DNMT1 and rheumatoid arthritis: Meanwhile, mRNA expression levels of DNA methyltransferases (DNMT1, DNMT3A, and DNMT3B) were similar between OA and RA samples, which is consistent with a previous report (ref. 37 and Supplemental Figure 5A), and suggests that RA-specific aberrant DNA methylation and/or RA heterogeneity of disease severity are dependent on UHRF1 expression level.