Blood donors’ family origins help identify rare blood groups
The increasing diversity of Finland’s population is also reflected in blood groups. For nearly two years, the Finnish Red Cross Blood Service has been asking blood donors about their parents’ countries of birth in order to identify rare blood groups. This information has helped identify rare blood groups and improved the ability to secure suitable blood products for all patients.
When a blood transfusion is needed, the aim is to provide blood that matches the patient’s own blood group as closely as possible. In addition to the common ABO blood groups, more than 350 other blood group antigens are known. In some transfusions, these factors must also be taken into account, even though many of them are very rare. In most cases, however, blood selected on the basis of ABO blood group and RhD factor is sufficient.
A new approach improves access to better-matched blood products
At the beginning of 2025, the Blood Service started asking blood donors about their parents’ countries of birth. The purpose is to target blood group testing more effectively and identify donors whose blood group characteristics are rare in the Finnish population.
A blood group is classified as rare when it occurs in no more than one person in a thousand. Donors with rare blood groups are especially important because they can be crucial in the treatment of individual patients.
“By collecting ancestry information, we have been able to identify new donors with rare blood group antigens,” says Johanna Castrén, Director of Blood Donation Services at the Finnish Red Cross Blood Service.
“When we identify donors with rare blood groups, we are better able to meet the needs of patients who require uncommon blood products,” Castrén says.
Hundreds of donors with rare blood groups identified
The Blood Service registry includes hundreds of donors with blood group antigens so rare that their red blood cell units are frozen and stored for possible future use.
In 2025, there were 365 donors in the blood donor registry with a rare blood group. In 2023, the corresponding figure was only 240. The number increased by approximately 50 percent over two years after ancestry information began to be collected.
The Finnish population also includes blood group antigens that are exceptionally rare elsewhere in the world. One example is the Jk- 3 blood group antigen, for which there were only 25 donors in the Blood Service registry in 2025.
A more diverse Finland broadens the range of blood groups
As Finland’s population becomes more diverse, the range of blood groups also expands. At the same time, certain rare blood disorders, such as sickle cell disease, may become more common. Patients with sickle cell disease often require repeated blood transfusions. Successful treatment depends on finding blood products that match the patient’s blood group characteristics as closely as possible.
“We need more blood donors and welcome people from all backgrounds. Every new donor improves our ability to find suitable blood for all patients
who need it,” Castrén concludes.
