New blood group on the horizon? Researchers break the spell after 50-year mystery

Medical science is on the precipice of a brand new discovery!


In 1972, a routine blood sample from a pregnant woman revealed an unusual absence of a surface molecule typically found on all known red blood cells at the time. This intriguing finding set the stage for a significant scientific breakthrough that would come to fruition over the next 50 years.

In 2024, researchers from the UK and Israel officially described a new blood group system in humans based on this discovery.


Louise Tilley, a hematologist with the UK National Health Service, emphasized the importance of this achievement, stating that it is the culmination of nearly two decades of research aimed at understanding this rare blood anomaly. The newly identified blood group system adds to the extensive array of blood types that already includes well-known groups like the ABO system and the Rh factor.

Human blood groups are based on a variety of cell-surface proteins and sugars that function as antigen molecules, playing a critical role in distinguishing the body's own cells from foreign invaders. Mismatched blood types during transfusions can result in severe reactions or even be fatal, making comprehension of these blood group systems essential for patient care.

Most major blood groups were characterized in the early 20th century, with some later discoveries, such as the Er blood system in 2022, affecting a limited number of individuals. The newly defined blood group, named the MAL blood group , follows this trend and is associated with a specific antigen known as AnWj, found in over 99.9 percent of the population. The absence of this antigen, which resides on a protein linked to myelin and lymphocytes, results in an AnWj-negative blood type.


Tilley and her team discovered three patients who lacked the AnWj antigen without exhibiting the genetic mutations typically responsible for this condition, indicating that blood disorders may also contribute to the suppression of the antigen.


Tim Satchwell, a cell biologist at the University of the West of England, explained the challenges of identifying the MAL protein due to its small size and complex properties, which required diverse investigative approaches to establish the blood group system convincingly. After years of research, the team confirmed their findings by successfully inserting the normal MAL gene into AnWj-negative blood cells, which resulted in the expression of the AnWj antigen.


The MAL protein is integral to maintaining cell membrane stability and facilitating cellular transport. Interestingly, research indicates that the AnWj antigen is absent in newborns but manifests shortly after birth.


All AnWj-negative patients studied exhibited the same genetic mutation, yet no associated cellular abnormalities or diseases were identified. With the genetic markers linked to the MAL mutation now identified, patients can undergo testing to determine whether their negative MAL blood type is inherited or a result of suppression, which may indicate other underlying health conditions.


Understanding these rare blood characteristics is crucial, as they can have significant impacts on patient health and safety. This research was published in the journal Blood, highlighting the ongoing efforts to deepen our understanding of blood group systems to improve patient care.


This research was published in the journal Blood, while an earlier version of this article appeared in September 2024.