Sickle cell disease (SCD) affects people of many racial and ethnic groups. In the United States, 90,000 to 100,000 people―mainly Blacks or African Americans―have SCD. The disease occurs among about 1 of every 500 Black or African-American births and among about 1 out of every 36,000 Hispanic-American births. Other people affected include those of Mediterranean, Middle Eastern, and Asian origin. In addition, more than 2 million people carry the sickle cell gene that allows them potentially to pass the disease on to their children.