Rh blood group incompatibility

The Rh blood group antigen is determined by three closely linked alleles on the first pair of chromosomes. There are 6 kinds of antigens, namely C and c; D and d; E and e. Among them, the D antigen was first discovered and has the strongest antigenicity. Therefore, the D antigen is called Rh-positive. No anti-d has been identified so far, so it is difficult to confirm the existence of the d antigen, and the lack of D is now represented by d. DD and dD are Rh positive, and dd is Rh negative. The frequency of Rh negatives varies by race: approximately 15% of whites and 5% of blacks in the United States. The Han population in China is less than 0.5%, and some ethnic minorities in China, such as the Uzbek and Tatar ethnic groups, account for more than 5% of the population. There are six types of antigens in the Rh blood group system, namely C, c, D, d, E, and e. Among them, d antigen has no antiserum, so only five can be detected. Among the 6 antigens, the D antigen is the strongest and has the highest pathogenicity, accounting for more than 80% of Rh factors. Therefore, anti-D serum is often used to determine Rh blood type in clinical practice.