Almost half a year after the first corona infections in China, the disease still puzzles scientists around the world. But at least there are now many approaches that could explain why the disease is particularly severe in some patients and hardly expresses itself in others. For example, age, an abnormally strong immune response and changes in blood clotting are risk factors for a serious illness. Researchers from Kiel and Oslo have now identified another factor: the patient's blood type.
Patients with blood group A are often more seriously ill
Molecular biologist Andre Franke from the University of Kiel and the Norwegian internist Tom Karlsen from the University of Oslo were able to show with their investigation that patients with blood group A have an increased risk of developing a severe disease with a corona infection. On the other hand, patients with blood group 0 have the lowest risk of a serious illness. The researchers published their results in a so-called preprint – these are preliminary study results that should still be assessed by independent other scientists.
For the study, the genome of a total of 1610 seriously ill corona patients from Spain and Italy was analyzed. All of those affected either needed oxygen therapy or were ventilated. Their DNA was compared to that of 2205 healthy people. In total, Franke, Karlsen and their colleagues analyzed more than 8.5 million SNPs. These are specific sections of DNA that differ from person to person and also occur differently in different population groups.
The scientists noticed a conspicuous SNP at the location of the DNA that determines the blood group. This SNP showed that patients with blood group A had an approximately 50 percent higher risk of developing a serious illness. On the other hand, patients with blood group 0 hardly suffered from symptoms of the infection.
Why does the blood type determine the degree of illness?
It is not yet entirely clear why the blood group could influence the severity of the course of the disease. However, there are already several possible causes that the researchers are now investigating. For example, the research group led by Franke and Karlsen points out that the SNP can also be associated with the so-called interleukins at the location of the DNA that defines the blood group. These are inflammatory messengers, which, according to other study results, are more common in some patients when the immune system overreacts. But blood clotting could also play a role.
Study confirms previous research
Indeed, previous studies suggested that the blood type could affect the course of the disease in a corona infection. Chinese researchers already presented in March a DNA analysis of over 2,000 patients found that patients with blood group A could have an increased risk. A preprint from US researchers in April also warned that people with blood group A were more likely to develop corona than people with other blood groups. However, based on the research data to date, it cannot yet be proven that there is a causal connection.
If the preprints have been checked and found to be good by independent scientists, a patient's blood type may play a role in treatment in the future. Patients with blood group A would therefore need more intensive medical care.