Researchers have developed a proof-of-concept treatment for blood disorders like sickle cell disease and beta-thalassemia that could raise hemoglobin levels by activating production of both fetal and adult hemoglobin. Using a viral vector engineered to reactivate fetal hemoglobin production, suppress mutant hemoglobin, and supply functional adult hemoglobin, the researchers developed an approach that could produce more hemoglobin through a single vector.