Do you know your own blood type? If not, a quick look at your medical records or your donor card can hopefully answer that question, and help practitioners identify the right type needed for transfusion in case of an emergency. But not so for one woman from France. Despite needing a transfusion in 2011, doctors could not identify her blood type — or match her with a donor.
After extensive genetic analysis of her blood samples, researchers from Inserm, Paris Cité University, the University of the Antilles, the French National Blood Service (EFS), and the National Reference Center for Blood Groups (CNRGS) published a surprising discovery: this patient had a never-before-seen blood type, now officially recognized as the 48th blood group system.
Blood Systems and Blood Types
Not all blood is the same — like the color of our eyes, our blood type is determined by our genes. Blood types vary based on specific antigens present (or absent) on the surface of red blood cells. These antigens are recognized by our immune system, meaning a transfusion with incompatible blood can trigger a severe or even life-threatening reaction.
The most familiar systems are ABO and Rh, typically shown as a letter followed by a + or – sign (e.g., A+, AB-, O+). These are the most clinically significant for transfusions because their antigens are very immunogenic, meaning that they are especially likely to provoke an immune response. While other blood group systems exist, their antigens are less reactive and are generally screened only if a patient shows rare or unexpected antibodies.
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An Ultra-Rare Blood Type
But even well-established systems have their limits. In 2011, the CNRGS hit a puzzling roadblock when they failed to identify the antibody present in a patient’s blood. Without knowing her blood type, no compatible donor could be found. Years later, in 2019, researchers revisited the case and requested additional samples to try again.
This time, they went all in: sequencing the patient’s entire genome, roughly 22,000 genes. What they uncovered led to the identification of a completely new blood group system, dubbed PigZ. So far, it contains only one known blood type: GWADA negative, named in reference to the patient’s Guadeloupean origin.
This makes GWADA negative an ultra-rare blood type — perhaps even unique to this one person. Its discovery wasn’t just a stroke of luck; it was the result of years of meticulous research and full genetic sequencing.
Discovering New Blood Systems
The discovery marks a major milestone for transfusion medicine and underscores the persistence of researchers like Slim Azouzi, a specialist in rare blood groups. His team worked for over two years to understand this medical mystery, ultimately uncovering a completely new classification.
Finding a new blood group system is a rare and significant achievement, the very first one, ABO, was identified in 1900 by Karl Landsteiner. But in recent years, scientific advancements have sped up the pace. Of the 17 blood group systems discovered globally since 2012, 10 have been uncovered by France’s EFS and its research collaborators.
For patients with rare blood types, discoveries like these offer hope. Every new blood group we identify adds another layer of precision and safety to modern transfusion practices — and could mean the difference between life and death when compatible blood is scarce.
This article is not offering medical advice and should be used for informational purposes only.
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Article Sources
Our writers at Discovermagazine.com use peer-reviewed studies and high-quality sources for our articles, and our editors review for scientific accuracy and editorial standards. Review the sources used below for this article:
American Red Cross: Facts About Blood and Blood Types
EFS: Our News
