The study is about helping kids with Sickle Cell Disease (SCD) using a special type of transplant from a brother or sister who is a perfect match. This transplant uses medicine like alemtuzumab (a type of drug to weaken the immune system), low doses of radiation, and sirolimus (a drug to prevent organ rejection) to make the process easier on the body. Researchers want to see if this "SUN" transplant can be safer and less toxic than usual methods, while still curing SCD.

• The study includes 30 children with SCD and takes place at multiple locations.
• The focus is on reducing side effects like graft-versus-host disease (GVHD), a condition where the new cells attack the body.
• Participants must have severe SCD symptoms to join, and the study lasts until 1 year after the transplant.