1. Department of Clinical Genetics, VU University Medical Center, Amsterdam, The Netherlands.
2. Department of EMGO Institute, VU University Medical Center, Amsterdam, The Netherlands.
3. Department of Paediatrics, Atrium Medical Center, Heerlen, The Netherlands.
4. Department of Pulmonology, Haga Hospital, The Hague, The Netherlands.
5. Department of Paediatric Gastroenterology and Nutrition, Hôpital Robert Debré, Paris, France.
6. Service de Génétique Médicale, CHU Pellegrin, Bordeaux, France.
7. Paediatric Respiratory Medicine, Hospital for Sick Children, Toronto, Canada.
8. Department of Paediatrics, Heinrich Heine University, Düsseldorf, Germany.