New study finds DNA link to schizophrenia, bipolar disorder, depression and other major psychiatric disorders

Ancient viral DNA still present in the human genome may be linked to major mental disorders, research suggests. Thousands of DNA sequences originating from ancient infections are found in the brain, some contributing to susceptibility to conditions such as schizophrenia, bipolar disorder and depression, the study led by King’s College London found.

About 8% of the genome – the complete set of DNA – is made up of sequences called Human Endogenous Retroviruses (HERVs) – products of ancient viral infections that appeared hundreds of thousands of years ago. These fossil viruses were thought to have no important function and were simply junk DNA.

However, scientists have discovered where in our DNA these fossil viruses are located, helping them understand what functions they may have. The study is the first to show that a set of specific HERVs expressed in the human brain contribute to susceptibility to psychiatric disorders.

Dr Timothy Powell, co-lead author of the study and senior lecturer at the Institute of Psychiatry, Psychology and Neuroscience (IoPPN), King’s College London, said: “This study uses a novel and robust approach to assess how genetic susceptibility in psychiatric disorders it transmits its effects on 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 originally thought, with specific HERV expression profiles associated with increased susceptibility. some mental disorders”.

The researchers analyzed data from large studies involving tens of thousands of people, both with and without mental health conditions, as well as information from autopsy brain samples from 800 people. They found that some genes preferentially affected HERV expression.

The researchers reported five robust HERV expression signatures associated with psychiatric disorders, including two that are associated with risk of schizophrenia, one associated with risk of both bipolar disorder and schizophrenia, and one associated with risk of depression.

Dr Rodrigo Duarte, first author and researcher at IoPPN, King’s College London, said: “We know that psychiatric disorders have a substantial genetic component, with many parts of the genome progressively contributing to susceptibility. In our study, we were able to investigate parts of the genome corresponding to HERVs, which led to the identification of five sequences that are relevant to psychiatric disorders. Although it is not yet clear how these HERVs affect brain cells to confer this increased risk, our findings suggest that regulating their expression. it’s important for brain function.”

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

Published in Nature Communications, the study was funded in part by the National Institute for Health and Care Research (NIHR) and the US National Institutes of Health (NIH).