We’re all familiar with the basic blood types—A, B, AB, and O—along with their positive or negative variants that indicate the presence or absence of the Rh factor. But did you know that the world of blood types is far more complex than that?
In fact, scientists have identified over 600 different antigens on human red blood cells. The unique combinations of these antigens can create millions of distinct blood types. However, only 48 blood group systems are officially recognized by the International Society of Blood Transfusion (ISBT) as of 2025.
And most fascinating of all? The 48th blood group was just recently discovered—and so far, it belongs to only one person in the world: a woman from Guadeloupe, a French overseas territory in the Caribbean.
The Mystery Begins: An Unusual Blood Test
The story began in 2011, when this 54-year-old woman, then living in Paris, underwent a routine blood test before surgery. The results revealed unusual antibodies in her blood—ones that couldn’t be explained by any known blood group system at the time.
Researchers were baffled. Her blood didn’t match any documented type, turning her case into a medical mystery that remained unsolved for years.
Genomic Technology and the Long-Awaited Answer
It wasn’t until eight years later, in 2019, that technology had advanced enough to crack the case. A team from the Établissement Français du Sang (EFS)—France’s national blood research institute—performed an in-depth DNA analysis using high-throughput gene sequencing.
This allowed them to read the woman’s entire genome in detail. And that’s when things got really interesting.
They discovered she carried a rare genetic mutation in a gene called PIGZ, which plays a role in how proteins attach to the surface of red blood cells. This mutation resulted in a previously undocumented combination of antigens, effectively creating a brand-new blood group in the history of transfusion medicine.
So Unique, It’s Only Compatible with Itself
The findings were so extraordinary that Thierry Peyrard, a medical biologist at EFS, stated that this woman is the only person in the world compatible with herself. Her newly identified blood type was named "Gwada Negative," derived from the local name for Guadeloupe, the patient’s homeland.
In the world of blood transfusion, this discovery is highly significant. Since the human immune system can react strongly to foreign antigens, receiving incompatible blood can trigger dangerous, even life-threatening, reactions. That’s why recognizing the existence of such rare blood types is crucial—it can save lives.
Why This Discovery Matters
While most blood transfusions are successful by simply matching the ABO and Rh factors—with a success rate as high as 99.8%—not everyone is fully protected by this standard approach. Some patients produce antibodies against rarer antigens that aren't part of the ABO-Rh system.
The discovery of Gwada Negative is a clear reminder that there is still much we don’t know about human blood. For patients with rare conditions like this, finding a compatible donor is an enormous challenge. That’s why identifying new blood systems can pave the way for more personalized and accurate medical care.
The Next Genetic Search Project
The research team now plans to continue their search to find out whether others around the world may carry the same genetic mutation. Because blood types are inherited, there’s a possibility that this mutation also exists among the descendants or population groups from the Guadeloupe region. As such, the next phase of the study will focus on screening blood donors from that area.
“Discovering new blood groups means offering patients with rare blood a better level of care,” stated the EFS team in an official release.
They hope that with advances in technology and growing awareness of the importance of rare blood donations, more cases like this can be identified earlier and treated more effectively.
The Evolution of Blood Type Science: From 1901 to Today
Our understanding of blood types began more than a century ago. In 1901, Austrian-American scientist Karl Landsteiner identified the ABO blood group system, which made blood transfusion a safe medical procedure. His groundbreaking discovery earned him the Nobel Prize in 1930.
Before this, blood transfusions often ended in disaster, as recipients’ bodies would reject the donor’s blood—causing dangerous clotting reactions. Landsteiner discovered that this clotting occurred due to the interaction between antigens on red blood cells and antibodies in the recipient’s plasma.
Since then, the classification of blood types has continued to evolve. Following the ABO system came the Rhesus (Rh) system, and over time, dozens of other systems have been identified thanks to advancements in technology.
Now, with the addition of "Gwada Negative" as the 48th recognized blood group system, we are reminded that the human body still holds many secrets yet to be uncovered.
Toward a More Personalized Future in Transfusions
The discovery of Gwada Negative is more than just an entry on a list of blood group systems. It represents how science and technology are enabling us to understand human biological diversity on a deeper level. The more we learn about blood type variations, the more lives we can potentially save.
One day, routine blood tests may not only report A, B, AB, or O—but include detailed systems that are still hidden today. And who knows, we may even discover that our own blood is far more unique than we ever imagined.
