Study Purpose: This study is looking at how a medication called etavopivat affects blood flow in the brain and muscles of children with sickle cell disease (SCD). Sickle cell disease is a condition where red blood cells are shaped differently, which can cause health problems.

Study Details: Participants will take etavopivat for 24 weeks and doctors will measure how it changes brain blood flow using special tools called FDNIRS/DCS. The study includes visits before, during, and after taking the medication, lasting up to 38 weeks total.

Who Can Join: To be part of the study, patients must have specific types of sickle cell disease and meet certain health conditions. People with regular blood transfusions, recent serious health issues, or certain other medical conditions cannot join.

• Participants will have regular visits and tests during the study's 38 weeks.
• The study involves taking the medication etavopivat for 24 weeks.
• Participants should not have had major illnesses or surgeries recently.