Association between interferon-gamma (IFN-γ) gene polymorphisms (+874A/T and+2109A/G), and susceptibility to hepatitis B viral infection (HBV)

Background: Interferon-gamma (IFN-gamma) is a chief proinflammatory cytokine with a significant role in the immune response against viral infections. Today there is increasing evidence about the association between individual genetic polymorphisms and cytokines in predicting HBV infection susceptibility. Aim: This study aimed to investigate the association between IFN-gamma gene polymorphisms and susceptibility to hepatitis B viral infection (HBV), and the impact of these genetic polymorphisms on IFN-gamma production. IFN-gamma (+874A/T, rs2430561, and +2109A/G, rs1861494) was genotyped by single-stranded polymorphism-polymerase chain reaction (SSP-PCR) in 126 Egyptians with chronic HBV infection and in 100 healthy control subjects. The plasma levels of IFN-gamma were measured by Enzyme-linked immunosorbent assay (ELISA). Results: Compared to the control subjects there was a slight increase in +874TT genotype frequency in HBV patients. However, no statistical significance in IFN-gamma (+874A/T and +2109A/G) genotype/allele distribution was demonstrated, indicating the lack of association between these SNPs and susceptibility to HBV infection. In +2109A/G, only AG genotype was observed with a complete abrogation of GG and AA genotypes. Haplotypes between different loci on selected genes showed insignificant changes in their frequency in patients and control subjects. HBV patients had a significantly higher level of IFN-gamma (P < 0.001) compared to controls. The maximum significant increase in IFN-gamma production was observed in subjects harboring the +874TA genotype. Conclusions: As no association could be characterized between the polymorphism in IFN-gamma (+874A/T and +2109A/G) and susceptibility to chronic HBV infection, our data support the concept that IFN-gamma gene polymorphisms are not predictors of HBV susceptibility in this segment of the Egyptian population.