1. Department of Obstetrics and Gynecology, People's Hospital of Zhengzhou University, Zhengzhou, Henan 450003, P.R. China
2. Henan Medical Genetics Institute, Henan Provincial People's Hospital, Zhengzhou, Henan 450003, P.R. China
3. International Office for Research and Development, Henan Red Cross Blood Center, Zhengzhou, Henan 450000, P.R. China