- Bilateral tonic-clonic seizure (HP:0002069): A bilateral tonic-clonic seizure is a seizure defined by a tonic (bilateral increased tone, lasting seconds to minutes) and then a clonic (bilateral sustained rhythmic jerking) phase. Evidence: PCS. Frequency: 4/7. (PMID:33245860)
- 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. Frequency: 3/7. (PMID:33245860)
- Cerebral atrophy (HP:0002059): Atrophy (wasting, decrease in size of cells or tissue) affecting the cerebrum. Evidence: PCS. (PMID:33245860)
- 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: PCS. Frequency: 1/7. (PMID:33245860)
- Developmental regression (HP:0002376): Loss of developmental skills, as manifested by loss of developmental milestones. Evidence: PCS. Frequency: 1/7. (PMID:33245860)
- Fetal pyelectasis (HP:0010945): Mild pyelectasis is defined as a hypoechoic spherical or elliptical space within the renal pelvis that measures at least 5mm and not more than 10 mm. The measurement is taken on a transverse section through the fetal renal pelvis using the maximum anterior-to-posterior measurement. Evidence: PCS. Frequency: 1/7. Onset: Fetal onset (HP:0011461). (PMID:33245860)
- Focal impaired awareness seizure (HP:0002384): Focal impaired awareness seizure (or focal seizure with impaired or lost awareness) is a type of focal-onset seizure characterized by some degree (which may be partial) of impairment of the person's awareness of themselves or their surroundings at any point during the seizure. Evidence: PCS. Frequency: 1/7. (PMID:33245860)
- Hypotonia (HP:0001252): Hypotonia is an abnormally low muscle tone (the amount of tension or resistance to movement in a muscle). Even when relaxed, muscles have a continuous and passive partial contraction which provides some resistance to passive stretching. Hypotonia thus manifests as diminished resistance to passive stretching. Hypotonia is not the same as muscle weakness, although the two conditions can co-exist. Evidence: PCS. Frequency: 2/7. (PMID:33245860)
- Infantile onset (HP:0003593): Onset of signs or symptoms of disease between 28 days to one year of life. Evidence: PCS. Frequency: 4/7. (PMID:33245860)
- 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: 1/7. (PMID:33245860)
- Profound global developmental delay (HP:0012736): A profound delay in the achievement of motor or mental milestones in the domains of development of a child. Evidence: PCS. Frequency: 2/7. (PMID:33245860)
- 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. Frequency: 5/7. (PMID:33245860)
- Ankle clonus (HP:0011448): Clonus is an involuntary tendon reflex that causes repeated flexion and extension of the foot. Ankle clonus is tested by rapidly flexing the foot upward. Evidence: PCS. Frequency: 1/7. (PMID:33245860)
- X-linked recessive inheritance (HP:0001419): A mode of inheritance that is observed for recessive traits related to a gene encoded on the X chromosome. In the context of medical genetics, X-linked recessive disorders manifest in males (who have one copy of the X chromosome and are thus hemizygotes), but generally not in female heterozygotes who have one mutant and one normal allele. Evidence: PCS. (PMID:33245860)
- Autistic behavior (HP:0000729): Persistent deficits in social interaction and communication and interaction as well as a markedly restricted repertoire of activity and interest as well as repetitive patterns of behavior. Evidence: PCS. Frequency: 4/7. (PMID:33245860)
- Limb hypertonia (HP:0002509). Evidence: PCS. Frequency: 3/7. (PMID:33245860)
- Hypothyroidism (HP:0000821): Deficiency of thyroid hormone. Evidence: PCS. Frequency: 1/7. (PMID:33245860)
- Apneic episodes in infancy (HP:0005949): Recurrent episodes of apnea occurring during infancy. Evidence: PCS. Frequency: 5/7. Onset: Neonatal onset (HP:0003623). (PMID:33245860)
- 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: 6/7. (PMID:33245860)
- Constipation (HP:0002019): Infrequent or difficult evacuation of feces. Evidence: PCS. Frequency: 1/7. (PMID:33245860)
- Atrial septal defect (HP:0001631): Atrial septal defect (ASD) is a congenital abnormality of the interatrial septum that enables blood flow between the left and right atria via the interatrial septum. Evidence: PCS. Frequency: 1/7. (PMID:33245860)
- Abdominal pain (HP:0002027): An unpleasant sensation characterized by physical discomfort (such as pricking, throbbing, or aching) and perceived to originate in the abdomen. Evidence: PCS. Frequency: 1/7. (PMID:33245860)
- Neonatal onset (HP:0003623): Onset of signs or symptoms of disease within the first 28 days of life. Evidence: PCS. Frequency: 3/7. (PMID:33245860)
These phenotypes are associated with the disease developmental and epileptic encephalopathy, 90 (OMIM:301058).