Absence of DOMR, a new antigen in the Dombrock blood group system that weakens expression of Do(b) , Gy(a) , Hy, Jo(a) , and DOYA antigens.

Background: The Dombrock (Do) blood group system consists of six distinct antigens: Do(a) , Do(b) , Gy(a) , Hy, Jo(a) , and DOYA. Our finding of a pregnant patient whose red blood cells (RBCs) were Hy+ but whose serum contained an apparent alloanti-Hy suggested the presence of a seventh antigen and prompted this study.

Study Design And Methods: Standard hemagglutination and polymerase chain reaction-based methods were used throughout.