SYNGAP1-related neurodevelopmental disorder
A monogenic developmental and epileptic encephalopathy — intellectual disability with a characteristic epilepsy and autism phenotype, and one of the most actively studied genetic synaptopathies.
SYNGAP1-related disorder is caused by heterozygous loss-of-function variants in SYNGAP1, encoding a synaptic Ras-GTPase activating protein essential for excitatory synapse maturation. The condition causes a fairly recognisable picture: global developmental delay and intellectual disability, an autism phenotype in a large proportion of children, and a typical epilepsy syndrome with eyelid myoclonia, absence-like episodes and myoclonic-atonic seizures often triggered by eating, chewing or pattern stimulation. Several precision-medicine programmes are in active development.
At a glance
- Inheritance
- Autosomal dominant — most often de novo
- Gene
- SYNGAP1 (6p21)
- Seizures
- Eyelid myoclonia with absences, myoclonic-atonic, often eating-/chewing-/pattern-triggered
- Neurodevelopment
- Intellectual disability (usually moderate-to-severe); autism in ~50%
- Prevalence
- ~1 in 10,000 — among the more common monogenic causes of intellectual disability
What SYNGAP1-related disorder is
SYNGAP1-related neurodevelopmental disorder (MRD5; OMIM 612621) is caused by loss-of-function variants — point mutations, small indels or copy-number losses — in SYNGAP1. The encoded protein, SynGAP, is a Ras-GTPase activating protein concentrated at excitatory synapses, where it regulates the maturation and plasticity of glutamatergic transmission. Haploinsufficiency disrupts this signalling and produces a fairly stereotyped clinical picture across affected children.
The classical clinical triad is global developmental delay and intellectual disability, an autism phenotype in around half of children, and a distinctive epilepsy that includes eyelid myoclonia with absences, atypical absences, myoclonic-atonic (drop) seizures and, in some children, generalised tonic-clonic seizures. Eating-, chewing- and pattern-induced reflex seizures are characteristic. Sleep disturbance, behavioural rigidity, attention difficulties, sensory differences and gait abnormalities are common.
How the diagnosis is made
Diagnosis is genetic. SYNGAP1 is included in current epilepsy and intellectual-disability gene panels and is reliably picked up by whole-exome and whole-genome sequencing. Where the clinical picture is suggestive — drop attacks with eyelid myoclonia in a child with intellectual disability and autistic features — the threshold to test should be low, because the phenotype overlaps with several other genetic generalised epilepsies and a specific diagnosis changes counselling and treatment.
EEG typically shows generalised spike-wave and polyspike-wave activity, sometimes with photosensitivity. Brain MRI is usually normal. Once SYNGAP1 is confirmed, the recurrence risk for siblings is low (most variants are de novo), and counselling for the parents and family becomes straightforward.
Treatment today
Treatment is currently symptomatic. Valproate, lamotrigine, ethosuximide, levetiracetam and clobazam can each help different children with the epilepsy phenotype; sodium-channel blockers are not contraindicated as in Dravet syndrome. The ketogenic diet has helped a meaningful subgroup. Behavioural, communication and special-education support are essential alongside seizure control.
Recurring reflex triggers — eating, chewing, certain visual or auditory patterns — should be identified and, where possible, managed with environmental adjustment alongside medication.
Precision-medicine pipeline
SYNGAP1 is one of the most active genetic-therapy targets in paediatric epilepsy. Antisense oligonucleotide (ASO) approaches aimed at boosting expression of the remaining functional SYNGAP1 allele are in preclinical and early clinical development. Several biotechs and academic consortia (the SYNGAP Research Fund, SRX-Health and others) are pursuing programmes simultaneously. Small-molecule modulators of downstream Ras–MAPK and mTOR signalling are being explored.
An educational review can help families understand where the pipeline stands today, which trials are recruiting, and what realistic expectations look like — without replacing the care of your treating clinician.
Pipeline status changes quickly. Always confirm trial availability with current registries (ClinicalTrials.gov, EUDRACT) and your treating team.
How an educational review can help
SYNGAP1 families often have a sharp epilepsy phenotype, a precision-medicine pipeline that is moving fast, and a lot of conflicting information online. An educational review can pull the current literature together, frame the medication options against the phenotype, explain the precision-medicine landscape honestly, and prepare focused questions for your treating team.
It is educational — not a diagnosis, treatment or prescription — and does not replace the care of your child's own clinicians.
Selected sources
- Vlaskamp DRM et al. SYNGAP1 encephalopathy: a distinctive generalized developmental and epileptic encephalopathy. Neurology. 2019;92:e96–e107.
- Holder JL Jr et al. SYNGAP1-related intellectual disability. GeneReviews. Updated 2024.
- Jimenez-Gomez A et al. The phenotypic spectrum of SYNGAP1 encephalopathy. Epilepsia. 2022.
- SYNGAP Research Fund and SRX-Health pipeline updates 2025–2026.
Last reviewed: 2026-05-28
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