Science Alert reports that researchers have introduced a new blood group system in humans called MAL after years of research.
In 1972, doctors found that sampled blood from a pregnant woman was oddly missing a surface molecule found on all other red blood cells at the time. Fifty years later, the missing molecules led researchers from the United Kingdom and Israel to find a new blood group system. The findings, first published in 2024, add the new MAL blood group to the already populated list of blood systems, including well-known groups like ABO and Rh.
This discovery is labeled a major milestone in hematology since it answers decades-old questions and opens the doors to improving medical care for people with rare blood types. “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,” UK National Health Service hematologist Louise Tilley said.
While Rh and ABO are the most common blood groups, MAL is different from them, according to Daily Galaxy, due to an absence of an antigen called AnWj. Researchers found over 99.9% of people have this antigen in red blood cells. The pregnant patient did not have the antigen at all, leading to the investigation led by Tilley.
Most major blood groups were identified in the early century. However, groups like MAL and the Er blood system, found in 2022, only impact a small number of people. “The work was difficult because the genetic cases are very rare,” Tilley explained.
The new addition gets its name from the MAL protein, which is known to play a vital role in cell membrane stability and cell transport. The new blood group discovery comes after years of research into the genetic cause of the AnWj-negative blood type.
The research team found three patients with the rare blood type didn’t have this mutation, heightening the idea that blood disorders can sometimes cause the antigen to be suppressed. “MAL is a very small protein with some interesting properties which made it difficult to identify and meant we needed to pursue multiple lines of investigation to accumulate the proof we needed to establish this blood group system,” University of the West of England cell biologist Tim Satchwell explained.
With genetic markers identified, patients can be tested to see if their negative MAL blood type is either inherited or present because of suppression, which could be looked at as a sign of another undiagnosed medical issue.
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