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Background Traditionally, the diagnosis and monitoring of disease activity in systemic lupus erythematosus (SLE) are contingent upon clinical manifestations and serological markers. However, researchers are struggling to find biomarkers with higher sensitivity and specificity. DNA methylation has been the most studied epigenetic feature in SLE. So, in this study, we performed a systematic review of studies about DNA methylation alterations in SLE patients compared to healthy controls. Methods By searching PubMed, Scopus, and Google Scholar up to July 2022, all case-control studies in which DNA methylation of specific genes was assessed by a non-high-throughput technique and passed the quality of bias assessment were included. Results In total, 44 eligible studies underwent a data extraction process. In all, 3471 SLE patients and 1028 healthy individuals were included. Among the studies that reported the patients’ gender ( n = 2853), 89.41% were female and 10.59% were male. Forty studies have been conducted on adult patients. The number of works on fractionated and unfractionated blood cells was almost equal. In this regard, 22 studies were conducted on whole blood or peripheral blood mononuclear cells and two studies on unfractionated white blood cells. Sorted blood cells were biological sources in 20 studies. The most investigated gene was IFI44L. Sensitivity, specificity, and diagnostic power of methylation levels were only reported for IFI44L in five studies. The most employed methylation profiling method was bisulfite sequencing polymerase chain reaction. The correlation between methylation patterns and clinical parameters was explored in 22 studies, which of them 16 publications displayed a remarkable association between DNA methylation status and clinical indices. Conclusions The methylation status of some genes especially IFI44L, FOXP3, and MX1 has been suggested as promising SLE biomarkers. However, given the conflicting findings between studies because of potential confounders such as different sample types, methylation profiling methods, and ethnicity as well as shared DNA methylation patterns of SLE and other autoimmune diseases, DNA methylation biomarkers are currently not reliable diagnostic biomarkers and do not represent surrogate markers of SLE disease activity. Future investigations on a larger scale with the discarding of limitations of previous studies would probably lead to a consensus.

Signal transducer and activator of transcription 3 (STAT3) has been introduced as one of the critical genetic factors in the pathogenesis of rheumatoid arthritis (RA). Single nucleotide polymorphisms (SNPs) in microRNA binding sites, known as miRSNPs, are a class of common variants in the 3′ untranslated regions of genes targeted by miRNAs. miRSNPs unbalance gene expression by disrupting the binding regions of microRNAs. In this study, we intended to evaluate the association of two miRSNPs with the risk of RA development and its clinical features. We studied 120 Iranian patients with RA and 125 non-RA subjects as controls. The genotypes and alleles of rs1053005 and rs1053023 in each individual were assessed by the high-resolution melting method. The distribution of STAT3 variants did not differ markedly in RA patients compared to healthy controls. Stratification analysis revealed that rs1053005 was linked with a higher concentration of C-reactive protein and an increased erythrocyte sedimentation rate, two indicators of inflammation and disease activity in RA patients. The rs1053023 variant was correlated with higher levels of creatinine as an indicator of renal involvement. Our data demonstrate an association between STAT3 variants and clinical characteristics of RA, such as disease activity and probably kidney impairment.  However, we did not observe a significant relationship between the two targeted variants and a predisposition to RA.