Many patients with sickle cell disease (SCD) receive chronic RBC transfusions to ensure non-sickled erythrocytes are in circulation. In 20-30% of chronic transfusion episodes, however, transfusion targets are not achieved because of poor survival of donor RBCs. To better understand recipient and donor traits that may affect RBC transfusion survival, 20 chronically transfused patients with SCD (ages 12 to 33…