1. Department of Hematology and Oncology Osaka University Graduate School of Medicine Suita Osaka Japan
2. Department of Advanced Diagnosis Clinical Research Center National Hospital Organization Nagoya Medical Center Nagoya Aichi Japan
3. Department of Pediatrics Nagano Red Cross Hospital Nagano Nagano Japan
4. Department of Pediatrics Keio University School of Medicine Shinjuku‐ku Tokyo Japan
5. Department of Pediatrics Tosei General Hospital Seto Aichi Japan
6. Department of Blood Transfusion Osaka University Hospital Suita Osaka Japan