Department of Paediatrics, The Medical University of Warsaw, Warsaw, Poland. Institute of Gastroenterology, Nutrition and Liver Diseases, Schneider Children's Medical Center of Israel, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel. Department of Clinical Sciences, Pediatrics, Umeå University, Umeå, Sweden. Department of Translation Medical Science, Pediatric Section European Laboratory for the Investigation of Food Induced Disease (ELFID), University Federico II, Naples, Italy. Dr. von Hauner Children's Hospital, Department of Pediatrics, University Hospital, LMU Munich, Munich, Germany. School of Medicine Collegium Medicum, Department of Pediatrics, Gastroenterology and Nutrition, University of Warmia and Mazury, Olsztyn, Poland. Department of Pediatrics, Faculty of Medicine and Clinical Center, University of Debrecen, Debrecen, Hungary. Celiac Disease Center, Heim Pál National Paediatric Institute, Budapest, Hungary. Willem Alexander Children's Hospital, Leiden University Medical Center, Leiden, The Netherlands. Pediatric Gastroenterology and Hepatology & Instituto de Investigacion Sanitaria, La Fe University Hospital, Valencia, Spain.