Which antibody will not be detected in the serum of a Bombay genotype?

Which antibody will not be detected in the serum of a Bombay genotype?

• A. anti-Oh
• B. anti-A
• C. anti-B
• D. anti-H

Answer: (A)

In this question the situation is the Bombay (Oh) genotype, where the H antigen is completely absent on red cells. Because Oh is just the absence of H antigen, antibodies that are directed specifically against Oh would have nothing to recognize in a serologic test, since there is no Oh antigen present to bind. In Bombay individuals, the prominent antibody that is detected is against the H antigen itself (anti-H), which reacts with any red cell that carries H. The antibody against Oh, however, would not be detected because there is no Oh antigen to serve as a target. Contextually, this reflects how the absence of a paradigmatic antigen changes which antibodies can be demonstrated in serum testing.

In this question the situation is the Bombay (Oh) genotype, where the H antigen is completely absent on red cells. Because Oh is just the absence of H antigen, antibodies that are directed specifically against Oh would have nothing to recognize in a serologic test, since there is no Oh antigen present to bind. In Bombay individuals, the prominent antibody that is detected is against the H antigen itself (anti-H), which reacts with any red cell that carries H. The antibody against Oh, however, would not be detected because there is no Oh antigen to serve as a target. Contextually, this reflects how the absence of a paradigmatic antigen changes which antibodies can be demonstrated in serum testing.