A rare infantile epilepsy syndrome characterized by early onset of seizures of variable type and severity, potentially associated with a spectrum of clinical signs and symptoms including delay or lack of psychomotor development, intellectual disability, poor or absent speech development, behavioral abnormalities, hypotonia, movement disorders, spasticity, microcephaly, and dysmorphic facial features, among others. Brain imaging findings are also variable and may include cerebral atrophy or white matter abnormalities. The disease is Monarch Disease Ontology term MONDO_0018614 (undetermined early-onset epileptic encephalopathy). Also known as: non-specific early-onset epileptic encephalopathy, undetermined EOEE.