Rare diseases · Sign or symptom
Generalized-onset seizure
HP:0002197
What it means
A generalized-onset seizure is a type of seizure originating at some point within, and rapidly engaging, bilaterally distributed networks. The networks may include cortical and subcortical structures but not necessarily the entire cortex.
in 2017 the ILAE Commission for Classification and Terminology recommended classifying a seizure as having focal or generalized onset only when there is a high degree of confidence (over 80%, arbitrarily chosen to parallel the usual allowable beta error) in the accuracy of this determination. Classifying a seizure as having apparently generalized onset does not rule out a focal-onset obscured by limitations of our current clinical methods.
Rare diseases that can present with this35
Very common80–99%
7Common30–79%
14- 16p13.11microdeletion syndrome
- Adult-onset autosomal recessive cerebellar ataxia
- Autosomal recessive cutis laxa type 2A
- Bilateral generalized polymicrogyria
- Familial adult myoclonic epilepsy
- Generalized epilepsy-paroxysmal dyskinesia syndrome
- Hyperinsulinism-hyperammonemia syndrome
- Hyperprolinemia type 2
- Lissencephaly type 1 due to doublecortin gene mutation
- Macrocephaly-intellectual disability-neurodevelopmental disorder-small thorax syndrome
- Primary hypomagnesemia-refractory seizures-intellectual disability syndrome
- Spinocerebellar ataxia type 10
- TK2-related mitochondrial DNA maintenance defect, myopathic form
- ZTTK syndrome
Sometimes5–29%
12- Bilateral polymicrogyria
- Corpus callosum agenesis-macrocephaly-hypertelorism syndrome
- Cysticercosis
- Isolated focal cortical dysplasia
- Microphthalmia-brain atrophy syndrome
- Niemann-Pick disease type C
- NMDA receptor encephalitis
- Pelizaeus-Merzbacher disease in female carriers
and 4 more in this range
The range is how often this sign appears among people diagnosed with each disease — it is not a probability of having any of them. Many of these signs also occur in common, non-rare conditions. A sign on this page is a conversation to have with a clinician, not a conclusion.
Part of the broader category
Also called: Generalised onset seizure · Generalised seizures · Generalised-onset seizure · Generalized onset seizure · Generalized seizures · Generalized-onset seizures · Primary generalised seizure · Primary generalized seizure
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Start free with EleplanThis page uses the Human Phenotype Ontology (2026-06-23) — Human Phenotype Ontology Consortium, hpo.jax.org. Disease associations from Orphanet (INSERM), CC BY 4.0. Content is educational and is not medical advice.