Nearly one in seven people worldwide lived with a mental illness in 2021, according to the World Health Organization (WHO), with anxiety and depression being the most common. These conditions typically arise from a combination of factors, including genetics. Having a close family member with a mental illness remains one of the strongest predictors. Until now, psychiatric disorders were thought to result from the combined influence of many genes.
“Our findings show that GRIN2A is the first known gene that can, on its own, cause a mental illness,” said Professor Johannes Lemke, lead author of the study and Director of the Institute of Human Genetics at the University of Leipzig Medical Center. “This sets it apart from the polygenic causes previously assumed.”
Study Links GRIN2A Variants to Early-Onset Psychiatric Disorders
Researchers analyzed data from 121 individuals carrying a change in the GRIN2A gene. They found that certain variants were linked not only to schizophrenia but also to other psychiatric disorders. “Remarkably, these conditions appeared in childhood or adolescence, unlike the usual adult onset,” Lemke noted. Some participants displayed only psychiatric symptoms, even though GRIN2A mutations are usually associated with epilepsy or intellectual disability.
GRIN2A’s Role in Brain Function and Potential Treatment
The GRIN2A gene regulates nerve cell activity by influencing electrical signaling in the brain. The study found that specific variants reduced NMDA receptor function, which is critical for communication between brain cells. Working with Dr. Steffen Syrbe, pediatric neurologist at Heidelberg University Hospital, the team reported that L-serine, a dietary supplement that activates the NMDA receptor, improved psychiatric symptoms in early treatment trials.
Professors Lemke and Syrbe have collaborated for nearly 15 years to study disorders involving the brain’s glutamate receptor in children with neurological conditions. Lemke also established an international registry of GRIN2A patients, which provided the largest known dataset for this study.
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