Ancient DNA Still Present In Human Genome Linked To Major Psychiatric Disorders, Says Study

Scientists have found that ancient DNA lingering in humans are responsible for major psychiatric disorders, such as depression, schizophrenia and bipolar disorder. About eight per cent of human DNA is made up of sequences called Human Endogenous Retroviruses (HERVs), products of ancient viral infections that occurred hundreds of thousands of years ago. So far, the HERVs were seen as 'junk DNA' with no purpose, but the new study by researchers from King's College London sees them in a new light, offering to revolutionise mental health treatment.

The research has been published in detail in Nature Communications.

It is based on the analysis of large studies involving tens of thousands of people, both with and without mental health conditions. The team combined this with information from autopsy brain samples from 800 people.

"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 associated with an increased susceptibility for some psychiatric disorders," Dr Timothy Powell, co-senior author, told The Evening Standard.

Dr Douglas Nixon, another co-senior author, told the outlet: "We think that a better understanding of these ancient viruses, and the known genes implicated in psychiatric disorders, have the potential to revolutionise mental health research and lead to novel ways to treat or diagnose these conditions."

Dr Nixon, however, added that further research is needed to understand the exact function of most HERVs.

The human genome is made up of over six billion individual letters of the DNA spread among 23 pairs of chromosomes. While analysing the DNA, scientists chop it up into pieces and then sequence it.

The sequencing machines present individual letters in each piece and scientists try to assemble the pieces in the right order.