Rare genetic mutation has given rise to a new human blood group, identified after 50 years

Blood does more than just carry oxygen and nutrients. Its many “markers,” known as antigens, can trigger unexpected responses. Most folks have heard about the blood groups A, B, and O, and the Rh factor categories, which are crucial for safe blood transfusions. 

Yet there are others with unique properties that affect certain patients. On September 16, 2024, researchers revealed a new blood group system called MAL. This news has medical experts paying close attention.

New system solves old puzzles

This recent work addresses an antigen once labeled AnWj. Earlier findings had hinted at its importance in certain patients, but its genetic basis was unclear. 

“The genetic background of AnWj has been a mystery for more than 50 years, and one which I personally have been trying to resolve for almost 20 years of my career,” explained Dr. Louise Tilley, Senior Research Scientist, IBGRL Red Cell Reference at NHS Blood and Transplant, at the end of a statement.

A deeper look at how it works

Scientists discovered that a key protein, referred to as Mal, plays a major role in whether a person’s blood cells show AnWj.

People lacking this protein are said to be AnWj-negative. If they need blood, receiving units from someone with AnWj-positive cells may cause a bad transfusion reaction. 

This risk highlights why researchers across the United Kingdom have been keen to confirm the exact genetic changes that remove the Mal protein from red blood cells.

Key players in the discovery

“It’s really exciting we were able use our ability to manipulate gene expression in the developing blood cells to help confirm the identity of the AnWj blood group, which has been an outstanding puzzle for half a century,” remarked Professor Ashley Toye from the University of Bristol, who leads research in developing blood products.

Gene manipulation studies have made all the difference. These lab methods helped the team locate the exact spot on the MAL gene that caused some folks’ cells to skip making that protein.

MAL blood group is number 47

This discovery adds MAL to a growing list of recognized blood group systems. Experts have classified it as the 47th system, which shows just how many different markers exist beyond ABO and Rh.

Each new system reveals a hidden detail about human genetics. That extra piece of knowledge can guide blood banks when they test donations, ensuring that rare donors and patients are matched more precisely.

“Now genotyping tests can be designed to identify genetically AnWj-negative patients and donors,” said Nicole Thornton at NHS Blood and Transplant.

Such tests allow hospitals to plan for patients with uncommon blood needs. Quick detection might save lives by avoiding adverse reactions.

Exome sequencing turns the tide

The break in this 50-year riddle emerged from a modern genetic tool called exome sequencing. This approach focuses on the parts of the DNA that build proteins.

With it, scientists rapidly narrowed down the small area of DNA that carried the faulty code.

Once they homed in on the MAL gene, the missing snippet explained why the Mal protein wasn’t produced.

The wide availability of exome sequencing in research labs has sped up efforts to sort out other rare blood issues as well.

Discovering the MAL blood group

The discovery didn’t come easy. Dr. Tim Satchwell at UWE Bristol mentioned how tricky it was to be certain about Mal’s involvement. 

“Mal is a very small protein with some interesting properties which made it difficult to identify and meant we needed to pursue multiple lines of investigation to accumulate the proof we needed to establish this blood group system,” said Dr. Satchwell. That perseverance paid off in ways that will aid clinicians and lab workers everywhere.

Why does any of this matter?

People who lack AnWj are extremely rare, but they require special attention. Simple awareness of MAL alerts medical staff to take extra steps if these patients need blood. 

It also means donors with a similar blood type will be more easily found, which reduces the chance of harmful interactions during transfusions.

“It represents a huge achievement, and the culmination of a long team effort, to finally establish this new blood group system and be able to offer the best care to rare, but important, patients,” summarized Dr. Tilley. 

Hearing that kind of relief underscores the personal stakes. Behind every lab test is someone who depends on correct identification.

MAL blood group system and human health

Experts believe that each refined test will empower hospitals and blood services to expand their screenings.

With advanced methods, the medical community aims to catch all sorts of unusual markers that affect patient care. 

Though the MAL system is new to many, it serves as a sign that diligent research can simplify once-mysterious conditions.

The study is published in Ash Publications.

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