Association of Interleukin-1 Receptor Antagonist Gene 86bp VNTR Polymorphism with Systemic Lupus Erythematosus in South East of Iran

Background: Systemic lupus erythematosus (SLE) is an autoimmune disease with unknown etiology. Interleukin-1 receptor antagonist (IL-1Ra) is naturally occurring cytokine that inhibits interleukin-1 (IL-1) activity by binding to the IL-1 receptors without signal transduction. The aim of this study was to investigate the association between IL-1Ra gene 86bp VNTR polymorphism and systemic lupus erythematosus in the South- East of Iran. Materials and Methods: In this case control study, genetic polymorphism was analyzed in 163 SLE patients and 183 healthy controls. Genotyping of IL-1Ra VNTR polymorphism was determined by gel electrophoresis after PCR amplification. Results: IL-1Ra VNTR alleles have different copies of 86bp tandem repeats: allele 1 (four repeats), allele 2 (two repeats), allele 3 (five repeats), allele 4 (three repeats) and allele 5 (six repeats). We found an increased frequency of IL-1Ra allele 4 and 1/4 genotype in SLE patients compared to healthy controls (p=0.001 and p=0.002 respectively). Whereas, the frequency of IL-1Ra allele 3 was higher in controls than SLE patients (p=0.01). There was no any association between the IL-1Ra allele 2 and SLE. We did not observe any association between IL-1Ra polymorphism and SLE manifestations. Conclusion: We concluded that IL-1Ra allele 4 was involved in the pathogenesis of SLE. However, there was no association between the IL-1Ra allele 2 and SLE in South East of Iran.