ABO Blood Group
Number of Antigens: 4
Transfusion Reaction: Yes — typically causes an acute hemolytic transfusion reaction
Most deaths caused by blood transfusion are the result of transfusing ABO-incompatibleblood.
Hemolytic Disease of the Newborn: No or mild disease
HDN may occur if a group O mother has more than one pregnancy with a child with blood groupA, B, or AB. Most cases are mild and do not require treatment.