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In 1972, a blood sample from a pregnant woman came back with something odd in it. Her red blood cells were missing a surface marker that more than 99.9% of people on earth carry.
Doctors could see the gap. They could test for it. They could not say what it was.
That question stayed open for more than fifty years. In September 2024, a team led by NHS Blood and Transplant in Bristol finally closed it, and the MAL blood group became the 47th blood group system ever described in human beings.
This is not breaking news. It is a finished story — and the part worth knowing is not the part that made the headlines.
A Blood Sample Nobody Could Classify
Most of us learn about blood in one sentence: A, B, AB or O, plus a plus or a minus. That is two systems — ABO and Rh — and they are the two that matter most often when someone needs a transfusion.
They are not the only two. A blood group system is any set of markers on the surface of a red blood cell that is controlled by a specific gene. Before 2024 there were 46 of them. Most people have never heard of any except the first two, because most people never need to.
The marker in that 1972 sample got the label AnWj. Even the name is a merger: an antigen called Anton and another called Wj had been described separately, and in 1985 they turned out to be the same thing.
Everything about AnWj could be measured. Nothing about it could be explained. There was no gene attached to it. No gene meant no DNA test, and no DNA test meant the only way to find one of these people was to run their blood, see the gap, and be confused by it all over again.
What the MAL Blood Group Actually Is
The answer turned out to be a protein called Mal — short for myelin and lymphocyte protein. It is very small. It was not on anybody’s list of likely suspects.
People who are AnWj-positive carry the full-length Mal protein on their red cells. People who are genetically AnWj-negative do not. When the researchers read the genomes of AnWj-negative individuals, every one of them had the same thing: both copies of the MAL gene missing a section, with deletions in exons 3 and 4.
That is what turns a curiosity into a blood group system. Not the marker — the gene behind it. Once you have the gene you can write a test. Once you have a test you can find people before they need finding.
Why It Took More Than Fifty Years
Three things stood in the way.
- The gene was not an obvious candidate. Mal was known in nerve and immune cells. Almost nothing was known about what it was doing on a red blood cell.
- The cases are vanishingly rare. Only five genetically AnWj-negative people were studied in the work that cracked it. One family was Arab-Israeli.
- The tools did not exist yet. The answer needed whole exome sequencing — reading the protein-coding stretches of a person’s DNA — and then laboratory work at the University of Bristol manipulating gene expression in developing blood cells, to prove that taking MAL away really did take the marker away.
Louise Tilley, the senior research scientist at NHSBT’s International Blood Group Reference Laboratory who led the project, described the genetic background of AnWj as a mystery of more than fifty years, “and one which I personally have been trying to resolve for almost 20 years of my career.”
Twenty years. On one question. For five known people.
Most People Who Test AnWj-Negative Were Never Born That Way
Here is the detail that gets stated once in the write-ups and then walked straight past.
If you find someone whose blood tests AnWj-negative, the most likely explanation is not their genes at all. It is illness. Certain blood disorders and some cancers suppress the antigen, and it fades from cells that used to carry it.
The inherited version — the one that produced a whole new blood group system — is the rare exception inside an already rare finding. And those people are perfectly healthy. Missing the marker does them no harm whatsoever. It only becomes dangerous if they ever need blood and are given the wrong kind.
So the thing that looked for fifty years like a rare identity was, in most cases, a symptom. That is a bigger deal than it sounds. It is the difference between “this person is unusual” and “something is happening to this person,” and only one of those needs a doctor. A test that can tell the two apart is worth a great deal to whoever is holding the chart — the same quiet value as any test that gives a warning long before anything is visible, like the blood test that can flag heart disease fifteen years early.
The Woman From 1972 Was Still There in 2015
One line in the announcement is very easy to skim.
Among the blood tested was a sample given in 2015 by a woman who had been the first AnWj-negative person ever identified, back in the 1970s.
Read that slowly. She was found decades ago and filed away as a result nobody could explain. More than forty years later she rolled up her sleeve again for the people who were still working on her question. She was still there. They were still looking. And the sample she gave helped finish it.
Think about the arithmetic for a moment. A national blood service. A specialist reference laboratory. Gene work in a university. Nearly twenty years of one scientist’s working life. All of it aimed at a number of people small enough to sit around one kitchen table.
Nothing about that is efficient. It is the reverse of how we normally decide what deserves our attention. We count first and care second, and the bigger the number, the easier the effort is to justify.
The oldest stories about God run the other way round. They keep interrupting the big account to go after the one — not because the one was remarkable, but because the one was missing. It is a strange way to run anything. It is also, more or less exactly, the arithmetic that kept a laboratory in Bristol chewing on a puzzle that will only ever apply to a handful of people.
And notice what they finally gave her. Not a cure. She was never sick. A name.
What This Means If You Are Not One of Them
Almost certainly you are AnWj-positive. You will probably never think about the MAL blood group again after today, and nothing in your week depends on it.
But nearly everyone knows the other feeling — being the result that does not fit the chart. Being seen without being understood. Being noticed, filed, and left unexplained. That gap between being observed and being known is a lonely place to sit, and it is far more common than rare blood. It is also not the same thing as low self-esteem, which is why the usual advice so often misses the mark. If you want a plain read on how much of it you are carrying right now, there is a short free assessment here.
What the Bristol team did was not glamorous. It was somebody refusing to let an unexplained result stay unexplained — for twenty years, for almost nobody.
If you have ever wondered whether the small unnoticed thing you keep doing for one person counts for anything, that is what fifty years of it looks like. One woman. One missing marker. One name, eventually.
And if you would like to put a tube of your own into the system that made this possible, blood services nearly everywhere are short. That part does not take fifty years.
Questions People Ask About the MAL Blood Group
What is the MAL blood group?
The MAL blood group is the 47th human blood group system, established in September 2024 by researchers at NHS Blood and Transplant in Bristol, NHSBT’s International Blood Group Reference Laboratory and the University of Bristol. It is defined by the Mal protein — myelin and lymphocyte protein — on the surface of red blood cells, which carries an antigen called AnWj. The findings were published in Blood, the journal of the American Society of Hematology.
When was the AnWj antigen discovered?
The AnWj antigen was discovered in 1972, in a blood sample from a pregnant woman whose red cells were missing a surface marker carried by more than 99.9% of people. Its genetic cause stayed unknown for more than fifty years, until deletions in the MAL gene were identified as the reason in 2024.
What does it mean to be AnWj-negative?
Being AnWj-negative means a person’s red blood cells do not carry the AnWj antigen. The most common cause is acquired rather than inherited: certain blood disorders and some cancers suppress the antigen. A much rarer inherited form is caused by carrying deletions in both copies of the MAL gene, and people with that inherited form are otherwise healthy.
How rare is AnWj-negative blood?
More than 99.9% of people are AnWj-positive, so AnWj-negative blood is extremely rare. The inherited genetic form is rarer still — only five genetically AnWj-negative individuals were studied in the research that established the MAL blood group system.
Why does finding a new blood group system matter?
Identifying the gene behind a blood group makes genetic testing possible. A person who is AnWj-negative can suffer a dangerous transfusion reaction if given AnWj-positive blood, so being able to identify those patients in advance — rather than discovering the mismatch during a transfusion — allows safer matching and better care for very rare patients. Reported by NHS Blood and Transplant.
Your Turn
Here is what we are curious about. Was half a century of work for a handful of people a good use of a laboratory’s time? Some would say those same hours spent on a common condition would have helped far more people. Others would say a health system that only chases big numbers eventually stops being a health system at all. Which way do you lean? Leave a comment and tell us.
Share This
“Somebody spent twenty years of their career solving a blood mystery that affects about five known people. Not because it scaled. Because she was still unexplained.” https://bgodinspired.com/index.php/health-and-wellness/mal-blood-group-50-year-mystery/
“In 1972 a woman’s blood came back missing something nobody could name. In 2015 she gave another sample. In 2024 they finally named it. Forty-three years, and she was still there — and so were they.” https://bgodinspired.com/index.php/health-and-wellness/mal-blood-group-50-year-mystery/
“Turns out most people who test negative for this ultra-rare blood marker aren’t born that way — illness strips it out. The ‘rare identity’ was usually a symptom.” https://bgodinspired.com/index.php/health-and-wellness/mal-blood-group-50-year-mystery/
