Yang H, et al. - In patients with idiopathic inflammatory myopathies (IIMs), experts gauged the associations between anti-nuclear matrix protein 2 (anti–NXP-2) autoantibody levels and disease activity as well as calcinosis severity. In patients with IIMs, anti–NXP-2 autoantibodies serve as a useful marker for disease activity, especially in the absence of calcinosis. There was a probable phenotypic difference between patients with and those without calcinosis; as suggested by the differential associations observed between anti–NXP-2 autoantibody levels and disease activity.