Xg antigen system

Xg antigen system is a blood group system that is characterized by the presence or absence of the Xg antigen on the surface of red blood cells. The Xg antigen system was first discovered in 1962 and is one of the 36 human blood group systems recognized by the International Society of Blood Transfusion (ISBT).

History

The Xg antigen system was first identified in 1962 by researchers Yvette C. Hirschorn and R. Ceppellini. They discovered the antigen while studying the genetics of blood groups and named it after the X chromosome, where it was initially believed to be located.

Genetics

The Xg antigen is encoded by the XG gene, which is located on the X chromosome. However, subsequent research has shown that the XG gene is actually located on the pseudoautosomal region of the X chromosome, which is a region that is shared with the Y chromosome. This means that both males and females can inherit the Xg antigen.

Antigen

The Xg antigen is a protein that is found on the surface of red blood cells. The presence or absence of the Xg antigen determines a person's Xg blood type. There are two possible Xg blood types: Xg(a+) and Xg(a-). People who are Xg(a+) have the Xg antigen on their red blood cells, while people who are Xg(a-) do not.

Clinical significance

The Xg antigen system has limited clinical significance in blood transfusion and pregnancy. Unlike other blood group systems, the Xg antigen does not seem to cause immune response in people who lack it, even when they are exposed to it through blood transfusion or pregnancy. Therefore, the Xg antigen system is not routinely tested for in blood banks or in prenatal care.

See also

• Blood group system
• Antigen
• Red blood cell

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