MX1 and dermatomyositis: Activation of the type I interferon (IFN-I) pathway is thought to be an important feature of the pathogenesis of DM, since increased IFN-stimulated gene (ISG) expression has been demonstrated in muscle, blood and skin tissue and the presence of IFN-I-inducible myxovirus resistance protein A (MxA) was detected in perifascicular myofibers in muscle biopsies [4–7].