In conclusion, our findings provide evidence that metabolic homeostasis is disrupted in IIM patients compared with age and gender-matched HCs; in addition, combinatorial analysis of five to seven metabolites in plasma possibly allows for distinguishing DM, PM, and ASS patients from HCs, between different subtypes of IIM patients, and even MDA5 + and MDA5- DM patients. Here, IFIH1 is linked to acquired idiopathic inflammatory myopathy.