We’re the same blood?

An erythrocyte of this form contains little hemoglobin and does not tolerate oxygen well – which is why anemia occurs. However, the malarial plasmodium does not survive in such an erythrocyte, so the disease is partly saving in tropical Africa, where 80% of all deaths from malaria are currently recorded.

A similar antimalarial effect is given by the Dantu antigen, open in 1976 and first described in 1984. It was first discovered in Canada in an African named Dantu, and is most commonly found in the area of ​​Kilifi in coastal Kenya.

In 2020, it was held clinical trial blood taken from 42 healthy children from Kilifi who had 2, 1 or 0 copies of the Dantu antigen. It turned out that the gene encoding this feature is also responsible for the increased rigidity of the erythrocyte membrane. This is a purely evolutionary adaptation, since such a gene is more difficult for the malarial plasmodium to penetrate. Potentially, malaria prevention drugs could be developed that would have the same effect. The discovery of Dantu antigens marked the beginning of a systematic search for such adaptations in humans. At the end of 2022, the University of Bristol had completed the work that made it possible to draw a genetic basis for a whole group of antigens, known for about 40 years under the general name “Er”.

Er antigens

Er antigensaErb and Er3 were discovered in 1982 in a study of blood transfusion deaths. Also, these relatively common genes caused the hemolytic jaundice of newborns mentioned above. Gradually turning off the genes by the method knockout, Bristol scientists discovered the PIEZO1 gene, which encodes proteins on the surface of cells. In the course of the work, new Er-antigens Er4 and Er5 were also discovered.

The scientists turned off the PIEZO1 genetic line in mouse erythroblasts, the progenitor cells of erythrocytes. Studies have shown that in this case, mice without the PIEZO1 gene can be born dead, and in surviving individuals, red blood cells turn out to be watery and fragile. The PIEZO1 gene is responsible for adding Er antigens to the surface of red blood cells. The function of these antigens, especially Er4 and Er5, which are most characteristic of African peoples, is apparently associated with increased resistance against malaria.

Conclusion

I undertook the preparation of this not too complete digression, wishing to demonstrate that it is at the level of blood types that the modern dynamics of human evolution is most clearly visible. Even 1500 years separating us from the emergence of the IV blood group is not such a long time by the standards of human civilization. But the development of exotic antigens and more complex blood groups like the Rh factor demonstrates a clear conflict between human variability and human immune function. Also, this aspect of evolution makes us take a fresh look at Africa, which remains the forge of genotypes that change under the influence of external factors (primarily diseases) and pay attention to statistically significant, and even growing genetic differences between individual human races. This does not surprise me, since it is on such diversity that the survival of the species depends.

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