1. Division of Gastroenterology, Department of Paediatrics, Cantons Hospital of Fribourg, Fribourg, Switzerland.
2. Division of Gastroenterology and Nutrition, University Children's Hospital Zurich, Zurich, Switzerland.
3. Division of Gastroenterology, University Children's Hospital of Lausanne, Lausanne, Switzerland.
4. Division of Gastroenterology, Children's Hospital of Lucerne, Lucerne, Switzerland.
5. Division of Gastroenterology, University Children's Hospital of Bern, Bern, Switzerland.
6. Children's Research Center, University Children's Hospital Zurich, Zurich, Switzerland.