More of the Australian population today has a positive blood type compared to the mid-90s, according to new figures.
Key points:
- The first Australia-wide study of its kind in almost 30 years found that the blood groups of the population change
- A larger proportion have positive blood today, and B and AB types have increased by 2-4 percent
- These changes reflect the migration and influx of different genes that come with it
A trio of researchers from Australian Red Cross Lifeblood analyzed blood types from more than a million people across the country, and found rates of some of traditionally rare blood types also jumped a few percentage points.
The results of the blood group audit were published in the Medical Journal of Australia.
Rena Hirani, who led the study, says that information about the shift in blood types of the nation not only gives blood donation organizations a better idea of what they can collect from the community, but it can also affect how emergency blood transfusions occur. of the track.
“Now we can start making some plans for the future [such as] Outreach programs to different communities to diversify the cultural representation of our blood donors, “said Dr. Hirani.
“If Australia continues to … become more positive, then I think we could see how positive blood becomes the universal way we use it in some emergencies.”
What is behind this blood group shift?
Like the eye color, your blood type is hereditary, and it refers to the presence or absence of certain molecules, called antigens, spread across the surface of your red blood cells.
When we see blood groups written as “O positive” or “AB negative”, this information is about two different blood group systems.
For the A, B, O and AB part, this is dictated by what your parents pass on: your mother and father have all given you an A, B or O version of the gene.
A and B genes are dominant, while O is recessive. So if you get an A from your mother and an O from your father, your blood type is A.
When you get an A and a B, your blood type is AB, and you have both A and B antigens on your red blood cells. Type O blood has no A or B antigen.
The positive or negative bit is shorthand for the presence or absence of an antigen called Rhesus D.
Again, this is inherited from your parents. Each offers either a positive or negative version of the gene that determines whether the Rhesus D antigen is present on your red blood cells.
If your blood type is negative, you have no Rhesus D antigen.
Different populations have different proportions of blood types, and as people move, so do their blood type genes.
For Australia, the group of people born overseas has been steadily rising since the turn of the millennium, and is currently sitting at just shy of 30 per cent.
Most are English immigrants, but the number of people moving from China, India and Southeast Asia has been steadily rising over the last decade.
To see if that was really the case, they and their Lifeblood colleagues analyzed data from pathology laboratories and blood donation centers across the country.
In all, they contain blood types of more than 1.3 million people.
Dr Hirani and her crew have found the proportion of negative blood across all A, B, AB and O types in the years since the last audit., using data from 1993-94.
Meanwhile, the percentage of B- and AB-positive types has increased significantly – which was expected because these blood types are very common in people from India and China.
There were also differences between states and territories.
The highest proportion of positive blood was found in the Northern Territory, followed by Victoria and New South Wales, said Dr Hirani.
“We think this is because the genetic background of the First Nations positive Rhesus D, and [the Northern Territory] is where we find a large number of indigenous communities.
“Foreign immigrants mostly move to the bigger cities like Sydney and Melbourne … and we find that the Rhesus D positivity follows them as well.”
What does this mean for blood transfusions?
Erica Wood, a transfusion medicine specialist and head of the Transfusion Research Unit at Monash University, says the new statistics highlight ongoing challenges in O negative blood supply.
When a person is transfused with an incompatible blood type – say someone who is O positive, they get positive blood – there is a risk that their immune system will detect the unknown antigens on the red cells and perform an immune response.
But O negative red blood cells do not have A, B or Rhesus D antigens, so anyone can give them, regardless of their blood type.
“[O negative red blood cells] they are used for O negative patients, but are also used in emergency transfusion settings before the patient’s own blood type is known, “said Professor Wood.
Now, with the proportion of the O-negative population in the single digits, and positive types generally increasing, some people may get O-positive blood in a bloody emergency.
“Most patients will have Rhesus D positive, so this is good for them,” Professor Wood said.
What about the smaller part of the population with a negative blood type?
If they get a positive blood transfusion, they can make antibodies against the Rhesus D antigen – just like we do antibodies against the COVID-19 spike protein – but not all of them will, she added.
But women who may one day have children get appropriate blood or O negative wherever possible, Professor Wood said.
This is because when a woman with a negative blood group makes antibodies against the rhesus D antigen, and later becomes pregnant with a baby with positive blood, some of her antibodies can slip through the placenta and into the bloodstream of the fetus, where they d ‘Destroy baby’s development. red blood cells.
And what about blood donors?
As Australia’s population changes, the country’s pool of blood donors should be representative – but it has a way to go, Dr Hirani said.
“We have such an influence from people all over the world, but only one in five of our blood donors represents these communities.”
A more diverse donor pool is important: not only to contribute to the Australian blood supply, but also to help people with rare blood types here and abroad.
Because in addition to ABO and Rhesus D types, there are dozens of additional blood group systems with hundreds of different antigens, said Dr. Hirani.
“Some of these combinations can only be found in certain ethnic backgrounds.
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