Genetic basis of AnWj blood antigen identified, establishing MAL blood group system
Researchers have traced the AnWj blood group antigen to its genetic origin, solving a puzzle from 1972. The new MAL blood group system will help identify rare AnWj-negative individuals and donors. This could prevent dangerous transfusion reactions.
The AnWj antigen has been present on red blood cells of over 99.9% of humans, yet its genetic basis remained elusive since its discovery in 1972. The research team employed whole exome sequencing to compare DNA from rare AnWj-negative individuals, ultimately pinpointing homozygous deletions in the MAL gene as the cause. The Mal protein, produced by this gene, was confirmed absent on red blood cells from affected individuals.
The investigation drew on samples from five genetically AnWj-negative people, including members of an Arab Israeli family and a blood donation from 2015 by the woman who first presented the mystery. Notably, most AnWj-negative cases stem from suppression tied to underlying conditions like cancers, while inherited absence is far rarer.
This discovery could significantly improve transfusion safety for a small but vulnerable patient population. By enabling genetic screening for the MAL blood group, hospitals may identify AnWj-negative individuals and compatible donors more readily, reducing the risk of serious transfusion reactions. The finding also underscores how rare blood types, though affecting few people, require sustained scientific attention. Future applications could include prenatal testing or donor registry expansion, potentially benefiting patients with rare antibodies worldwide.