At school they taught us a basic rule of the biology of our blood that would accompany us throughout our lives: o we are A, or B, AB or else O. He ABO system of the blood discovered by Landsteiner For more than a century, it has been the pillar of modern hematology and is essential for performing a transfusion or transplant. However, genetics has a habit of reminding us that biology does not follow the dogmas we have been taught in textbooks.
Other blood types. The ABO system is undoubtedly the majority in our species and that’s what we’re completely used to handling. But the reality is that there are other groups that are really minorities, like the one they have discovered a group of researchers from Thailandwhich has confirmed what seemed like a statistical anomaly.
In this way, after analyzing the blood of 544,000 people, they have found a “hybrid type” of blood that It is extremely rare. So rare, that in that massive sample only three people own it. And this is not only a challenge for the different health systems that must have greater control over blood transfusions, since giving blood that is not compatible to these patients can be a death sentence.
A goal. The study, carried out by researchers linked to the National Blood Center of Thailand and recently reviewed, started from a brute force premise: mass analysis. By screening more than half a million donors, the goal was identify rare phenotypes that escape the standard typing tests used in hospitals for the majority group. And so much so that they have achieved it.
What they found in this case were three subjects who did not fit the usual patterns. This was not simply a rare blood type (as AB negative might be in certain populations), but a genetic structure that defies the Mendelian genetics that are classic in the human blood group.
And to see it in magnitude, of the 544,000 subjects, only three presented this variant, which means that it has a prevalence of 0.00055%.
Hybrid blood. Once we know how rare it is, the question becomes clear: what is hybrid blood? In general, it is necessary to know that the blood group is determined by a series of antigens that are on the surface of the red blood cells that travel through the bloodstream. These antigens are placed there by specific enzymes.
If a person has enzyme A, they will be blood group A. If they have enzyme B they will be group B and if they have both they will be AB. And this is where the deep science comes in: the ABO gene is incredibly diverse in our environment.
What these three individuals present seems to be a variant of what in hematology known as cis-AB phenotypes or B(A) hybrids. Instead of inheriting an A allele from one parent and a B allele from the other, they possess a mutation that allows a single allele to code for both enzymes at once, or create a “mutant” enzyme capable of performing both functions.
A confirmation. This is an idea that On paper it looked very good.especially after research that pointed to the possibility of a hybrid enzyme that had both functions. Now the Thai team has only confirmed that this phenomenon really exists in humans.
The problem of transfusions. We might think this is just a curiosity for geneticists, but it has real implications. If one of these three people needed an urgent transfusion and was misclassified with a standard test, the consequences could be fatal, since they would develop a major immunological reaction at the time of being transfused, which would seriously put their life at risk.
All this because the immune system is ready to attack everything that is foreign, that is, everything that does not resemble what is inside. Thus, if blood is transfused that has small modifications to the red blood cells, it can react by destroying them and creating a potentially fatal reaction.
It is not an isolated event. Although this may seem like an oddity that has only now been discovered, the reality is that there are many blood types that fall outside the classic ABO. One of the most curious It is known as ‘golden blood’ where you are neither Rh positive nor negative, but null. This makes him a universal donor (hence his name), but the problem is that he can only receive transfusions from his own blood group, which is extremely rare to find. Although it is not the only one, since we have rarer groups such as Gwada-Negative which is accompanied by other important neurological symptoms.
Images | Aman Chaturvedi
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