Scientists from NHS Blood and Transplant (NHSBT) and the University of Bristol have identified a new blood group system named MAL, which clarifies a 50-year-old mystery regarding the AnWj blood group antigen. This discovery allows for the development of a genetic test to identify individuals lacking the AnWj antigen, potentially benefiting approximately 400 patients globally each year. The MAL system, now the 47th recognized blood group, is crucial for patients who are AnWj-negative, as they risk severe reactions if given AnWj-positive blood. The research utilized whole exome sequencing to link deletions in the MAL gene to the AnWj-negative phenotype. This advancement is expected to enhance transfusion safety and aid in finding compatible blood donors. Senior researcher Louise Tilley emphasized the significance of this breakthrough in providing better care for rare blood type patients.