In the current research, a large number of bioinformatic analysis tools have been used to identify five hub genes (TRIM22, IFI6, IFITM1, IFI35, and IRF9) between PM/DM and health control subjects on the basis of gene expression profiles attained from GSE1551 (DM), GSE3112 (PM), GSE39454 (DM), GSE39454 (PM), GSE46239 (DM), GSE128470 (DM), and GSE128470 (PM) datasets. The gene discussed is IRF9; the disease is dermatomyositis.