Children with HbSβ0 thalassemia have higher hemoglobin levels and lower incidence rate of acute chest syndrome compared to children with HbSS.

We have provided preliminary evidence that clinically relevant differences occur in ACS rates and TCD velocities between children with HbSβ0 thalassemia and HbSS. Future SCD RCTs should consider balanced allocation of these SCD genotypes, particularly when ACS and abnormal TCD velocities are primary outcome measures.