Scientists Identify New Human Blood Group, MAL

Researchers in the United Kingdom and Israel identified the genetic cause of the AnWj blood group, establishing a new blood group system called MAL. The team, led by NHS Blood and Transplant’s International Blood Group Reference Laboratory, used whole exome sequencing to pinpoint deletions in the MAL gene as the source of the rare AnWj-negative blood type. This antigen was first detected in 1972, but its genetic basis remained unknown for over 50 years.

People with AnWj-negative blood lack a protein called Mal, which is present on red blood cells in those with the more common AnWj-positive type. The study found only five individuals with the inherited genetic deletion, but notes that the AnWj-negative state can also appear temporarily in patients with certain blood disorders or cancers.

The discovery allows for the development of genetic tests to identify rare donors and patients at risk of transfusion reactions. While most people—over 99.9%—are AnWj-positive, accurate identification of those who are not is vital for safe transfusions. Researchers continue to investigate the function of the Mal protein and search for other undiagnosed cases globally.