Old viral DNA in human genome linked to serious psychiatric disorders

New research led by King’s College London has found that thousands of DNA sequences from ancient viral infections are expressed in the brain, some of which contribute to susceptibility to psychiatric disorders such as schizophrenia, bipolar disorder and depression.

The work appears in Nature communication.

About 8% of our genome consists of sequences called Human Endogenous Retroviruses (HERVs), which are products of ancient viral infections that occurred hundreds of thousands of years ago. Until recently it was assumed that these ‘fossil viruses’ were simply junk DNA, without important function in the body. However, thanks to advances in genomics research, scientists have now discovered where these fossil viruses are located in our DNA, helping us better understand when they are expressed and what functions they may have.

This new study builds on these advances and is the first to demonstrate that a series of specific HERVs expressed in the human brain contribute to susceptibility to psychiatric disorders, representing a step forward in understanding the complex genetic components that drive contribute to these conditions.

Dr. Timothy Powell, co-senior author of the study and senior lecturer at the Institute of Psychiatry, Psychology & Neuroscience (IoPPN), King’s College London, said: “This study uses a novel and robust approach to assess how genetic susceptibility to psychiatric disorders affects the expression of ancient viral sequences present in the modern human genome. Our results suggest that these viral sequences likely play a more important role in the human brain than previously thought, with specific HERV expression profiles associated with them. With an increased sensitivity. “

The study analyzed data from large genetic studies involving tens of thousands of people, both with and without mental illness, as well as information from autopsy brain samples from 800 individuals, to investigate how DNA variations associated with psychiatric disorders influence the expression of HERVs.

Although most genetic risk variants related to psychiatric diagnoses influenced genes with well -known biological functions, the researchers discovered that some genetic risk variants preferably influenced the expression of Hervs. The researchers reported five robust Herv expression signs related to psychiatric disorders, including two HVs related to the risk of schizophrenia, one associated with both bipolar disorder and schizophrenia, and one associated with risk of depression.

Dr. Rodrigo Duarte, first author and Research Fellow at the IoPPN, King’s College London, said: “We know that psychiatric disorders have a substantial genetic component, with many parts of the genome contributing incrementally to susceptibility. In our study we were able to to examine parts of the genome that correspond to HERVs, leading to the identification of five sequences relevant to psychiatric disorders. Although it is not yet clear how these HERVs influence brain cells to cause this increase in risk, our findings suggest that. Their expression is important for brain function. “

Dr. Douglas Nixon, co-senior author of the study and researcher at the Feinstein Institutes for Medical Research at Northwell Health, in the US, said: “Further research is needed to understand the exact function of most HERVs, including those identified in We believe that better understanding these ancient viruses and the known genes involved in psychiatric disorders have the potential to revolutionize mental health research and lead to new ways to treat these conditions treat or diagnose.”