- 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: PCS. Frequency: 79/105. (PMID:29939203)
- 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. (OMIM:601068)
- Jerk-locked premyoclonus spikes (HP:0001351): Jerk-locked averaging (JLA) is used to record the timing and distribution of brain activity preceding brisk involuntary movements such as those observed in patients with myoclonus. JLA is capable of revealing a premyoclonus spike in the absence of paroxysmal activity in the routine EEG. Evidence: IEA. (OMIM:601068)
- Adult onset (HP:0003581): Onset of disease manifestations in adulthood, defined here as at the age of 16 years or later. Evidence: PCS. (PMID:29939203)
- Nonprogressive (HP:0003680): Applies to a disease manifestation that does not increase in scope or severity over the course of time, i.e., that does not worsen with age. Evidence: TAS. (OMIM:601068)
- Enhancement of the C-reflex (HP:0001340): Increase in amplitude of a long-loop response upon somatosensory evoked potential testing, representing an electrically evoked myoclonic response. Evidence: PCS. Frequency: 61/71. (PMID:29939203)
- EEG with photoparoxysmal response (HP:0010852): EEG abnormalities (epileptiform discharges) evoked by flashing lights or black and white striped patterns. Evidence: TAS. (OMIM:601068)
- Giant somatosensory evoked potentials (HP:0001312): An abnormal enlargement (i.e. increase in measured voltage) of somatosensory evoked potentials. Evidence: PCS. Frequency: 74/82. (OMIM:601068;PMID:29939203)
- Autosomal dominant inheritance (HP:0000006): A mode of inheritance that is observed for traits related to a gene encoded on one of the autosomes (i.e., the human chromosomes 1-22) in which a trait manifests in heterozygotes. In the context of medical genetics, an autosomal dominant disorder is caused when a single copy of the mutant allele is present. Males and females are affected equally, and can both transmit the disorder with a risk of 50% for each child of inheriting the mutant allele. Evidence: PCS. (PMID:29507423)
- Intellectual disability (HP:0001249): The term intellectual disability or intellectual developmental disorder is used to describe significantly sub-average intellectual and adaptive functioning based on clinical assessment and as measured by individually administered, appropriately normed, standardized and validated tests of intellectual functioning and adaptive behavior, with onset during the developmental period from infancy through adolescence. Evidence: TAS. Frequency: Occasional (HP:0040283). (OMIM:601068)
- Tremor (HP:0001337): An unintentional, oscillating to-and-fro muscle movement about a joint axis. Evidence: PCS. (PMID:29939203)
- EEG with irregular generalized spike and wave complexes (HP:0001326): EEG shows spikes (<80 ms) and waves, which are recorded over the entire scalp and do not have a specific frequency. Evidence: TAS. (OMIM:601068)
These phenotypes are associated with the disease epilepsy, familial adult myoclonic, 1 (OMIM:601068).