Our blood type contributes to our uniqueness as individuals just like our fingerprints and our genetics, but what are the characteristics of each blood type that makes them unique, and how does the absence or presence of antigens make an individual’s blood type rare?

The Four Major Recognized Blood Groups

Although there are millions of possible blood type combinations, medical professionals like to stick with 8 basic blood types for simplicity. They are: A, AB, B, and O. Any of which can be either negative or positive, adding to the complexity.


Each blood type is unique based on the presence or absence of a substance known as antigens. If a patient undergoes a blood transfusion and is given incompatible blood, these antigens set off an immune response that will cause the immune system to respond by attacking the foreign blood.

The four major blood groups are unique in their presence or lacking of the two antigens; A and B. They can be broken down like so:

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

Source: http://www.redcrossblood.org/learn-about-blood/blood-types

Aside from the two previous antigens, a third one known as Rh factor can also be present or absent in a person’s blood. Typically, Rh negative blood is given to other Rh negative patients, and likewise with Rh positive patients.

Speaking of compatibility; If you’re a Type O, you’re capable of donating blood that can be used universally for all other blood types. Or if you’re a Type AB, your plasma may be used universally for other plasma types.


Blood Type Based On Ethnic Groups

Out of the known combinations of blood types, Type O + is the most common blood type available today, Yet the occurrence of certain blood types is more common with certain ethnic groups compared to others. For instance, people of Hispanic origins may have a higher chance of being a Type O, while people of Asian origins have a higher chance of being a Type B.

How Is an Individual’s Blood Type Determined?

Like other genetic factors such as your eye color or hair color, you can thank your parents for the inheritance of your blood type.

The World’s Rarest Blood Type

So we know what the most common blood types available are, but what are the rarest, and why is their blood so unique?

In order for a blood type to be constituted as rare, only one in a thousand people must carry the particular blood type. One of the rarest blood types is Rh-null, which is absent of any antigens. A unique characteristic of individuals who carry this special blood, is their capability of donating their blood to any individual; regardless of the patient’s blood type. Unfortunately, Rh-null individuals can only accept blood transfusions from other Rh-null donors.

The American Red Cross also recognizes AB negative, B negative and O negative as the rarest blood types in America today. In fact, individuals expecting to undergo an intensive medical procedure may bank their own blood to eliminate the hassle and stress of trying to compatible blood.

Our blood type is as unique to our individuality as our fingerprints and our genetics.



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