The ABO-Rh system of blood group typing is an immensely successful method that helps medical professionals safely perform blood transfusions throughout the world.
Scientists from the French Blood Establishment (EFS) has successfully identified the ultra-rare 48th blood type group, known as “Gwada negative,” which came from a blood sample originally drawn some 15 years ago.
Although rare, it’s important for physicians to know about these blood types so that impacted patients can receive the best care possible.
Most people are familiar with the four broad human blood types—A, B, AB, and O—and it’s likely they may even know that they come in positive or negative varieties (an indicator of what’s called an Rh factor) as well. However, that’s really only the tip of the iceberg when it comes to the complexity of human blood types. In fact, humans theoretically contain millions of different blood types, as there are more than 600 antigens that have been identified on human blood cells. Any combination of those antigens could be considered a new blood type.
However, the International Society of Blood Transfusion (ISBT) only recognizes 47 distinct blood type groups, with the latest being added just last year after a 50-year-long mystery. Now, according to a press statement published on LinkedIn by the French Blood Establishment (EFS), a 48th member has officially joined the party. Some 15 years ago, researchers received blood from a French woman originating from the Caribbean island of Guadeloupe, colloquially referred to as “Gwada.” The patient drew blood while undergoing routine tests before surgery.
An unusual antibody associated with this blood was discovered in 2011, but it wasn’t until 2019 that DNA sequencing found that a genetic mutation was responsible for the unique blood type, which was officially recognized by the ISBT this month. The researchers named the group “Gwada negative,” after the patient’s homeland, and confirmed that the woman inherited the blood type from her parents, who each contained the mutated gene.
“[This] is undoubtedly the only known case in the world,” Thierry Peyrard, a medical biologist at EFS, told Agence France-Presse (AFP). “She is the only person in the world who is compatible with herself.”
Its immensely important to know the antigen make-up of your blood before undergoing blood transfusions, as mismatch can trigger a life-threatening immune response. Essentially, your body thinks the antigens attached to the foreign blood cells are invaders. Although there are potentially millions of blood types, transfusions made with blood that matches your type according to the well-established ABO-Rh type system have a 99.8 percent chance of success. This is because your body’s immune response doesn’t attack all antigens equally, so even if there are some differences, the transfusion will likely be a success.
However, it’s still important to identify these ultra-rare blood types so that life-threatening immune responses can be avoided. “Discovering new blood groups means offering patients with rare blood a better level of care,” the EFS team said in a press statement.
Although the current number of blood groups sits at 48, that likely won’t be the last count. Advancements in gene sequencing have supercharged the discovery of these blood groups. For example, the 44th member of this group, known simply as “Er,” was discovered in 2022, meaning that scientists are currently discovering more than one new blood group a year.
2025 might hold one or two more blood-based surprises of its own.
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