We hope to gain valuable information about the safety, success of engraftment, and rates of complications using alternate donor transplantation for children with severe SCD. Crucial information will be also collected about late effects from alternate donor BMT sickle cell, providing valuable information to clinicians and families making decisions among interventions for children with severe sickle cell disease. If successful, alternate donor transplantation in this setting could pave the way to offering curative treatment to many more patients with severe SCD.