1 Department of Allergology, Rheumatology and Clinical Immunology, University Children's Hospital, University Medical Centre Ljubljana, Ljubljana, Slovenia.
2 Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia.
3 Department of Pediatric Immunology & Rheumatology, Wilhelmina Children's Hospital, University Medical Centre Utrecht, Utrecht, Netherlands.
4 Faculty of Medicine, Utrecht University, Utrecht, Netherlands.
5 Pediatric Rheumatology Unit, Department of Pediatrics, Meir Medical Center, Kfar Saba, Israel.
6 Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel.