1 Central Diagnostic Laboratory, Maastricht University Medical Center, Maastricht, the Netherlands. Electronic address: jan.damoiseaux@mumc.nl.
2 Muscle Disease Unit. Laboratory of Muscle Stem Cells and Gene Regulation, National Institute of Arthritis and Musculoskeletal and Skin Diseases, National Institutes of Health, Bethesda, United States.
3 Department of Rheumatology, Ghent University Hospital, Ghent, Belgium; Department of Internal Medicine, Ghent University, Ghent, Belgium.
4 Department of Internal Medicine and Clinical Immunology, Sorbonne Université, INSERM, UMR974, Pitié-Salpêtrière University Hospital, Paris, France.