- 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: Very frequent (HP:0040281). (ORPHA:101071)
- Hemiparesis (HP:0001269): Loss of strength in the arm, leg, and sometimes face on one side of the body. Hemiplegia refers to a complete loss of strength, whereas hemiparesis refers to an incomplete loss of strength. Evidence: TAS. Frequency: Very frequent (HP:0040281). (ORPHA:101071)
- Cortical dysplasia (HP:0002539): The presence of developmental dysplasia of the cerebral cortex. Evidence: TAS. Frequency: Very frequent (HP:0040281). (ORPHA:101071)
- Cerebral hypoplasia (HP:0006872): Underdevelopment of the cerebrum. Evidence: TAS. Frequency: Very frequent (HP:0040281). (ORPHA:101071)
- Thick cerebral cortex (HP:0006891). Evidence: TAS. Frequency: Very frequent (HP:0040281). (ORPHA:101071)
- Lateral ventricle dilatation (HP:0006956). Evidence: TAS. Frequency: Very frequent (HP:0040281). (ORPHA:101071)
- 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: Very frequent (HP:0040281). (ORPHA:101071)
- Neurodevelopmental delay (HP:0012758): Neurodevelopmental delay (NDD) refers to delays in the maturation of the brain and central nervous system; infants and young children with NDD may experience delays in the development of one or more skills including gross motor abilities, fine-motor coordination, language abilities and ability to solve increasingly complex problems. Evidence: TAS. Frequency: Very frequent (HP:0040281). (ORPHA:101071)
- 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: Frequent (HP:0040282). (ORPHA:101071)
- EEG with focal epileptiform discharges (HP:0011185): EEG discharges recorded in particular areas of a localized (focal) abnormality in cerebral electrical activity recorded along the scalp by electroencephalography (EEG). Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:101071)
- Widened subarachnoid space (HP:0012704): An increase in size of the anatomic space between the arachnoid membrane and pia mater. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:101071)
- 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: Occasional (HP:0040283). (ORPHA:101071)
- Infantile spasms (HP:0012469): Infantile spasms represent a subset of "epileptic spasms". Infantile Spasms are epileptic spasms starting in the first year of life (infancy). Evidence: TAS. Frequency: Occasional (HP:0040283). (ORPHA:101071)
- Focal atonic seizure (HP:0020220): A focal seizure characterized at onset by sudden loss or diminution of muscle tone without apparent preceding myoclonic or tonic activity, typically lasting more than 500 ms but less than 2 seconds. It may involve the head, trunk, jaw or limb musculature. Evidence: TAS. Frequency: Occasional (HP:0040283). (ORPHA:101071)
These phenotypes are associated with the disease Unilateral hemispheric polymicrogyria (ORPHA:101071).