Blood Type B
From Halbeeg, the open encyclopedia · Af-Soomaali
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Blood type B is one of the four types in the ABO blood group system, which classifies a person's blood as A, B, AB, or O. A person with this blood type has the B antigen—a sugar-like molecule recognized as foreign by the immune system—on the surface of their red blood cells (erythrocytes). The plasma of such a person contains antibodies (immune cells) that act against the A antigen.
The ABO system was identified in the early 20th century and originates from the ABO gene located on chromosome 9. Blood type is inherited: parents pass it to their children. Type B results when a person inherits the B allele from one or both parents, while the other allele is either B or O.
Antigens and antibodies
ABO antigens are carbohydrate structures on the surface of red blood cells. The B allele produces an enzyme that adds galactose sugar to the H antigen. Because of the anti-A antibodies in the plasma, type A blood transfused into a type B person can trigger a rapid immune reaction that destroys the red blood cells (hemolysis). This is why blood type testing is essential before every transfusion.
Blood transfusion
A person with type B blood can typically receive type B or type O blood, and can donate blood to those with type B and AB blood. When considering transfusion, the Rh system (RhD) must also be taken into account, so type B is described as either "B positive" (B+) or "B negative" (B−). Other antigen systems—such as Kell and Duffy—become important when someone receives transfusions over a long period.
Pregnancy and infant health
ABO blood type incompatibility between mother and infant can sometimes cause mild jaundice in the newborn, a condition called ABO hemolytic disease. It is generally less severe than Rh incompatibility, but monitoring is necessary.
Geographic distribution
The percentage of people with type B blood varies by region. It is generally higher in central, south, and east Asia, and lower in some parts of western Europe and among populations originating from the Americas. These differences are explained by human migration history, geographic isolation, and disease patterns.