This study is exploring a special type of bone marrow transplant called **Haploidentical Donor Hematopoietic Cell Transplant (HCT)** aimed at treating **Sickle Cell Disease (SCD)**. This transplant uses a donor who shares some, but not all, genetic markers with the patient. The study hopes to reduce side effects and complications like **Graft Versus Host Disease (GVHD)**, where the transplanted cells attack the patient's body.

• The study is for children and young adults up to 22 years old with SCD who don't have a fully matched sibling donor.
• Participants need to undergo a special conditioning treatment before transplant.
• Donors must be family members, HIV negative, and not pregnant.

Children and young adults with SCD who have serious symptoms like strokes, chest syndrome, or severe pain might benefit from this study. The main goal is to improve the chances of survival without rejection or GVHD after transplant. Participants must meet several health criteria and have family donors willing to donate cells. If you join, your health will be closely monitored to ensure safety and the success of the transplant. Please discuss with your doctor to see if this study is right for you.