- Who Has It?
- 8 Blood Types Charts
- O Negative
- 3 Rarest Blood Types
- Blood Types Affect COVID-19
The golden blood type or Rh null blood group contains no Rh antigens (proteins) on the red blood cells (RBCs). This is the rarest blood group in the world, with less than 50 individuals having this blood group. It was first seen in Aboriginal Australians.
The worry with the golden blood group is that the donations of Rh null are incredibly scarce and difficult to obtain. An Rh null person has to rely on the cooperation of a small network of regular Rh null donors around the world if they need the blood. Across the globe, there are only nine active donors for this blood group. This makes it the world’s most precious blood type, hence the name "golden" blood.
Our red blood cells have proteins called antigens on their surface. Depending on the antigen present, we have A, B, O, or AB blood type. The ABO system has a further distinction as Rh-positive or Rh-negative depending on the presence or absence of the "Rh-D" factor on the cells.
With the golden blood group, a person lacks all the Rh antigens whereas a person with Rh-negative blood group lacks only RhD antigen.
Why do some people have the golden blood type?
The golden blood group seems to be a result of genetic mutation (spontaneous change in a gene). It is commonly seen with mutations in the RHAG gene, which codes the Rh-associated glycoprotein. This protein is required for directing the Rh antigens to the RBC membrane.
RHAG mutation is often associated with a disease called hereditary stomatocytosis. These individuals can have long-term, mild, hemolytic anemia and increased RBC breakdown. The Rh-null phenotype can also be seen in the case of certain anemias a person may be born with.
The following conditions may put you at a higher risk of golden blood group:
Can golden blood be donated?
Yes, golden blood can be donated. Because of the absence of antigens on RBCs, a person with Rh null blood is considered to be a universal donor, and this blood can be donated to anyone with rare blood types within the Rh systems.
This blood is excellent for transfusion because it lacks common antigens, and it can be accepted by anyone who needs a transfusion without the risk of a blood transfusion reaction. However, due to its rarity, it gets extremely difficult to find this type.
Conversely, Rh null is usually not so good for the people who have it. If they ever require a blood transfusion, receiving any blood that does have the Rh antigen may inevitably cause a transfusion reaction.
What are potential complications of the golden blood type?
People with Rh null or golden blood type may have:
- Mild to moderate hemolytic anemia since birth: This leads to faster destruction of RBCs, which may cause low hemoglobin levels and lead to paleness and weariness. This occurs due to structural defects in RBCs like:
- Mouth-like or slit-like shape
- Less elastic structure of red cells
- Abnormal red cell covering
- Increased fragility due to the lack of Rh antigen
- Altered blood cell volume
- Blood transfusion challenges: People with the golden blood type may face challenges during a blood transfusion. If the person’s blood is exposed to Rh antigens (proteins on the surface of RBC) from the other person’s blood, they readily form corresponding autoantibodies and there may be a severe transfusion reaction. Therefore, for these types of patients, hospitals need to have special protocols in place and quick response management.
- Rh incompatibility during pregnancy: If the mother is Rh null and the baby is Rh-positive, and if the mother’s blood gets sensitized by the baby’s positive blood, then the mother’s blood may produce protective proteins called antibodies that could target future pregnancies or lead to abortion or miscarriage.
- Hemolytic crisis: Several studies have found that an infection or sepsis in such individuals may precipitate massive hemolysis, subsequent kidney failure, and other complications.
How many blood types are there?
A, B, AB, and O are the four main blood groups. Each blood group can be RhD-positive or RhD-negative, resulting in a total of eight blood groups:
|Blood type||Blood group antigen||Rh factor|
|A+||A present, B absent||Present|
|A−||A present, B absent||Absent|
|B+||B present, A absent||Present|
|B−||B present, A absent||Absent|
|AB+||Both A and B antigens present||Present|
|AB−||Both A and B antigens present||Absent|
|O+||Both A and B antigens present||Present|
|O−||Both A and B antigens present||Absent|
Blood transfusion these days is only done after blood typing. Hence, people with certain blood groups can only donate to and receive from specific blood groups.
|Blood group||Can donate blood to||Can receive blood from|
|A+||A+, AB+||A+, A−, O+, O−|
|A−||A+, A−, AB+, AB−||A-, O−|
|B+||B+, AB+||B+, B−, O+, O−|
|B−||B+, B−, AB+, AB−||B−, O−|
|AB+||AB+||All blood group types|
|AB−||AB+, AB−||AB-, O−, A−, B−|
|O+||O+, A+, B+, AB+||O+, O−|
|O−||All blood group types||O−|
Blood groups are passed down from parents:
Is O negative the rarest blood type?
According to research, the distribution of O-negative (O−) blood type among the world's population is approximately 2.55%. According to the American Red Cross, about 38% of Americans have blood group O-positive and 7% (1 in every 15 individuals) have blood group type O-negative.
The prevalence of type O− varies with ethnicities:
- 37% among Caucasians
- 47% among African Americans
- 39% among Asians
- 53% among Latino-Americans
O− blood, also called "universal donor," is perhaps the most valuable blood in the world because it can be transfused to nearly any blood type (except when the person has some rare antigen outside of the main ones).
- When the recipient's blood type is unknown, such as during trauma or an emergency, O− blood is frequently used in transfusions.
- Unfortunately, O− blood is quite rare, and donors are in high demand all over the world due to the importance of this blood type.
- Because of its universality, O− blood is always the first to run out during a blood shortage according to the American Red Cross (can be given to people with type A, B, AB, or O)
- Unfortunately, people with O− blood can only receive O− blood, which is often in short supply.
Though only 3%-7% of the world's population is O+, it is not the only rare blood type.
What are the 3 rarest blood types?
- Rh-null or golden blood
- It is the world's rarest blood type, with fewer than 50 known cases ever reported. When a person's blood lacks all 61 possible antigens, they are said to be Rh-null.
- Because Rh-null lacks all possible antigens, it can be donated to people who have blood types that are very different from the main eight. However, Rh-null can only accept blood from people with Rh-null blood type.
- The scarcity of Rh-null blood, combined with its unique properties, makes it extremely valuable for scientific research, earning it the name "Golden Blood."
- AB− is the rarest of the eight basic blood types, accounting for less than one percent of the world's population. Within the United States, the least common of the eight well-known blood types is AB− with only 1 in every 167 people in the United States having it.
- While AB− can receive blood from all other Rh types, it can only donate blood to others who have AB blood, both Rh-negative and positive.
- Because AB− has both A and B antigens on its red cells, it is compatible with all the other major Rh-negative blood types.
- It is the universal plasma donor, and anyone from any blood group can receive plasma from AB blood.
- HH blood type, rare ABO group, or Bombay blood group
- This extremely rare phenotype blood group is found in approximately four per million of the world's population. One in every 10,000 people in Bombay may have it.
- There are approximately 179 people in India who have the Bombay phenotype blood group.
- Though the people with Bombay blood group are also O−, the additional H antigen that functions as a component of the ABO blood group is missing here. The absence of H antigen is referred to as the "Bombay phenotype."
- A person with the Bombay blood group can give blood to someone with the ABO blood group. They, however, can only take blood from their blood type, which is the HH blood type.
How may blood type affect COVID-19?
The potential role of blood type in predicting COVID-19 infection risk and complications has become a hot topic, and new studies add to the evidence that there may be a link between blood type and COVID-19 vulnerability.
According to recent research:
- People with blood type O may have the lowest infection risk.
- Individuals with A and AB may be at a higher risk of having serious clinical outcomes.
- Anti-A antibodies in people with blood groups O or B may block the virus's interaction with the cell receptor for angiotensin-converting enzyme 2 (ACE2), which is a mechanism for virus transmission.
Additional research is needed, however, to better understand why this is happening and what it means for patients.
Clinicians should continue to follow current protocols in the care of COVID-19 patients until more data is collected. Furthermore, the public must remain vigilant in wearing masks, maintaining physical distance, and maintaining strict hand hygiene.
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Uhl L. Red Blood Cell Antigens and Antibodies. UpToDate. https://www.uptodate.com/contents/red-blood-cell-antigens-and-antibodies? search=Rh%20null&source=search_result&selectedTitle=1~2&usage_type=default&display_rank=1
NHS blood transplant. Rare Blood Types. https://www.blood.co.uk/why-give-blood/demand-for-different-blood-types/rare-blood-types/
Cleveland Clinic. Blood Types. https://my.clevelandclinic.org/health/articles/21213-blood-types
Pruthi RK. Universal Blood Donor Type: Is There Such a Thing? Mayoclinic. April 25, 2019.