1. Department of Pediatric Gastroenterology, VU Medical Center, Amsterdam, The Netherlands
2. Department of Pediatric Rheumatology, Leiden University Medical Center, Leiden, The Netherlands
3. Department of Rheumatology, Leiden University Medical Center, Leiden, The Netherlands
4. Department of Pediatric Rheumatology, Emma Children's Hospital/Academic Medical Center, Amsterdam, The Netherlands
5. Department of Pediatric Rheumatology, Sophia Children's Hospital Erasmus Medical Center, Rotterdam, The Netherlands
6. Department of Pediatric Rheumatology, Amsterdam Rheumatology and immunology Center, Amsterdam, The Netherlands
7. Department of Medical Microbiology, VU University Medical Center, Amsterdam, The Netherlands