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| Scanning electron micrograph of red and white human blood cells. (Steve Gschmeissner/Science Photo Library/Brand X Pictures/Getty Images) |
In 1972, when a pregnant woman's blood was collected, researchers found that it was oddly devoid of a surface molecule that was present on all other red blood cells at the time.
Fifty years later, researchers from Israel and the UK eventually described a new human blood group system because of this odd molecular lack. The team's publication on the discovery was published in September.
Louise Tilley, a hematologist with the UK National Health Service, said, "After nearly 20 years of personally researching this bloody quirk, it represents a huge achievement, and the culmination of a long team effort, to finally establish this new blood group system and be able to offer the best care to rare, but important, patients."
Based on the vast array of cell-surface proteins and carbohydrates that cover our blood cells, humans actually have numerous blood group systems, even though we are all more familiar with the ABO blood group system and the rhesus factor (that's the plus or minus portion).
Among other things, our bodies use these antigen molecules as identifying markers to distinguish between potentially dangerous not-selves and our "self."
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| Blood type (or blood group) is determined, in part, by the ABO blood group antigens present on red blood cells. Antibodies in our blood plasma detect when a foreign antigen marker is present. (InvictaHOG/Public Domain/Wikimedia Commons) |
When getting a blood transfusion, this life-saving strategy may result in responses or even be lethal if certain markers do not match.
Early in the 20th century, the majority of the major blood types were determined. Many that have since been found only affect a few people, such as the Er blood system that was initially reported by researchers in 2022. This is true for the new blood group as well.
Tilley noted, "The genetic cases are very rare, so the work was challenging."
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| Transfusion reactions can be severe. (Africa images/Canva) |
According to earlier studies, the AnWj antigen that was absent from the blood of the 1972 patient is present in almost 99.9% of persons. The researchers named the recently described system the MAL blood group since this antigen is found on a myelin and lymphocyte protein.
AnWj-negative blood types, such as the pregnant patient's, are caused by mutations in both copies of the MAL gene. Three patients with the unusual blood type who did not have this mutation were found by Tilley and colleagues, indicating that blood diseases might occasionally also result in the suppression of the antigen.
"MAL is a very small protein with some interesting properties which made it difficult to identify and meant we had to pursue multiple lines of investigation to accumulate the proof we needed to establish this blood group system," said Tim Satchwell, a cell biologist at the University of the West of England.
After decades of investigation, the scientists put the normal MAL gene into AnWj-negative blood cells to confirm they had the right gene. The AnWj antigen was successfully transmitted to those cells as a result.
It is well known that the MAL protein is essential for maintaining the stability of cell membranes and facilitating cell transport. Furthermore, prior studies have shown that the AnWj emerges shortly after birth rather than being present in newborns.
It's interesting to note that every AnWj-negative patient in the research had the identical mutation. Nevertheless, this mutation was not linked to any other disorders or cell abnormalities.
Patients can now be examined to see whether their negative MAL blood type is hereditary or the result of suppression, which could indicate another underlying medical issue, now that the researchers have determined the genetic markers causing the MAL mutation.
More lives can be spared if we can better understand these uncommon blood oddities, which can have catastrophic effects on people.
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