Rh-null: Uncovering the secrets of “Golden Blood”
By Nitish Bhamidipati
Blood Types:
You’ve probably heard of the 4 basic blood types: A, B, AB, and O. The way that these 4 blood types are classified is by the presence or absence of the A and B antigens on Red Blood Cells (RBCs). Blood type is hereditary, and comes from a combination of both parents’ blood types. A Punnett square, which is a way to visualize genetic combinations from parents to offspring, can help visualize how blood types are determined.
Beyond the basic differentiation of A, B, AB, or O blood type, blood types are classified by the presence or absence of an Rh, or Rhesus (Since it was discovered in Rhesus Monkeys), factor. This gives us 8 main blood types, A+, A-, B+, B-, AB+, AB-, O+, O-.
The positive (+) and negative (-) symbols on the A, B, AB, and O blood types actually only refer to one specific antigen within the Rh factor group, known as the Rh D antigen. Beyond the D antigen, there are at least 48 more antigens within the Rh group that can be present on cells.
Although we’ve currently talked about the Rh group, A, B, and O antigens, there are still about 300 more antigens that exist on red blood cells. As of December 2022, scientists have discovered 354 total antigens on red blood cells, of which the Rh group is the largest antigen group.
Rh null blood:
Rh null blood refers to blood that lacks every single one of the 49 Rh antigens that can be present on blood. The odds of lacking every single antigen from the largest blood antigen group in the body are so low that less than 50 people in the world have this blood type. Since it was first discovered in an Aboriginal Australian in 1961, it has since been referred to as “golden” blood due to its rarity.
What does “golden” mean for people who have it? What kind of challenges are faced with being one of the world’s 43 people that have Rh null blood? Let’s dive deeper.
Consequences of Rh null blood: Transfusions
Although it might sound nice to have golden blood, it makes the lives of those who have it incredibly scary. Let’s think about how blood donations work. If a patient needs blood, it’s common knowledge that they can’t just take anyone’s blood, because in addition to the body’s red blood cells having unique antigens, they have unique antibodies that fit with those antigens. If blood with different antigens is transfused, it could cause the body to attack that blood, inevitably attacking its own, leading to a major infection which could be fatal. This explains why certain blood types are better for donation than others. Take O- blood for example. Known as the “universal donor” blood due to its lack of antigens, it will elicit a much smaller immune response from the recipient than any of the other 7 major blood types due to it being unreactive with antibodies, the immune response coordinators. There exists a large demand and short supply of O- blood, since only 7% of the population has it but 100% can use it, making it an invaluable resource to hospitals.
If you’re eligible for blood donation: https://www.redcrossblood.org/donate-blood/how-to-donate/eligibility-requirements.html
Schedule a blood donation here: https://www.redcrossblood.org/give.html/find-drive
Because donated blood must closely match the blood of the recipient and properly respond to the recipient’s antibodies to prevent potential infection and even death, it makes sense that a blood type as rare as Rh-null could lead to issues if an Rh-null patient requires a transfusion after lost blood.
In order to effectively prepare for a potential future transfusion for Rh-null patients, people with Rh-null blood actually donate blood in a separate Rh-null network, and oftentimes the blood used for their blood transplants comes from earlier blood donations from THEMSELVES.
Consequences of Rh null blood: Autoimmune diseases and anemia
In addition to the lack of available blood for transfusions due to the rarity of Rh null blood, the presence of autoimmune diseases and anemia is a major concern. As previously stated, Rh null blood lacks all Rh antigens, which help maintain the integrity of the Red Blood Cell (RBC) membrane, causing Rh null blood cells to have an abnormal shape. This abnormal shape is unrecognizable to the immune system and causes the body to generate an immune response against the abnormally shaped RBCs. This drastically reduces the RBC levels in the blood leading to a condition known as autoimmune hemolytic anemia (anemia is the term for a lowered amount of healthy RBCs).
Rh null is a fascinating blood type. When we go into depth on how Rh null blood cells vary in structure and thus function from normal RBCs, as well as observe the interactions between Rh null RBCs and other blood types, we can truly understand the secrets behind “Golden blood”. Although Rh null blood has some negative effects and requires those who have it to be extra careful of the potential for blood loss and the lack of donors, those with Rh null blood can comfortably live a normal life and experience all its treasures.
Citations:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6305262/
https://www.discovery.com/science/Rhnull-Rarest-Blood-Type-on-Earth
https://www.ncbi.nlm.nih.gov/books/NBK2269/
https://www.science.org.au/curious/people-medicine/rare-blood-types
https://interestingengineering.com/science/golden-blood-rh-null-blood-type