1. Department of Dermatology Radboud University Medical Centre Nijmegen the Netherlands
2. Department of Dermatology Academic Medical Centre Amsterdam the Netherlands
3. Department of Allergology University Medical Center Groningen the Netherlands
4. Department of Clinical Chemistry Endocrine Laboratory VU University Medical Center Amsterdamthe Netherlands
5. Department of Laboratory Medicine Radboud University Medical Centre Nijmegen the Netherlands
6. Department of Dermatology Ziekenhuis Gelderse Vallei Ede the Netherlands
7. Department of Gastroenterology and Hepatology Radboud University Medical Centre Nijmegen the Netherlands
8. Radboud University Nijmegen the Netherlands