Bloodtype

Bloodtype

Blood type is a classification of blood based on the presence or absence of inherited antigenic substances on the surface of red blood cells (RBCs). These antigens may be proteins, carbohydrates, glycoproteins, or glycolipids, depending on the blood group system. Some of these antigens are also present on the surface of other types of cells of various tissues. The two most important blood group systems are the ABO blood group system and the Rhesus (Rh) blood group system.

ABO Blood Group System

The ABO blood group system is the most significant blood group system in human blood transfusion. The associated anti-A and anti-B antibodies are usually IgM type antibodies, which are produced in the first years of life by sensitization to environmental substances such as food, bacteria, and viruses. The ABO blood group system divides human blood into four types:

• Type A has the A antigen on red cells (and B antibody in the plasma)
• Type B has the B antigen on red cells (and A antibody in the plasma)
• Type AB has both A and B antigens on red cells (but neither A nor B antibody in the plasma)
• Type O has neither A nor B antigens on red cells (but both A and B antibody are in the plasma)

Rhesus (Rh) Blood Group System

The Rh system is the second most significant blood-group system in human-blood transfusion with currently 50 antigens. The most clinically significant Rh antigen is the D antigen. If your blood has the antigen, you are Rh positive. If your blood lacks the antigen, you are Rh negative. Rh status is usually denoted by a "+" or "-" sign after the ABO blood type.

Compatibility

Blood transfusions must be compatible with both the ABO and Rh systems to avoid an immune response in the recipient. For example, a person with A+ blood can receive A+ or A- blood, but not B+ or B- blood.

Inheritance

Blood types are inherited from both parents. The ABO blood type is determined by the ABO gene, while the Rh factor is determined by the RHD gene.

Clinical Significance

Blood type testing is essential for blood transfusions, organ transplants, pregnancy, and forensic investigations. The wrong blood type transfusion can lead to severe, often fatal, transfusion reactions. In pregnancy, the mother's and baby's Rh compatibility must be assessed to prevent hemolytic disease of the newborn.

Blood Type Distribution

Blood type distribution varies significantly among ethnic groups and countries. For example, Type O is the most common worldwide, while Type AB is the least common.