By: Clare Logan
What is the GRIN2B Gene?
The GRIN2B gene provides instructions for making a protein called GluN2B, a crucial component of the N-methyl-D-aspartate (NMDA) receptor. NMDA receptors are involved in brain development, learning, memory, and higher cognitive processes. These receptors control how calcium and other molecules enter nerve cells, helping neurons communicate and form strong connections, especially during early development. Variants in the GRIN2B gene, most commonly de novo (spontaneous and not inherited), can disrupt the NMDA receptor’s functions. These mutations may either reduce receptor activity (loss of function) or overactivate it (gain of function), both of which interfere with brain signaling. In rare cases, a GRIN2B variant may be inherited from a parent with mosaicism, meaning the parent carries the mutation in only some cells and may not show symptoms themselves. Because NMDA receptors are critical to brain development and function, changes in the GRIN2B gene can result in neurodevelopmental disorders and other challenges, such as epilepsy.
Universally, children with GRIN2B-related disorders experience developmental delays and intellectual disability, although the severity ranges from mild to severe. In fact, delays in reaching early milestones, such as sitting, walking, or speaking, are often the first indication of a GRIN2B-related disorder. In addition to these delays, children may also present with autistic features, attention difficulties, and behavioral challenges. It is important to note that no hallmark signs can confirm a diagnosis of a GRIN2B-related disorder based on clinical features alone. A genetic test is required for diagnosis, and additional tests such as an electroencephalogram (EEG), to assess brain activity, and magnetic resonance imaging (MRI), to look at brain structure, are often recommended.
GRIN2B-Related Epilepsy
Epilepsy is a common symptom of GRIN2B-related disorders, affecting around half of all children with this condition. Seizures can begin in infancy or early childhood, and their type and severity vary widely depending on the individual and the specific GRIN2B variant. Some of the most frequently reported seizure types include:
● Focal impaired awareness seizures: episodes where a child suddenly stops what they are doing and becomes unresponsive or unaware.
● Focal motor seizures: episodes characterized by jerking or abnormal movements in one part of the body.
● Other types, such as infantile spasms, generalized seizures, and atypical absence seizures, have also been observed.
Children with GRIN2B mutations may be diagnosed with complex epilepsy syndromes like West syndrome, Lennox-Gastaut syndrome, or developmental and epileptic encephalopathies (DEE), conditions where frequent seizures and abnormal brain activity contribute to cognitive and developmental difficulties. A 2014 study by Lemke et al. identified GRIN2B mutations in children with both epilepsy and intellectual disability. More recent findings by Krey et al. (2023) suggest that gain-of-function mutations are more likely to cause early-onset epilepsy and severe developmental issues, while loss-of-function mutations tend to result in intellectual disabilities without seizures.
Research and Treatment
There is currently no single treatment for GRIN2B-related disorders. Management of epilepsy and developmental concerns must be individualized based on a child’s specific symptoms and genetic findings. Anti-seizure medications, such as valproic acid, levetiracetam, and others, are often prescribed to help manage seizures, though treatment success varies. In some cases, research explores the potential for more targeted treatments that modulate NMDA receptor activity based on whether a child has a gain or loss-of-function mutation. However, these therapies remain experimental and are not yet part of standard care.
Because NMDA receptors are involved in both epilepsy and cognitive development, understanding how a specific GRIN2B variant affects receptor activity may eventually help tailor treatment strategies. A multidisciplinary approach to care, including, but not limited to, neurologists, genetic counselors, pediatricians, and therapists, is strongly recommended. Additionally, early diagnosis through genetic testing can help families connect to necessary interventions sooner and improve long-term outcomes. Though GRIN2B-related disorders are still being studied, research collaborations, advocacy groups, and family networks continue to drive progress in understanding and treating this condition.
References
Austra Health. (n.d.). Understanding GRIN2B-related neurodevelopmental disorder: Causes, symptoms, and treatment options. Retrieved May 13, 2025, from https://www.austrahealth.com.au/grin2b-related-neurodevelopmental-disorder.html
“GRIN2B-Related Neurodevelopmental Disorder.” GeneReviews®, NCBI Bookshelf, www.ncbi.nlm.nih.gov/books/NBK501979/. Accessed 7 May 2025.
“GRIN2B-Related Disorders.” Children’s Hospital of Philadelphia, www.chop.edu/conditions-diseases/grin2b-related-disorders. Accessed 7 May 2025.
Lemke, Johannes R., et al. “Targeted next generation sequencing as a diagnostic tool in epileptic disorders.” Epilepsia, vol. 55, no. 5, 2014, pp. 830–841. doi:10.1111/epi.12620.
Krey, J. F., et al. “Emerging roles of GRIN2B variants in epilepsy and neurodevelopmental disorders.” Neuroscience & Biobehavioral Reviews, vol. 151, 2023, 105313. doi:10.1016/j.neubiorev.2023.105313.
“GRIN2B Mutations, West Syndrome and Intellectual Disability with Focal Epilepsy.” Epilepsy Foundation, www.epilepsy.com/stories/grin2b-mutations-west-syndrome-and intellectual-disability-focal-epilepsy. Accessed 7 May 2025.
“Genetics and GRIN2B.” GRIN2B Foundation, www.grin2b.com/genetics-and-grin2b. Accessed 7 May 2025.
