When did blood type AB first evolve?

Submitted by Novel_Estimate_3845 t3_xyllm9 in askscience

Some people say that AB is the most recent and didn’t occur until the 16th Century when group A populations from Europe and group B populations from Asia began to mix.

However, it is known that gibbons and humans both have variants for both A and B blood types, and those variants come from a common ancestor that lived 20 million years ago. Then doesn't it mean blood type AB existed at least before 16th century, while AB is just a mixture of A and B?

Which one is correct? What is the scholars' mainstream opinion about it now?

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Bad_DNA t1_irinhr7 wrote

Do you have citations for each of these positions? Better yet, do you have an understanding of the ABO system?

Here's a decent review of blood types:

https://relevantgenetics.com/the-genetics-of-blood-types/

Then you start a basic search engine query and find human AB typing predates the blog rumor of 16th century stuff:

https://www.rhesusnegative.net/staynegative/blood-types-ancient-hebrews/

So the real question would be when did the 'B' allele evolve, and how long did it take for that linage to go mate with the 'A' allele population?

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rmlmr-98 t1_irjpcnn wrote

This is a great read. I am wondering if blood type compatibility is always enough when it comes to donations? I hear about cases such as organ implants were are different measures taken to ensure compatibility. Is that correct?

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england_man t1_irkabfv wrote

>I am wondering if blood type compatibility is always enough when it comes to donations?

No.

ABO is the most important compatibility factor, and second is Rh factor (rhesus factor, either positive or negative). Beyond that, there are many other antigen groups that may affect the transfusion.

More on the topic

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Bad_DNA t1_irjr2ai wrote

Um... usually if a recipient gets a unit or more of mismatched blood, they won't fair well at all. Immune-suppression drugs might help - but I'd think the risk of infection would counter this 'technique' for blood infusion. Look into RhoGAM treatment with pregnancies for some interesting side notes.

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Catsnotrats t1_irkuri1 wrote

Immunosuppressant drugs aren't used for the treatment of AHTRs. The antibodies are already present and acting, which is the issue.

A patient's blood is grouped and then screened for 'clinically significant' antibodies to many of the common red cell antigens. (There are tons more than ABO/RhK) Antigen negative blood is provided dependent on the outcome of the antibody screen/panel. A patient that has a positive antibody screen also has to have all units fully crossmatched against their plasma before provision.

It's a different story for solid organ transplants, they have a ton more testing requirements e.g. HLA typing and also require immunosuppression.

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