OBJECTIVETo assess the association of interferon gamma gene (IFNγ ) tag single nucleotide polymorphisms (Tag SNPs) with hepatitis B virus (HBV) infection in ethnic Dai and Hani minorities from Xishuangbanna, Yunnan.

METHODSPeripheral blood samples were collected from 300 Dai minorities and 300 Hani minorities, each included 100 healthy controls and 200 HBV infected individuals (including 100 spontaneous recovery subjects and 100 chronic HBV infected patients). Matrix-Assisted Laser Desorption/Ionization Time of Flight Mass Spectrometry (MALDITOF-MS) was used to determine the Tag SNPs of IFNγ gene. Haplotypes were constructed.

RESULTSIn Hani and Dai minorities, the frequencies of rs1861494 CC genotype in HBV infected group was significantly higher than the healthy group (Dai: χ2=10.017, P=0.001; Hani: χ2=6.515, P=0.039), and there was a significant difference between the HBV infected group and the control group under the C allele recessive mode (CC/TC+TT) (Dai: P=0.035, OR=9.567, 95%CI: 1.166-78.499; Hani: P=0.027, OR=5.484, 95%CI: 1.216-24.726). In Dai minorities, the frequencies of rs2069705 CC genotype and C allele in chronic HBV infected group was significantly higher than the spontaneous recovery group (genotype: χ2=8.112, P=0.017; allele: χ2=4.066, P=0.044), and there was a significant difference between chronic HBV infected group and spontaneous recovery group under the C allele recessive mode (CC/CT+TT) (P=0.013, OR=0.341, 95%CI: 0.146-0.796).

CONCLUSIONAbove results suggested that the rs1861494 CC genotype of the IFNγ gene has conferred an increased risk for HBV susceptibility in both Dai and Hani minorities. In addition, the rs2069705 CC genotype may be a risky factor for Dai minorities to develop chronic HBV infection.