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  • 2 weeks later...

I am not sure what your question was:


In case you wanted the term to be explained:

Actually in most other languages the system is called AB0 (a zero) and not ABO (an O).

Humans have either the A antigen, the B antigen or no antigen (this is why it is called zero in most other languages).

So the term "O-positive" is a bit strange (means you positively have nothing :) ).


In case you wanted to know why the majority has O:

I do not know :), but maybe somebody else in the forum knows...

Edited by Jens
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i would hazard a guess that having no antigen is cheaper (in resources) then having an antigen


also mothers occasionally produce IgG antibodies against foetal blood, which cross the placenta (may cause miscarriage), and since O type has no antigens it is the "safe" blood type


don’t quote me on this though its just a guess...



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The "positive" or + designation refers to the presence of "Rhesus factor", a certain kind of protein in the membrane of most people's red blood cells - O+ blood has the antigen, and sensitized people of any ABO type who lack it (such as Rh- people who have been pregnant with an Rh+ fetus, or received a previous transfusion of Rh+ blood) will suffer adverse reactions to transfusions of O+ blood (or any other Rhesus positive blood regardless of ABO type) which can be severe.


Rh- mothers will often create an immune reaction against (and inside) second or subsequent Rh+ fetuses (the first one sensitized their immune system, like a vaccination), and this special concern is one of the differences between Rhesus factor and the blood type factors of the ABO system.


The persistence of Rh negative populations (mostly among northern Europeans and their descendants) in a world of people mostly Rh positive, despite this targeted risk to reproduction, indicates by presumption the likelihood of advantage of some kind.

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