Authors:Banu Aygun, Steven and Alexandra Cohen Children's Medical CenterNicole A. Mortier, Cincinnati Children's Hospital Medical CenterKaren Kesler, Rho Inc.Alexandre Lockhart, Rho Inc.William H. Schultz, Cincinnati Children's Hospital Medical CenterAlan R. Cohen, Children's Hospital of PhiladelphiaOfelia Alvarez, University of MiamiZora R. Rogers, University of Texas Southwestern Medical CenterJanet L. Kwiatkowski, Children's Hospital of PhiladelphiaScott T. Miller, SUNY DownstatePamela Sylvestre, Duckworth Pathology GroupRathi Iyer, University of MississippiPeter Lane, Emory UniversityRussell E. Ware, Cincinnati Children's Hospital Medical CenterStroke With Transfusions Changing to Hydroxyurea (SWiTCH) Trial Investigators, SWiTCH