Objectives: To investigate serum levels of mitokines GDF15 and FGF21 in JDM patients at diagnosis, before start of immunosuppressive and glucocorticoid treatment, and evaluate possible correlations with clinical and laboratory findings, as well as with IFN-related biomarkers (type I IFN score, CXCL10, CXCL9 and neopterin). This evidence concerns the gene FGF21 and juvenile dermatomyositis.