A newly discovered blood type has been identified in a 68-year-old woman from Guadeloupe, making her the only known person in the world with this rare classification. Scientists uncovered the unique case during routine testing, marking a major development in the ongoing study of human blood groups.
The woman, who was living in Paris in 2011, underwent standard pre-surgery tests. But her results puzzled doctors—her blood didn’t match any known type, and no compatible donors could be found. At the time, testing technology could not explain the anomaly. The case was left unresolved for nearly a decade.
Researchers reopened the case in 2019, using advanced DNA analysis methods to examine her blood in greater depth. Over two years, the team sequenced her entire genome and found the answer: a mutation in a gene called PIGZ.
This gene affects how certain proteins attach to red blood cells. Because of this rare mutation, her blood does not align with any previously known group. Scientists named the newly recognized classification “Gwada negative,” after a local nickname for Guadeloupe.
A decade-old mystery solved through advanced DNA research
The discovery was presented at the International Society of Blood Transfusion’s Congress in Milan, which concluded on June 4. It has since been officially added as the 48th recognized blood group system.
While most people are familiar with the eight common blood types based on the ABO and Rh systems, the field is much broader. These two systems determine whether red blood cells have A, B, or Rh antigens, which play a critical role in transfusions.
But beyond these, dozens of lesser-known systems exist. As of 2024, the international blood transfusion community recognizes 45 of them, with Gwada negative now included.
A French woman’s rare genetic trait has led to the discovery of a brand new blood group – Gwada Negative, now officially recognized as the 48th blood group system by ISBT.
She’s the only known match for herself. #Health #SriLanka #lka #GwadaNegative #MedicalDiscovery pic.twitter.com/WMdnMDoxDa
— Dr Chandana Wickaramasinghe (@DrChandanaWick) June 25, 2025
Understanding blood types is essential because our immune systems are designed to reject unfamiliar antigens. If a person receives the wrong type of blood, their body may react dangerously.
That’s why matching blood types is vital for safe transfusions. For instance, people with AB blood can accept donations from nearly anyone, while those with type O can only receive blood from other type O donors.
Discovery matters for the future of transfusions
In the case of the woman from Guadeloupe, her mutation means no one else on record can safely donate to her or receive her blood. “She is the only person in the world compatible with herself,” said Thierry Peyrard, a biologist at France’s national blood service, Établissement français du sang.
Scientists now hope to find others who may share this newly discovered blood type. Since blood traits are inherited, the team plans to search among donors in Guadeloupe, where the woman’s ancestry lies.
“Discovering new blood types means offering patients with rare blood a better level of care,” the national blood agency said in a statement.
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