- Progressive distal muscle weakness (HP:0009063): Progressively reduced strength of the distal musculature. Evidence: TAS. Frequency: Very frequent (HP:0040281). (ORPHA:641)
- Diminished deep tendon reflex (HP:0001315): A reduction (hyporeflexia) or complete absence (areflexia) of the involuntary muscle contraction normally elicited by a reflex stimulus, such as tapping a deep tendon. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:641)
- 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: Frequent (HP:0040282). (ORPHA:641)
- Increased CSF protein concentration (HP:0002922): Increased concentration of protein in the cerebrospinal fluid. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:641)
- Progressive muscle weakness (HP:0003323). Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:641)
- Muscle spasm (HP:0003394): Sudden and involuntary contractions of one or more muscles. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:641)
- Limb muscle weakness (HP:0003690): Reduced strength and weakness of the muscles of the arms and legs. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:641)
- Functional motor deficit (HP:0004302). Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:641)
- Ganglioside accumulation (HP:0004345): Defects in the lysosomal glycosidases or specific co-activators, result in accumulation of the substrates, such as glycosphingolipids, including gangliosides in GM1 gangliosidosis (Tay-Sachs disease) and GM2 gangliosidosis (Sandhoff disease). Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:641)
- Limited wrist extension (HP:0006251). Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:641)
- Weakness of long finger extensor muscles (HP:0009077). Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:641)
- Motor conduction block (HP:0012078): Blockade of impulses at a focal site along the course of a motor axon. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:641)
These phenotypes are associated with the disease Multifocal motor neuropathy (ORPHA:641).