- Mask-like facies (HP:0000298): A lack of facial expression often with staring eyes and a slightly open mouth. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:306692)
- Apathy (HP:0000741): Apathy is a quantitative reduction of interest, motivation and the initiation and persistence of goal-directed behavior, where often the accompanying emotions, thoughts, and social interactions are also diminished. The individual is typically non-reactive to provocations, positive or negative, and appears to not care. Distinguished from lethargy which involves lack of physical or mental energy. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:306692)
- 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:306692)
- Parkinsonism (HP:0001300): Characteristic neurologic anomaly resulting from degeneration of dopamine-generating cells in the substantia nigra, a region of the midbrain, characterized clinically by shaking, rigidity, slowness of movement and difficulty with walking and gait. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:306692)
- Rigidity (HP:0002063): Continuous involuntary sustained muscle contraction. When an affected muscle is passively stretched, the degree of resistance remains constant regardless of the rate at which the muscle is stretched. This feature helps to distinguish rigidity from muscle spasticity. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:306692)
- 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:306692)
- Cerebral cortical atrophy (HP:0002120): Atrophy of the cortex of the cerebrum. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:306692)
- Abnormal speech pattern (HP:0002167): An abnormality in the sound (volume) or cadence (rate) of speech. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:306692)
- 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: Frequent (HP:0040282). (ORPHA:306692)
- Resting tremor (HP:0002322): A resting tremor occurs when muscles are at rest and becomes less noticeable or disappears when the affected muscles are moved. Resting tremors are often slow and coarse. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:306692)
- Shuffling gait (HP:0002362): A type of gait (walking) characterized by by dragging one's feet along or without lifting the feet fully from the ground. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:306692)
- Anarthria (HP:0002425): A defect in the motor ability that enables speech. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:306692)
- Falls (HP:0002527). Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:306692)
- Elbow flexion contracture (HP:0002987): An elbow contracture that limits the ability of the elbow joint to be extended (straightened), meaning that the elbow is fixed in an flexed (bent) position. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:306692)
- Decreased facial expression (HP:0004673): A reduced degree of voluntary and involuntary facial movements involved in responded to others or expressing emotions. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:306692)
- Generalized hyperreflexia (HP:0007034). Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:306692)
- Short stepped shuffling gait (HP:0007311). Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:306692)
- Hypometric horizontal saccades (HP:0007975): Saccadic undershoot of horizontal saccadic eye movements, i.e., a horizontal saccadic eye movement that has less than the magnitude that would be required to gain fixation of the object. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:306692)
- Abnormal skin morphology (HP:0011121): Any morphological abnormality of the skin. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:306692)
- Subcortical cerebral atrophy (HP:0012157): Atrophy of the cerebral subcortical white and gray matter, termed subcortical atrophy, reflects loss of nerve cells in the basal ganglia or fibers in the deep white matter. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:306692)
These phenotypes are associated with the disease Cyanide-induced parkinsonism-dystonia (ORPHA:306692).