- Muscle weakness (HP:0001324): Reduced strength of muscles. Evidence: TAS. Frequency: Very frequent (HP:0040281). (ORPHA:65684)
- Tremor (HP:0001337): An unintentional, oscillating to-and-fro muscle movement about a joint axis. Evidence: TAS. Frequency: Occasional (HP:0040283). (ORPHA:65684)
- 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:65684)
- Degeneration of anterior horn cells (HP:0002398). Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:65684)
- Abnormality of the immune system (HP:0002715): An abnormality of the immune system. Evidence: TAS. Frequency: Occasional (HP:0040283). (ORPHA:65684)
- Abnormality of the upper limb (HP:0002817): An abnormality of the arm. Evidence: TAS. Frequency: Very frequent (HP:0040281). (ORPHA:65684)
- Abnormality of peripheral nerve conduction (HP:0003134): An abnormality of the conduction of electrical impulses by peripheral (motor or sensory) nerves. This finding is elicited by a nerve conduction study (NCS). Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:65684)
- EMG abnormality (HP:0003457): Abnormal results of investigations using electromyography (EMG). Evidence: TAS. Frequency: Very frequent (HP:0040281). (ORPHA:65684)
- Distal upper limb amyotrophy (HP:0007149): Muscular atrophy of distal arm muscles. Evidence: TAS. Frequency: Very frequent (HP:0040281). (ORPHA:65684)
- Abnormality of movement (HP:0100022): An abnormality of movement with a neurological basis characterized by changes in coordination and speed of voluntary movements. Evidence: TAS. Frequency: Occasional (HP:0040283). (ORPHA:65684)
These phenotypes are associated with the disease Monomelic amyotrophy (ORPHA:65684).