Scientists Discover New Blood Group After 50-Year Mystery Solved

In 1972, when a pregnant woman’s blood was tested, doctors found it was unusually lacking a surface molecule present on all other known red blood cells at that time.

After 50 years, the mystery of the missing molecular marker led researchers from the UK and Israel to identify a new blood group system in humans. In September, the team published their findings on the discovery.

A Significant Achievement in Blood Group Research

“This represents a significant achievement and the result of years of teamwork to establish this new blood group system, allowing us to provide the best care for rare but important patients,” said UK National Health Service hematologist Louise Tilley, who spent nearly two decades researching this peculiar case.

While many are familiar with the ABO blood group system and the rhesus factor (the positive or negative designation), humans actually have several different blood group systems, defined by the diverse range of cell-surface proteins and sugars that coat our red blood cells.

These antigen molecules, among other functions, serve as markers to help the body distinguish between ‘self’ and potentially harmful foreign entities.

If these markers don’t align during a blood transfusion, it can lead to adverse reactions or even be life-threatening.

New Blood Group Identified Among Rare Blood Systems

Most major blood groups were identified in the early 20th century. Many more recently discovered groups, such as the Er blood system identified by researchers in 2022, affect only a small population. The newly identified blood group follows this trend.

“The research was challenging because the genetic cases are extremely rare,” Tilley explained.

AnWj Antigen Leads to Identification of MAL Blood Group

Earlier research revealed that over 99.9 percent of people have the AnWj antigen, which was absent in the 1972 patient’s blood. This antigen is present on a myelin and lymphocyte protein, prompting the researchers to name the newly identified system the MAL blood group.

When someone inherits mutated versions of both copies of their MAL genes, they develop an AnWj-negative blood type, as seen in the pregnant patient. Tilley and her team discovered three patients with this rare blood type who didn’t have the mutation, indicating that blood disorders could sometimes cause the antigen to be suppressed.

“MAL is a very small protein with unique properties, making it difficult to identify. This complexity required us to explore multiple research avenues to gather the evidence needed to establish this blood group system,” said Tim Satchwell, a cell biologist from the University of the West of England.

Gene Confirmation Through Experimental Insertion

After years of research, the team confirmed the correct gene by inserting the normal MAL gene into AnWj-negative blood cells, which successfully introduced the AnWj antigen to those cells.

The MAL protein is crucial for maintaining cell membrane stability and assisting with cell transport. Additionally, previous studies showed that the AnWj antigen is absent in newborns but appears shortly after birth.

Interestingly, all the AnWj-negative patients in the study shared the same mutation. However, no other cell abnormalities or diseases were linked to this mutation.

With the genetic markers for the MAL mutation now identified, patients can be tested to determine whether their negative MAL blood type is inherited or a result of suppression, which could indicate an underlying health issue.

These rare blood abnormalities can have serious consequences for patients, so the more we learn about them, the more lives we can potentially save.

Read the original article on: Science Alert

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