Blood type

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The International Society of Blood Transfusion (ISBT) recognises 29 blood grouping systems,[1] among which the best know are the ABO and Rhesus systems.

Many people will know their blood type in terms of these systems, and some have this tattooed on their body. Hospitals will always test before giving blood; however, in an emergency, "universal donor" (O neg) blood may be administered before the tests confirm a person's blood type.

The International Council for Commonality in Blood Banking Automation (ICCBBA Inc) is instituting an international standard for blood and tissue product identification (ISBT 128) that will ensure safe transmission of blood products between donors and recipients even across borders.

Contents

ABO system

Under the ABO system there are four main Blood types; type A, type B, type AB and type O.

These relate to blood cell types and can be available in any combination in a person. Thus, a person's blood may contain both type A and B cell types. They would then be classified as type AB. Having neither of these cell types indicates type O.

Under the so-called ABO blood classification system in use for more than a century, Type O blood can be given to anyone, because it lacks such antigens. People with this blood type are known as "Universal Donors" and are much in demand by phlebotomists. But Type A blood can only be given to people whose blood is Types A or AB, and Type B blood can only be used in those with blood Types B or AB. Type AB people are known as "Universal Recipients" as they can receive blood from any other blood type as well as their own, and each would be equally accepted.[2]

Rhesus blood groups

The Rhesus (Rh) blood group system refers to five main Rhesus antigens (C, c, D, E and e) as well as many other less frequent Rhesus antigens. The terms Rhesus factor and Rh factor are equivalent and refer solely to the Rh D antigen. The Rhesus system is more complicated than the ABO system as several times more combinations are possible.

Preferred nomenclature is "Rh pos/neg", as the "+/-" symbols can be mistaken in medical records with dire results.

The Rh(D) antigen is inherited on the first chromosome: Rh pos is dominant and Rh neg is recessive. The gene codes for a polypeptide on the red cell membrane. Rh neg individuals - those with a recessive DD (that is, dd) genotype - do not produce this antigen, and thus may be sensitized to Rh pos blood.

The principal discoveries were made in 1937 by Karl Landsteiner and Alexander S. Wiener[3]. Experiments in which rabbits immunized with Rhesus monkey red cells showed an antibody that results in clumping of the red blood cells of many humans. Dr. Phillip Levine working at the Newark Beth Israel Hospital linked the Rh factor and the incidence of erythroblastosis fetalis (wherein maternal red cells attack the foetal red cells); Wiener realized that adverse reactions from transfusions were also resulting from the Rh factor.

Blood group differences by ethnic origin

The ethnic origin of people can be a good, but not certain, indicator of their blood type[4].

For instance:

See Also

Blood Type Diet

External links

References

  1. Table of blood group systems. International Society of Blood Transfusion (September 2007). Retrieved on 2008-01-01.
  2. Washington Times article
  3. Landsteiner K, Wiener AS. An agglutinable factor in human blood recognized by immune sera for rhesus blood. Proc Soc Exp Biol Med 1940;43:223-224
  4. Dean, L., Blood Group and Red Cell Antigens, Chapter 2, National Institute for Health: National Centre for Biotechnical Information, accessed 1 January 2008
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