Tumor necrosis factor-alpha (TNF-α), a multifunctional proinflammatory cytokine, plays an essential role in the host immune response to hepatitis B virus (HBV). The aim of this study was to examine the relationship between single-nucleotide polymorphism (SNP) in the TNF-308 gene locus promoter and the susceptibility to chronic HBV infection. Materials and Methods: In this case-control study, genomic DNA was extracted from peripheral blood samples of 119 chronically HBV infected patients

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... to Tehran Taleghani hospital and 111 healthy controls using the phenol-chloroform method. Afterwards, genotyping was performed by the ARMS-PCR method. Data were analyzed using the Chi-square test. Results: The frequencies of TNF-α genotypes (GG and GA) 308 on locus were 84.9%, 15.1% and 80.2%, 19.8% in the case and control groups, respectively. No AA genotype was seen in both groups. Moreover, no significant difference was found between the case and control groups. Conclusion: The genetic capacity for cytokine production in individuals has a major effect on their immune system response. Several SNPs have been identified in the human TNF-α gene promoter; the polymorphism at 308 locus, which involves substituting guanine (G) for adenine (A), has been linked to an increased susceptibility to several chronic inflammatory diseases. However, the results of this study indicate that there is no relation between the TNF-α-308 locus SNP and susceptibility to chronic HBV infection in Iranian population.