Blood Group: Dombrock

Common: Antigen is present in 64% of Caucasians and has a lower frequency in Indians and Negroes. Dob is present in 84% of Caucasions. 36% are Doa- (2). There is also a Dombrock null phenotype, which is Gya-.

Causes HDN: Yes

Critical Titer: 1:16


This antibody developed in Mrs. Dombrock after a blood transfusion (1). Dombrock A, anti-Doa antibodies are usually the IgG type of antibodies, which do cross the placenta. This makes them an antibody with the potential of causing hemolytic disease of the fetus and newborn (HDFN), and there have been cases of anti-Doa needing an intrauterine transfusion. Dombrock mRNA has been found on fetal liver & spleen (10).

The Dombrock antibodies are an HTLA antibody (High Titer, Low Avidity), but unlike other HTLA antibodies which do not cause hemolytic transfusion reactions (HTR), or HDFN, anti-Doa does cause both immediate and delayed HTR, and HDFN. The clinical significance should not be underestimated with Dombrock antibodies. There have been cases of anti-Doa causing delayed HTR up to 8 weeks after transfusion (7). 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 (9). 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 (3). The DOYA antigen removes the expression of Doa and weakens the expression of the Hy, Joa, and Gya antigens (5). 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.


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