How rare can the blood that flows in your veins be? For a 60-year-old woman from Guadeloupe, the answer is simple: unique in the world. Her new blood type, christened “Gwada negative“, took fourteen years of research to identify and is now officially the 48th classification system ever discovered in human history.
To be clearer (but no less romantic, eh eh): it is a drop of blood that has rewritten the manuals of transfusion medicine and opened up new scenarios for patients with rare groups. The protagonist of this scientific story did not know it, but she carried within herself a genetic code never seen before, inherited from both parents.
A mystery that began in 2011
The story begins in a Parisian hospital during a routine pre-operative check-up. The patient, then fifty-four years old, is undergoing standard blood tests when the lab technicians notice something unusual: a mysterious antibody that does not correspond to any known classification. Thierry Peyrard, medical biologist of theFrench Blood Institute (EFS), remembers that moment as the beginning of a puzzle that seemed unsolvable.
At the time, the available technologies did not allow for further investigation. The anomalous antibody was catalogued and archived, awaiting more sophisticated instruments. The woman returned to her daily life, unaware that she was carrying with her one of the most significant discoveries in modern medicine. As we anticipated some time ago, the world of blood groups still hides many secrets.
New Blood Type Revealed by DNA
In 2019, Slim Azouzi and the team of researchers decide to reopen the case. Thanks to high-speed genetic sequencing, they analyze the patient's entire genome: about 22.000 genes scrutinized one by one. The result leaves them speechless. The woman has a genetic mutation never observed before, inherited from both parents. This peculiarity has given rise to a new blood group completely new.
The official classification will arrive in June 2025, when the International Society of Blood Transfusion recognizes in Milan the existence of the 48th human blood group system. The chosen name, “Gwada negative”, pays homage to the patient’s Guadeloupean origins (Gwada is the affectionate nickname of the island) and belongs to the PigZ system.

New blood group, total incompatibility and the search for new carriers
The rarity of the new blood type poses real medical challenges. The patient is literally incompatible with any other human being for transfusions. In case of surgery or medical emergencies, can receive blood only from itself.
Discovering new blood groups means offering patients with rare blood groups a better level of care
Thierry Peyrard emphasizes how this discovery opens up new perspectives for transfusion medicine. Researchers are now developing specific protocols to identify other carriers of the mutated gene, focusing mainly on Guadeloupe and Caribbean communities.
The future of transfusion medicine
The discovery of the new blood group shows how human genetics still holds surprises. Since 1900, when Karl Landsteiner identified the first ABO system, science has progressively revealed the complexity of blood compatibility. According to recent studies, the pace of discovery has accelerated in recent years thanks to improvements in genetic sequencing techniques.
Experts hope that identifying more individuals with the new Gwada-negative blood type could improve treatment options for patients with rare blood types and facilitate research into autoimmune diseases or transplant rejections. If you’re there, Gwada friends, please raise a bell!