[1] Chulalongkorn Univ, Dept Med, Div Hematol, Bangkok 10330, Thailand
[2] Pramongkutkloa Hosp, Bangkok, Thailand
[3] Rajvidhi Hosp, Bangkok, Thailand
[4] Chiangmai Univ, Chiang Mai, Thailand
[5] Mahidol Univ, Bangkok 10700, Thailand
[6] Kyoto Univ, Kyoto 606, Japan