- Muscle weakness (HP:0001324): Reduced strength of muscles. Evidence: TAS. Frequency: Very frequent (HP:0040281). (ORPHA:401953)
- Slurred speech (HP:0001350): Abnormal coordination of muscles involved in speech. Evidence: TAS. Frequency: Very frequent (HP:0040281). (ORPHA:401953)
- Postural instability (HP:0002172): A tendency to fall or the inability to keep oneself from falling; imbalance. The retropulsion test is widely regarded as the gold standard to evaluate postural instability, Use of the retropulsion test includes a rapid balance perturbation in the backward direction, and the number of balance correcting steps (or total absence thereof) is used to rate the degree of postural instability. Healthy subjects correct such perturbations with either one or two large steps, or without taking any steps, hinging rapidly at the hips while swinging the arms forward as a counterweight. In patients with balance impairment, balance correcting steps are often too small, forcing patients to take more than two steps. Taking three or more steps is generally considered to be abnormal, and taking more than five steps is regarded as being clearly abnormal. Markedly affected patients continue to step backward without ever regaining their balance and must be caught by the examiner (this would be called true retropulsion). Even more severely affected patients fail to correct entirely, and fall backward like a pushed toy soldier, without taking any corrective steps. Evidence: TAS. Frequency: Very frequent (HP:0040281). (ORPHA:401953)
- Nystagmus (HP:0000639): Rhythmic, involuntary oscillations of one or both eyes related to abnormality in fixation, conjugate gaze, or vestibular mechanisms. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:401953)
- 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:401953)
- Tremor (HP:0001337): An unintentional, oscillating to-and-fro muscle movement about a joint axis. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:401953)
- Gait ataxia (HP:0002066): A type of ataxia characterized by the impairment of the ability to coordinate the movements required for normal walking. Gait ataxia is characteirzed by a wide-based staggering gait with a tendency to fall. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:401953)
- Abnormal involuntary eye movements (HP:0012547): Anomalous movements of the eyes that occur without the subject wanting them to happen. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:401953)
- Migraine (HP:0002076): Migraine is a chronic neurological disorder characterized by episodic attacks of headache and associated symptoms. Evidence: TAS. Frequency: Occasional (HP:0040283). (ORPHA:401953)
- Myokymia (HP:0002411): Myokymia consists of involuntary, fine, continuous, undulating contractions that spread across the affected striated muscle. Evidence: TAS. Frequency: Occasional (HP:0040283). (ORPHA:401953)
These phenotypes are associated with the disease Episodic ataxia with slurred speech (ORPHA:401953).