- Seizure (HP:0001250): A seizure is an intermittent abnormality of nervous system physiology characterized by a transient occurrence of signs and/or symptoms due to abnormal excessive or synchronous neuronal activity in the brain. Evidence: TAS. Frequency: Very frequent (HP:0040281). (ORPHA:352582)
- Generalized myoclonic seizure (HP:0002123): 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. Evidence: TAS. Frequency: Very frequent (HP:0040281). (ORPHA:352582)
- Dysarthria (HP:0001260): Dysarthric speech is a general description referring to a neurological speech disorder characterized by poor articulation. Depending on the involved neurological structures, dysarthria may be further classified as spastic, flaccid, ataxic, hyperkinetic and hypokinetic, or mixed. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:352582)
- Cerebellar atrophy (HP:0001272): Cerebellar atrophy is defined as a cerebellum with initially normal structures, in a posterior fossa with normal size, which displays enlarged fissures (interfolial spaces) in comparison to the foliae secondary to loss of tissue. Cerebellar atrophy implies irreversible loss of tissue and result from an ongoing progressive disease until a final stage is reached or a single injury, e.g. an intoxication or infectious event. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:352582)
- Thick cerebral cortex (HP:0006891). Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:352582)
- Focal-onset seizure (HP:0007359): A focal-onset seizure is a type of seizure originating within networks limited to one hemisphere. They may be discretely localized or more widely distributed, and may originate in subcortical structures. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:352582)
- Simple febrile seizure (HP:0011171): A short generalized seizure, of a duration of <15 min, not recurring within 24 h, occurring during a febrile episode not caused by an acute disease of the nervous system intracranial infection or severe metabolic disturbance. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:352582)
- EEG with focal spike waves (HP:0011197): EEG with focal sharp transient waves of a duration less than 80 msec followed by a slow wave. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:352582)
- Bilateral tonic-clonic seizure with generalized onset (HP:0025190): A bilateral tonic-clonic seizure with generalized onset is a type of bilateral tonic-clonic seizure characterized by generalized onset; these seizures rapidly engage networks in both hemispheres at the start of the seizure. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:352582)
- Interictal EEG abnormality (HP:0025373): Interictal refers to a period of time between epileptic seizures. Electroencephalographic (EEG) patterns are important in the differential diagnosis of epilepsy, and the EEG is almost always abnormal during a seizure. Some persons with seizures may show EEG abnormalities between seizures, while others do not. In some cases, multiple interictal EEGs must be recorded before an abnormality is observed. In most cases the electrographic pattern of seizure onset is completely different from the activity recorded during interictal discharge. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:352582)
- Proptosis (HP:0000520): An eye that is protruding anterior to the plane of the face to a greater extent than is typical. Evidence: TAS. Frequency: Occasional (HP:0040283). (ORPHA:352582)
- Blepharospasm (HP:0000643): A focal dystonia that affects the muscles of the eyelids and brow, associated with involuntary recurrent spasm of both eyelids. Evidence: TAS. Frequency: Occasional (HP:0040283). (ORPHA:352582)
- Delayed speech and language development (HP:0000750): A degree of language development that is significantly below the norm for a child of a specified age. Evidence: TAS. Frequency: Occasional (HP:0040283). (ORPHA:352582)
- Ataxia (HP:0001251): Ataxia refers to impaired coordination of voluntary muscle movement. Cerebellar ataxia refers to ataxia due to dysfunction of the cerebellum. This causes a variety of elementary neurological deficits including asynergy (lack of coordination between muscles, limbs and joints), dysmetria (lack of ability to judge distances that can lead to under- or overshoot in grasping movements), and dysdiadochokinesia (inability to perform rapid movements requiring antagonizing muscle groups to be switched on and off repeatedly). Evidence: TAS. Frequency: Occasional (HP:0040283). (ORPHA:352582)
- Mild intellectual disability (HP:0001256): Mild intellectual disability (ID) is defined as a type of ID characterized by mildly sub-average adaptive functioning and intellectual functioning, with an intelligence quotient (IQ) the range of 50-69. Evidence: TAS. Frequency: Occasional (HP:0040283). (ORPHA:352582)
- Global developmental delay (HP:0001263): A delay in the achievement of motor or mental milestones in the domains of development of a child, including motor skills, speech and language, cognitive skills, and social and emotional skills. This term should only be used to describe children younger than five years of age. Evidence: TAS. Frequency: Occasional (HP:0040283). (ORPHA:352582)
- Motor delay (HP:0001270): A type of Developmental delay characterized by a delay in acquiring motor skills. Evidence: TAS. Frequency: Occasional (HP:0040283). (ORPHA:352582)
- Gait disturbance (HP:0001288): The term gait disturbance can refer to any disruption of the ability to walk. Evidence: TAS. Frequency: Occasional (HP:0040283). (ORPHA:352582)
- Bilateral tonic-clonic seizure (HP:0002069): A bilateral tonic-clonic seizure is a seizure defined by a tonic (bilateral increased tone, lasting seconds to minutes) and then a clonic (bilateral sustained rhythmic jerking) phase. Evidence: TAS. Frequency: Occasional (HP:0040283). (ORPHA:352582)
- Clumsiness (HP:0002312): Lack of physical coordination resulting in an abnormal tendency to drop items or bump into objects. Evidence: TAS. Frequency: Occasional (HP:0040283). (ORPHA:352582)
- Moderate intellectual disability (HP:0002342): Moderate intellectual disability (ID) is defined as a type of ID characterized by moderately sub-average adaptive functioning and intellectual functioning, with an intelligence quotient (IQ) the range of 35-49. Evidence: TAS. Frequency: Occasional (HP:0040283). (ORPHA:352582)
- Borderline intellectual disability (HP:0006889): Borderline intellectual disability is defined as an intelligence quotient (IQ) in the range of 70-85. Evidence: TAS. Frequency: Occasional (HP:0040283). (ORPHA:352582)
- Abnormal hippocampus morphology (HP:0025100): Any structural anomaly of the hippocampus,. Evidence: TAS. Frequency: Occasional (HP:0040283). (ORPHA:352582)
- Periventricular nodular heterotopia (HP:0032388): Nodules of heterotopia along the ventricular walls. There can be a single nodule or a large number of nodules, they can exist on either or both sides of the brain at any point along the higher ventricle margins, they can be small or large, single or multiple. Evidence: TAS. Frequency: Occasional (HP:0040283). (ORPHA:352582)
- Limb myoclonus (HP:0045084). Evidence: TAS. Frequency: Occasional (HP:0040283). (ORPHA:352582)
These phenotypes are associated with the disease Familial infantile myoclonic epilepsy (ORPHA:352582).