1. Division of Hematology, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21205
2. Vanderbilt–Meharry Center of Excellence in Sickle Cell Disease, Department of Pediatrics, Vanderbilt University Medical Center, Nashville, TN 37232
3. Vanderbilt–Meharry Center of Excellence in Sickle Cell Disease, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN 37232