Doctors Detected a Mysterious Antibody in a French Woman’s Body. It Turned Out to Be a Brand New Blood Type
Called “Gwada negative,” it marks the discovery of the 48th known blood group system in humans
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In 2011, a French woman was undergoing routine medical testing before surgery when doctors discovered a mysterious antibody in her blood.
Now, scientists say the woman is the only known carrier of a new blood type called “Gwada negative.” It’s the only blood type within a new blood group system that scientists have dubbed “PigZ,” which is now the 48th known blood group system in humans, as the French Blood Establishment (EFS) announced last week.
The woman, who has not been identified publicly, is from Guadeloupe, a French-controlled island group in the Caribbean. When the woman had her blood drawn nearly 15 years ago, she was 54 years old and living in Paris. At the time, doctors knew something was unusual about her blood, but they didn’t have the resources to investigate further.
In 2019, researchers revisited the case. After requesting additional blood samples, they sequenced the woman’s entire genome, which contained approximately 22,000 genes. Her DNA revealed that she had a genetic mutation, which she inherited from both of her parents, that resulted in a previously unknown blood type.
“She is the only person in the world who is compatible with herself,” says Thierry Peyrard, a biologist with the EFS, to the Agence France-Presse (AFP).
The name “Gwada negative” comes from the phonetic pronunciation of Guadeloupe, the woman’s home region. It “sounds good in all languages,” Peyrard tells the AFP, and so far has been a popular name among experts.
Moving forward, researchers are eager to know if other people might have the same genetic mutation and the same blood group.
“Discovering new blood groups offers patients with rare blood types a higher level of care,” according to a LinkedIn post from EFS, translated by Smithsonian magazine. “It’s one of the commitments that the EFS pursues daily.”
Human blood types were initially discovered in 1901 by Karl Landsteiner. The Austrian-American physician was later awarded the 1930 Nobel Prize in Physiology or Medicine for his work, which led to safe and effective blood transfusions.
Did you know that medicine laureate Karl Landsteiner’s research in the early 1900s led to the classification of blood into groups?
— The Nobel Prize (@NobelPrize) June 17, 2025
The discovery of blood groups completely changed the view on blood transfusions, and it didn’t take long before the first successful attempts were… pic.twitter.com/4Zn7c3QxEQ
Doctors in Europe had been attempting blood transfusions since the 1600s, but these procedures were largely unsuccessful and typically resulted in the recipient’s death, according to the Nobel Foundation. No one understood why transfusions were often so disastrous—until Landsteiner solved the mystery.
His work revealed that red blood cells from one person had a tendency to clump together when mixed with red blood cells from another person, in a process known as “agglutination.” In the human body, he realized, these clumped red blood cells could cause all sorts of problems, including clogged blood vessels and death.
Landsteiner categorized patients into three groups based on their blood types—now known as A, B and O. Not long after, a fourth group, dubbed AB, was discovered. Together, these comprised the first known blood group system, called ABO. Through his research, Landsteiner realized that blood transfusions could only be performed safely between patients from compatible blood groups.
That’s because each blood type has its own combination of antigens on red blood cells, which are responsible for triggering the body’s immune response to—or acceptance of—foreign blood introduced during an infusion. For instance, in a person with type A blood, the body will attack blood cells with B antigens, but not those with A antigens.
Did you know? The universal donor
- Type O negative blood is known as the “universal donor,” because it can be transfused to people with any A, B, O or AB blood type. Only about 7 percent of people have O negative blood.
- O positive blood is the most common type, representing about 38 percent of the population.
Humans have four major blood groups—the same ones identified at the beginning of the 20th century: A, B, O and AB. Since then, scientists have also determined that blood cells are influenced by a protein called the Rhesus factor. Some patients’ blood cells have a particular antigen related to this protein (positive), while others don’t (negative). As a result, humans have eight common blood types: A positive, A negative, B positive, B negative, O positive, O negative, AB positive and AB negative.
But the full range of human blood is more complex. Scientists now know blood types result from the presence or absence of at least 366 antigens, according to the International Society of Blood Transfusion. Slight variations in which of these antigens are present can lead to rare blood types. The ABO blood group system is only one of many—with the new French research bringing that total to 48.
Identifying a patient’s blood type is key to safely giving them a transfusion, reports the AFP. In the United States, doctors transfuse more than 14 million units of blood each year, according to the Centers for Disease Control and Prevention.
