Scientists solve a 50-year mystery and discover a new human blood group

Scientists have identified the genetic cause behind the mysterious AnWj blood group antigen, solving a puzzle that began in 1972 and establishing a new blood group system called MAL. The discovery could make it much easier to find extremely rare AnWj-negative patients and donors and protect them from potentially dangerous transfusion reactions. More than half a century after scientists first encountered a mysterious marker on human red blood cells, researchers finally traced it to its genetic source. The breakthrough established MAL as a human blood group system and gave doctors a new way to identify the exceptionally rare people whose blood lacks the AnWj antigen.

The work was led by scientists at NHS Blood and Transplant in Bristol, including researchers from the International Blood Group Reference Laboratory (IBGRL), together with colleagues at the University of Bristol. Their findings solved a puzzle dating back to 1972 and could help prevent dangerous transfusion reactions in a small number of patients. Although most people are familiar with the ABO and Rh blood groups, those are only part of a much larger biological system. Red blood cells carry hundreds of different molecules on their surfaces. Many of these molecules act as antigens, markers that the immune system can recognize. For most transfusions, ABO