RhD antigen on erythrocytes (RhD)

The **RhD antigen on erythrocytes**, also known as **Rh blood group D antigen**, is a transmembrane protein encoded by the *RHD* gene. It forms part of a complex with other related proteins such as RHCE and RHAG, expressed exclusively on red blood cell membranes. The presence or absence of this protein defines an individual's "Rh positive" or "Rh negative" status, which has major clinical significance in transfusion medicine and obstetrics. The primary biological role appears related to maintaining normal red cell shape; its absence leads to abnormal morphology, increased fragility, shortened lifespan, and mild hemolytic anemia. There is evidence that it may function as part of an ammonia transporter complex within erythroid cells but its precise physiological substrate remains uncertain. Antibodies against this molecule are highly clinically significant because they can mediate severe immune destruction of RBCs after incompatible transfusions or during pregnancy when an Rh-negative mother carries an Rh-positive fetus.

Other names

Rh blood group D antigenRhesus D antigenCD240DRh polypeptide 1 (RhPI)Cluster of differentiation 240D (CD240D)RHD protein

For anti-D immunoglobulin: - Binds to fetal RhD-positive erythrocytes in maternal circulation, preventing maternal immune sensitization and subsequent antibody production against the D antigen.