Researchers have discovered a new blood group system, named MAL, while seeking to decode a mystery that has lasted over 50 years regarding an antigen missing from red blood cells.
In 1972, doctors identified a blood sample from a pregnant woman that lacked an antigen present on the surface of all other known red blood cells at the time.
After more than 50 years, this unusual deficiency has led a team of researchers from the UK and Israel to a new blood group system in humans.
Scientists have now recorded a total of 46 different blood group systems – (Illustrative photo: AFP).
“This is a tremendous achievement and a sweet fruit of the long-term efforts of the entire team, to finally discover a new blood group system that can provide the best care for these rare but important patients,” said hematologist Louise Tilley, who works at the National Health Service (NHS) in the UK. Tilley has been researching this mystery for nearly 20 years.
We often hear about the ABO blood group system (which includes blood types A, B, AB, and O) along with the Rh factor (+ and -). However, humans actually have many different blood group systems based on the diversity of antigens on the surface of red blood cells.
According to ScienceAlert on September 18, as of November 2023, the International Society of Blood Transfusion (ISBT) has recorded a total of 45 different blood group systems, including the Er blood group system discovered in 2022. After decoding the aforementioned mystery, we now have an additional new blood group system named MAL.
The discovery of a new blood group system is quite challenging because such genetic cases are extremely rare. The AnWj antigen missing in the blood of the pregnant woman in 1972 is present in over 99.9% of humans worldwide. This antigen exists on myelin protein and lymphocytes, which is why the research team named the blood group system MAL.
When an individual has both copies of the MAL gene mutated, they belong to the AnWj- blood type, like the pregnant woman from 1972. Interestingly, all patients with the AnWj- blood type share the same mutation.
The research team has now identified the genetic markers responsible for the MAL mutation. Patients belonging to this blood group system can be tested to confirm whether they are AnWj- due to genetic inheritance or suppression (caused by certain blood disorders).
The research team stated that the more we understand about the characteristics of rare blood group systems, the more lives we can save.
The study was published in the journal Blood of the American Society of Hematology.
