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Researchers identify new blood group MAL, ending 50-year search

Researchers identify new blood group MAL, ending 50-year search

New Capabilities

Genetic cause of the rare AnWj-negative blood type is found, and the resulting tests are now guiding transfusions.

September 20th, 2026: Case reports describe treating patients with anti-AnWj antibodies

Overview

Updated Sep 20

In 1972, blood from a pregnant woman showed red cells missing a surface marker everyone else carried. It took until 2024 to trace that marker to a gene called MAL, establishing a new human blood group system.

People with AnWj-negative blood can have fatal reactions to incompatible transfusions. A new genetic test finds these rare patients and donors before transfusion. Case reports in 2026 show it guiding care, including the first use of the drug sutimlimab against anti-AnWj-related cell destruction.

Why it matters

A new genetic test identifies the rare patients whose blood would otherwise trigger a fatal transfusion reaction, and it is already reaching hospitals.

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Key Indicators

47th
Human blood group system
The MAL system is the 47th officially recognized by the International Society of Blood Transfusion; a newer system, JAMA, became the 49th in September 2026.

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People Involved

LT
Louise Tilley
Senior research scientist, NHS Blood and Transplant
Led the team that identified the MAL gene behind AnWj-negative blood
NT
Nicole Thornton
Head of IBGRL Red Cell Reference at NHS Blood and Transplant; coauthor of the MAL study
Leads the reference laboratory that developed the MAL genotyping test
UP
Unnamed 1972 patient
First known AnWj-negative person
Her case launched the 50-year search

Organizations Involved

NHS Blood and Transplant
NHS Blood and Transplant
UK national blood service
Led the research

The UK body that manages blood donation and transfusion, whose reference laboratory led the MAL discovery.
University of Bristol
University of Bristol
Research university
Academic partner in the discovery

Provided the genetic sequencing and cell-biology expertise that confirmed the MAL gene's role.
International Society of Blood Transfusion
International Society of Blood Transfusion
Medical standards body
Ratified MAL as an official blood group system; added JAMA as the 49th system in September 2026

The international body that sets blood group nomenclature and rare-donor standards.

Timeline

1972 September 2026

6 events Latest: September 20th, 2026 · 2 months ago
Tap a bar to jump to that date

  1. Case reports describe treating patients with anti-AnWj antibodies

    Latest Clinical

    Two reports in 2026 describe patients with anti-AnWj antibodies. Genetic testing showed one man's antibody was acquired, not inherited; he received unmatched red cells without a reaction. In another, sutimlimab was used for the first time against anti-AnWj-associated hemolysis.

  2. JAMA ratified as 49th blood group system

    Regulatory

    The International Society of Blood Transfusion added JAMA as the 49th human blood group system in September 2026, after MAL and other genetically defined systems.

  3. Discovery highlighted in new reporting

    Report

    ScienceDaily featured the MAL discovery, emphasizing the new genetic test that identifies rare AnWj-negative patients and donors.

  4. MAL gene identified as the cause

    Scientific publication

    NHS Blood and Transplant and University of Bristol researchers reported tracing the AnWj antigen to the MAL gene, establishing the 47th blood group system. The study was released as a preprint in Blood.

  5. Original sample retested

    Research

    The 1970s patient's stored blood was retested and remained AnWj-negative, serving as a key reference for later research.

  6. AnWj antigen first detected

    Discovery

    A pregnant woman's blood test revealed red cells missing the AnWj antigen, puzzling doctors who could not explain the absence.

Scenarios

1

NHSBT adds MAL genotyping to routine blood screening

Likely Resolves by End of 2027

Discussed by: NHS Blood and Transplant researchers, who wrote that tests can be added to existing genotyping platforms

The International Blood Group Reference Laboratory already built a genetic test for the condition. The next step is folding MAL typing into the standard donor and patient screening panels that blood services run. That would identify AnWj-negative people before a transfusion rather than after a reaction.

2

Global rare-donor registry expands with AnWj-negative donors

Possible Resolves by Q2 2028

Discussed by: WIRED's analysis of Nicole Thornton's comments

Thornton said the new test makes it easier to find AnWj-negative people willing to donate blood for the few patients who need it. Rare-donor programs coordinated by the International Society of Blood Transfusion would log newly identified genetic cases. Each new donor shrinks the pool of patients dependent on a handful of known compatible units.

3

MAL suppression emerges as a cancer diagnostic marker

Possible Resolves by End of 2028

Discussed by: Researchers who observed that certain cancers suppress MAL expression

The team noted that some patients develop AnWj-negative blood because a cancer or blood disorder suppresses the MAL gene rather than because of inherited DNA. That link could make MAL expression useful in monitoring certain cancers. Research would need to show the suppression tracks with tumor activity over time.

4

Sutimlimab becomes a rescue therapy for anti-AnWj hemolysis

Possible Resolves by End of 2027

Discussed by: Clinicians who reported the 2026 lymphoma case

The 2026 case is the first use of sutimlimab, a complement inhibitor, against anti-AnWj-associated red-cell destruction. Lab values improved, but the short treatment window left effectiveness unproven. More case reports will determine whether the drug becomes a standard option for this rare antibody.

Historical Context

3 moments from history that rhyme with this story — and how they unfolded.

1939–1940

Rhesus (Rh) factor (1939–1940)

Karl Landsteiner, Alexander Wiener and Philip Levine identified the Rh factor after finding that blood from a rhesus monkey produced antibodies against human red cells. The work explained why some women's immune systems attacked their babies' red cells, causing hemolytic disease of the newborn, and why some transfusions failed.

Then

Rh testing became standard in pregnancy and transfusion within a decade.

Now

Rh remains the second most clinically important blood group after ABO, and anti-D prophylaxis now prevents most cases of hemolytic disease.

Why this matters now

Like the MAL discovery, Rh showed that matching blood beyond the ABO groups saves lives in transfusion medicine.

1950

Duffy blood group (1950)

The Duffy blood group was named in 1950 after a multiply-transfused hemophiliac patient whose blood produced a new antibody. Later research found that most people of West African descent lack Duffy antigens, and that this absence protects against a malaria parasite that uses the Duffy receptor to enter red cells.

Then

The discovery added Duffy to routine blood typing for transfusions.

Now

It explained malaria resistance in large populations and made Duffy a central tool in malaria biology.

Why this matters now

Duffy shows that a rare or absent blood antigen can carry real clinical weight across large populations, the same reason AnWj matters.

1951

Kidd blood group (1951)

In 1951, a woman named Mrs. Kidd gave birth to a baby with hemolytic disease caused by an antibody later named anti-Jka. Kidd antibodies became known for causing delayed, sometimes severe, transfusion reactions in patients who had been sensitized by earlier pregnancies or transfusions.

Then

Kidd typing was added to pre-transfusion testing.

Now

The case established that newly discovered antibodies should be treated as clinically significant until proven otherwise.

Why this matters now

Kidd is the classic example of a blood group discovered because it caused a bad reaction, the exact scenario the new MAL test now prevents.

Sources

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