French scientists have made a remarkable breakthrough by identifying a new blood group, informally dubbed “Gwada negative.” This addition now marks the 48th recognized blood group system in the world. So far, researchers have found this extraordinarily rare blood type in only one individual—a French woman originally from the Caribbean island of Guadeloupe.
Earlier this month, the French Blood Establishment (EFS) officially announced the discovery. The International Society of Blood Transfusion (ISBT) recognized it soon after, in June 2025. This finding highlights the complexity and diversity of human blood. It also underscores how crucial blood research is for transfusion medicine and personalized healthcare.
Tracing the Origins of “Gwada Negative”
The story of “Gwada negative” began in 2011, when doctors in Paris conducted routine pre-surgical tests on the 54-year-old woman. During this process, they detected an “unusual” antibody in her blood. At that time, researchers couldn’t solve the mystery due to technological constraints. However, with the advent of high-throughput DNA sequencing in 2019, scientists finally identified a unique genetic mutation responsible for this new blood type.
Thierry Peyrard, a medical biologist at the EFS and a key figure in the discovery, later confirmed that the woman had inherited this rare blood trait from both parents. In contrast, her siblings—who inherited just one copy of the mutated gene—did not exhibit this specific blood group.
Why “Gwada Negative” Is So Unique
What sets “Gwada negative” apart is the absence of the EMM antigen, which is typically found on red blood cells and classified as a high-incidence antigen. Because this antigen is missing, her blood type is considered exceptionally rare. Peyrard explained that she is “undoubtedly the only known case in the world,” meaning that she is only compatible with herself for transfusions.
Consequently, the challenges in sourcing compatible blood for her are immense—a transfusion from anyone else could prove fatal. The nickname “Gwada negative” honors both the patient’s Guadeloupean heritage (“Gwada” being a popular nickname for Guadeloupe) and the term’s global phonetic accessibility for experts.
