Department of Clinical Hematology, Second Affiliated Hospital of Xi'an Jiaotong University, West Five Road, No. 157, Xi'an, 710004, Shaanxi Province, China. Department of Clinical Hematology, Second Affiliated Hospital of Xi'an Jiaotong University, West Five Road, No. 157, Xi'an, 710004, Shaanxi Province, China. zhangwanggang2003@yahoo.com.