Transfusion for a patient of cis-AB blood type undergoing a redo cardiac operation

cis-AB, a rare ABO genotype, is the result of a mutated gene resulting in dual specific hybrid enzymes. A single-point mutation reverses the specificity of human blood group B synthesizing galactosyltransferase. This may lead to misclassification in ABO grouping and adverse transfusion reactions. Recently, the authors experienced a case of a patient with cis-AB blood type undergoing pulmonary valve replacement and tricuspid valvuloplasty. We transfused the patient with Rh+ A packed red blood cell, fresh frozen plasma and platelet concentrates without any clinically significant transfusion reactions.