ISG15 and dermatomyositis: Marginal ISG expression was observed in muscle biopsies using RNA sequencing (e.g. 1.8 vs 101-fold increase of ISG15 in IMNM vs DM, respectively) and normal Siglec-1 expression was detected in whole blood samples of IMNM patients (n = 8, including juvenile patients and analyses of samples beyond 3 months since diagnosis) [6, 17].