Clinical Guidance

GRIN2B-related neurodevelopmental disorder is characterized in all affected individuals by mild to profound developmental delay / intellectual disability (DD/ID). Epilepsy (seen in 51%) and autism spectrum disorder (ASD) and autistic-like behaviors (26%) are common. Other infantile- or childhood-onset findings include microcephaly; muscle tone abnormalities (hypotonia, spasticity); dystonic, dyskinetic, or choreiform movement disorder; and/or cortical visual impairment. To date, fewer than 100 individuals with GRIN2B-related neurodevelopmental disorder have been reported in cohorts of individuals with DD/ID/ASD, early-onset epilepsy, and malformations of cortical development (MCD). Unless otherwise noted, the information in this section is based on extended data of .

Diagnostic Criteria

Formal diagnostic criteria for GRIN2B-related neurodevelopmental disorder have not been established.

Suggestive Findings

GRIN2B-related neurodevelopmental disorder should be considered in individuals with the following clinical and/or brain MRI findings.

Clinical findings

• Mild-to-profound developmental delay (DD) or intellectual disability (ID); AND

Management Guidelines

Evaluations Following Initial Diagnosis To establish the extent of disease and needs in an individual diagnosed with GRIN2B-related neurodevelopmental disorder, the evaluations summarized (if not performed as part of the evaluation that led to diagnosis) are recommended. Table 3. Recommended Evaluations Following Initial Diagnosis in Individuals with GRIN2B-Related Neurodevelopmental Disorder

Surveillance Guidelines

Table 5.

Recommended Surveillance for Individuals with GRIN2B-Related Neurodevelopmental Disorder

System/Concern | Evaluation | Frequency

Ocular

| Ophthalmologic | As clinically indicated

Gastrointestinal

| Feeding, nutrition status, weight gain