- Hyporeflexia (HP:0001265): Reduction of neurologic reflexes such as the knee-jerk reaction. Evidence: TAS. (OMIM:615048)
- Skeletal muscle atrophy (HP:0003202): The presence of skeletal muscular atrophy (which is also known as amyotrophy). Evidence: PCS. Frequency: 4/5. (PMID:22535186)
- Elevated circulating creatine kinase activity (HP:0003236): The activity of creatine kinase in the blood circulation is above the upper limit of normal. Evidence: TAS. (OMIM:615048)
- Middle age onset (HP:0003596): A type of adult onset with onset of symptoms at the age of 40 to 60 years. Evidence: PCS. Frequency: 4/5. (PMID:22535186)
- Gait disturbance (HP:0001288): The term gait disturbance can refer to any disruption of the ability to walk. Evidence: TAS. (OMIM:615048)
- Pes cavus (HP:0001761): An increase in height of the medial longitudinal arch of the foot that does not flatten on weight bearing (i.e., a distinctly hollow form of the sole of the foot when it is bearing weight). Evidence: TAS. (OMIM:615048)
- Muscle spasm (HP:0003394): Sudden and involuntary contractions of one or more muscles. Evidence: PCS. Frequency: 5/5. (PMID:22535186)
- Areflexia (HP:0001284): Absence of neurologic reflexes such as the knee-jerk reaction. Evidence: PCS. Frequency: 5/5. (PMID:22535186)
- 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. (OMIM:615048)
- Calf muscle hypertrophy (HP:0008981): Muscle hypertrophy affecting the calf muscles. Evidence: TAS. Frequency: Occasional (HP:0040283). (OMIM:615048)
- Distal sensory impairment (HP:0002936): An abnormal reduction in sensation in the distal portions of the extremities. Evidence: TAS. Frequency: Occasional (HP:0040283). (OMIM:615048)
- Late young adult onset (HP:0025710): Onset of disease at an age of greater than or equal to 25 to under 40 years. Evidence: PCS. Frequency: 1/5. (PMID:22535186)
- Spinal muscular atrophy (HP:0007269): Muscular weakness and atrophy related to loss of the motor neurons of the spinal cord and brainstem. Evidence: PCS. (PMID:22535186)
- Muscle weakness (HP:0001324): Reduced strength of muscles. Evidence: PCS. Frequency: 5/5. (PMID:22535186)
- Pes planus (HP:0001763): A foot where the longitudinal arch of the foot is in contact with the ground or floor when the individual is standing; or, in a patient lying supine, a foot where the arch is in contact with the surface of a flat board pressed against the sole of the foot by the examiner with a pressure similar to that expected from weight bearing; or, the height of the arch is reduced. Evidence: TAS. (OMIM:615048)
- Autosomal dominant inheritance (HP:0000006): A mode of inheritance that is observed for traits related to a gene encoded on one of the autosomes (i.e., the human chromosomes 1-22) in which a trait manifests in heterozygotes. In the context of medical genetics, an autosomal dominant disorder is caused when a single copy of the mutant allele is present. Males and females are affected equally, and can both transmit the disorder with a risk of 50% for each child of inheriting the mutant allele. Evidence: PCS. (PMID:22535186)
- Slowly progressive (HP:0003677): Applies to a disease manifestation that only slowly increases in scope or severity over the course of time. Evidence: TAS. (OMIM:615048)
- Tremor (HP:0001337): An unintentional, oscillating to-and-fro muscle movement about a joint axis. Evidence: TAS. Frequency: Occasional (HP:0040283). (OMIM:615048)
- Hammertoe (HP:0001765): Hyperextension of the metatarsal-phalangeal joint with hyperflexion of the proximal interphalangeal (PIP) joint. Evidence: TAS. (OMIM:615048)
These phenotypes are associated with the disease lower motor neuron syndrome with late-adult onset (OMIM:615048).