Dombrock Blood Group
Number of Antigens: 7
Transfusion Reaction: Yes
Anti-Doa can cause both immediate and delayed hemolytic transfusion reactions. Delayed reactions have occurred up to 8 weeks later (1).
Hemolytic Disease of the Newborn: Yes
The Dombrock blood group also contains Gregory (Gya), Holley (Hy), and Joseph (Joa) antigens. All Hy- cells are Joa-, but not all Joa- cells are Hy- (2). Gya- is the null of the Dombrock system (3). The Dombrock antibodies can also weakly agglutinate, making them harder to detect. PCR assays are better than hemagglutination for diagnosis and to get an accurate picture of the antibodies (4). Part of this is due to the influence of other antibodies on the expression and reactivity of the Dombrock antibodies.
The presence of anti-Bg antibodies (not in the Dombrock blood group), can cause weaker than normal reactions for anti-Doa (5). The DOYA antigen removes the expression of Doa and weakens the expression of the Hy, Joa, and Gya antigens (6). If you don’t have the DOYA antigen (this is a high frequency antigen, so most people do have it), then the Doa antigen won’t express itself, and the Gya, Hy, and Joa antigens will be weakened - ie there is less risk of a transfusion reaction. DOYA- people may type as Doa-b-, but really be Doa+, just that the + does not react. The absence of DOMR does similar and weakens the Dob, Gya, Hy, Joa, and Doya antigens.