1 *Division of Paediatric Gastroenterology and Hepatology, Dr. von Hauner Children's Hospital, Ludwig-Maximilian University Munich, München, Germany †Department of Medical Translational Sciences and European Laboratory for the Investigation of Food-Induced Diseases, University Federico II, Naples, Italy ‡Department of Paediatrics, University Medical Center, Maribor, Slovenia §Department of Paediatric Gastroenterology, Royal Hospital for Sick Children, Edinburgh, Scotland. ||University of Debrecen, Medical and Health Science Center, Debrecen ¶Heim Pál Children's Hospital, Budapest, Hungary #Paediatric Research Centre, University of Tampere **Tampere University Hospital, Tampere, Finland ††Department of Pediatrics, Leiden University Medical Center, Leiden, The Netherlands ‡‡University of Medicine and Pharmacy Carol Davila, National Institute for Mother and Child Health "Alessandrescu-Rusescu", Bucharest, Romania §§Department of Pediatric Gastroenterology, La Fe University Hospital, Valencia, Spain ||||Schneider Children's Medical Center of Israel, Sackler Faculty of Medicine, Tel-Aviv University, Petach-Tikva, Israel ¶¶Paediatric Department, Ostfold Hospital Trust, Fredrikstad, Norway ##Hospital, Arnhem, the Netherlands ***Department for General Paediatrics and Neonatology, Justus-Liebig University, Gießen, Germany †††Hans Christian Andersen Children's Hospital, Odense University Hospital, Odense, Denmark.