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

Summary The human interleukin 6 receptor consists of two membrane‐bound glycoproteins ( IL ‐6 R α, IL‐6RA and gp130/ IL ‐6 R β, 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 ‐6 RA in K orean patients with systemic lupus erythematosus ( SLE ) ( n  = 300) and normal controls ( NC , n  = 299). Three SNP s were identified in the IL ‐6 RA 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 HT 2 [ ATC ]. These data suggest that genetic polymorphisms of IL ‐6 RA gene may be associated with disease phenotypes of SLE in K orean.