Blood transfusions have changed the face of modern medicine. When someone is injured or needs major surgery, donated blood can save their life.
However, not everyone can easily receive donated blood. People with very rare blood types often struggle to find a match.
One of the rarest blood types in the world is Rh null — sometimes called “golden blood.” Only about 50 people are known to have it. Because their blood type is so unique, it’s very hard to find a donor if they ever need a transfusion. To stay safe, people with Rh null blood are often advised to store their own blood for emergencies.
Despite its rarity, Rh null blood is extremely valuable to science and medicine. It can be used to help develop universal blood — a type that could be given to anyone, regardless of their blood group.
Why Blood Types Matter
Blood types are grouped based on special markers called antigens found on red blood cells. These markers act like ID tags for your body. If you receive blood with antigens that your body doesn’t recognize, your immune system may attack it — which can be dangerous.
The two main blood group systems are ABO and Rhesus (Rh):
- People with A blood have A antigens.
- People with B blood have B antigens.
- AB blood has both.
- O blood has neither.
Each type can also be Rh positive or Rh negative, depending on whether a specific Rh antigen is present.
Many people think O negative blood is universal, but that’s not entirely true. There are over 47 blood group systems and 366 known antigens, so reactions can still occur if other antigens don’t match.
People with Rh null blood have no Rh antigens at all — not just the common D antigen, but none of the 50 Rh antigens. This makes their blood highly useful for research and sometimes for transfusions in critical cases, because it can safely match with almost any Rh type.
But there’s a catch: people with Rh null can only receive Rh null blood, which is incredibly hard to find.
How Scientists Are Trying to Create “Golden Blood”
Researchers are now using gene editing technologies like CRISPR to try to make Rh null or other ultra-compatible blood types in the lab. Scientists in the UK, the US, Canada, and Spain have already made progress by editing blood stem cells to remove the genes that produce antigens.
If successful, this could help people with rare blood types and make emergency transfusions safer.
However, growing red blood cells in the lab is still very difficult. In the human body, bone marrow provides complex signals that help red cells mature properly — a process not easily copied in the lab. It may take years before lab-grown blood can be used widely in hospitals.
For now, people with rare blood types rely on blood banks and research projects that collect and store their blood for emergencies.
As Professor Ash Toye from the University of Bristol explains, “Donated blood will always be essential. But for people with rare blood, being able to grow more of their own blood would be life-changing.”
