The genetic risk factor discovered lies on chromosome 6 in the FOXP4 gene region. The protein encoded by this gene plays a key role in regulating lung function and the immune response. Carrying the variant raises the risk of developing long Covid by roughly 60 percent.
The research team stresses that long Covid is a complex condition and that this genetic factor represents only one piece of a much larger puzzle. As datasets grow in size and accuracy, future genomic studies are expected to reveal additional, more precise risk factors.
Long Covid is associated with a broad spectrum of symptoms, ranging from fatigue and cognitive disturbances, often referred to as brain fog, to breathing difficulties. One of the study’s key findings is that genetic susceptibility to long Covid is linked to the regulation of lung function.
“Symptoms such as fatigue and those affecting mental functions, including memory, often have a physiological basis,” says post-doctoral researcher Vilma Lammi from the Institute for Molecular Medicine Finland (FIMM), University of Helsinki, who coordinated the international collaboration.
The findings underscore the importance of the Finnish FinnGen project and other population-based studies in efforts to understand chronic illnesses that follow infections.
“By combining genetic research with cell models, we can get closer to understanding why some people do not recover normally from a viral infection. Genetic tools can also uncover previously unrecognized disease mechanisms,” said group leader Hanna Ollila from the University of Helsinki.
The study was based on a collaboration between researchers from the University of Helsinki, Harvard University, the Karolinska Institute, the Estonian Biobank and several large international research consortia. The results have been published in the scientific journal Nature Genetics.
Original publication:
Lammi, V., Nakanishi, T., Jones, S.E. et al. Genome-wide association study of long COVID. Nat Genet (2025). https://doi.org/10.1038/s41588-025-02100-w