A blood group is the category of blood determined by the antibodies and inherited substances that the blood contains or lacks. The antigens exist on the red blood cells, and they can be carbohydrates, proteins, glycolipids, or glycoproteins. Therefore, blood is categorized based on the presence of these antigens in the blood. Parents pass their blood groups to their offspring who inherit them as the contribution of the blood types of both parents. ABO and Rh blood types are the major human blood types.
It is possible that the blood type of a pregnant woman can be different from that of her fetus, a typical case for most pregnant women. Such a scenario is not an issue, but it is important to know if the baby is RhD- or RhD+. RhD+ babies face the risk of suffering from low fetal blood counts or fetal hydrops if their mothers are RhD. The description below explains the major blood groups and highlights some minor types.
In the ABO blood group system, the antigens present in the human red blood cells are antigens A and B. The blood also contains antibody A and antibody B in the serum. From the antigen content of human blood, there are four groups of people. Group A, group B, group AB, and group O have antigens A, B, A and B, and no antigen respectively. Each group has antibodies in its blood serum, group A, B, AB have antibodies B 2, B, and A3. Individuals with blood group O lack antibodies while those in the no-antigen group have the AB antibody.
Agglutination reaction in bloods typically occurs when similar antigens and antibodies mix. Therefore, a blood transfusion would be safe if the antibodies in the recipient's serum are not similar to antigen in the donor's red blood cells. Thus, the ABO blood group system is essential for blood transfusion in humans.
Rh blood group is the blood type with fifty Rh antigens and is an important factor in blood transfusion in humans. Five Rh antigens in the Rh system of blood are major antigens. Moreover, the major antigen among the five top antigens is the D antigen. The antigen is the most important Rh antigen since it can easily provoke a response from the immune system. The D-negative individual does not need to have the anti-D antibodies since external substances cannot induce their production. However, they can produce the antibodies from events such as occasional blood transfusion with D positive red blood cells. The presence or absence of the Rhesus factor in the human blood means that a person is positive or negative, as far as Rh (D) is concerned. For example, someone who is O positive has the Rh (D) antigen and belongs to group O ABO blood type.
Other Blood Groups
The ABO and Rh are the two main types of the existing 35 blood groups. Some of them are the MNS system, Lewis System, and the Kell system. The names of the systems mostly came from the patients whom antibodies were first discovered.