to Rh positive patients. The universal red cell donor has Type O negative blood type. The universal plasma donor has Type AB positive blood type. Blood Types and the Population O positive is the most common blood type. Not all ethnic groups have the same mix of these blood types. Hispanic people, for example, have a relatively high number of O's, while Asian people have a relatively high number of B's. The mix of the different blood types in the U.S. population is: Caucasians African American Hispanic Asian O + 37% 47% 53% 39% O - 8% 4% 4% 1% A + 33% 24% 29% 27% A - 7% 2% 2% 0.5% B + 9% 18% 9% 25% B - 2% 1% 1% 0.4% AB + 3% 4% 2% 7% AB - 1% 0.3% 0.2% 0.1% Some patients require a closer blood match than that provided by the ABO positive/negative blood typing. For example, sometimes if the donor and recipient are from the same ethnic background the chance of a reaction can be reduced. That's why an African-American blood donation may be the best hope for the needs of patients with sickle cell disease, 98 percent of whom are of African-American descent. How Is My Blood Type Determined? It's inherited. Like eye color, blood type is passed genetically from your parents. Whether your blood group is type A, B, AB or O is based on the blood types of your mother and father. This chart shows the potential blood types