A generalized myoclonic seizure is a type of generalized motor seizure characterized by bilateral, sudden, brief (<100 ms) involuntary single or multiple contraction of muscles or muscle groups of variable topography (axial, proximal limb, distal). Myoclonus is less regularly repetitive and less sustained than is clonus. The phenotype is Human Phenotype Ontology entry HP_0002123 (Generalized myoclonic seizure). Also known as: Generalised epileptic myoclonus, Generalised myoclonic seizure, Generalised myoclonic seizures, Generalized epileptic myoclonus, Generalized myoclonic seizures, Myoclonus seizures.