Discovery of the MAL blood group system and its implications for transfusion safety
Researchers at the NHS Blood and Transplant International Blood Group Reference Laboratory and the University of Bristol have identified a new blood group system named MAL. The research detailing MAL was published in Blood, a leading journal in hematology and transfusion science. The collaboration marks a significant step in expanding how blood groups are classified and understood in clinical practice, particularly for patients in Canada and the United States where transfusion safety is a priority for diverse populations.
Red blood cells carry a variety of surface markers, known as antigens, that help define blood groups. Historically, scientists have cataloged multiple systems, and today there are 47 recognized blood group systems with more than 360 distinct antigens. MAL adds a new layer to this landscape, highlighting how a single protein, the Mal protein, and its associated AnWj antigen can influence transfusion compatibility. The discovery emphasizes that the blood’s composition goes beyond the classic groupings and that precise antigen typing can improve patient outcomes in transfusion medicine.
The MAL system centers on the AnWj antigen, transmitted by the Mal protein. In practical terms, transfusing blood from a donor with a positive AnWj genotype to a recipient with a negative AnWj genotype may trigger an adverse reaction. This finding underlines the importance of including MAL status in pretransfusion screening to reduce the risk of immune reactions and to ensure safer matches for patients with rare genetic profiles. The work adds a new consideration to how blood banks assess compatibility and plan donor selection for complex cases.
More than 99.9 percent of the population carries a positive AnWj genotype, while a small minority show a negative variant. The rare negative cases have been linked to certain hematological diseases and some cancers. Genetic factors appear to explain why only a small subset of individuals expresses the negative trait, making MAL screening particularly relevant for patients with unusual transfusion needs or a history of disease that affects blood compatibility.
For clinicians and blood services, the MAL discovery provides a clearer picture of how to identify donors and recipients with rare blood characteristics. This insight supports more precise matching during transfusion, improves safety for affected patients, and helps blood banks plan targeted donor recruitment and inventory management. The advance also reinforces ongoing efforts to broaden antigen typing and ensure safer transfusion practices across diverse populations in North America and beyond.
Earlier research noted the development of a highly accurate blood test to screen for a paralyzing disease, illustrating how diagnostic tools evolve in parallel with antigen discovery. This broader progress in blood science demonstrates the field’s commitment to patient safety and personalized transfusion care, where precise genetic information guides clinical decisions and reduces risk for recipients.