Larger than 100 years up to now, Dr. Karl Landsteiner discovered that not all pink blood cells are alike. He found that, when completely completely different people’s blood was blended, it might often clump up and curdle, destroying the cells inside it. His work on the a number of kinds of pink blood cells led to the invention of the ABO blood group system, which gained him the 1930 Nobel Prize in physiology or medication and as well as helped make blood transfusion a safe, reliable observe that saves hundreds and hundreds of lives yearly.
Many people know the place they match into the standard ABO blood typing system, which designates blood as variety A, B, AB or O. Nevertheless these 4 basic blood groups aren’t the highest of the story.
So what variety of blood types are there, truly?
Counting on how deep you dig, the reply may amount throughout the an entire lot or further — and the itemizing continues to be rising.
Related: What’s the rarest blood variety?
Blood types exist because of pink blood cells, which relay oxygen by the use of the bloodstream, carry completely completely different proteins and sugars on their surfaces. These are known as antigens. Each specific particular person has a specific combination of antigens on the surfaces of their blood cells, and that combination determines their blood variety.
Landsteiner’s ABO blood group system categorizes a person’s blood primarily based totally on whether or not or not they’ve one, every or neither of the antigens typically referred to as A and B. ABO blood variety is set by a single gene, one copy of which is handed down by each mum or dad.
O is the most common mannequin of that gene — however it is recessive, so a person should inherit two copies to have an O blood variety. Every the A and B variations of the gene are dominant, in order that they overpower any copy of the O gene. Having one copy of A or B will end in an A or B blood variety, respectively, and a person might have an AB blood variety if every A and B are present.
“The ABO blood group system is essential blood group to ponder all through a blood transfusion,” Dr. Emily Coberly, divisional chief medical officer on the Purple Cross, suggested Dwell Science in an e mail. “All of us make antibodies in direction of the ABO antigens that aren’t on our private pink blood cells.”
For example, in case you could have variety A blood, you’ll have antibodies, or defending immune proteins, that assault B antigens. In order that you wouldn’t want variety B blood in your physique. (This helpful graphic from the Purple Cross illustrates the thought.)
You moreover might need heard of blood types being “optimistic” or “unfavourable.” This categorization comes all the way down to a special antigen, known as the Rh challenge. Of us with the Rh challenge on their cells have Rh-positive blood, whereas people with out the Rh challenge are Rh-negative. The Rh challenge is managed by a cluster of genes influencing various antigens, so the genetics are further troublesome than throughout the ABO system, nevertheless being Rh-positive is every a dominant trait and further frequent throughout the inhabitants.
The various mixtures of the ABO system and Rh challenge create the eight principal blood groups. Usually, realizing which of these blood groups a person matches into is enough to current them a safe transfusion.
Nevertheless positive illnesses can complicate points, and blood types get far more sophisticated when you concentrate on the an entire lot of various antigens present on the ground of pink blood cells.
What are the other blood types?
Furthermore the A, B and Rh challenge antigens, there are a minimal of 350 completely different acknowledged antigens on pink blood cells, Coberly talked about. That amount continues to be going up as researchers decide very important new proteins. If cells assemble merely one amongst these antigens otherwise than completely different cells do, that justifies labeling a model new, distinctive blood variety. So, theoretically, there are as many blood types as there are mixtures of flooring antigens on the pink blood cell.
As of 2024, the Worldwide Society of Blood Transfusion acknowledges 47 blood group methods. Each of these blood group methods can embody various blood types, just because the ABO system consists of A, B, AB and O.
Coberly talked about some examples of these rarer blood types embrace the McLeod phenotype, by which a person’s pink blood cells don’t particular a protein known as Kx; the Kidd-null phenotype, by which cells don’t particular a bunch of proteins typically referred to as the Kidd group; and the Bombay phenotype, by which cells don’t particular a protein known as the H antigen.
Similar to the ABO group and Rh challenge, these unusual blood types are genetic. They may even be associated to quite a few properly being circumstances and indicators; as an example, the McLeod phenotype is expounded to the neurological dysfunction McLeod syndrome.. And as a result of genetic factor, they may very well be tied to positive racial or ethnic backgrounds.
For example, sickle cell sickness (SCD), a state of affairs that causes pink blood cells to variety in a crescent-moon kind, primarily impacts people of African or Hispanic descent. Of us affected by SCD often need repeated blood transfusions, which could lead the immune methods to alter into sensitized to the donor blood. This causes about half of those dealt with for the sickness to develop antibodies in direction of the myriad antigens present on the donor blood cells. That happens even when the donated blood is matched to the victims’ ABO variety and Rh challenge.
After creating antibodies, these victims require meticulously matched blood that accounts for these additional immune proteins. In some other case, their immune methods may assault and destroy the donor blood, which could quickly end in life-threatening issues.
These complexities in blood types are one goal why blood banks on a regular basis need new donors, Coberly emphasised.
“For that reason it is so very important that we maintain a numerous blood present from blood donors of all backgrounds,” she talked about. “Blood shall be on the market for all victims after they need it, along with individuals who need blood that is further fastidiously matched to them.”
Some scientists attempt to bypass this example utterly by creating frequent donor blood — whether or not or not it’s by rising pink blood cells from scratch or eradicating antigens from present donated blood.