- Encephalopathy (HP:0001298): Encephalopathy is a term that means brain disease, damage, or malfunction. In general, encephalopathy is manifested by an altered mental state. Evidence: TAS. Frequency: Very frequent (HP:0040281). (ORPHA:209370)
- Respiratory insufficiency (HP:0002093). Evidence: TAS. Frequency: Very frequent (HP:0040281). (ORPHA:209370)
- 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: TAS. Frequency: Very frequent (HP:0040281). (ORPHA:209370)
- 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: TAS. Frequency: Very frequent (HP:0040281). (ORPHA:209370)
- Microcephaly (HP:0000252): Head circumference below 2 standard deviations below the mean for age and gender. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:209370)
- 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: TAS. Frequency: Frequent (HP:0040282). (ORPHA:209370)
- Spasticity (HP:0001257): A motor disorder characterized by a velocity-dependent increase in tonic stretch reflexes with increased muscle tone, exaggerated (hyperexcitable) tendon reflexes. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:209370)
- Growth delay (HP:0001510): A deficiency or slowing down of growth pre- and postnatally. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:209370)
- Gastroesophageal reflux (HP:0002020): A condition in which the stomach contents leak backwards from the stomach into the esophagus through the lower esophageal sphincter. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:209370)
- Poor suck (HP:0002033): An inadequate sucking reflex, resulting in the difficult of newborns to be breast-fed. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:209370)
- 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: TAS. Frequency: Frequent (HP:0040282). (ORPHA:209370)
- Involuntary movements (HP:0004305): Involuntary contractions of muscle leading to involuntary movements of extremities, neck, trunk, or face. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:209370)
- Generalized neonatal hypotonia (HP:0008935): Muscular hypotonia (abnormally low muscle tone) manifesting in the neonatal period and affecting the entire musculature. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:209370)
- EEG with focal slow activity (HP:0010843): Focal (localized) slow activity reflects focal dysfunction, not diffuse dysfunction (i.e., encephalopathy). Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:209370)
- Gastrostomy tube feeding in infancy (HP:0011471): Feeding problem necessitating gastrostomy tube feeding. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:209370)
- High palate (HP:0000218): Height of the palate more than 2 SD above the mean (objective) or palatal height at the level of the first permanent molar more than twice the height of the teeth (subjective). Evidence: TAS. Frequency: Occasional (HP:0040283). (ORPHA:209370)
- Cerebral atrophy (HP:0002059): Atrophy (wasting, decrease in size of cells or tissue) affecting the cerebrum. Evidence: TAS. Frequency: Occasional (HP:0040283). (ORPHA:209370)
- 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. Frequency: Occasional (HP:0040283). (ORPHA:209370)
- 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: TAS. Frequency: Occasional (HP:0040283). (ORPHA:209370)
These phenotypes are associated with the disease MECP2-related severe neonatal encephalopathy (ORPHA:209370).