- Typified by somatic mosaicism (HP:0001442): Description of conditions in which affected individuals typically display somatic mosaicism, i.e., genetically distinct populations of somatic cells in a given organism caused by DNA mutations, epigenetic alterations of DNA, chromosomal abnormalities or the spontaneous reversion of inherited mutations. In many conditions typified by somatic mosaicism, constitutive mutation is lethal and cases are exclusively or predominantly mosaic. Evidence: TAS. (OMIM:607341)
- Focal impaired awareness seizure (HP:0002384): Focal impaired awareness seizure (or focal seizure with impaired or lost awareness) is a type of focal-onset seizure characterized by some degree (which may be partial) of impairment of the person's awareness of themselves or their surroundings at any point during the seizure. Evidence: TAS. (OMIM:607341)
- Adult onset (HP:0003581): Onset of disease manifestations in adulthood, defined here as at the age of 16 years or later. Evidence: IEA. (OMIM:607341)
- Infantile onset (HP:0003593): Onset of signs or symptoms of disease between 28 days to one year of life. Evidence: IEA. (OMIM:607341)
- Cognitive impairment (HP:0100543): Abnormal cognition is characterized by deficits in thinking, reasoning, or remembering. Evidence: TAS. (OMIM:607341)
- Focal cortical dysplasia type II (HP:0032051): A type of focal cortical dysplasia that is characterized by disrupted cortical lamination and specific cytological abnormalities. Evidence: PCS. (PMID:25799227)
- Focal white matter lesions (HP:0007042). Evidence: IEA. (OMIM:607341)
- Cortical dysplasia (HP:0002539): The presence of developmental dysplasia of the cerebral cortex. Evidence: IEA. (OMIM:607341)
- 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: IEA. (OMIM:607341)
- Sporadic (HP:0003745): Cases of the disease in question occur without a previous family history, i.e., as isolated cases without being transmitted from a parent and without other siblings being affected. Evidence: TAS. (OMIM:607341)
- 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. (OMIM:607341)
- Hemimegalencephaly (HP:0007206): Enlargement of all or parts of one cerebral hemisphere. Evidence: PCS. (PMID:22497611)
- Astrocytosis (HP:0002446): Proliferation of astrocytes in the area of a lesion of the central nervous system. Evidence: TAS. (OMIM:607341)
These phenotypes are associated with the disease isolated focal cortical dysplasia type II (OMIM:607341).