Haemolytic disease of fetus and newborn caused by ABO antibodies in a cisAB offspring

ABO hemolytic disease of fetus and newborn (ABO-HDFN) occurs almost exclusively in infants of blood group A or B who are born to group 0 mothers because IgG anti-A or -B occurs more commonly in group 0 than in group A or B individuals. We report a case of clinically significant ABO-HDFN where the mother was blood group 0 with elevated IgG anti-A and anti-B titers and delivered a child with an A(2)B phenotype. This unusual ABO constellation between mother and infant was based on the inheritance of a rare ABO allele encoding for a glycosyltransferase capable of synthesizing both A and B antigens. Because both anti-A and anti-B antibodies may have been involved in hemolysis in this case, it may be relevant to consider the cisAB phenomenon when monitoring ABO-incompatible pregnancies and births. (C) 2008 Published by Elsevier Ltd.