An antigen is a substance on red blood cells and helps to determine your blood type. The four main blood types are A, B, O and AB. There are more than 600 known antigens, and some are unique to specific racial and ethnic groups. For example, many African American individuals and people of African descent have rare blood types, such as types U negative and Duffy negative.
Additionally, about half of the African American population has type O positive blood, which is the most transfused blood type in the U.S. Type O positive blood is one of the first types to run out during a shortage due to high demand, which is why O positive donors of all backgrounds are needed to maintain a healthy blood supply.
Some patients require an even closer blood type match than the main blood types. In fact, a person with sickle cell disease may need a precise pairing with a blood donor, especially if frequent transfusions are necessary. If a patient receives a transfusion of a blood type that is not a close match, they may form antibodies against the mismatched antigens. To help avoid transfusion-related complications, a patient is more likely to find the most compatible blood match from a donor of the same race or similar ethnicity.