Scientists Identified a New Blood Group After a 50-Year Mystery : ScienceAlert

For over 50 years, a medical mystery lingered: a pregnant woman’s blood sample from 1972 lacked a surface molecule found on all other known red blood cells. Now, researchers in the UK and Israel have finally identified this anomaly as a new human blood group system, publishing their findings in 2024.

Unveiling a New Blood Group System

Hematologist Louise Tilley from the UK National Health Service described the discovery as “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.” Tilley has personally researched this unusual case for nearly two decades.

Did You Know? The AnWj antigen, missing in the 1972 patient’s blood, is present in over 99.9 percent of people.

Humans possess many different blood group systems, determined by the variety of proteins and sugars coating red blood cells, beyond the commonly known ABO system and Rh factor. These antigens act as identifiers, helping the body distinguish between ‘self’ and potentially harmful ‘not-self.’

The Importance of Blood Group Matching

Mismatched blood types during transfusions can cause severe reactions, even proving fatal. Most major blood groups were identified in the early 20th century, with more recent discoveries, like the Er system described in 2022, often found in only a small number of individuals. This new blood group follows that pattern of rarity.

Researchers found the missing antigen resides on a myelin and lymphocyte protein, leading them to name the new system the MAL blood group. The work proved challenging due to the rarity of genetic cases, as explained by Tilley.

Expert Insight: Identifying rare blood group systems is crucial for patient safety. Understanding these variations ensures that individuals receive compatible blood transfusions, minimizing the risk of potentially life-threatening reactions.

To confirm the genetic basis of the anomaly, the team inserted the normal MAL gene into AnWj-negative blood cells, successfully restoring the antigen. The MAL protein is vital for maintaining cell membrane stability and aiding cellular transport, and it typically appears soon after birth, according to previous research.

Genetic Factors and Future Implications

Patients with AnWj-negative blood types, like the original 1972 patient, often have mutated versions of the MAL gene. However, researchers also identified three patients without this mutation, suggesting that certain blood disorders can suppress the antigen’s expression.

Now that the genetic markers are known, testing can determine if a negative MAL blood type is inherited or due to suppression, potentially indicating an underlying medical condition. Further research could explore the function of the MAL protein and its role in overall health.

Frequently Asked Questions

What is a blood group system?

Humans have many different blood group systems based on the variety of proteins and sugars that coat our blood cells.

Why is identifying new blood groups important?

Identifying new blood groups is important because mismatched blood types during transfusions can cause reactions or even be fatal.

What is the MAL blood group?

The MAL blood group is a newly described blood group system named after the myelin and lymphocyte protein on which the AnWj antigen resides.

What further discoveries about rare blood types might improve patient care in the future?