We aimed to validate galectin‐9 and CXCL10 as biomarkers for active disease in patients with juvenile DM, to examine their disease specificity in adult patients with DM, adult patients with nonspecific myositis (NSM), and patients with other systemic autoimmune diseases, to assess their potency in predicting flares, and to test the applicability of the biomarkers in minimally invasive dried blood spots, in order to aid broad implementation into clinical practice. This evidence concerns the gene CXCL10 and dermatomyositis.