Clinical Guidance

Since the original description of SYNGAP1-related intellectual disability (SYNGAP1-ID) in three individuals , more than 50 affected individuals with detailed clinical information have been reported [, , , , , , , , , , , , , , , ]. The following description of the phenotypic features associated with this condition is based on these reports. Developmental delay and intellectual disability. The great majority of affected children present with developmental delay or intellectual disability that is typically moderate to severe but can be mild. Early motor development is characterized by hypotonia. The average age at walking was 26 months (range: 10.5 months to 5 years). A subset of these children had an ataxic gait that remained stable or improved over time.

Diagnostic Criteria

No formal diagnostic criteria have been published for SYNGAP1-related intellectual disability.

Suggestive Findings

SYNGAP1-related intellectual disability (SYNGAP1-ID) should be considered in individuals with developmental delay or intellectual disability with or without:

• Generalized epilepsy;

and/or

Management Guidelines

Evaluations Following Initial Diagnosis To establish the extent of disease and needs in an individual diagnosed with SYNGAP1-related intellectual disability, the evaluations summarized (if not performed as part of the evaluation that led to diagnosis) are recommended. Table 2. Recommended Evaluations Following Initial Diagnosis in Individuals with SYNGAP1-Related Intellectual Disability

Surveillance Guidelines

Monitor those with seizures as clinically indicated. Assess as needed for anxiety, attention, and aggressive or self-injurious behavior. Monitor developmental progress and educational needs.

Source: GeneReviews — "SYNGAP1-Related Intellectual Disability"