A neonatal/infantile epilepsy syndrome that is characterized by the onset of myoclonic seizures between the ages of 6-18 months (range 4 months to 3 years). Males are twice as likely to be affected as females. Antecedent and birth history is unremarkable. Head size and neurological examination are normal. Prior development is usually normal. Cognitive, motor and behavioral difficulties are reported, especially if seizures are poorly controlled. Developmental outcome is normal in 60-85% of cases. Mild intellectual impairment and attention problems can be seen. The disease is myoclonic epilepsy in infancy (MONDO_0100566, a Monarch Disease Ontology term). Also known as: MEI, benign myoclonic epilepsy of infancy, benign myoclonus epilepsy of infancy.