GENE GUIDE

GRIK2-Related Syndrome

This guide is not meant to take the place of medical advice. Please consult with your doctor about your genetic results and health care choices. This Gene Guide was last updated on 2024. As new information comes to light with new research we will update this page. You may find it helpful to share this guide with friends and family members or doctors and teachers of the person who has GRIK2-Related Syndrome.
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GRIK2-related syndrome happens when there are changes in the GRIK2 gene. These changes can keep the gene from working as it should.

Key Role

The GRIK2 gene plays a key role in communication among brain cells. The GRIK2 gene codes for a unit of the glutamate receptor. The gene is called GRIK2, and the protein is called GluR6. 

Symptoms

Because the GRIK2 gene is important for brain activity, many people who have GRIK2-related syndrome have:

  • Intellectual disability
  • Global developmental delay
  • Speech delay or absent speech
  • Delayed walking or inability to walk
  • Movement issues, such as ataxia
  • Brain changes observed on magnetic resonance imaging (MRI)
  • Low muscle tone
  • Sleep issues
  • Features of autism
  • Anxiety
  • Impulsivity or hyperactivity

GRIK2-related syndrome is a genetic condition, which means that it is caused by variants in genes. Our genes contain the instructions, or code, that tell our cells how to grow, develop, and work. Every child gets two copies of the GRIK2 gene: one copy from their mother’s egg, and one copy from their father’s sperm. In most cases, parents pass on exact copies of the gene to their child. But the process of creating the egg or sperm is not perfect. A change in the genetic code can lead to physical issues, developmental issues, or both. 

Sometimes a spontaneous variant happens in the sperm, egg or after fertilization. When a brand new genetic variant happens in the genetic code is called a ‘de novo’ genetic variant. The child is usually the first in the family to have the genetic variant.

De novo variants can take place in any gene. We all have some de novo variants, most of which don’t affect our health. But because GRIK2 plays a key role in development, de novo variants in this gene can have a meaningful effect. 

Research shows that GRIK2-related syndrome is often the result of a de novo variant in GRIK2. Many parents who have had their genes tested do not have the GRIK2 genetic variant found in their child who has the syndrome. In some cases, GRIK2-related syndrome happens because the genetic variant was passed down from a parent.

Autosomal dominant conditions

GRIK2-related syndrome is an autosomal dominant genetic condition. This means that when a person has the one damaging variant in GRIK2 they will likely have symptoms of GRIK2-related syndrome. For someone with an autosomal dominant genetic syndrome, every time they have a child there is a 50 percent chance they pass on the same genetic variant and a 50 percent chance they do not pass on the same genetic variant.

Autosomal Dominant Genetic Syndrome

GENE / gene
GENE / gene
Genetic variant that happens in sperm or egg, or after fertilization
GENE / gene
Child with de novo genetic variant
gene / gene
Non-carrier child
gene / gene
Non-carrier child

Why does my child have a change in the GRIK2 gene?

No parent causes their child’s GRIK2-related syndrome. We know this because no parent has any control over the gene changes that they do or do not pass on to their children. Please keep in mind that nothing a parent does before or during the pregnancy causes this to happen. The gene change takes place on its own and cannot be predicted or stopped.

Each family is different. A geneticist or genetic counselor can give you advice on the chance that this will happen again in your family.

The risk of having another child who has GRIK2-related syndrome depends on the genes of both biological parents. 

  • If neither biological parent has the same genetic variant found in their child, the chance of having another child who has the syndrome is on average 1 percent. This 1 percent chance is higher than the chance of the general population. The increase in risk is due to the very unlikely chance that more of the mother’s egg cells or the father’s sperm cells carry the same genetic variant. 
  • If one biological parent has the same genetic variant found in their child, the chance of having another child who has the syndrome is 50 percent. 

For a symptom-free brother or sister of someone who has GRIK2-related syndrome, the sibling’s risk of having a child who has GRIK2-related syndrome depends on the sibling’s genes and their parents’ genes. 

  • If neither parent has the same genetic variant causing GRIK2-related syndrome, the symptom-free sibling has a nearly 0 percent chance of having a child who would inherit GRIK2-related syndrome. 
  • If one biological parent has the same genetic variant causing GRIK2-related syndrome, the symptom-free sibling has a 50 percent chance of also having the same genetic variant. If the symptom-free sibling has the same genetic variant, their chance of having a child who has the genetic variant is 50 percent. 

For a person who has GRIK2-related syndrome, the risk of having a child who has the syndrome is about 50 percent.

As of 2024, at least 10 people with GRIK2-related syndrome have been identified in a medical clinic. About 12 people have been described in medical research.

People who have GRIK2-related syndrome might not look very different. Some people have a smaller than average head size.

Scientists and doctors have only just begun to study GRIK2-related syndrome. At this point, there are no medicines designed to treat the syndrome. A genetic diagnosis can help people decide on the best way to track the condition and manage therapies. Doctors can refer people to specialists for:

  • Physical exams and brain studies
  • Genetics consults
  • Development and behavior studies
  • Other issues, as needed

A developmental pediatrician, neurologist, or psychologist can follow progress over time and can help:

  • Suggest the right therapies. This can include physical, occupational, speech, or behavioral therapy.
  • Guide individualized education plans (IEPs).

Specialists advise that therapies for GRIK2-related syndrome should begin as early as possible, ideally before a child begins school.

If seizures happen, consult a neurologist. There are many types of seizures, and not all types are easy to spot. To learn more, you can refer to resources such as the Epilepsy Foundation’s website: epilepsy.com/…t-is-epilepsy/seizure-types

This section includes a summary of information from major published articles on GRIK2. To learn more about the articles, see the Sources and references section of this guide.

There are few research publications on people with GRIK2-related syndrome. The information below includes 12 people. The oldest person included was 37 years old.

Most people had intellectual disability or developmental delay. Many people had autism, and some people had seizures.

  • 11 out of 12 people had intellectual disability (92 percent)
  • 2 out of 12 people had autism (17 percent)
  • 4 out of 12 people had seizures (33 percent)
92%
11 out of 12 people had intellectual disability.
17%
2 out of 12 people had autism.
33%
4 out of 12 people had seizures.

Some people had brain changes observed on magnetic resonance imaging (MRI). All people had some sort of walking issue, such as ataxia or uncoordinated walking, or were unable to walk.

  • 5 out of 9 people had findings on MRI (56 percent)
  • 7 out of 11 people had ataxia, imbalance, or uncoordinated walking (64 percent)
  • 4 out of 11 people were unable to walk (36 percent)
59%
5 out of 9 people had findings on MRI.
64%
7 out of 11 people had ataxia, imbalance, or uncoordinated walking.
36%
4 out of 11 people were unable to walk.

Where can I find support and resources?

CureGRIN Foundation

CureGRIN Foundation is dedicated to improving the lives of people around the world with GRI Disorders (GRIA, GRID, GRIK, and GRIN) and their families through research, education, and support. We work closely with scientists and the medical community to drive patient-centered research that will lead to treatments and cures. ​

Simons Searchlight

Simons Searchlight is an online international research program, building an ever growing natural history database, biorepository, and resource network of over 175 rare genetic neurodevelopmental disorders. By joining their community and sharing your experiences, you contribute to a growing database used by scientists worldwide to advance the understanding of your genetic condition. Through online surveys and optional blood sample collection, they gather valuable information to improve lives and drive scientific progress. Families like yours are the key to making meaningful progress. To register for Simons Searchlight, go to the Simons Searchlight website at www.simonssearchlight.org and click “Join Us.

Sources and References

The content in this guide comes from published studies about ADNP-related syndrome. Below you can find details about each study, as well as links to summaries or, in some cases, the full article.

  • Guzmán, Y. F., Ramsey, K., Stolz, J. R., Craig, D. W., Huentelman, M. J., Narayanan, V., & Swanson, G. T. (2017). A gain-of-function mutation in the GRIK2 gene causes neurodevelopmental deficits. Neurology Genetics, 3(1), e129. https://pubmed.ncbi.nlm.nih.gov/28180184/
  • Stolz, J. R., … Swanson, G. T. (2021). Clustered mutations in the GRIK2 kainate receptor subunit gene underlie diverse neurodevelopmental disorders. American Journal of Human Genetics, 108(9), 1692-1709. https://pubmed.ncbi.nlm.nih.gov/34375587/

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