Rhnull: The ‘Golden Blood’ Type

One of the rarest blood types on Earth.

Super rare blood type by Karolina Grabowska from Pexels

Sorry AB-negative; you’re not the only rare blood type in the world.

First discovered in an Aboriginal Australian woman in 1961, the Rhnull (Rhesus null) is one of the rarest and most precious blood types in the world. Like a needle in a haystack, less than 50 people in the world are known to have it!

To find out why this blood type was coined as the ‘golden blood’, we need to open the world of blood types and its systems.

The relationship between our immune system and blood types

Blood type (also called blood group) is genetically determined. Blood is primarily categorised based on the presence and/or absence of antigens on the surface of our red blood cells (RBCs). Antigens are distinct molecules or substances capable of coaxing an immune response. Our immune system sends out mini soldiers called antibodies (also known as immunoglobulins), which are special proteins that recognise and bind to these antigens.

If our antibodies recognise these antigens as allies or naturally part of our body, our immune system happily leaves it alone. But if they detect enemy or foreign antigens, our immune system will go on an all-out war to destroy them. Unfortunately, our immune system isn’t perfect. In rare cases, it does attack ‘self’ antigens, as seen in some cases of autoimmune blood disorders.

A, B, O is not easy as 1-2-3 in human-blood transfusion

Now that we know how blood types are determined, you might be wondering “How many blood types are there?”. At present, the International Society of Blood Transfusion recognises 36 human blood group systems and more than 300 different antigens.

You might be familiar with the ABO blood group system. When you ask someone what blood type they are, they might respond with “AB”. They are referring to this most important blood group system in human-blood transfusion. It comprises of only two antigens (antigen A and antigen B), but it can produce these four ABO blood types: A, B, AB or O. This site provides neat animations about the ABO group system and more details of its importance in human-blood transfusions.

ABO blood type by InvictaHOG (Public Domain) on Wikimedia Commons


But there’s another equally significant blood group system to consider in human-blood transfusion: the Rh system (again, Rh pronounced as Rhesus).

Positive or negative, it critically matters

The Rh blood group system has a colourful history. It consists of 61 blood group antigens (Rh antigens), which are expressed as part of a protein complex found only in RBC membranes. Rh antigens are believed to be essential for maintaining the integrity of RBCs.

Briefly going back to ABO blood group system, some people might tell you that they’re “O negative” or “A positive”. The negative/positive part refers to the absence or presence of one Rh antigen: the Rh(D) antigen. It’s the main Rh antigen considered for human-blood transfusion and it’s severely implicated in foetal loss and death of newborn babies.

So… what about Rhnull?

People who have the ‘golden blood’ type lack these Rh antigens. Their DNA lacks the genes responsible for building those RBC protein complexes. These people don’t just lack one, two or three of these 61 Rh antigens, they actually lack all of them. Yes, you read that right: all of them. As you might have guessed, people with Rhnull blood type have abnormal RBCs. They have deformed shapes, leaky membranes and shorter lifespans, which sometimes result in mild anaemia for the individual. Still, the absence of all Rh antigens makes Rhnull the ‘golden blood’, which is highly admired for its rarity and medical purposes.

With great blood type comes great responsibilities (and consequences too!)

Rare blood types within the Rh blood type system can make it difficult or even impossible to get a blood transfusion. This makes Rhnull blood as the ‘universal’ life-saving blood for the Rh blood type system (especially if the donor has an ABO blood type O too). This article follows the story of an individual with this ‘golden blood’ and how it was used to save a life across the world.

But rarity comes at a price. If people with Rhnull blood type requires a blood transfusion, they can only receive Rhnull blood themselves. Even if they receive an O-negative blood, the presence of other Rh antigens on the RBCs may trigger a severe immune response. Therefore, these ‘golden blood’ carriers are solely dependent on other Rhnull donors, but only a few of them regularly donate and they are all spread out across the world.

This is why Rhnull blood is considered as the ‘golden blood’, but it’s not all sunshine and rainbows for those people who carry it. Still, we can’t deny the life-saving properties of this rare blood type and we can deeply appreciate the generosity of those selfless donors.


Antigens-antibodies interaction

6 Responses to “Rhnull: The ‘Golden Blood’ Type”

  1. Janine Jaramillo says:

    Thank you for reading and for your kind words, Calandra. Regarding the encouragement of blood donation from people with rare blood types, I’ll answer that in 2 parts.
    1) Safety net for rare blood type carriers. What prevents majority of rare blood type donation is the fear that if they donate and have some sort of blood loss incident shortly afterwards, there’s a high risk of death. In a way, they want to ‘preserve’ their blood for themselves and I sympathise with them. To alleviate this, I think that a portion of their donated blood could be reserved for them in case of emergencies.
    2) More blood donations from other people. Blood donation rates around the world are really low and it’s usually the same people who donate. Therefore, we don’t really know how many people in the world have rare blood types. It would be great if we can get more blood donations from everyone. Who knows, their blood may actually match better than giving the blood of a ‘universal’ blood type.

  2. Janine Jaramillo says:

    Thank you for reading, Fangfeih. I’m very happy to hear that your friend’s surgery went ok and she didn’t require the additional blood. I think we don’t really consider how important knowing what our blood types are until something happens. I think it’s crucial to explore more of this area, as with all other fields in science, we still don’t know a lot about blood and blood typing.

  3. Janine Jaramillo says:

    Canis, thank you for reading and I’m glad to hear that it was straightforward!
    O-negative is considered the ‘universal life-saving’ blood type, but this only holds true for the ABO system (as ‘O’ blood type can donate to all blood type within the ABO system) and people who don’t have other complicated RH antigens. The negative part of O-negative says that the donor doesn’t have the Rh(D) antigen, which is what doctors and nurses mainly watch out for when performing ‘normal’ blood transfusion.

    But O-negative may still contain other Rh antigens, such as Rh(C), Rh(c), Rh(E) or Rh(e). Unfortunately, some people require very specific Rh blood type compatibility, which is why receiving an Rhnull blood type would be the most ideal for such cases. To be even more ‘golden’, a donor with an ‘O’ and Rhnull blood types would be most preferred. But do keep in mind there are other blood groups systems out there that requires even more specificity!

    I’m not sure if you’re referring to the O-negative or the Rhnull as a recent discovery. From my understanding, the ABO system (and O-negative) was discovered more than 100 years ago and the person who discovered it won the Noble Prize in 1930. The Rhnull blood was first discovered in 1961, but because it’s very rare (and doctors at the time didn’t believe it could exist), people thought that it might just be a random event. But now we know that there are around 43 people in the world with Rhnull.

    Additionally, all blood transfusions were working fine for some time using only the ABO blood group system, so the Rh system wasn’t given much notice. Recently, more and more cases require specific Rh blood type and hence, Rhnull became quickly sought after.

  4. Calandra Grima says:

    This article was interesting and insightful into the peculiarities of rare blood types. Great work!

    I have heard of the Bombay blood type but the Rh null type is new to me. It is really interesting how each of these blood types arise genetically.

    This article raises the discussion of blood donation from those with rare blood types. What do you think should be done (if anything) to encourage more people to donate blood if they have a rare blood type?

  5. fangfeih says:

    A really comprehensive introduction about blood type! I have a friend who has Rh AB-negative blood type. There was no blood storge of her type in the hospital when she got surgery. Luckily she didn’t need it. It’s worthwhile for scientists to explore in this field to find a way to save golden blood people under this circumstance.

  6. Canis Nugroho says:

    This was a very interesting and informative read! I’ve never properly understood how blood types worked until reading this, so it was definitely very well explained. The diagram and video was also really helpful too!

    I found it particularly interesting because at the place where I donate blood, there were a whole bunch of posters that claim that O-negative is the ‘universal life-saving’ blood type. I was wondering whether this blood type was a recent discovery, or is it just not often spoken about?