Ancient viral DNA still present in the human genome may be linked to major psychiatric disorders, research suggests. Thousands of DNA sequences originating from ancient infections are found in the brain, with some contributing to susceptibility for conditions like 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 occurred hundreds of thousands of years ago.
It had been thought that these fossil viruses had no important function and were simply junk DNA. However, scientists have discovered where in our DNA these fossil viruses are located, helping them to 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 psychiatric disorder susceptibility.
Dr Timothy Powell, co-senior author on 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 for psychiatric disorders imparts its effects on the expression of ancient viral sequences present in the modern human genome. Our results suggest that these viral sequences probably play a more important role in the human brain than originally thought, with specific HERV expression profiles being as.
