Association of IRF5 gene single nucleotide polymorphism with systemic lupus erythematosus susceptibility in Iranian population

Background: Systemic lupus erythematous (SLE) is an autoimmune disease characterized by autoantibody production, immune complex deposition, and involvement of the type I interferon (IFN) pathway. Interferon regulatory factor 5 (IRF5) is a transcription factor that regulates the transactivation of type I IFN system-related genes. The association of IRF5 gene single nucleotide polymorphisms (SNP) with SLE has been reported in different populations. The aim of this study was to investigate the association of IRF5 gene rs2004640 SNP with SLE susceptibility in Iranian population. Methods and results: Genomic DNA was isolated from the peripheral blood leukocytes of 492 patients and 468 healthy individuals using the phenol-chloroform method. The TaqMan allelic discrimination Real-Time PCR method was applied to genotype rs2004640. The frequency of the rs2004640 T allele was significantly higher in SLE patients compared with healthy individuals. Among the rs2004640 genotypes of IRF5 gene, GT and TT genotypes were significantly associated with risk of SLE. Considering the dominant model of TT+GT, the disease risk was elevated significantly. No significant association was observed between rs2004640 genotypes and clinical features. Conclusion: These results confirm that rs2004640 T allele as well as TT and GT genotypes are associated with SLE and seem to significantly increase susceptibility to the disease in Iranian population, as they had associations with SLE proneness in other populations.