- 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: TAS. Frequency: Very frequent (HP:0040281). (ORPHA:263410)
- Abnormal basal ganglia morphology (HP:0002134): Abnormality of the basal ganglia. Evidence: TAS. Frequency: Very frequent (HP:0040281). (ORPHA:263410)
- Small basal ganglia (HP:0012697): Decreased size of the basal ganglia. Evidence: TAS. Frequency: Very frequent (HP:0040281). (ORPHA:263410)
- Restlessness (HP:0000711): A state of unease is characterized by diffuse motor activity or motion, which is subject to limited control, nonproductive, or disorganized behavior. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:263410)
- Irritability (HP:0000737): An emotional state characterized by negative feelings of heightened frustration, annoyance, or feeling upset, often triggered by internal factors (e.g., fatigue, hunger, unfulfilled desires) or external factors (e.g., social or environmental challenges). Irritability may be unpredictable, and is accompanied by a lowered threshold for emotional reactivity and observable features (speech, facial expressions, or psychomotor activity). Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:263410)
- 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:263410)
- Ataxia (HP:0001251): Ataxia refers to impaired coordination of voluntary muscle movement. Cerebellar ataxia refers to ataxia due to dysfunction of the cerebellum. This causes a variety of elementary neurological deficits including asynergy (lack of coordination between muscles, limbs and joints), dysmetria (lack of ability to judge distances that can lead to under- or overshoot in grasping movements), and dysdiadochokinesia (inability to perform rapid movements requiring antagonizing muscle groups to be switched on and off repeatedly). Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:263410)
- Dysarthria (HP:0001260): Dysarthric speech is a general description referring to a neurological speech disorder characterized by poor articulation. Depending on the involved neurological structures, dysarthria may be further classified as spastic, flaccid, ataxic, hyperkinetic and hypokinetic, or mixed. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:263410)
- Confusion (HP:0001289): Lack of clarity and coherence of thought, perception, understanding, or action. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:263410)
- Dystonia (HP:0001332): An abnormally increased muscular tone that causes fixed abnormal postures. There is a slow, intermittent twisting motion that leads to exaggerated turning and posture of the extremities and trunk. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:263410)
- Hyperreflexia (HP:0001347): Hyperreflexia is the presence of hyperactive stretch reflexes of the muscles. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:263410)
- Tetraparesis (HP:0002273): Weakness of all four limbs. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:263410)
- Drowsiness (HP:0002329): Abnormal feeling of sleepiness or difficulty staying awake. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:263410)
- Poor speech (HP:0002465). Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:263410)
- Infantile encephalopathy (HP:0007105): Encephalopathy with onset in the infantile period. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:263410)
- Loss of consciousness (HP:0007185): Loss of awareness of oneself or one's surroundings, involving (i) a loss of normal motor control is evident as flaccidity or stiffness, either of which can be accompanied by jerking movements, and postural control is lost so that patients fall if they are in an upright position; (ii) normal responsiveness is lost; and (iii) the patient experiences amnesia for the event. Loss of consciousness my be transitory (e.g., syncope) or prolonged. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:263410)
- Abnormal brainstem MRI signal intensity (HP:0012747): A deviation from normal signal on magnetic resonance imaging (MRI) of the brainstem. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:263410)
- Inappropriate crying (HP:0030215): Uncontrolled episodes of crying occur without any apparent motivating stimuli. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:263410)
- Downslanted palpebral fissures (HP:0000494): The palpebral fissure inclination is more than two standard deviations below the mean. Evidence: TAS. Frequency: Occasional (HP:0040283). (ORPHA:263410)
- Respiratory insufficiency (HP:0002093). Evidence: TAS. Frequency: Occasional (HP:0040283). (ORPHA:263410)
- Status epilepticus (HP:0002133): Status epilepticus is a type of prolonged seizure resulting either from the failure of the mechanisms responsible for seizure termination or from the initiation of mechanisms which lead to abnormally prolonged seizures (after time point t1). It is a condition that can have long-term consequences (after time point t2), including neuronal death, neuronal injury, and alteration of neuronal networks, depending on the type and duration of seizures. Evidence: TAS. Frequency: Occasional (HP:0040283). (ORPHA:263410)
- Spastic tetraplegia (HP:0002510): Spastic paralysis affecting all four limbs. Evidence: TAS. Frequency: Occasional (HP:0040283). (ORPHA:263410)
- Functional motor deficit (HP:0004302). Evidence: TAS. Frequency: Occasional (HP:0040283). (ORPHA:263410)
- Floppy infant (HP:0008947): Floppiness/hypotonia is defined as reduced resistance to passive movement of joints. Physical examination of floppy/hypotonic infants shows head lag, lack of shoulder and elbow muscle contraction on traction response, inability to tighten the shoulder girdle muscles (or slipping through) when held under the axillae, scarf sign (when the arm is pulled to the opposite side, the arm wraps around the neck with the elbow crossing midline), hyperdorsiflexion of the feet, easy apposition of the thumb against the forearm, feet touching the cheek with ease and without discomfort, frog leg position, and inverted U sign on ventral suspension (head, arms, and legs hanging down without elbow or knee flexion and the trunk rounded in a dome shape). Evidence: TAS. Frequency: Occasional (HP:0040283). (ORPHA:263410)
- Infantile spasms (HP:0012469): Infantile spasms represent a subset of "epileptic spasms". Infantile Spasms are epileptic spasms starting in the first year of life (infancy). Evidence: TAS. Frequency: Occasional (HP:0040283). (ORPHA:263410)
These phenotypes are associated with the disease Infantile spasms-psychomotor retardation-progressive brain atrophy-basal ganglia disease syndrome (ORPHA:263410).