Both clinal and discontinuous distributions exist, suggesting a complicated evolutionary history for humanity. This can be seen with the global frequency patterns of the type B blood allele shown in the map below. Note that it is highest in C entral Asia and lowest among the indigenous peoples of the Americas and Australia. However, there are relatively high frequency pockets in Africa as well.
Overall in the world, B is the rarest ABO blood allele. T he A blood allele is somewhat more common around the world than B. The O blood type usually resulting from the absence of both A and B alleles is very common around the world.
It also is relatively high among Australian Aborigines and in Western Europe especially in populations with Celtic ancestors. Other Blood Type Systems. However, it is more common in some regions. This does not imply that Native Americans and Australian Aborigines are historically closely related to each other.
The accumulation of knowledge about the genetic diversity of the human blood group systems also offers new opportunities for research in genetics, biochemistry, immunology and anthropology and has contributed to changes in transfusion medicine practices 6.
Moreover, this has favored the understanding of many aspects of immune hemolytic transfusion reactions in animal models In conclusion, the knowledge on the genes and alleles responsible for the diversity of antigens that comprise human blood group systems aid the understanding of the biological role played by these molecules in the development and maintenance of homeostasis of living systems.
Conflict-of-interest disclosure: The author declares no competing financial interest. National Center for Biotechnology Information , U. Rev Bras Hematol Hemoter. Luiz Carlos de Mattos. Author information Article notes Copyright and License information Disclaimer.
Received Sep 2; Accepted Sep 3. Copyright notice. This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. See the article " Dombrock genotyping in Brazilian blood donors reveals different regional frequencies of the HY allele " in volume 35 on page Footnotes Conflict-of-interest disclosure: The author declares no competing financial interest.
References 1. Human biological variation. New York: Oxford University Press; Anstee DJ. We do not yet know the functions of the A and B blood group factors. The O blood type is defined as the absence of A and B factors. They are most likely important, however, because they are expressed on many cells and tissues in addition to blood cells, and circulate in the plasma as well.
There are statistical differences in the frequency of certain malignancies that correlate with the ABO blood groups: Group A subjects have about a 20 percent greater risk of developing cancer of the stomach than do group O individuals, for instance, whereas the latter appear to have a greater risk of developing ulcers. The reasons are unclear. These disease susceptibilities are unlikely to confer a significant survival advantage on a population, however, because unlike malaria they often occur beyond a subject's reproductive years.
On the other hand, there is some evidence that group O members are more susceptible than other blood type individuals to the agent that causes bubonic plague, whereas group A people are more susceptible to smallpox virus. These correlations may account for the increased frequency of the B gene in China, India and parts of Russia, which suffered epidemics of both of these diseases.
Infectious organisms that carry A- and B-like antigens may have indeed played a role in the somewhat different distribution of blood types worldwide. These correlations may not be due to the actual blood type, but to the absence or presence of antibodies in people with certain blood types, or even other direct effects such as the antigen being recognised specifically by the pathogen.
So, considering some of the potential links to disease, you may be tempted to ask if you could change your blood type. This is because most of your red blood cells are made in your bone marrow. If the marrow donor has a different blood type, your blood type will eventually change to the donor's type.
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