PARP9 and systemic sclerosis: Global hypomethylation of type I IFN signaling pathway-associated genes, including interferon induced protein 44 like (IFI44L), interferon induced transmembrane protein 1 (IFITM1), MX dynamin like GTPase 1 (MX1), and poly (ADP-ribose) polymerase 9 (PARP9), has been found in CD8+ T cells of SSc patients, which may contribute to the pathogenesis of SSc (127) (Table 2).