rhnull blood typeWe all know we should donate blood but probably don't as much as we should. Almost 5 million Americans need blood transfusions each year, and the network of blood donation and transfusion is vital to keeping people alive.

Rare blood types can be life-threatening

Some people have such rare blood types that any injury, procedure, or accident can be life-threatening. Rh-null people are the most dangerous blood type to have because no one else's blood would be compatible with theirs.

Most people have heard of the ABO and Rh systems, which determine who we can donate blood to or receive it from. The ABO system classifies blood based on the presence of antigens, antigen A and antigen B. Blood types A, B, AB, and O have both antigens and antibodies but neither antibodies on the blood cells nor in the serum.

Blood is donated, and the red blood cells are separated from the plasma where the antibodies are located. If a person with type A blood receives type B blood, their immune system will produce antibodies against the new blood cells. If you have type AB blood, you can donate blood to anyone, but you cannot donate to people with type A or B blood.

There are 60 different blood types in the rhesus system, with the D antigen being the most significant. People who are Rh-D negative can only receive Rh-D negative blood, while people who are Rh-D+ can receive either Rh-D positive or Rh-D negative blood.

There are eight blood types, and each of these eight types can be subdivided much further. Most people don't need to worry about the antigen called Vel, but for every 5,000 people, there is one person who does lack the antigen and should not receive blood.

World's rarest blood type: golden blood

Rh-null is the world's rarest blood type because it has none of the 61 antigens present in the Rh blood system. It is called the golden blood because it can be accepted where other blood types cannot.

Rh-null blood has enormous life-saving capabilities, but for those who have it it can be a curse. Only 42 people with the same blood type are active donors, and the logistics of shipping blood around the world are complicated.

Anyone with this rare type of blood is given the gift of being able to help someone at a time of need, but this also comes with the unfortunate burden of being on call for your entire life, should the need for your blood arise.

The American Red Cross flew almost two hundred thousand pints of blood from the US to the Allied forces in Europe during World War II.


The term "Rhesus" was originally an abbreviation of "Rhesus factor," which was first described in 1937 by Karl Landsteiner and Alexander S. Wiener. 

The significance of their discovery was not immediately apparent. Philip Levine and Rufus Stetson discovered it later, in 1940.

In 1939, Phillip Levine and Rufus Stetson reported a woman with a hemolytic disease in a newborn. The serum of this woman reacted with 80% of human red blood cells.

Based on serologic similarities, Rh factor was then also used for antigens and anti-Rh for antibodies found in humans. However, the factors differ in rhesus macaques according to the Landsteiner-Weiner antigen system.

Rh factor is important for:
  • blood transfusion
  • newborn hemolysis
  • prevention by screening and prophylaxis