1. From the Departments of Medicine, Pharmacy, Pathology, and Molecular Medicine, Queen's University, Kingston, ON, Canada; National Institute for Biological Standards and Control, Potters Bar, United Kingdom; Department of Hematology, Hôpital Sainte-Justine, Montreal, QC, Canada; Departments of Medicine, Pediatrics, and Oncology, University of Calgary, Calgary, AB, Canada; and Department of Medicine, McGill University, Montreal, QC, Canada.