A team of scientists has discovered a new blood type in a 68-year-old woman from the French overseas region of Guadeloupe. The researchers recently announced their finding at the congress of the International Society of Blood Transfusion in Milan.
How Was This Unknown Blood Type Discovered?
This Guadeloupe native is currently the only known person with the blood type dubbed “Guada negative.” The research team first encountered her in 2011 when she was living in Paris and undergoing routine examinations prior to surgery. At that time, medical professionals were unable to identify her blood type: it simply didn’t exist.
In 2019, scientists re-examined the patient’s blood. They utilized a high-throughput gene sequencing method that allows for faster and deeper DNA analysis. Over two years of detailed research, the team sequenced her entire genome, as reported by Live Science.
The unusual results from the woman’s laboratory tests ultimately led to the discovery of a mutation in the PIGZ gene, which affects how proteins attach to the surface of blood cells. The unique mutations in this woman mean that “she is the only person in the world compatible with herself,” said Thierry Peyrard, a biologist at the French blood research center Établissement français du sang (EFS).
What You Need to Know About Blood Types
The systems of human blood types are more complex than one might think. These classifications relate to the proteins and sugars on the surface of red blood cells, known as antigens. Our immune system recognizes these antigens. Austrian-American biologist Karl Landsteiner identified the first and most well-known blood type system—ABO—in 1901, earning him the Nobel Prize in 1930.
The classic ABO blood type system describes whether individuals have one or both of the A and B antigens on their blood cells (or neither). The second most recognized blood type system is the Rh factor classification, which considers whether cells are positive or negative based on the presence of an antigen known as the Rh factor.
In total, the key systems define eight main blood types, while there are dozens of lesser-known types. As of 2024, 45 of these have been recognized by the International Society of Blood Transfusion (ISBT). The new blood type “Guada negative” has been assigned the number 48.
The next goal for the research team is to determine whether there are other individuals on our planet with this unique characteristic. Since blood type is a genetic factor, the researchers plan to begin their search in Guadeloupe, particularly among local blood donors.
Such discoveries are crucial primarily because they enable the provision of quality medical care to patients with rare blood types, noted EFS.