Health and Me

Ishita Roy

This One Gene May Be Triggering Mental Illness In Children; Scientists Say It Changes Everything

For decades, <span>mental health</span> issues were explained as a result of many small <span>gene</span>tic risks piling up over time. However, a study led by German scientists has now identified one gene whose specific variants could appear to directly impact psychiatric symptoms, even in the absence of neurological problems. In rare cases, the study suggests, a single faulty gene may be enough to directly cause <span>mental disorders</span>, much earlier tan doctors typically expect. 

Scientists studying mutations in the GRIN2A gene found evidence that certain rare variants do not increase the likelihood of <span>mental illness</span>, but they appear to trigger it. This happens due to a clear biological mechanism, often in the beginning of childhood itself. The findings challenge long-held assumptions about how conditions like schizophrenia, anxiety, and mood disorders develop. 

The findings are published in journal Molecular Psychiatry. The study describes GRIN2A null variants as the first known example of a single gene directly causing early-onset and even isolated psychiatric disorders, including early-onset schizophrenia. 

<h2>How An Unexpected Pattern Emerged</h2>

The research team, led by Johannes Lemke from the University of Leipzig Medical Center, did not set out to study psychiatric genetics. They were working with a global registry of people diagnosed with GRIN2A-related disorders, most of whom were tested as children for epilepsy or developmental delays.

When the researchers began asking physicians about mental health diagnoses, a striking pattern emerged. Out of 121 individuals with disease-causing GRIN2A mutations, 25 had been diagnosed with psychiatric disorders. Of those 25, 23 carried null variants that completely shut down the gene’s function. In contrast, only 2 of 37 people with missense variants, which alter but do not eliminate the protein, developed mental illness.

To understand how high and unusual this risk was, the team of researchers compared their findings with 21 years of national health records in Finland. This included records of over 5 million people, and the results were stark. 

The analysis of this large population showed that by age 12, carriers of GRIN2A null variants showed an 87-fold higher rate of psychotic disorder compared to the general population. Although this estimate was based on just four cases, risks for mood disorders were nearly 12 times higher, and anxiety disorder six times higher. 

What stood out most was timing. Schizophrenia typically appears in late adolescence or early adulthood. Anxiety and mood disorders usually emerge in the teenage years or later. In people with GRIN2A null variants, symptoms began as early as ages 8, 10, or 12.

<h2>How Does This Gene Operate In Your Brain?</h2>

GRIN2A carriers instruction for making a protein known as GluN2A. This is a critical component of NDMA receptors, which help brain cells respond to glutamate, brain's main excitatory chemical messenger. 

When GluN2A is missing, these receptors cannot assemble or function normally. This is what leads to disruption in brain signaling that appears to directly drive psychiatric symptoms. Unlike polygenic risk scores that reflect tiny contributions from thousands of genes, GRIN2A null variants remove a key part of the brain's signaling machinery in one decisive step. 

Interestingly, people with missense mutations had similar rates of epilepsy and intellectual disability as those with null variants. But when it came to psychiatric illness, only null variants carried substantial risk.

<h2>Mental Illness That Comes Without Warning Signs </h2>

Six people in the study developed psychiatric disorders without any intellectual disability. Two of them never experienced epilepsy. Without any known family history, these individuals would have never undergone a genetic testing otherwise. Current psychiatric guidelines also do not recommend genetic screening for isolated mental illness. This is because most participants who were initially tested for seizures or developmental delays, cases with only psychiatric symptoms are likely undercounted. The true prevalence may be higher.

Four people with GRIN2A null-related psychiatric disorders were treated with the amino acid L-serine for over a year, at doses up to 500 mg per kilogram daily. All four showed improvement. In one case, hallucinations stopped entirely. Others saw paranoid symptoms resolve, behavioral control improve, or seizures decrease.

L-serine converts to D-serine in the brain, which helps activate NMDA receptors. Boosting this pathway may compensate for the missing GluN2A subunits, offering a targeted approach rather than trial-and-error treatment.

More than 80 percent of people with GRIN2A null-related mental illness also had epilepsy at some point, though seizures did not predict who developed psychiatric symptoms. In most cases, mental illness appeared after epilepsy had resolved.

The findings suggest genetic testing could eventually become part of evaluating early-onset psychiatric disorders. For a small but significant group of patients, the cause of mental illness may be clearly identifiable, biologically grounded, and potentially treatable.

For most people living with mental disorders, the origins will remain complex. But this research shows that, sometimes, the answer may lie in a single gene.

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For decades, mental health issues were explained as a result of many small genetic risks piling up over time. However, a study led by German scientists has now identified one gene whose specific variants could appear to directly impact psychiatric symptoms, even in the absence of neurological problems. In rare cases, the study suggests, a single faulty gene may be enough to directly cause mental disorders, much earlier tan doctors typically expect. Scientists studying mutations in the GRIN2A gene found evidence that certain rare variants do not increase the likelihood of mental illness, but they appear to trigger it. This happens due to a clear biological mechanism, often in the beginning of childhood itself. The findings challenge long-held assumptions about how conditions like schizophrenia, anxiety, and mood disorders develop. The findings are published in journal Molecular Psychiatry. The study describes GRIN2A null variants as the first known example of a single gene directly causing early-onset and even isolated psychiatric disorders, including early-onset schizophrenia. How An Unexpected Pattern EmergedThe research team, led by Johannes Lemke from the University of Leipzig Medical Center, did not set out to study psychiatric genetics. They were working with a global registry of people diagnosed with GRIN2A-related disorders, most of whom were tested as children for epilepsy or developmental delays.When the researchers began asking physicians about mental health diagnoses, a striking pattern emerged. Out of 121 individuals with disease-causing GRIN2A mutations, 25 had been diagnosed with psychiatric disorders. Of those 25, 23 carried null variants that completely shut down the gene’s function. In contrast, only 2 of 37 people with missense variants, which alter but do not eliminate the protein, developed mental illness.To understand how high and unusual this risk was, the team of researchers compared their findings with 21 years of national health records in Finland. This included records of over 5 million people, and the results were stark. The analysis of this large population showed that by age 12, carriers of GRIN2A null variants showed an 87-fold higher rate of psychotic disorder compared to the general population. Although this estimate was based on just four cases, risks for mood disorders were nearly 12 times higher, and anxiety disorder six times higher. What stood out most was timing. Schizophrenia typically appears in late adolescence or early adulthood. Anxiety and mood disorders usually emerge in the teenage years or later. In people with GRIN2A null variants, symptoms began as early as ages 8, 10, or 12.How Does This Gene Operate In Your Brain?GRIN2A carriers instruction for making a protein known as GluN2A. This is a critical component of NDMA receptors, which help brain cells respond to glutamate, brain's main excitatory chemical messenger. When GluN2A is missing, these receptors cannot assemble or function normally. This is what leads to disruption in brain signaling that appears to directly drive psychiatric symptoms. Unlike polygenic risk scores that reflect tiny contributions from thousands of genes, GRIN2A null variants remove a key part of the brain's signaling machinery in one decisive step. Interestingly, people with missense mutations had similar rates of epilepsy and intellectual disability as those with null variants. But when it came to psychiatric illness, only null variants carried substantial risk.Mental Illness That Comes Without Warning Signs Six people in the study developed psychiatric disorders without any intellectual disability. Two of them never experienced epilepsy. Without any known family history, these individuals would have never undergone a genetic testing otherwise. Current psychiatric guidelines also do not recommend genetic screening for isolated mental illness. This is because most participants who were initially tested for seizures or developmental delays, cases with only psychiatric symptoms are likely undercounted. The true prevalence may be higher.A Targeted Treatment Shows Early PromiseFour people with GRIN2A null-related psychiatric disorders were treated with the amino acid L-serine for over a year, at doses up to 500 mg per kilogram daily. All four showed improvement. In one case, hallucinations stopped entirely. Others saw paranoid symptoms resolve, behavioral control improve, or seizures decrease.L-serine converts to D-serine in the brain, which helps activate NMDA receptors. Boosting this pathway may compensate for the missing GluN2A subunits, offering a targeted approach rather than trial-and-error treatment.Rethinking Early DiagnosisMore than 80 percent of people with GRIN2A null-related mental illness also had epilepsy at some point, though seizures did not predict who developed psychiatric symptoms. In most cases, mental illness appeared after epilepsy had resolved.The findings suggest genetic testing could eventually become part of evaluating early-onset psychiatric disorders. For a small but significant group of patients, the cause of mental illness may be clearly identifiable, biologically grounded, and potentially treatable.For most people living with mental disorders, the origins will remain complex. But this research shows that, sometimes, the answer may lie in a single gene.