- Progressive microcephaly (HP:0000253): Progressive microcephaly is diagnosed when the head circumference falls progressively behind age- and gender-dependent norms. Evidence: PCS. (PMID:31538237)
- Hypertonia (HP:0001276): A condition in which there is increased muscle tone so that arms or legs, for example, are stiff and difficult to move. Evidence: PCS. (PMID:31538237)
- Axial hypotonia (HP:0008936): Muscular hypotonia (abnormally low muscle tone) affecting the musculature of the trunk. Evidence: PCS. (PMID:31538237)
- Hypsarrhythmia (HP:0002521): Hypsarrhythmia is abnormal interictal high amplitude waves and a background of irregular spikes. There is continuous (during wakefulness), high-amplitude (>200 Hz), generalized polymorphic slowing with no organized background and multifocal spikes demonstrated by electroencephalography (EEG). Evidence: PCS. (PMID:31538237)
- Everted lower lip vermilion (HP:0000232): An abnormal configuration of the lower lip such that it is turned outward i.e., everted, with the Inner aspect of the lower lip vermilion (normally opposing the teeth) being visible in a frontal view. Evidence: PCS. (PMID:31538237)
- 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. (PMID:31538237)
- Global developmental delay (HP:0001263): 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: PCS. (PMID:31538237)
- Depressed nasal bridge (HP:0005280): Posterior positioning of the nasal root in relation to the overall facial profile for age. Evidence: PCS. (PMID:31538237)
- Hypoplasia of the pons (HP:0012110): Underdevelopment of the pons. Evidence: PCS. (PMID:31538237)
- Infra-orbital crease (HP:0100876): Skin crease extending from below the inner canthus laterally along the malar process of the maxilla and zygoma. Evidence: PCS. (PMID:31538237)
- Inferior cerebellar vermis hypoplasia (HP:0007068): Underdevelopment of the inferior portion of the vermis of cerebellum. Evidence: PCS. (PMID:31538237)
- 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:31538237)
- High forehead (HP:0000348): An abnormally increased height of the forehead. Evidence: PCS. (PMID:31538237)
- Partial agenesis of the corpus callosum (HP:0001338): A partial failure of the development of the corpus callosum. Evidence: PCS. (PMID:31538237)
- Epileptic encephalopathy (HP:0200134): A condition in which epileptiform abnormalities are believed to contribute to the progressive disturbance in cerebral function. Epileptic encephalaopathy is characterized by (1) electrographic EEG paroxysmal activity that is often aggressive, (2) seizures that are usually multiform and intractable, (3) cognitive, behavioral and neurological deficits that may be relentless, and (4) sometimes early death. Evidence: PCS. (PMID:31538237)
- Hyperglutamatemia (HP:0500149): Concentration of glutamate in the blood circulation above the upper limit of normal. Evidence: PCS. (PMID:31538237)
- Growth delay (HP:0001510): A deficiency or slowing down of growth pre- and postnatally. Evidence: PCS. (PMID:31538237)
These phenotypes are associated with the disease developmental and epileptic encephalopathy, 88 (OMIM:618959).