In a major scientific breakthrough, German researchers have identified a single gene that can independently cause schizophrenia and other mental illnesses—a discovery that could transform diagnosis and treatment approaches in psychiatry. The study, published in the journal Molecular Psychiatry, spotlights the GRIN2A gene as a crucial factor, challenging the long-held belief that such disorders arise solely from a combination of multiple genetic and environmental influences.

Led by Professor Johannes Lemke, Director of the Institute of Human Genetics at the University of Leipzig Medical Centre, the research team analysed genetic data from 121 individuals carrying alterations in the GRIN2A gene. The findings revealed that certain variants of this gene can directly trigger schizophrenia, as well as other psychiatric conditions. “Our current findings indicate that GRIN2A is the first known gene that, on its own, can cause a mental illness,” Lemke stated, noting that this distinguishes it from the polygenic origins previously associated with psychiatric disorders.

The study further observed that individuals with GRIN2A alterations often develop symptoms during childhood or adolescence, much earlier than the typical onset of schizophrenia and related disorders in adulthood. Interestingly, while GRIN2A mutations are usually linked to neurological conditions like epilepsy or intellectual disabilities, some individuals in this study presented solely with psychiatric symptoms.

GRIN2A plays a vital role in regulating the electrical excitability of nerve cells. The researchers noted that specific genetic variants reduce the activity of the NMDA receptor—an essential molecule in brain signaling—resulting in altered neural pathways that may contribute to the development of mental illness.

In an encouraging development, early treatment attempts using L-serine, a dietary supplement known to activate NMDA receptors, brought significant improvement in psychiatric symptoms among affected patients. While preliminary, these results open the door to targeted therapies that could benefit individuals with GRIN2A-related conditions.

According to the World Health Organization (WHO), nearly one in seven people worldwide was living with a mental illness in 2021, with depression and anxiety disorders being the most prevalent. Given the large global burden and the complexity of mental health disorders, the identification of GRIN2A as a direct cause marks a significant milestone.

Experts believe this discovery could pave the way for more precise diagnostic tools and early intervention strategies, particularly for children and adolescents showing early symptoms. As research advances, the GRIN2A gene may become a critical focus for developing personalised treatments in psychiatry.