- Epicanthus (HP:0000286): A fold of skin starting above the medial aspect of the upper eyelid and arching downward to cover, pass in front of and lateral to the medial canthus. Evidence: PCS. (PMID:28335020)
- Narrow forehead (HP:0000341): Width of the forehead or distance between the frontotemporales is more than two standard deviations below the mean (objective); or apparently narrow intertemporal region (subjective). Evidence: PCS. (PMID:28335020)
- 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:28335020)
- Tented upper lip vermilion (HP:0010804): Triangular appearance of the oral aperture with the apex in the midpoint of the upper vermilion and the lower vermilion forming the base. Evidence: PCS. (PMID:8460530)
- 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:8723564)
- 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. (PMID:2070547)
- Profound intellectual disability (HP:0002187): Profound intellectual disability (ID) is defined as a type of ID characterized by profoundly sub-average adaptive functioning and intellectual functioning, with an intelligence quotient (IQ) below 20. Evidence: PCS. (PMID:8301648)
- Short nose (HP:0003196): Distance from nasion to subnasale more than two standard deviations below the mean, or alternatively, an apparently decreased length from the nasal root to the nasal tip. Evidence: PCS. (PMID:2070547)
- Severe muscular hypotonia (HP:0006829): A severe degree of muscular hypotonia characterized by markedly reduced muscle tone. Evidence: PCS. (PMID:28335020)
- Generalized hypotonia (HP:0001290): Generalized muscular hypotonia (abnormally low muscle tone). Evidence: IEA. (OMIM:260565)
- Developmental stagnation (HP:0007281): A cessation of the development of a child in the areas of motor skills, speech and language, cognitive skills, and social and/or emotional skills. Evidence: PCS. (PMID:8301648)
- Edema of the dorsum of feet (HP:0012098): An abnormal accumulation of fluid beneath the skin on the back of the feet. Evidence: PCS. (PMID:8723564)
- 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. (PMID:8301648)
- Infantile encephalopathy (HP:0007105): Encephalopathy with onset in the infantile period. Evidence: PCS. (PMID:2070547)
- Pachygyria (HP:0001302): 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. (OMIM:260565)
- Retrognathia (HP:0000278): An abnormality in which the mandible is mislocalised posteriorly. Evidence: IEA. (PMID:2070547)
- Undetectable visual evoked potentials (HP:0007965). Evidence: PCS. (PMID:8301648)
- Hyperreflexia (HP:0001347): Hyperreflexia is the presence of hyperactive stretch reflexes of the muscles. Evidence: PCS. (PMID:2070547)
- Peripheral dysmyelination (HP:0003469): Defective structure and function of myelin sheaths. Dysmyelination is distinguished from demyleination where there is destruction or damage of previously normal myelination. Evidence: PCS. (PMID:8335020)
- Progressive microcephaly (HP:0000253): Progressive microcephaly is diagnosed when the head circumference falls progressively behind age- and gender-dependent norms. Evidence: PCS. (PMID:2070547)
- Hypoplasia of the corpus callosum (HP:0002079): Underdevelopment of the corpus callosum. Evidence: TAS. (OMIM:260565)
- Open mouth (HP:0000194): A facial appearance characterized by a permanently or nearly permanently opened mouth. Evidence: PCS. (PMID:2070547)
- Full cheeks (HP:0000293): Increased prominence or roundness of soft tissues between zygomata and mandible. Evidence: PCS. (PMID:2070547)
- 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:8460530)
- Tapered finger (HP:0001182): The gradual reduction in girth of the finger from proximal to distal. Evidence: PCS. (PMID:2070547)
- Edema (HP:0000969): An abnormal accumulation of fluid beneath the skin, or in one or more cavities of the body. Evidence: PCS. (PMID:28335020)
- 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:8301648)
- Neuronal loss in central nervous system (HP:0002529). Evidence: PCS. (PMID:28335020)
- Optic atrophy (HP:0000648): Atrophy of the optic nerve. Optic atrophy results from the death of the retinal ganglion cell axons that comprise the optic nerve and manifesting as a pale optic nerve on fundoscopy. Evidence: PCS. (PMID:2070547)
- Polymicrogyria (HP:0002126): 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. (OMIM:260565)
- Edema of the dorsum of hands (HP:0007514): An abnormal accumulation of fluid beneath the skin on the back of the hands. Evidence: PCS. (PMID:8723564)
- Myoclonus (HP:0001336): Very brief, involuntary random muscular contractions occurring at rest, in response to sensory stimuli, or accompanying voluntary movements. Evidence: TAS. (OMIM:260565)
These phenotypes are associated with the disease PEHO syndrome (OMIM:260565).