- Microcephaly (HP:0000252, a Human Phenotype Ontology term): Head circumference below 2 standard deviations below the mean for age and gender. Evidence: TAS. Frequency: Obligate (HP:0040280, a Human Phenotype Ontology term). (ORPHA:1083)
- Delayed speech and language development (HP:0000750, a Human Phenotype Ontology term): A degree of language development that is significantly below the norm for a child of a specified age. Evidence: TAS. Frequency: Very frequent (HP:0040281, a Human Phenotype Ontology term). (ORPHA:1083)
- Global developmental delay (HP:0001263, a Human Phenotype Ontology term): 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: Very frequent (HP:0040281, a Human Phenotype Ontology term). (ORPHA:1083)
- Hypoplasia of the corpus callosum (HP:0002079, a Human Phenotype Ontology term): Underdevelopment of the corpus callosum. Evidence: TAS. Frequency: Very frequent (HP:0040281, a Human Phenotype Ontology term). (ORPHA:1083)
- Neuronal loss in the cerebral cortex (HP:0007190, a Human Phenotype Ontology term). Evidence: TAS. Frequency: Very frequent (HP:0040281, a Human Phenotype Ontology term). (ORPHA:1083)
- Cerebral dysmyelination (HP:0007266, a Human Phenotype Ontology term): Defective structure and function of myelin sheaths of the white matter of the brain. Evidence: TAS. Frequency: Very frequent (HP:0040281, a Human Phenotype Ontology term). (ORPHA:1083)
- Severe intellectual disability (HP:0010864, a Human Phenotype Ontology term): Severe intellectual disability (ID) is defined as a type of ID characterized by severely sub-average adaptive functioning and intellectual functioning, with an intelligence quotient (IQ) the range of 20-34. Evidence: TAS. Frequency: Very frequent (HP:0040281, a Human Phenotype Ontology term). (ORPHA:1083)
- Bilateral tonic-clonic seizure with generalized onset (HP:0025190, a Human Phenotype Ontology term): 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: Very frequent (HP:0040281, a Human Phenotype Ontology term). (ORPHA:1083)
- Hypertonia (HP:0001276, a Human Phenotype Ontology term): A condition in which there is increased muscle tone so that arms or legs, for example, are stiff and difficult to move. Evidence: TAS. Frequency: Frequent (HP:0040282, a Human Phenotype Ontology term). (ORPHA:1083)
- Lissencephaly (HP:0001339, a Human Phenotype Ontology term): A spectrum of malformations of cortical development caused by insufficient neuronal migration that subsumes the terms agyria, pachygyria and subcortical band heterotopia. See also neuropathological definitions for 2-, 3-, and 4-layered lissencephaly. Evidence: TAS. Frequency: Frequent (HP:0040282, a Human Phenotype Ontology term). (ORPHA:1083)
- Hyperreflexia (HP:0001347, a Human Phenotype Ontology term): Hyperreflexia is the presence of hyperactive stretch reflexes of the muscles. Evidence: TAS. Frequency: Frequent (HP:0040282, a Human Phenotype Ontology term). (ORPHA:1083)
- Abnormal facial shape (HP:0001999, a Human Phenotype Ontology term): An abnormal morphology (form) of the face or its components. Evidence: TAS. Frequency: Frequent (HP:0040282, a Human Phenotype Ontology term). (ORPHA:1083)
- Ventriculomegaly (HP:0002119, a Human Phenotype Ontology term): An increase in size of the ventricular system of the brain. Evidence: TAS. Frequency: Frequent (HP:0040282, a Human Phenotype Ontology term). (ORPHA:1083)
- Cerebral cortical atrophy (HP:0002120, a Human Phenotype Ontology term): Atrophy of the cortex of the cerebrum. Evidence: TAS. Frequency: Frequent (HP:0040282, a Human Phenotype Ontology term). (ORPHA:1083)
- Thick cerebral cortex (HP:0006891, a Human Phenotype Ontology term). Evidence: TAS. Frequency: Frequent (HP:0040282, a Human Phenotype Ontology term). (ORPHA:1083)
- Cerebellar atrophy (HP:0001272, a Human Phenotype Ontology term): 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: Occasional (HP:0040283, a Human Phenotype Ontology term). (ORPHA:1083)
- Pachygyria (HP:0001302, a Human Phenotype Ontology term): Pachygyria is a malformation of cortical development with abnormally wide gyri with sulci 1,5-3 cm apart and abnormally thick cortex measuring more than 5 mm (radiological definition). See also neuropathological definitions for 2-, 3-, and 4-layered lissencephaly. Evidence: TAS. Frequency: Occasional (HP:0040283, a Human Phenotype Ontology term). (ORPHA:1083)
- Pneumonia (HP:0002090, a Human Phenotype Ontology term): Inflammation of any part of the lung parenchyma. Evidence: TAS. Frequency: Occasional (HP:0040283, a Human Phenotype Ontology term). (ORPHA:1083)
- Polymicrogyria (HP:0002126, a Human Phenotype Ontology term): Polymicrogyria is a congenital malformation of the cerebral cortex characterized by abnormal cortical layering (lamination) and an excessive number of small gyri (folds). Evidence: TAS. Frequency: Occasional (HP:0040283, a Human Phenotype Ontology term). (ORPHA:1083)
- Periventricular heterotopia (HP:0007165, a Human Phenotype Ontology term): A form of gray matter heterotopia were the mislocalized gray matter is typically located periventricularly, also sometimes called subependymal heterotopia. Periventricular means beside the ventricles. This is by far the most common location for heterotopia. Subependymal heterotopia present in a wide array of variations. There can be a small single node or a large number of nodes, can exist on either or both sides of the brain at any point along the higher ventricle margins, can be small or large, single or multiple, and can form a small node or a large wavy or curved mass. Evidence: TAS. Frequency: Occasional (HP:0040283, a Human Phenotype Ontology term). (ORPHA:1083)
- Simplified gyral pattern (HP:0009879, a Human Phenotype Ontology term): An abnormality of the cerebral cortex with fewer gyri but with normal cortical thickness. This pattern is usually often associated with congenital microcephaly. Evidence: TAS. Frequency: Occasional (HP:0040283, a Human Phenotype Ontology term). (ORPHA:1083)
- Subcortical heterotopia (HP:0032391, a Human Phenotype Ontology term): A form of heterotopia were the mislocalized gray matter is located deep within the white matter. Evidence: TAS. Frequency: Occasional (HP:0040283, a Human Phenotype Ontology term). (ORPHA:1083)
These phenotypes are associated with the disease Microlissencephaly (ORPHA:1083, an Orphanet rare-disease identifier).