Unmasking the 'golden blood' type: the rare Rh‑null that could be in one out of every six million

This rarest of blood types is defined by an unusual Rh factor that is neither negative nor positive. It is designated as Rh-null by scientists. Blood consists of various molecules, including proteins or blood group antigens. Using these, various systems can be established. To date, 32 combinations have been discovered.

To understand better, let's go over the basic blood groups and what defines them. The O blood group lacks any antigens while group A, B, and AB are successively characterized by antigen A, B, and AB. Noteworthy are the antibodies, produced in response to antigens absent from the blood cells:

• Group O produces anti-A and anti-B antibodies,
• Group A generates anti-B antibodies,
• Group B forms anti-A antibodies,
• Group AB does not produce any antibodies.

Apart from antigen A and B, there's also the antigen D. This antigen is present in 85% of people (those with an Rh-positive blood group). Similarly, its absence characterizes the Rh-negative blood group. Of the 61 known blood group antigens, the negative/positive distinction refers solely to antigen D. During blood transfusion, people with Rh- factor can donate plasma to those with both Rh+ and Rh- factors. Those carrying a positive factor can only donate to individuals with the identical factor. Rh- is particularly sought after because it can be given to anyone, due to the absence of the aforementioned antigens.

"Golden blood" is not golden in literal terms, but it carries a unique characteristic that makes it fit for royalty. Specifically, this type of blood lacks any of the 61 Rh antigens. Its distinctive factor is indeterminable, thereby earning it the 'null' label. The first individual diagnosed with this condition, in 1961, was an Australian woman. Scientists speculate that this blood type could be present in one person out of every six million! So far, only 43 people have been confirmed to possess this blood type.

We know that blood characteristics are hereditary, and the same holds true in this case. Research points to the appearance of this condition being due to the autosomal recessive inheritance pattern (both parents pass on a copy of the mutated gene). Such individuals can donate blood to any group, but they can only receive blood from people with the same condition. Doctors thus advise them to donate and store blood for themselves in an emergency.