Author Question: Blood Types and Blood Transfusions

Ryana Asks:

I want to do a story set in WWII and one of my climaxes is when a Jewish soldier gives blood to save a German soldier’s life (or vice versa). My question is this: do different races have different blood types? Like, do Jews have a blood type no one else has? I don’t want to do something medically incorrect just because I think my story is good.

Jordyn Says:

There are eight different blood types and all ethnicities/races can have one of these blood types though some are more prevalent in a race than others. Here is an interesting link where the Oklahoma Blood Institute looked at what blood types certain races were and their break down.

I think the harder part of your question is would these two soldiers, by chance, have the same blood type where it wouldn’t cause a life threatening reaction in the soldier receiving blood. I was able to Google this question and found this link. As you can see, the best odds are if both soldiers are O-positive and yet that random chance that both are the same blood type is only 38%. The next highest is if both are A-positive at 34%. The other blood types fall precipitously after that. Of course, if the soldier giving the blood is O-negative (this is the universal donor) then there should be no reaction regardless of what blood type the receiving soldier is. On the reverse side, the universal recipient (someone who can get anyone’s blood) is AB-positive.

It would actually increase conflict in your story if the soldier receiving blood DID have a transfusion reaction. This type of reaction would be called a hemolytic transfusion reaction. This article reviews some of the varied responses a patient can have. Of course, you’d have to consider the time frame of your piece and what treatment would have been available then.

Hope this helps and good luck with the story!

How to Determine Blood Type

In the age of DNA testing, blood typing seems to have fallen by the wayside in use in novels but I think it can still be very valuable and add an element of suspense and surprise. A child’s blood type may be the first clue to a parent that they may not be biologically related.

Blood type is determined from two allele’s. An allele is a “form of genetic information that is present in our DNA at a specific location on a specific chromosome”.

There are four blood types: A, B, AB, and O. Blood type A can be designated either by AA or AO. Blood type B can be designated by BB or BO. This will be clearer below.

This is the easiest way I’ve been shown to determine a child’s potential blood type. In the square below, the top horizontal portion is one parent, the vertical side is the other parent. Each box with a single letter is the one allele that parent will give their child. A child receives one allele from each parent so you need to “cross multiply” each square to determine blood type.


In the above instance you have one parent that is blood type A (designated AO) and one that is blood type O (designated OO). As you can see, their child would have a 50% chance of having blood type A and a 50% chance of having blood type O.

Let’s look at another example. Take a look at what happens when both parents are blood type AB.


In this case, their biological child would have a 25% chance of being blood type A, a 50% chance of being blood type AB, and a 25% chance of being blood type B.

How can this work for your fiction? Let’s look at this example. You’re writing a novel that centers around a child diagnosed with leukemia. The child needs a bone marrow transplant. The presumed parents are blood type A (AO) and blood type AB. You have a child with blood type O. Can this child be the biological offspring of these two parents?


Give your answer in the comments section.


Resources: This resource includes a blood type calculator!

Who Can Get Whose Blood?

Recently, a very astute reader by the name of David wrote to me regarding my latest novel Fractured Memory.

In the letter he writes:

blood-donation-376952_1280“On page 67, you referred to a child with ‘the most rare blood type–AB negative.’ You then implied that to give a transfusion to the child, AB negative blood would be required. As far as blood type is concerned, it was my understanding that AB negative is close to being the Universal Recipient (which would actually be AB positive). Thus, while AB- may be extremely rare, such a person could still accept blood which is AB-, A-, B- or O-, so the rarity of AB- itself doesn’t necessarily mean it would be difficult to find donor blood for a transfusion.”

Strong work, David, strong work.

With a couple of caveats.

Why do we even worry about blood types and who can accept whose blood? The issue comes down to whether or not your body will identify the donated blood as a foreign tissue or not. If the body looks at those newly infused blood cells and cries out in terror because it doesn’t recognize it as self— it mounts a war on a cellular level to kill those foreign red blood cells, which leads to a drastic systemic reaction that can lead to some very serious complications for patients.

The trick in transfusing blood is to give something the body doesn’t recognize as foreign. The letters in your blood signify antigens but also signify which type of antibodies are in the blood. So a person who is blood type A has B antibodies in their blood which means if they get any blood with a “B” in it (B or AB), that person’s body is going to want to kill those blood cells. People who are blood type “O” carry antibodies to both A and B blood. Therefore, a person with type O blood can only receive type O blood.

So, yes, a person who is AB negative can safely receive blood from a person who is A-, B-, AB-, and O negative. But for the purposes of a planned surgery, which was the case in the novel, usually type specific blood is sought out. Also, the other blood types this patient could receive are about ten percent of the population combined. Individually they number a lot less. Certainly not impossible to find depending on what’s in stock in the blood bank. Because O negative blood is so valuable in the sense that anyone can receive it it is generally reserved for emergency situations and would likely not be used for a planned surgery.

This article is a great resource for writers when it comes to blood types and who can get whose blood.

Do you know how a person’s blood type is determined?