1. Department of Epidemiology, Capital Institute of Paediatrics, Beijing, P.R. China.
2. Centre de Recherche de l'Institut Universitaire de Cardiologie & Pneumologie de Québec (CRIUCPQ), Université Laval, Québec, Canada.
3. Key Laboratory of Endocrinology, Department of Endocrinology, Ministry of Health, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College (CAMS & PUMC), Beijing, P.R. China.