1 Department of Pharmacy, Beijing Friendship Hospital, Capital Medical University, Beijing, China.
2 Harvard Celiac Disease Research Program, Division of Gastroenterology, Hepatology & Nutrition, Boston Children's Hospital, Boston, MA, USA.
3 Department of Medicine, Duke University School of Medicine, Durham, NC, USA.
4 Department of Epidemiology, University of North Carolina Gillings School of Global Public Health, Chapel Hill, NC, USA.
5 Department of Epidemiology and Biostatistics, School of Public Health, Peking University, Beijing, China.
6 Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina at Chapel Hill, 2101 McGavran-Greenberg Hall, Campus Box 7453, 27599 Chapel Hill, NC 27515, USA.