Case report:DNA testing resolves unusual results in the Dombrock system

Typing for antigens in the Dombrock blood group system and identifying the corresponding antibodies are notoriously difficult tasks. The reagents are scarce and the antibodies are weakly reactive. When RBCs from family members of a patient with an antibody to a high-prevalence Dombrock antigen were tested for compatibility,an unusual pattern of inheritance was observed:RBCs from the patient's children and one niece, in addition to those from some of the patient's siblings,were compatible. This prompted the performance of DNA-based assays for DO alleles and the results obtained were consistent with and explained the compatibility test results. It was possible to study this large kindred because of the cooperation of family members, hospital personnel, and reference laboratory staff.