1. Department of Pediatrics, Zhujiang Hospital, Southern Medical University, Guangzhou, Guangdong 510515, P.R.�China
2. Department of Hematology, The First Affiliated Hospital of Jishou University, Jishou, Hunan�416000, P.R.�China
3. Department of Pediatrics, Boai Hospital of Zhongshan City, Zhongshan, Guangdong 528400, P.R.�China
4. Department of Pediatrics, Zhujiang Hospital, Southern Medical University, Guangzhou, Guangdong 510515, P.R. China