We determined that the mRNA expression level of DNMT3A, but not that of DNMT1, DNMT3B, LSH or MeCP2, was selectively downregulated in AIBD and DM compared to that in HC and SLE (HC vs. AIBD, P < 0.05; HC vs. DM, P < 0.001) (Fig. 1C and S1A). This evidence concerns the gene DNMT1 and dermatomyositis.