Azeri population of Iran.