The interleukin 6 receptor alpha gene polymorphisms are associated with clinical manifestations of systemic lupus erythematosus in Koreans.

Abstract

The human interleukin 6 receptor consists of two membrane-bound glycoproteins (IL-6Rα, IL-6RA and gp130/IL-6Rβ, IL-6RB) interacting with IL-6, which is a multifunctional cytokine essential to the regulation of the immune response and acute-phase reactions. We have genotyped a single-nucleotide polymorphism (SNP) of the IL-6RA in Korean patients with systemic lupus erythematosus (SLE) (n = 300) and normal controls (NC, n = 299). Three SNPs were identified in the IL-6RA gene; -208 G ≥ A (NM_000565.3:c.-208G ≥ A, rs4845617) in the promoter region, 48841 T ≥ A (NM_000565.3:c.1067-17T ≥ A, rs4845374) in the intron 8 region and 48864 A ≥ C (NM_000565.3:c.1073A ≥ C, rs2228145) in the exon 9 region. There were no differences between the SLE and the NC in the genotype and haplotype frequencies. The 48864 A>C polymorphism was significantly associated with rash (P = 0.008). Also, the frequency of rash (P = 0.037), leucopenia (P = 0.033) and lymphopenia (P = 0.027) was significantly higher in patients with SLE having the haplotype HT2 [ATC]. These data suggest that genetic polymorphisms of IL-6RA gene may be associated with disease phenotypes of SLE in Korean.