- Axial hypotonia (HP:0008936): Muscular hypotonia (abnormally low muscle tone) affecting the musculature of the trunk. Evidence: PCS. Frequency: 11/11. (PMID:31031012)
- Microcephaly (HP:0000252): Head circumference below 2 standard deviations below the mean for age and gender. Evidence: PCS. Frequency: 6/11. (PMID:31031012)
- Cerebral atrophy (HP:0002059): Atrophy (wasting, decrease in size of cells or tissue) affecting the cerebrum. Evidence: PCS. Frequency: 3/10. (PMID:31031012)
- Absent speech (HP:0001344): Complete lack of development of speech and language abilities. Evidence: PCS. Frequency: 8/8. (PMID:31031012)
- Inability to walk (HP:0002540): Incapability to ambulate. Evidence: PCS. Frequency: 7/8. (PMID:31031012)
- Delayed CNS myelination (HP:0002188): Delayed myelination in the central nervous system. Evidence: PCS. Frequency: 1/12. (PMID:31031012)
- Hypoplasia of the corpus callosum (HP:0002079): Underdevelopment of the corpus callosum. Evidence: PCS. Frequency: 6/10. (PMID:31031012)
- 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: PCS. Frequency: 11/11. Onset: Infantile onset (HP:0003593). (PMID:31031012)
- 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: PCS. Frequency: 1/10. (PMID:31031012)
- Periventricular white matter hyperintensities (HP:0030891): Areas of brighter than expected signal on magnetic resonance imaging emanating from the cerebral white matter that surrounds the cerebral ventricles. Evidence: PCS. Frequency: 2/11. (PMID:31031012)
- Lower limb spasticity (HP:0002061): Spasticity (velocity-dependent increase in tonic stretch reflexes with increased muscle tone and hyperexcitable tendon reflexes) in the muscles of the lower limbs, hips, and pelvis. Evidence: PCS. (PMID:31031012)
- Multifocal epileptiform discharges (HP:0010841): An abnormality in cerebral electrical activity recorded along the scalp by electroencephalography (EEG) and being identified at multiple locations (foci). Evidence: PCS. Frequency: 7/9. (PMID:31031012)
- Severe global developmental delay (HP:0011344): A severe delay in the achievement of motor or mental milestones in the domains of development of a child. Evidence: PCS. (PMID:31031012)
- Death in childhood (HP:0003819): Death in during childhood, defined here as between the ages of 2 and 10 years. Evidence: PCS. Frequency: 3/11. (PMID:31031012)
- Autosomal recessive inheritance (HP:0000007): 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 individuals with two pathogenic alleles, either homozygotes (two copies of the same mutant allele) or compound heterozygotes (whereby each copy of a gene has a distinct mutant allele). Evidence: PCS. (PMID:31031012)
- Feeding difficulties in infancy (HP:0008872): Impaired feeding performance of an infant as manifested by difficulties such as weak and ineffective sucking, brief bursts of sucking, and falling asleep during sucking. There may be difficulties with chewing or maintaining attention. Evidence: PCS. Frequency: 9/11. (PMID:31031012)
- 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: PCS. Frequency: 11/11. (PMID:31031012)
- Upper limb spasticity (HP:0006986). Evidence: PCS. (PMID:31031012)
These phenotypes are associated with the disease developmental and epileptic encephalopathy, 76 (OMIM:618468).