[1] Univ Pittsburgh, Magee Womens Res Inst, Dept Pathol, Pittsburgh, PA 15213 USA
[2] Univ Philippines, Philippines Gen Hosp, Hematol Oncol Sect, Dept Internal Med, Metro Manila 1101, Philippines
[3] Inst Transfus Med, Pittsburgh, PA USA
[4] Virginia Commonwealth Univ, Med Coll Virginia, Dept Pediat, Richmond, VA 23298 USA