British researchers may have cracked the code to make blood donations accessible to people who lack a key antigen in their red blood cells, identifying these rare mutations at the same time.
For decades, scientists have been perplexed by a handful of blood samples missing a surface marker dubbed “AnWj.” The mutation was detected in 1972, and is extremely rare. If people classified as AnWj-negative receive blood from someone who is AnWj-positive, it could very well be a fatal transfusion. Solving the mystery of detecting this missing antigen has remained the focus of researchers such as Louise Tilley.
Tilley, a senior scientist at NHS Blood and Transplant, spent 20 years researching the new blood group and striving to prove the basis of AnWj-negative blood. She and her team suspected a protein called MAL was involved with the antigen’s absence, and conducted a genetic sequencing process on five genetically AnWj-negative participants.
Tilley discovered that the individuals all had homozygous deletions in the MAL gene. Since the gene binds AnWj antibodies, the mutations cause their blood to be AnWj-negative.
In a subsequent experiment to prove MAL’s significance, Tilley’s team proceeded to insert a complete MAL gene into AnWj-negative blood cells, which generated the missing antigen on the cell surface. The cells turned AnWj-positive, which proved that MAL mutations are responsible for this blood cell type. Additionally, their research found that MAL binds AnWj antibodies, so new genotyping tests can be created in order to identify who is at risk for transfusion reactions.
Another detection of AnWj-negative blood revealed people with certain cancers that affect the expression of MAL can develop AnWj-negative blood, so having the tools to identify it opens up not only knowledge of how to find donors for cancer patients but also how to research reversing the mutation to their blood types.
Scientists found no clear link to trace why people develop this mutation. Research thus far has indicated that most people who are AnWj-negative have no genetic predisposition to it, but rather have a hematological disorder or the aforementioned cancers that cause their MAL gene to mutate. Nicole Thornton, a co-author of Tilley’s, stated that the antigen is, in these cases, not “truly negative,” but rather just “suppressed.”
Regardless of the new findings this fall, this is only the 47th blood group system to be discovered. There are still plenty of medical mysteries to be solved in this domain, and many more unexplained mutations and gene absences that puzzle scientists to this day.
During the past decade, new blood groups have been discovered on almost a yearly basis. This uncovered information about why AnWj-negative blood occurs and how to identify it opens the doors for safer blood donations and more accurate blood typing, no matter how rare the mutation may be.
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