Th1 and Th2 cytokine gene polymorphisms in two indigenous ethnic groups in Iran

Cytokines are important immunomodulatory molecules in immune responses against microorganisms and also have an important role in the setting of disorders affecting immune system. Cytokine single nucleotide polymorphisms have been extensively studied in different normal populations as well as in relation to diseases. Some of these polymorphisms (SNP) affect cytokine gene transcription and expression. The polymorphisms of cytokine genes are potentially important as genetic predictors of the disease susceptibility and clinical outcome or as a tool for anthropological studies. In this study, samples have been collected from 261 healthy individuals located in two different regions of Iran (Tehran and Yazd). The allele and genotype frequencies of Th1 and Th2 cytokines SNP including interleukin (IL)-2, IL-4, IL-6, IL-10, tumour necrosis factor (TNF)-alpha and interferon (IFN)-gamma have been investigated, using the polymerase chain reaction-sequence-specific primer method. The allele and genotype frequencies in Tehran and Yazd populations were similar except for the IL-2, IL-4, IL-6 and IL-10. The IL-4 C allele, C/C -33 and T/T -1098 genotype were significantly more frequent in Tehran than in Yazd population (P = 0.04, P = 0.004 and P = 0.001, respectively). The G/A genotype of the IL-6 (nt565) and IL-10 (-1082) was significantly less frequent in Tehran than in Yazd population (P = 0.01 and P = 0.003, respectively). The GT haplotype of the IL-2 (-330, +166) was significantly less frequent in Tehran than in Yazd population (P = 0.0002). We have also compared our whole samples with the reported data from other countries showing that Iranian population have cytokine gene polymorphism profile similar to that of Caucasians, especially Italian population.