Single-nucleotide polymorphisms of IRF8 gene are associated with systemic lupus erythematosus in Chinese Han population

Interferon regulatory factor 8 (IRF8) has been shown to have diverse roles in the regulation of the immune system. Two recent studies had revealed the association between the single-nucleotide polymorphisms (SNPs; rs11644034 and rs2280381) of IRF8 and systemic lupus erythematosus (SLE) in a multiethnic population. The purpose of this study was to evaluate whether the association could be replicated in a Chinese Han population. Genotypes were determined by a multiplex polymerase chain reaction-ligase detection reaction (PCR-LDR) in 358 patients and 357 geographically matched healthy controls. Significant differences in genotype frequency were found between SLE and control individuals (rs11644034: AA vs. GG, P=0.014, odds ratio (OR)=0.980, 95% confidence internal (CI): 0.964-0.996; rs2280381: CC vs. TT, P=0.005, OR=0.150, 95% CI: 0.033-0.676). Conditional logistic regression analysis showed that the association of rs2280381 remained significant (P adjusted=0.028) after adjustment for rs11644034, but not vice versa (P adjusted=0.361).When stratifying patients with SLE according to clinical subtypes, SNP rs2280381 was found to be associated with low complement in patients with SLE. However, SNP rs11644034 was not found to be associated with SLE clinical subgroups. Analysis of the haplotypes revealed that haplotype G-T and G-C were also significantly associated with SLE (P=0.002 and P=0.012, respectively). Our study indicated that the IRF8 gene polymorphisms might be associated with susceptibility to SLE and with disease-related clinical manifestations in Chinese Han population.