- Exaggerated startle response (HP:0002267): An exaggerated startle reaction in response to a sudden unexpected visual or acoustic stimulus, or a quick movement near the face. Evidence: PCS. Frequency: 22/22. (PMID:15852396)
- Progressive (HP:0003676): Applies to a disease manifestation that increases in scope or severity over the course of time, i.e., that worsens with age. Evidence: PCS. (PMID:15852396)
- Scoliosis (HP:0002650): The presence of an abnormal lateral curvature of the spine. Evidence: PCS. Frequency: 14/22. (PMID:15852396)
- Inability to walk (HP:0002540): Incapability to ambulate. Evidence: PCS. Frequency: 3/22. (PMID:15852396)
- 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: IEA. (OMIM:609541)
- Babinski sign (HP:0003487): Upturning of the big toe (and sometimes fanning of the other toes) in response to stimulation of the sole of the foot. If the Babinski sign is present it can indicate damage to the corticospinal tract. Evidence: PCS. Frequency: 2/22. (PMID:15852396)
- Flexion contracture (HP:0001371): A flexion contracture is a bent (flexed) joint that cannot be straightened actively or passively. It is thus a chronic loss of joint motion due to structural changes in muscle, tendons, ligaments, or skin that prevents normal movement of joints. Evidence: PCS. (PMID:15852396)
- Distal amyotrophy (HP:0003693): Muscular atrophy affecting muscles in the distal portions of the extremities. Evidence: PCS. Frequency: 19/22. Onset: Young adult onset (HP:0011462). (PMID:15852396)
- 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: PCS. Frequency: 19/22. Onset: Young adult onset (HP:0011462). (PMID:15852396)
- Infantile onset (HP:0003593): Onset of signs or symptoms of disease between 28 days to one year of life. Evidence: PCS. Frequency: 17/18. (PMID:15852396)
- Sensory axonal neuropathy (HP:0003390): An axonal neuropathy of peripheral sensory nerves. Evidence: PCS. (PMID:15852396)
- Motor delay (HP:0001270): A type of Developmental delay characterized by a delay in acquiring motor skills. Evidence: PCS. (PMID:15852396)
- Ankle clonus (HP:0011448): Clonus is an involuntary tendon reflex that causes repeated flexion and extension of the foot. Ankle clonus is tested by rapidly flexing the foot upward. Evidence: PCS. Frequency: 8/22. (PMID:15852396)
- Nystagmus (HP:0000639): Rhythmic, involuntary oscillations of one or both eyes related to abnormality in fixation, conjugate gaze, or vestibular mechanisms. Evidence: PCS. Frequency: 17/22. (PMID:15852396)
- Kyphosis (HP:0002808): Exaggerated anterior convexity of the thoracic vertebral column. Evidence: PCS. Frequency: 14/22. (PMID:15852396)
- Proximal hyperreflexia (HP:0007054): Hyperactive stretch reflexes of muscles that move proximal joints (elbow, knee). Evidence: PCS. Frequency: 19/22. (PMID:15852396)
- Childhood onset (HP:0011463): Onset of disease at the age of between 1 and 5 years. Evidence: PCS. Frequency: 1/18. (PMID:15852396)
- Motor axonal neuropathy (HP:0007002): Progressive impairment of function of motor axons with muscle weakness, atrophy, and cramps. The deficits are length-dependent, meaning that muscles innervated by the longest nerves are affected first, so that for instance the arms are affected at a later age than the onset of deficits involving the lower leg. Evidence: PCS. (PMID:15852396)
- Hyperhidrosis (HP:0000975): Abnormal excessive perspiration (sweating) despite the lack of appropriate stimuli like hot and humid weather. Evidence: PCS. Frequency: 16/22. (PMID:15852396)
- Autosomal recessive inheritance (HP:0000007): 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 individuals with two pathogenic alleles, either homozygotes (two copies of the same mutant allele) or compound heterozygotes (whereby each copy of a gene has a distinct mutant allele). Evidence: PCS. (PMID:26385635)
- 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: PCS. Frequency: 21/22. (PMID:15852396)
- Spastic paraplegia (HP:0001258): Complete loss of the ability to move the lower limbs accompanied by spasticity of the lower limbs. Evidence: PCS. (PMID:15852396)
- Optic disc pallor (HP:0000543): A pale yellow discoloration of the optic disc (the area of the optic nerve head in the retina). The optic disc normally has a pinkish hue with a central yellowish depression. Evidence: PCS. (PMID:15852396)
- Absent Achilles reflex (HP:0003438): Absence of the Achilles reflex (also known as the ankle jerk reflex), which can normally be elicited by tapping the tendon is tapped while the foot is dorsiflexed. Evidence: PCS. Frequency: 14/22. (PMID:15852396)
These phenotypes are associated with the disease spastic paraplegia, optic atropy, and neuropathy (OMIM:609541).