[1] Univ Wales Hosp, Sch Med, Cardiff, Wales
[2] Hosp Sick Children, Toronto, ON M5G 1X8, Canada
[3] Univ Med Ctr, Van Creveld Klin, Utrecht, Netherlands
[4] Malmo Univ Hosp, Dept Hematol & Coagulat Disorders, Malmo, Sweden
[5] Baxter BioSci, Westlake Village, CA USA