Investigation of rs531564 Polymorphism in the Primary MicroRNA-124 Gene in Patients with Systemic Lupus Erythematosus and Rheumatoid Arthritis: Association with Disease Susceptibility and Clinical Characteristics.

MicroRNA-124 (miR-124) is known as an important regulator of the immune system and inflammatory response. Studies have reported that this miRNA is dysregulated in autoimmune disorders such as systemic lupus erythematosus (SLE) and rheumatoid arthritis (RA). A functional analysis demonstrated that rs531564 (C>G) affects the biogenesis of primary microRNA transcript-124 (pri-miR-124) and changes the expression of mature miR-124. In the present study, for the first time, we intended to evaluate the possible association between rs531564 polymorphism with SLE and RA risk.  In this case-control study, 110 patients with SLE, 115 patients with RA, and 120 healthy subjects were enrolled to evaluate rs531564 genotypes with real-time polymerase chain reaction (PCR) high resolution melting method. Our findings demonstrated that frequency of GC genotype and G allele were considerably higher in the control group than RA patients, demonstrating that that GC genotype and G allele have a protective effect for healthy individuals (GC vs CC; OR: 0.29; 95%CI [0.12,0.67] and G vs C; OR: 0.42; 95%CI [0.23,0.78]). However, no significant correlation was confirmed between allele and genotype frequencies of rs531564 with SLE risk (p>0.05). However, the G allele in rs531564 polymorphism was associated with serum level of C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), anti-dsDNA antibody, C3, C4, and creatinine, and frequency of renal involvements in SLE patients (p<0.05). Moreover, in RA patients, the G was correlated with lower concentration ESR and CRP (p<0.001).  Our findings propose a considerable association between rs531564 polymorphism in the pri-miR-124 gene with susceptibility and clinical characteristics of RA and SLE in the Iranian population.