1. Department of Obstetrics and Gynecology, Southwest Hospital, Third Military Medical University, Chongqing 400038, P.R. China
2. Department of Orthopedics, Southwest Hospital, Third Military Medical University, Chongqing 400038, P.R. China
3. Department of Medical Genetics, College of Basic Medical Science, Third Military Medical University, Chongqing 400038, P.R. China
4. Department of Respiratory Medicine, The General Hospital of PLA Rocket Force, Beijing 100088, P.R. China