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Disease Profile

GRIN2B related syndrome

Prevalence estimates on Rare Medical Network websites are calculated based on data available from numerous sources, including US and European government statistics, the NIH, Orphanet, and published epidemiologic studies. Rare disease population data is recognized to be highly variable, and based on a wide variety of source data and methodologies, so the prevalence data on this site should be assumed to be estimated and cannot be considered to be absolutely correct.


US Estimated

Europe Estimated

Age of onset





Autosomal dominant A pathogenic variant in only one gene copy in each cell is sufficient to cause an autosomal dominant disease.


Autosomal recessive Pathogenic variants in both copies of each gene of the chromosome are needed to cause an autosomal recessive disease and observe the mutant phenotype.


dominant X-linked dominant inheritance, sometimes referred to as X-linked dominance, is a mode of genetic inheritance by which a dominant gene is carried on the X chromosome.


recessive Pathogenic variants in both copies of a gene on the X chromosome cause an X-linked recessive disorder.


Mitochondrial or multigenic Mitochondrial genetic disorders can be caused by changes (mutations) in either the mitochondrial DNA or nuclear DNA that lead to dysfunction of the mitochondria and inadequate production of energy.


Multigenic or multifactor Inheritance involving many factors, of which at least one is genetic but none is of overwhelming importance, as in the causation of a disease by multiple genetic and environmental factors.


Not applicable


Other names (AKA)

GRIN2B-related intellectual disability; Autosomal dominant intellectual disability-6; GRIN2B encephalopathy;


GRIN2B related syndrome is a genetic disorder that causes developmental delay and intellectual disability. Intellectual disability ranges from mild to severe. Other symptoms may include low muscle tone (hypotonia), seizures, behavior problems including autistic features, abnormal movements, a very small head (microcephaly), and developmental regression.[1][2][3] Some children have brain malformations that can be seen in brain imaging exams.[1]  This disorder is caused by variations (mutations) in the GRIN2B gene, which plays a role in the transmission of signals in the brain. Inheritance is autosomal dominant. Treatment depends on the symptoms seen in each person. In some cases, the medication memantine was used with good results, but more studies are needed to know if it is broadly effective.[1]


This table lists symptoms that people with this disease may have. For most diseases, symptoms will vary from person to person. People with the same disease may not have all the symptoms listed. This information comes from a database called the Human Phenotype Ontology (HPO) . The HPO collects information on symptoms that have been described in medical resources. The HPO is updated regularly. Use the HPO ID to access more in-depth information about a symptom.

Medical Terms Other Names
Learn More:
1%-4% of people have these symptoms
Abnormally small skull
Decreased circumference of cranium
Decreased size of skull
Reduced head circumference
Small head circumference

[ more ]

Percent of people who have these symptoms is not available through HPO
Autosomal dominant inheritance
Behavioral abnormality
Behavioral changes
Behavioral disorders
Behavioral disturbances
Behavioral problems
Behavioral/psychiatric abnormalities
Behavioural/Psychiatric abnormality
Psychiatric disorders
Psychiatric disturbances

[ more ]

Disorder of involuntary muscle movements
EEG abnormality
Generalized hypotonia
Decreased muscle tone
Low muscle tone

[ more ]

Global developmental delay
Intellectual disability
Mental deficiency
Mental retardation
Mental retardation, nonspecific

[ more ]

Involuntary muscle stiffness, contraction, or spasm
Variable expressivity


Support and advocacy groups can help you connect with other patients and families, and they can provide valuable services. Many develop patient-centered information and are the driving force behind research for better treatments and possible cures. They can direct you to research, resources, and services. Many organizations also have experts who serve as medical advisors or provide lists of doctors/clinics. Visit the group’s website or contact them to learn about the services they offer. Inclusion on this list is not an endorsement by GARD.

Organizations Supporting this Disease

    Learn more

    These resources provide more information about this condition or associated symptoms. The in-depth resources contain medical and scientific language that may be hard to understand. You may want to review these resources with a medical professional.

    Where to Start

    • The GRIN2B Foundation provides answers to common questions about GRIN2B related syndrome. Click on the link to visit their website.
    • Unique is a source of information and support for families and individuals affected by rare chromosome disorders. Click on the link to view information about GRIN2B related syndrome.

      In-Depth Information

      • Online Mendelian Inheritance in Man (OMIM) is a catalog of human genes and genetic disorders. Each entry has a summary of related medical articles. It is meant for health care professionals and researchers. OMIM is maintained by Johns Hopkins University School of Medicine. 
      • PubMed is a searchable database of medical literature and lists journal articles that discuss GRIN2B related syndrome. Click on the link to view a sample search on this topic.


        1. Adams DR, Yuan H, Holyoak T, et al. Three Rare Diseases in One Sib Pair: RAI1, PCK1, GRIN2B Mutations Associated with Smith-Magenis Syndrome, Cytosolic PEPCK Deficiency and NMDA Receptor Glutamate Insensitivity. Molecular genetics and metabolism. 2014.; 113 (3):161-170. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4219933/.
        2. Platzer K, Yuan H, Schütz H, et al. GRIN2B encephalopathy: novel findings on phenotype, variant clustering, functional consequences and treatment aspects. Journal of medical genetics. 2017; 54(7):460-470. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5656050/.
        3. GRIN2B related syndrome. UNIQUE. 2016; https://www.rarechromo.org/information/Single%20Gene%20Disorders/GRIN2B%20related%20syndrome%20FTNW.pdf.