We analyzed MxA expression using immunohistochemical assessment in 23 muscle biopsies from our cohort (10 patients with DM, 3 with IBM, 3 with PM, 4 with OM and 3 healthy controls), including patients with DM who were negative for RIG-I, to see if the combination of both biomarkers may improve the diagnostic power. Here, MX1 is linked to polymyositis.