Rh Antigens —―Rh - Positive‖ and ―Rh - Negative‖ People. There are six common types of
Rh antigens, each of which is called an Rh factor. These types are designated C, D, E, c, d, and e. A
person who has a C antigen does not have the c antigen, but the person missing the C antigen always
has the c antigen. The same is true for the D-d and -e antigens. Also, because of the manner of
inheritance of these factors, each person has one of each of the three pairs of antigens. The type D
antigen is widely prevalent in the population and considerably more antigenic than the other Rh
antigens. Anyone who has this type of antigen is said to be Rh positive, whereas a person who does not
have type D antigen is said to be Rh negative. However, it must be noted that even in Rh-negative
people, some of the other Rh antigens can still cause transfusion reactions, although the reactions are
usually much milder. About 85 percent of all white people are Rh positive and 15 percent, Rh
negative. In American blacks, the percentage of Rh-positives is about 95 percent, whereas in African
blacks, it is virtually 100 percent.
