According to the World Health Organization (WHO), about one in seven people worldwide had a mental illness in 2021. The most common conditions were anxiety and depression.
These illnesses usually develop from a mix of different causes, including life experiences and genetics. In fact, having a close family member with a mental illness is one of the strongest known risk factors.
Until now, scientists believed that mental illnesses usually happen because of the combined effects of many genes. But a new study led by Professor Johannes Lemke at the University of Leipzig Medical Center and published in Molecular Psychiatry has found something different.
The study shows that a single gene, called GRIN2A, can directly cause a mental illness on its own. This makes it the first gene known to do this without needing other genetic factors.
The researchers studied data from 121 people who had a change in the GRIN2A gene. They found that these changes were linked not only to schizophrenia, but also to other mental health conditions. Interestingly, these disorders often began in childhood or teenage years—much earlier than usual.
Another surprising finding was that some people only had mental health symptoms, even though GRIN2A has also been linked to epilepsy and intellectual disabilities in the past.
The GRIN2A gene plays an important role in how brain cells send signals to each other. It helps control how active nerve cells are by affecting their electrical signals.
In this study, some variants of the GRIN2A gene reduced the activity of something called the NMDA receptor, which is essential for brain communication. This reduction in activity seems to be related to the mental health problems observed.
The research team, which included Dr. Steffen Syrbe from Heidelberg University Hospital, also explored a possible treatment. They found that giving patients a dietary supplement called L-serine—which helps activate the NMDA receptor—led to noticeable improvements in their psychiatric symptoms.
Professors Lemke and Syrbe have worked together for nearly 15 years to better understand conditions related to glutamate receptors in children with brain disorders. Over time, Professor Lemke built the largest international database of GRIN2A patients, which made this discovery possible.
In conclusion, this research marks a major step forward in understanding mental illness. It shows that a single gene can play a key role, especially in early-onset conditions. It also opens up new possibilities for treatment, like using L-serine to improve brain function in affected individuals. These findings could help doctors better diagnose and treat mental health issues in the future.
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