Researchers discover a new blood group

Published by Cédric - Wednesday, October 9, 2024 - Other Languages: FR, DE, ES, PT
Article author: Cédric DEPOND
Source: Blood

The discovery of a new blood group system, MAL, marks a significant advancement in the field of hematology. An enigma of over 50 years has now been solved, offering new hope for patients.

This research, conducted by a team from NHS Blood and Transplant and the University of Bristol, focuses on the AnWj antigen, whose understanding had long remained elusive. By identifying the MAL gene, scientists have shed light on the mystery surrounding this little-known antigen.


The AnWj antigen was initially identified in a woman in 1972, but its genetics remained elusive. Researchers have shown that AnWj-negative individuals do not produce the MAL protein, which is essential for the expression of this antigen.

A key element of this discovery is that 99.9% of the population are AnWj-positive, while those who are AnWj-negative represent an exceptional case, often linked to hematological disorders or genetic mutations. The research also revealed that homozygous deletions in the MAL gene are responsible for this absence.

Blood transfusions can be risky for AnWj-negative individuals, as the administration of AnWj-positive blood can trigger severe reactions. Thanks to these new discoveries, genotyping tests can be implemented to better identify these at-risk patients.

The use of exome sequencing allowed researchers to identify these genetic deletions. This has enhanced the understanding of the impact of the MAL gene on the expression of the AnWj antigen. Future genetic testing should help reduce transfusion-related complications.

The identification of this blood group system, the 47th of its kind, has notable implications for blood transfusions and the care of pregnant women. The presence of anti-AnWj antibodies can influence the course of pregnancies, necessitating increased monitoring.

This advancement also raises questions about the ethnic origins of genetic cases of AnWj-negativity. While some have been identified in specific families, the scope of this mutation remains to be explored.

The collaborative expertise of this team was essential to establishing these results. The challenges encountered were numerous, but solving a long-standing mystery is a testament to the researchers' commitment to improving patient care.

What is a blood antigen?

Blood antigens are molecules found on the surface of red blood cells that determine an individual's blood group. They allow the immune system to recognize cells as "self" or "non-self." The most well-known systems are the ABO systems, but others, such as the MAL system, add to this classification.

How important are blood groups in transfusions?

Compatibility between donor and recipient blood is essential to prevent transfusion reactions. When a person receives incompatible blood, it can lead to serious, even fatal, complications. Knowledge of blood groups, including lesser-known systems like MAL, improves transfusion safety and helps manage cases of patients with rare antigens.

What is exome sequencing?

Exome sequencing is a technique that targets and sequences only the exons, the parts of the genome that code for proteins. This method allows for the identification of genetic mutations responsible for various diseases by focusing on the DNA segments that have the greatest functional impact.

How does exome sequencing aid in medical research?

By enabling the precise identification of mutations in specific genes, exome sequencing plays a key role in diagnosing and understanding hereditary diseases and rare conditions. In the case of the MAL blood group, this technique revealed deletions in the MAL gene, clarifying the link between the gene and the absence of the AnWj antigen in certain individuals.
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