f has historically been described as a “compound antigen” in the Rh blood group system. The f antigen is present when a person inherits an allele of the RHCE gene that codes for both the c and e antigens (specifically, the RHce allele of the RhCE gene), and absent if the person does not inherit that allele. This means that the Rh haplotypes R0 and r are f-positive, since both haplotypes include the RHce allele (See my educational entry on Rh genetics if that does not make any sense!). Since most D-negative people have the rr genotype, f is present in the vast majority of D-negative (“Rh-negative”) individuals. Note that the antigen is not really “compound”, in that it isn’t formed by the mere presence of c and e on the same red cell, but rather by the action of the Rhce allele that also encodes both c and e. So, it might be better to say that RHce codes for c, e, and f. The f antibody (anti-f) acts much like other Rh antibodies, with evidence of hemolytic disease of the fetus/newborn (HDFN) and possible hemolytic transfusion reactions.
Back to Glossary List