Association of interleukin-1 receptor antagonist gene 86bp VNTR polymorphism with systemic lupus erythematosus in South East of Iran

ABSTRACT

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. 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. 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. 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