Infectious mononucleosis

Science and technology

A groundbreaking discovery in Finland has unveiled a new gene defect linked to severe cases of infectious mononucleosis (IM), commonly known as the "kissing disease." This revelation offers not only insight into the genetic foundations of this condition but also promises potential pathways for treating a range of serious illnesses associated with the Epstein-Barr virus (EBV).

Infectious mononucleosis, caused by EBV and transmitted through saliva, is almost a universal experience among Finns, either with obvious symptoms or silently.

While most individuals encounter the virus in childhood with minor to no symptoms, a fraction suffers from severe manifestations requiring hospitalization. These can include high fever, significant lymph node and spleen swelling, and in dire cases, spleen rupture.

The newly identified gene defect, which results from inheriting affected genes from both parents, has been linked to severe infectious mononucleosis outcomes. However, it also appears to offer a form of resilience against the disease. "This constitutes a new hereditary disease within Finland, affecting approximately 300 Finns. Its primary manifestation is severe infectious mononucleosis, which, despite its severity, typically resolves on its own," explained Chief Physician Mikko Seppänen of HUS Children and Adolescents and the University of Helsinki.

The study, featuring in the prestigious journal Nature and conducted as part of international collaboration, including the FinnGen project's Mark Daly from the University of Helsinki, shines a hopeful light on potential treatments. The gene defect impacts the gene's function in communication pathways, leading to inflammation and symptomatic overreactions. Intriguingly, it also seems to protect against the kind of uncontrolled inflammation that can precipitate tumor diseases and severe lymphatic tissue hyperplasia—conditions that can lead to lymph node cancers or severe lymph node inflammation.

Looking forward, the research team is eager to explore treatments that could inhibit the communication pathway affected by the gene defect. Such treatments have the potential to halt the progression of challenging blood cancers and lymph node tumors. "Our future efforts will focus on whether we can prevent the development of lymphatic hyperplasia through treatments targeting the discovered communication pathway. Success in this endeavor could significantly advance our ability to treat some of the most difficult hematological cancers," Seppänen elaborated.

The initial study's duration was only a few years, prompting plans for further research to explore the full spectrum of the disease and its prevalence among Finnish children treated for infectious mononucleosis. Finnish biobanks, particularly those involved in the FinnGen project, which has compiled genome and health register data for over 540,000 Finns, played a crucial role in identifying the genetic defect. This defect is around 50 times more common in Finns than in other populations and is most prevalent in the Kymenlaakso, Helsinki region, and Savo.

This discovery not only underscores the importance of genetic research in understanding complex diseases but also highlights the unique position of Finnish biobanks and the FinnGen project in global health research.