1. Section of Hematology, Department of Pediatrics, New York Medical College-Metropolitan Hospital Center, New York, N.Y. 10029, and the Department of Medicine, State University of New York, Downstate Medical Center, Brooklyn, N.Y. 11203.
2. New York Medical College. Metropolitan Hospital Center, New York. N.Y.
3. SUNY Downstate Medical Center, Brooklyn, N.Y.