1. From the Division of Hematology, Department of Medicine, University of Washington, Seattle; Pediatric Service Hospital St Louis, Paris, France; Department of Pediatrics, Memorial Sloan-Kettering Cancer Center, New York, NY; Children's Memorial Hospital, Chicago, IL; Department of Pediatrics, University of Texas Southwestern Medical Center, Dallas; Department of Pediatrics, Wake Forest University, Winston-Salem, NC; and Cook Children's Medical Center, Fort Worth, TX.