Kg, a New Low‐Frequency Red Cell Antigen Responsible for Hemolytic Disease of the Newborn

Abstract

Hemolytic disease of the newborn in a Japanese infant led to studies which indicate that an antibody detected in the maternal serum is recognizing a hitherto unknown red cell antigen. The antigen, which we have named Kg, was found in two generations of the family and it is inherited as a Mendelian dominant character. The maternal serum failed to react with the red cells of more than 600 random Japanese blood donors, 64 red cell samples known to possess low‐frequency antigens and all but one of 75 red cell samples known to lack high‐frequency antigens without recognized low‐frequency antigens. The father's red cells were tested extensively for established low‐frequency antigens; only Di^a was demonstrated and the maternal antibody was shown not to contain anti‐Di^a.