1 Harvard Medical School, Boston, United States; MassGeneral Hospital for Children, Division of Pediatric Gastroenterology and Nutrition, Boston, United States; MassGeneral Hospital for Children, Department of Pediatrics, Basic, Clinical and Translational Research, Boston, United States; Massachusetts General Hospital, Center for Celiac Research and Treatment, Charlestown, United States; Massachusetts General Hospital, Mucosal Immunology and Biology Research Center, Charlestown, United States. Electronic address: afasano@mgh.harvard.edu.