Rare diseases · Sign or symptom
EEG abnormality
HP:0002353
What it means
Abnormality observed by electroencephalogram (EEG), which is used to record of the brain's spontaneous electrical activity from multiple electrodes placed on the scalp.
Rare diseases that can present with this135
Very common80–99%
52- 1p36deletion syndrome
- 3-methylglutaconic aciduria type 9
- Alexander disease
- Alopecia-epilepsy-pyorrhea-intellectual disability syndrome
- Amelocerebrohypohidrotic syndrome
- Angelman syndrome
- Angelman syndrome due to maternal 15q11q13 deletion
- Atypical Rett syndrome
- Bangstad syndrome
- Bonnemann-Meinecke-Reich syndrome
- Canavan disease
- Carnosinase deficiency
- Cartilage-hair hypoplasia
- Classic glucose transporter type 1 deficiency syndrome
- Corpus callosum agenesis-neuronopathy syndrome
- Deafness-vitiligo-achalasia syndrome
- Dermotrichic syndrome
- DOORS syndrome
- Familial adult myoclonic epilepsy
- Familial or sporadic hemiplegic migraine
- Febrile infection-related epilepsy syndrome
- Gamma-aminobutyric acid transaminase deficiency
- Glycine encephalopathy
- Hartnup disease
- Hernández-Aguirre Negrete syndrome
- Herpes simplex virus encephalitis
- Infantile hypotonia-oculomotor anomalies-hyperkinetic movements-developmental delay syndrome
- Infantile spasms-broad thumbs syndrome
- Japanese encephalitis
- Linear nevus sebaceus syndrome
- Maternal hyperthermia-induced birth defects
- MEHMO syndrome
- MELAS
- Microcephalic primordial dwarfism, Montreal type
- Microcephaly-intellectual disability-sensorineural hearing loss-epilepsy-abnormal muscle tone syndrome
- Microlissencephaly-micromelia syndrome
- Miller-Dieker syndrome
- Muscle-eye-brain disease
- Neonatal adrenoleukodystrophy
- Neurodevelopmental delay-seizures-ophthalmic anomalies-osteopenia-cerebellar atrophy syndrome
- Nodular neuronal heterotopia
- PEHO syndrome
- Peroxisomal acyl-CoA oxidase deficiency
- Qazi-Markouizos syndrome
- Ring chromosome 20 syndrome
- Schizencephaly
- Skeletal dysplasia-epilepsy-short stature syndrome
- Spastic paraplegia-facial-cutaneous lesions syndrome
- Symmetrical thalamic calcifications
- Vici syndrome
- Xeroderma pigmentosum
- Zellweger syndrome
Common30–79%
28- 17p11.2microduplication syndrome
- 20p13microdeletion syndrome
- 3-hydroxy-3-methylglutaric aciduria
- Aicardi syndrome
- Alacrimia-choreoathetosis-liver dysfunction syndrome
- Alopecia-intellectual disability syndrome
- Angelman syndrome due to a point mutation
- Angelman syndrome due to imprinting defect in 15q11-q13
- Angelman syndrome due to paternal uniparental disomy of chromosome 15
- Argininemia
- Argininosuccinic aciduria
- Arthrogryposis multiplex congenita-whistling face syndrome
- Aymé-Gripp syndrome
- Beta-mercaptolactate cysteine disulfiduria
- Bickerstaff brainstem encephalitis
- Cardiofaciocutaneous syndrome
- Childhood-onset motor and cognitive regression syndrome with extrapyramidal movement disorder
- Christianson syndrome
- Congenital muscular dystrophy, Fukuyama type
- Dihydropyrimidine dehydrogenase deficiency
- Early infantile developmental and epileptic encephalopathy
- Early-onset spastic ataxia-myoclonic epilepsy-neuropathy syndrome
- Flynn-Aird syndrome
- Fountain syndrome
- Galloway-Mowat syndrome
- Gingival fibromatosis-hypertrichosis syndrome
- Global developmental delay-neuro-ophthalmological abnormalities-seizures-intellectual disability syndrome
- Global developmental delay-osteopenia-ectodermal defect syndrome
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, and Orphanet separately records 2 diseases where this sign is specifically absent. A sign on this page is a conversation to have with a clinician, not a conclusion.
Part of the broader category
Also called: Abnormal EEG · Abnormal electroencephalogram · EEG abnormalities · Electroencephalogram abnormal · Electroencephalogram abnormalities
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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.