E Mas1, L Michaud2, J Viala3. 1. Unité de gastroentérologie, hépatologie, nutrition, diabétologie et maladies héréditaires du métabolisme, hôpital des enfants, TSA 70034, 330, avenue de Grande-Bretagne, 31059 Toulouse cedex 9, France; IRSD, université de Toulouse, INSERM, INRA, ENVT, UPS, Toulouse, France. Electronic address: mas.e@chu-toulouse.fr. 2. Division of gastroenterology, hepatology and nutrition, department of paediatrics, faculty of medicine, reference center for chronic and malformative oesophageal diseases, Lille university, children's hospital, 59000 Lille, France. 3. Pediatric gastroenterology department, hopital Robert-Debré, AP-HP, Denis-Diderot faculty, INSERM, 75019 Paris, France.