Common Genetic Basis Found in Eight Psychiatric Disorders

Recent research has uncovered that eight distinct psychiatric disorders share a common genetic foundation. A study released this year has identified specific genetic variants among these shared genes and examined how they operate during brain development.

The team from the US discovered that many of these variants remain active for prolonged periods. This activity could influence several developmental stages and potentially offer new avenues for treatments that might target multiple disorders simultaneously.

“The proteins produced by these genes are also highly interconnected,” explains Hyejung Won, a geneticist at the University of North Carolina. “Any alterations to these proteins could have cascading impacts on the network, which might lead to widespread effects on the brain.”

In 2019, an international group of researchers identified 109 genes linked to various combinations of eight psychiatric disorders, including autism, ADHD, schizophrenia, bipolar disorder, major depressive disorder, Tourette syndrome, obsessive-compulsive disorder, and anorexia.

This could shed light on why these disorders frequently co-occur—for instance, as much as 70 percent of individuals diagnosed with autism or ADHD may also have the other—and why they often appear in the same families.

Each of these eight conditions also presents unique gene variations. Consequently, Won and her team compared the unique genes with those that the disorders have in common.

They assessed nearly 18,000 variations of both shared and unique genes in precursor cells, which develop into neurons, to evaluate how these variations might affect gene expression during human development.

This analysis led to the identification of 683 genetic variants that affect gene regulation. The team conducted further examination using neurons from developing mice.

Genetic variants that influence multiple seemingly unrelated traits—or conditions—are referred to as pleiotropic. The pleiotropic variants were found to be involved in more protein-to-protein interactions than those unique to specific psychological conditions and were active across various types of brain cells.

Pleiotropic variants also played roles in regulatory processes affecting multiple stages of brain development. This capability might clarify why identical variants could contribute to different psychiatric conditions.

“Traditionally, pleiotropy has been considered a challenge because it complicates the classification of psychiatric disorders,” says Won.

“However, understanding the genetic underpinnings of pleiotropy could allow us to create treatments addressing these shared genetic elements, potentially aiding in the treatment of numerous psychiatric disorders with a singular approach.”

Such a strategy could prove beneficial, especially considering that the World Health Organization estimates around 1 in 8 individuals—almost a billion people—live with a form of psychiatric condition.

This research was published in Cell.