Scientists solve a 50-year mystery and discover a new human blood group — SkimNews
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- NHS Blood and Transplant and University of Bristol scientists identified homozygous deletions in the MAL gene as the cause of inherited AnWj-negative blood after studying five affected individuals, including members of an Arab Israeli family and a woman first identified as AnWj-negative in the 1970s.
- The International Society of Blood Transfusion formally designated MAL as blood group system ISBT 047 — the 47th recognized human blood group system, with AnWj as its defining antigen — after lab experiments confirmed the Mal protein is both necessary and sufficient for AnWj expression on red blood cells.
- Whole exome sequencing unexpectedly pointed to MAL after researchers scanned thousands of genes for variants shared by AnWj-negative individuals; gene-expression manipulation in developing blood cells, led by Professor Ash Toye at the University of Bristol, then confirmed the causal link.
- Because more than 99.9% of people carry the AnWj antigen, finding compatible blood for the rare AnWj-negative minority has been near-impossible — but new MAL-based genotyping tests can now be designed to identify both rare donors and at-risk patients carrying inherited changes.
- Louise Tilley, Senior Research Scientist at IBGRL, said the genetic background of AnWj had been a mystery for over 50 years and one she personally had pursued for nearly two decades; IBGRL head Nicole Thornton called resolving it one of the lab's most challenging projects.
- A 2026 case report described the first documented use of sutimlimab, a complement-pathway inhibitor, to treat anti-AnWj-associated hemolysis in a patient with high-grade B-cell lymphoma after incompatible transfusions triggered red blood cell destruction, while a separate 75-year-old patient with an anti-AnWj autoantibody received unmatched blood because compatible units could not be found.
Why it matters: For the tiny fraction of AnWj-negative patients whose immune systems can mount dangerous reactions to donor blood carrying a marker present in over 99.9% of people, MAL-based genotyping gives blood banks a direct, long-missing way to locate matching donors and prevent hemolytic transfusion reactions.
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