1. From the Department of Laboratory Medicine, Children's Hospital, Columbus, Ohio (Dr Qualman and Mr Bowen); the Department of Pathology, St Jude Medical Center, Fullerton, Calif (Dr Fitzgibbons); the Department of Pediatrics, Northwestern University, Chicago, Ill (Dr Cohn); and the Department of Pathology and Laboratory Medicine, Children's Hospital Los Angeles, Los Angeles, Calif (Dr Shimada)