- Progressive cerebellar ataxia (HP:0002073). Evidence: TAS. Frequency: Very frequent (HP:0040281). (ORPHA:98755)
- Peripheral neuropathy (HP:0009830): Peripheral neuropathy is a general term for any disorder of the peripheral nervous system. The main clinical features used to classify peripheral neuropathy are distribution, type (mainly demyelinating versus mainly axonal), duration, and course. Evidence: TAS. Frequency: Very frequent (HP:0040281). (ORPHA:98755)
- Abnormality of eye movement (HP:0000496): An abnormality in voluntary or involuntary eye movements or their control. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:98755)
- Slow saccadic eye movements (HP:0000514): An abnormally slow velocity of the saccadic eye movements. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:98755)
- 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:98755)
- Cerebellar atrophy (HP:0001272): Cerebellar atrophy is defined as a cerebellum with initially normal structures, in a posterior fossa with normal size, which displays enlarged fissures (interfolial spaces) in comparison to the foliae secondary to loss of tissue. Cerebellar atrophy implies irreversible loss of tissue and result from an ongoing progressive disease until a final stage is reached or a single injury, e.g. an intoxication or infectious event. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:98755)
- Gait disturbance (HP:0001288): The term gait disturbance can refer to any disruption of the ability to walk. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:98755)
- 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:98755)
- Slurred speech (HP:0001350): Abnormal coordination of muscles involved in speech. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:98755)
- Dysphagia (HP:0002015): Difficulty in swallowing. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:98755)
- Bradykinesia (HP:0002067): Bradykinesia literally means slow movement, and is used clinically to denote a slowness in the execution of movement (in contrast to hypokinesia, which is used to refer to slowness in the initiation of movement). Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:98755)
- Chorea (HP:0002072): Chorea (Greek for 'dance') refers to widespread arrhythmic involuntary movements of a forcible, jerky and restless fashion. It is a random-appearing sequence of one or more discrete involuntary movements or movement fragments. Movements appear random because of variability in timing, duration or location. Each movement may have a distinct start and end. However, movements may be strung together and thus may appear to flow randomly from one muscle group to another. Chorea can involve the trunk, neck, face, tongue, and extremities. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:98755)
- Memory impairment (HP:0002354): An impairment of memory as manifested by a reduced ability to remember things such as dates and names, and increased forgetfulness. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:98755)
- Bulbar signs (HP:0002483). Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:98755)
- Loss of Purkinje cells in the cerebellar vermis (HP:0007001). Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:98755)
- Atrophy/Degeneration affecting the brainstem (HP:0007366). Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:98755)
- Abnormality of somatosensory evoked potentials (HP:0007377): An abnormality of somatosensory evoked potentials (SSEP), i.e., of the electrical signals of sensation going from the body to the brain in response to a defined stimulus. Recording electrodes are placed over the scalp, spine, and peripheral nerves proximal to the stimulation site. Clinical studies generally use electrical stimulation of peripheral nerves to elicit potentials. SSEP testing determines whether peripheral sensory nerves are able to transmit sensory information like pain, temperature, and touch to the brain. Abnormal SSEPs can result from dysfunction at the level of the peripheral nerve, plexus, spinal root, spinal cord, brain stem, thalamocortical projections, or primary somatosensory cortex. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:98755)
- Abnormal flash visual evoked potentials (HP:0007928): Anomaly of the visual evoked potentials elicited by a flash stimulus, generally a flash of light subtending an angle of at least 20 degrees of the visual field and presented in a dimly lit room. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:98755)
- Upgaze palsy (HP:0025331): A limitation of the ability to direct one's gaze above the horizontal meridian. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:98755)
- Staring gaze (HP:0025401): An abnormality in which the eyes are held permanently wide open. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:98755)
- Inertia (HP:0030216): Reduction of goal-directed behaviors linked to the impairment in frontal executive functions (planning of an action for example). Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:98755)
- Abnormal nerve conduction velocity (HP:0040129). Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:98755)
- Cognitive impairment (HP:0100543): Abnormal cognition is characterized by deficits in thinking, reasoning, or remembering. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:98755)
- Ophthalmoparesis (HP:0000597): Ophthalmoplegia is a paralysis or weakness of one or more of the muscles that control eye movement. Evidence: TAS. Frequency: Occasional (HP:0040283). (ORPHA:98755)
- Nystagmus (HP:0000639): Rhythmic, involuntary oscillations of one or both eyes related to abnormality in fixation, conjugate gaze, or vestibular mechanisms. Evidence: TAS. Frequency: Occasional (HP:0040283). (ORPHA:98755)
- 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). (ORPHA:98755)
- Hyporeflexia (HP:0001265): Reduction of neurologic reflexes such as the knee-jerk reaction. Evidence: TAS. Frequency: Occasional (HP:0040283). (ORPHA:98755)
- Generalized hypotonia (HP:0001290): Generalized muscular hypotonia (abnormally low muscle tone). Evidence: TAS. Frequency: Occasional (HP:0040283). (ORPHA:98755)
- Dysmetria (HP:0001310): A type of ataxia characterized by the inability to carry out movements with the correct range and motion across the plane of more than one joint related to incorrect estimation of the distances required for targeted movements. Evidence: TAS. Frequency: Occasional (HP:0040283). (ORPHA:98755)
- Dysdiadochokinesis (HP:0002075): A type of ataxia characterized by the impairment of the ability to perform rapidly alternating movements, such as pronating and supinating his or her hand on the dorsum of the other hand as rapidly as possible. Evidence: TAS. Frequency: Occasional (HP:0040283). (ORPHA:98755)
- Gait imbalance (HP:0002141). Evidence: TAS. Frequency: Occasional (HP:0040283). (ORPHA:98755)
- Postural tremor (HP:0002174): A type of tremors that is triggered by holding a limb in a fixed position. Evidence: TAS. Frequency: Occasional (HP:0040283). (ORPHA:98755)
- Abnormal brainstem morphology (HP:0002363): An anomaly of the brainstem. Evidence: TAS. Frequency: Occasional (HP:0040283). (ORPHA:98755)
- Fasciculations (HP:0002380): Fasciculations are observed as small, local, involuntary muscle contractions (twitching) visible under the skin. Fasciculations result from increased irritability of an axon (which in turn is often a manifestation of disease of a motor neuron). This leads to sporadic discharges of all the muscle fibers controlled by the axon in isolation from other motor units. Evidence: TAS. Frequency: Occasional (HP:0040283). (ORPHA:98755)
- Respiratory failure (HP:0002878): A severe form of respiratory insufficiency characterized by inadequate gas exchange such that the levels of oxygen or carbon dioxide cannot be maintained within normal limits. Evidence: TAS. Frequency: Occasional (HP:0040283). (ORPHA:98755)
- Skeletal muscle atrophy (HP:0003202): The presence of skeletal muscular atrophy (which is also known as amyotrophy). Evidence: TAS. Frequency: Occasional (HP:0040283). (ORPHA:98755)
- Hyperactive deep tendon reflexes (HP:0006801). Evidence: TAS. Frequency: Occasional (HP:0040283). (ORPHA:98755)
- Hypermetric saccades (HP:0007338): A saccade that overshoots the target with the dynamic saccade. Evidence: TAS. Frequency: Occasional (HP:0040283). (ORPHA:98755)
- Impaired proprioception (HP:0010831): A loss or impairment of the sensation of the relative position of parts of the body and joint position. Evidence: TAS. Frequency: Occasional (HP:0040283). (ORPHA:98755)
- Abnormality of masticatory muscle (HP:0410011): Any abnormality of the masticatory muscle. Evidence: TAS. Frequency: Occasional (HP:0040283). (ORPHA:98755)
These phenotypes are associated with the disease Spinocerebellar ataxia type 1 (ORPHA:98755).