Most people know their blood type — A, B, AB, or O — and whether it’s positive or negative. But what if there were still unknown blood groups hidden within us?
Now, half a century after an unexplained case baffled doctors, scientists have finally solved the puzzle — and revealed a brand-new human blood group system.
A mystery that began in 1972
In 1972, doctors studying a pregnant woman noticed something strange: her red blood cells were missing a specific molecule found in everyone else’s blood.
For decades, no one could explain why. Now, researchers from the University of Bristol and Israel’s National Blood Service have identified the cause — a newly classified blood group system known as MAL.
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This discovery, published in the journal Blood, closes a scientific chapter that remained open for 50 years.
It not only explains the genetic origin of the anomaly but could also improve the safety of blood transfusions worldwide.
What makes the MAL blood group unique
The key to the mystery lies in a protein called AnWj, found in more than 99.9% of people.
Those missing it — a rare genetic condition — belong to the newly identified MAL blood group. The protein is linked to a gene that controls cell membrane stability and blood cell transport.
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When both copies of the MAL gene are altered, a person’s blood completely lacks the AnWj antigen.
This tiny genetic change can have major implications during transfusions, as standard blood matching may fail to detect it.
Researchers confirmed their findings by reintroducing a healthy MAL gene into the altered blood cells — instantly restoring the missing antigen.
The result provided the long-awaited proof that the MAL gene defines a new blood group system in humans.
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Why this discovery matters
Understanding rare blood types like MAL is more than a scientific milestone — it can save lives.
Knowing whether a missing antigen is caused by genetics or an underlying blood disorder helps doctors provide safer transfusions and more accurate diagnoses.
For patients with rare blood profiles, even a single compatible donor can mean the difference between life and death.
The discovery of MAL expands the global blood-matching database and strengthens our ability to identify these rare cases before complications occur.
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Looking ahead
Researchers emphasize that cases of MAL-negative blood are extremely rare, but documenting them is essential for global transfusion networks.
This breakthrough also shows how genetic tools can solve decades-old medical mysteries — and how much we still have to learn about the hidden complexity of human biology.
Article based on information from Blood Journal and WP
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