Researchers from the UK and Israel have identified a new blood group system in humans, marking a major breakthrough in hematology. The discovery, published in September, stems from a puzzling case in 1972, solving a half-century-old mystery and deepening our understanding of human blood diversity.
The case involved a pregnant woman whose blood lacked a surface molecule found on almost all human red blood cells. This molecule, now identified as the AnWj antigen, ultimately led to the classification of the MAL blood group system after decades of dedicated research.
“This represents a huge achievement and the culmination of a long team effort,” says Dr. Louise Tilley, a hematologist at the United Kingdom’s National Health Service, who has spent almost 20 years studying this rare blood variation. “This discovery allows us to provide the best care to rare but important patients.”
According to the World Health Organization’s Global Blood Safety Database, understanding variations in blood types is essential to ensuring the safety of transfusions. Although most people are familiar with the ABO blood system and the Rh factor, the classification of human blood is much more complex.
The National Institutes of Health reports that scientists have identified more than 30 blood group systems, each defined by distinct proteins and sugars on the surface of blood cells.
The global distribution of blood types varies greatly by region. In Kenya, data from the Kenya National Blood Transfusion Service shows that approximately 30 percent of the population has blood type O+, making it the most common blood type in the country. Globally, according to WHO statistics, the O+ blood group remains the most common, present in approximately 38 percent of the world’s population.
The recently discovered MAL blood group system, however, is exceptionally rare. Research indicates that more than 99.9 percent of people have the AnWj antigen, making its absence extraordinary. Dr Tim Satchwell from the University of the West of England explains: “MAL is a very small protein with interesting properties, which made it difficult to identify and required us to pursue several lines of research. »
This discovery has enormous implications for medical science. The MAL protein plays a crucial role in maintaining cell membrane stability and facilitating cellular transport. Interestingly, the AnWj antigen is absent in newborns but develops shortly after birth, a phenomenon that researchers are still working to understand.
The research team identified three patients with this rare blood group who did not have the expected genetic mutation, suggesting that certain blood disorders may suppress the antigen.
This discovery opens new avenues for diagnostic medicine, as testing for the MAL mutation could help determine whether a patient’s MAL-negative blood type is inherited or is a sign of an underlying medical condition.
The WHO emphasizes that understanding rare blood groups is crucial for emergency medicine and maternal health. In cases where patients with rare blood types require transfusions, having detailed knowledge of these variations can mean the difference between life and death.
The National Institutes of Health estimates that 1 in 100,000 people could have an extremely rare blood type, making research into these variations vital to public health.
