Response to: "Myositis-specific autoantibodies as relevant adjusting variables in myositis research" by Pinal Fernandez et al. Correspondence on "From diagnosis to prognosis: Revisiting the meaning of muscle ISG15 overexpression in juvenile inflammatory myopathies".

We thank Drs Pinal-Fernandez and Mammen for their constructive comments on our article (1). We also thank them about their remark related to the correlations between muscle levels of ISG15 and muscle involvement. We fully agree that an accurate classification of Juvenile Idiopathic Inflammatory Myositis (JIIM), including MSA screening is of utmost importance (2). In Juvenile Dermatomyositis (JDM), it is also now demonstrated that the global "type 1 interferon (IFN-I) signature" in blood associates with disease severity, including the degree of muscle weakness (3).