Sickle cell disease (SCD) is a genetic blood disease that damages red blood cells. The disease affects millions of people worldwide and approximately 80,000 patients in the United States, particularly one in every 500 African-American births. A defect in hemoglobin (a protein that helps cells carry oxygen through the body) causing red blood cells to become stiff and crescent shaped (sickle), blocking small blood vessels and causing decreased blood flow, inflammation, pain and strokes. children. To date, the only drug approved by the Food and Drug Administration (FDA) to treat sickle cell disease is hydroxyurea, a cancer drug indicated only for adults. Hydroxyurea is only moderately effective and has undesirable side effects that limit its use.