It’s often said that no matter who we are, “we all bleed red”. But although our blood may be the same colour, we’re as individual on the inside as we are on the surface.
Just like our background determines the way we look, where we come from is one of the major factors that influences the make up of our blood.
About half of people living in Australia today were either born overseas, or have a parent born overseas. This increase in diversity in our population leads to a corresponding increase in diversity in the people who need medical treatment – and their blood types.
Limited diversity is an issue
A broad mix of ethnicities is needed in our donor pool to meet the needs of patients with rare blood types. Providing the right blood and blood products for an ethnically diverse population presents an evolving challenge for blood collection agencies around the world, including here in Australia.
People from diverse backgrounds tend to be underrepresented in blood donor populations. While Australians born overseas account for roughly one-third of the population, they account for only one in five blood donors.
This limited diversity in our pool of blood donors creates challenges in identifying blood matches for transfusion to patients with rare blood types.
The link between your blood group and where you come from
Blood types consist not only of the commonly recognised groups such as A, B and O, but also include more than 300 other variants. Each of these variants is a marker on the surface of our red blood cells, and is known as an “antigen”.
Our blood type is inherited from our parents. Like other inherited characteristics such as skin and hair colour, the frequency of blood types in a population shift in response to stresses in the environment (known as “selection pressure”).
For example, in parts of the world where malaria thrives, the proportion of the population with various blood types has altered over time to make people less prone to infection.
So this effect has more to do with where you and your ancestors lived than your ethnic group. One blood type, known as Duffy null, is much more frequent in Africans in Africa than in African-Americans, possibly because African Americans are no longer exposed to the malaria parasite.
In short, one reason we have different blood groups is to improve our chances of fighting disease.
Who needs specially matched blood?
Most transfusions of red cells are matched for the commonly recognised ABO and Rh blood groups (the Rh group is the one that gives you the “positive” or “negative” in your blood type).
If someone receives a transfusion of blood that doesn’t match their own type, their body may recognise the transfused blood as foreign. In this case, the body will develop antibodies to try and destroy the “invader”. Antibodies will continue to be made, which can then interfere with future transfusions.
Some patients need specially matched red cells for transfusion. This means on top of being matched by ABO and Rh type, the donor’s blood is matched to make sure it doesn’t contain blood group variants that aren’t present in the recipient’s blood. This is more difficult to achieve.
With this in mind, patients who need specially matched blood can be placed into three groups.
The first is patients who have already developed antibodies because they have previously had a transfusion of blood that is not completely matched.
The second is patients who have developed antibodies to blood group antigens, but other conditions or drug treatments make it hard for their doctors to test for antibodies.
The final group includes patients who need to have many transfusions throughout their life. These patients include those with disorders affecting the blood such as sickle cell anaemia, thalassemia major and myelodysplasia. In these cases, doctors may want to avoid the development of blood group antibodies.
Some groups are most in need
There are many different blood group antigens, so combinations of even the most common blood group types are found in only a small proportion of donors, making it difficult to provide blood fully matched for a particular patient.
In addition, as our patient population becomes more diverse, there is a greater need for blood types that are rare in a Caucasian population.
Ultimately, the distribution of blood groups that we collect from our donors should reflect the distribution of blood groups required by patients who need transfusion.
Blood centres in many countries have introduced a variety of campaigns to attract a broader donor group.
The Red Cross Blood Service in Australia, is interviewing donors from diverse backgrounds to learn more about their experiences in donating blood. Their goal is to build a donor panel that represents the diversity of the broader Australian community.
The benefits are not only for the patients and the health system – research suggests participating in blood donation facilitates social inclusion among migrant communities.
This article was first published on Australia’s Science Channel, the original news platform of The Royal Institution of Australia.
