[1] Nagoya Univ, Dept Pediat, Grad Sch Med, Nagoya, Aichi, Japan
[2] Hirosaki Univ, Grad Sch Med, Dept Pediat, Hirosaki, Aomori, Japan
[3] St Lukes Int Hosp, Dept Pediat, Tokyo, Japan
[4] St Lukes Int Hosp, Dept Lab Med, Tokyo, Japan
[5] Shizuoka Childrens Hosp, Dept Hematol & Oncol, Shizuoka, Japan
[6] Japanese Red Cross Nagoya First Hosp, Dept Pathol, Nagoya, Aichi, Japan