Interleukin-21 gene polymorphisms and chronic hepatitis B infection in a Chinese population

To investigate the relationship between interleukin-21 (IL21) gene polymorphisms and chronic hepatitis B virus (HBV) infection in a Chinese population.

In this case-control study, 366 Chinese HBV-infected patients were recruited and divided into hepatocellular carcinoma (HCC; n = 94) and non-HCC (n = 272) groups at The First Affiliated Hospital of Sun Yat-Sen University, from April 2009 to December 2012. In the non-HCC group, the patients were classified into three clinical subsets, 76 patients had chronic hepatitis B, 101 were HBV carriers and 95 patients had HBV-related cirrhosis. Two hundred eight unrelated healthy controls were also included. Genomic DNA was extracted from peripheral blood. Single nucleotide polymorphisms (SNPs) rs13143866, rs2221903, and rs907715 were subsequently genotyped using the SNaPshot SNP technique.

There were no significant differences in allele and genotype frequencies of SNPs rs13143866, rs2221903, and rs907715 between chronic HBV-infected patients and control subjects. Furthermore, no significant differences were found in the frequencies of all alleles and genotypes between the HCC group and the non-HCC group. However, in the subgroup analysis, IL21 rs13143866 genotype AA frequency in the HBV carrier group was higher than in controls (OR = 6.280, 95%CI: 1.238-31.854; P = 0.019), and the effect of the recessive model (AA vs GG + GA, OR = 6.505, 95%CI: 1.289-32.828) was observed in the HBV carrier group. IL21 rs2221903 genotype TC frequency in the HBV carrier group was higher than in controls (OR = 1.809, 95%CI: 1.043-3.139; P = 0.035). In the haplotype analysis, the ATA haplotype (rs13143866, rs2221903, and rs907715) of IL21 was more frequent in the HCC group than in the non-HCC group (0.165 vs 0.104, P = 0.044; OR = 1.700, 95%CI: 1.010-2.863).

Genotypes rs13143866 AA and rs2221903 TC are risk factors for carrying HBV; ATA haplotype increases the risk of HBV-related HCC onset in a Chinese population.