The rhesus or Rh blood group is one of the most important blood groups in the human body. The group contains many antigens, or substances that cause an immune response. Mainly, the antigens are Antigen C, E, and D, which are all encoded by the same gene, called the RHCE gene. One of these antigens in the Rh blood group, antigen E, causes the immune system to make the antibody anti-E. When an individual does not have antigen E in their blood, this can cause a range of problems. Symptoms of HDN range in severity but the disease can often be life threatening.
The presence of the E antigen is important for blood transfusions. If an individual does not have antigen E in their naturally ocurring blood and receives a blood transfusion from someone who does have antigen E, the recipient’s immune system might attack those blood cells because it sees them as foreign invaders to their body. This occurence is called a hemolytic transfusion reaction (HTR).
Additionally, Rh status can also play an important role in pregnancy. For example, if a fetus's blood has antigen E and the mother does not, the mother’s immune system may attack the fetus’s red blood cells because the antigen looks foreign to the mother's body. When the mother's immune system attacks the fetus due to the presence of different antigens, it is called hemolytic disease of the newborn (HDN).
A doctor can detect HDN during pregnancy with a Coombs blood antigen test. The direct Coombs test finds antibodies that have already attached to the baby's red blood cells. The indirect Coombs test finds these antibodies before they attack the baby's red blood cells. Treatment of HDN after delivery may involve methods to help the baby breathe or blood transfusions to help replenish destroyed red blood cells. To avoid HDN, it is important to screen the mother’s blood to determine her risk.
Description Last Updated: Feb 06, 2018