- 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. Frequency: 1/2. (PMID:27282648)
- Progressive (HP:0003676): Applies to a disease manifestation that increases in scope or severity over the course of time, i.e., that worsens with age. Evidence: PCS. (PMID:27282648)
- Clonus (HP:0002169): A series of rhythmic and involuntary muscle contractions (at a frequency of about 5 to 7 Hz) that occur in response to an abruptly applied and sustained stretch. Evidence: TAS. (OMIM:614498)
- Hypothermia (HP:0002045): Reduced body temperature due to failed thermoregulation. Evidence: PCS. Frequency: 4/4. (PMID:22279524)
- Delayed CNS myelination (HP:0002188): Delayed myelination in the central nervous system. Evidence: PCS. Frequency: 1/2. (PMID:27282648)
- Inguinal hernia (HP:0000023): Protrusion of the contents of the abdominal cavity through the inguinal canal. Evidence: IEA. (OMIM:614498)
- Generalized myoclonic seizure (HP:0002123): A generalized myoclonic seizure is a type of generalized motor seizure characterized by bilateral, sudden, brief (<100 ms) involuntary single or multiple contraction of muscles or muscle groups of variable topography (axial, proximal limb, distal). Myoclonus is less regularly repetitive and less sustained than is clonus. Evidence: PCS. Frequency: 1/2. (PMID:27282648)
- Rigidity (HP:0002063): Continuous involuntary sustained muscle contraction. When an affected muscle is passively stretched, the degree of resistance remains constant regardless of the rate at which the muscle is stretched. This feature helps to distinguish rigidity from muscle spasticity. Evidence: PCS. Frequency: 3/3. Onset: Congenital onset (HP:0003577). (PMID:22279524)
- Infantile onset (HP:0003593): Onset of signs or symptoms of disease between 28 days to one year of life. Evidence: PCS. Frequency: 1/2. (PMID:27282648)
- Thin corpus callosum (HP:0033725): An abnormally thin corpus callous, due to atrophy, hypoplasia or agenesis. This term is intended to be used in situations where it is not known if thinning of the corpus callosum (for instance, as visualized by magnetic resonance tomography) is due to abnormal development (e.g. a leukodystrophy) or atrophy following normal development (e.g. neurodegeneration). Evidence: PCS. Frequency: 1/2. (PMID:27282648)
- Abnormal autonomic nervous system physiology (HP:0012332): A functional abnormality of the autonomic nervous system. Evidence: TAS. (OMIM:614498)
- Cerebral visual impairment (HP:0100704): A form of loss of vision caused by damage to the visual cortex rather than a defect in the eye. Evidence: PCS. Frequency: 1/2. (PMID:27282648)
- Death in infancy (HP:0001522): Death within the first 24 months of life. Evidence: PCS. Frequency: 5/6. (PMID:22279524;PMID:27282648)
- Cytochrome C oxidase-negative muscle fibers (HP:0003688): An abnormally reduced activity of the enzyme cytochrome C oxidase in muscle tissue. Evidence: PCS. Frequency: 1/2. (PMID:27282648)
- Neonatal onset (HP:0003623): Onset of signs or symptoms of disease within the first 28 days of life. Evidence: PCS. Frequency: 1/2. (PMID:27282648)
- Hyperreflexia (HP:0001347): Hyperreflexia is the presence of hyperactive stretch reflexes of the muscles. Evidence: TAS. (OMIM:614498)
- Progressive microcephaly (HP:0000253): Progressive microcephaly is diagnosed when the head circumference falls progressively behind age- and gender-dependent norms. Evidence: TAS. (OMIM:614498)
- Axial hypotonia (HP:0008936): Muscular hypotonia (abnormally low muscle tone) affecting the musculature of the trunk. Evidence: PCS. Frequency: 1/2. (PMID:27282648)
- Microcephaly (HP:0000252): Head circumference below 2 standard deviations below the mean for age and gender. Evidence: TAS. (OMIM:614498)
- Bradycardia (HP:0001662): A slower than normal heart rate (in adults, slower than 60 beats per minute). Evidence: PCS. Frequency: 4/4. (PMID:22279524)
- Babinski sign (HP:0003487): Upturning of the big toe (and sometimes fanning of the other toes) in response to stimulation of the sole of the foot. If the Babinski sign is present it can indicate damage to the corticospinal tract. Evidence: TAS. (OMIM:614498)
- Feeding difficulties (HP:0011968): Impaired ability to eat related to problems gathering food and getting ready to suck, chew, or swallow it. Evidence: PCS. Frequency: 1/2. (PMID:27282648)
- 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. Frequency: 2/2. (PMID:27282648)
- Gliosis (HP:0002171): Gliosis is the focal proliferation of glial cells in the central nervous system. Evidence: TAS. (OMIM:614498)
- Focal motor status epilepticus (HP:0032663): Status epilepticus with focal motor signs originating within networks limited to one hemisphere. Involves musculature in any form. The motor event could consist of an increase (positive) or decrease (negative) in muscle contraction to produce a movement. Evidence: PCS. Frequency: 1/2. (PMID:27282648)
- EEG with burst suppression (HP:0010851): The burst suppression pattern in electroencephalography refers to a characteristic periodic pattern of low voltage (<10 microvolts) suppressed background and a relatively shorter pattern of higher amplitude slow, sharp, and spiking complexes. Evidence: PCS. Frequency: 1/2. (PMID:27282648)
- Joint contracture (HP:0034392): A limitation in the passive range of motion of a joint resulting from loss of elasticity in the periarticular tissues owing to structural changes of non-bony tissues, such as muscles, tendons, ligaments, joint capsules or skin. A contracture prevents movement of the associated body part. Evidence: PCS. Frequency: 2/2. (PMID:27282648)
- Multifocal seizures (HP:0031165): Seizures that start from several different areas of the brain (i.e., with multiple ictal onset locations). Evidence: TAS. (OMIM:614498)
- Limb hypertonia (HP:0002509). Evidence: PCS. Frequency: 1/2. (PMID:27282648)
- Neuronal loss in central nervous system (HP:0002529). Evidence: TAS. (OMIM:614498)
- Myoclonic spasms (HP:0003739). Evidence: PCS. Frequency: 3/3. Onset: Antenatal onset (HP:0030674). (PMID:22279524)
- 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:22279524)
- 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: TAS. Frequency: Occasional (HP:0040283). (OMIM:614498)
- Focal-onset seizure (HP:0007359): A focal-onset seizure is a type of seizure originating within networks limited to one hemisphere. They may be discretely localized or more widely distributed, and may originate in subcortical structures. Evidence: PCS. Frequency: 4/4. Onset: Neonatal onset (HP:0003623). (PMID:22279524)
- Micrognathia (HP:0000347): Developmental hypoplasia of the mandible. Evidence: TAS. Frequency: Occasional (HP:0040283). (OMIM:614498)
- Apnea (HP:0002104): Lack of breathing with no movement of the respiratory muscles and no exchange of air in the lungs. This term refers to a disposition to have recurrent episodes of apnea rather than to a single event. Evidence: PCS. Frequency: 5/6. (PMID:22279524;PMID:27282648)
These phenotypes are associated with the disease neonatal-onset encephalopathy with rigidity and seizures (OMIM:614498).