- Dystonia (HP:0001332): An abnormally increased muscular tone that causes fixed abnormal postures. There is a slow, intermittent twisting motion that leads to exaggerated turning and posture of the extremities and trunk. Evidence: IEA. (OMIM:250100)
- Seizure (HP:0001250): A seizure is an intermittent abnormality of nervous system physiology characterized by a transient occurrence of signs and/or symptoms due to abnormal excessive or synchronous neuronal activity in the brain. Evidence: IEA. (OMIM:250100)
- Urinary incontinence (HP:0000020): Loss of the ability to control the urinary bladder leading to involuntary urination. Evidence: IEA. (OMIM:250100)
- Hypotonia (HP:0001252): Hypotonia is an abnormally low muscle tone (the amount of tension or resistance to movement in a muscle). Even when relaxed, muscles have a continuous and passive partial contraction which provides some resistance to passive stretching. Hypotonia thus manifests as diminished resistance to passive stretching. Hypotonia is not the same as muscle weakness, although the two conditions can co-exist. Evidence: IEA. (OMIM:250100)
- Ataxia (HP:0001251): Ataxia refers to impaired coordination of voluntary muscle movement. Cerebellar ataxia refers to ataxia due to dysfunction of the cerebellum. This causes a variety of elementary neurological deficits including asynergy (lack of coordination between muscles, limbs and joints), dysmetria (lack of ability to judge distances that can lead to under- or overshoot in grasping movements), and dysdiadochokinesia (inability to perform rapid movements requiring antagonizing muscle groups to be switched on and off repeatedly). Evidence: IEA. (OMIM:250100)
- Generalized hypotonia (HP:0001290): Generalized muscular hypotonia (abnormally low muscle tone). Evidence: TAS. (OMIM:250100)
- Hallucinations (HP:0000738): Perceptions in a conscious and awake state that, in the absence of external stimuli, have qualities of real perception. These perceptions are vivid, substantial, and located in external objective space. Evidence: IEA. (OMIM:250100)
- Gallbladder dysfunction (HP:0005609). Evidence: IEA. (OMIM:250100)
- Emotional lability (HP:0000712): Unstable emotional experiences and frequent mood changes; emotions that are easily aroused, intense, and/or disproportionate to events and circumstances. Evidence: PCS. (OMIM:250100)
- Mental deterioration (HP:0001268): Loss of previously present mental abilities, generally in adults. Evidence: PCS. (OMIM:250100)
- Intellectual disability (HP:0001249): The term intellectual disability or intellectual developmental disorder is used to describe significantly sub-average intellectual and adaptive functioning based on clinical assessment and as measured by individually administered, appropriately normed, standardized and validated tests of intellectual functioning and adaptive behavior, with onset during the developmental period from infancy through adolescence. Evidence: TAS. (OMIM:250100)
- Hyperreflexia (HP:0001347): Hyperreflexia is the presence of hyperactive stretch reflexes of the muscles. Evidence: IEA. (OMIM:250100)
- Hyporeflexia (HP:0001265): Reduction of neurologic reflexes such as the knee-jerk reaction. Evidence: IEA. (OMIM:250100)
- EMG: neuropathic changes (HP:0003445): The presence of characteristic findings of denervation on electromyography (fibrillations, positive sharp waves, and giant motor unit potentials). Evidence: IEA. (OMIM:250100)
- Spastic tetraplegia (HP:0002510): Spastic paralysis affecting all four limbs. Evidence: PCS. (OMIM:250100)
- Gait disturbance (HP:0001288): The term gait disturbance can refer to any disruption of the ability to walk. Evidence: IEA. (OMIM:250100)
- 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: IEA. (OMIM:250100)
- Bulbar palsy (HP:0001283): Bulbar weakness (or bulbar palsy) refers to bilateral impairment of function of the lower cranial nerves IX, X, XI and XII, which occurs due to lower motor neuron lesion either at nuclear or fascicular level in the medulla or from bilateral lesions of the lower cranial nerves outside the brain-stem. Bulbar weakness is often associated with difficulty in chewing, weakness of the facial muscles, dysarthria, palatal weakness and regurgitation of fluids, dysphagia, and dysphonia. Evidence: IEA. (OMIM:250100)
- 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: IEA. (OMIM:250100)
- Loss of speech (HP:0002371). Evidence: IEA. (OMIM:250100)
- Chorea (HP:0002072): Chorea (Greek for 'dance') refers to widespread arrhythmic involuntary movements of a forcible, jerky and restless fashion. It is a random-appearing sequence of one or more discrete involuntary movements or movement fragments. Movements appear random because of variability in timing, duration or location. Each movement may have a distinct start and end. However, movements may be strung together and thus may appear to flow randomly from one muscle group to another. Chorea can involve the trunk, neck, face, tongue, and extremities. Evidence: IEA. (OMIM:250100)
- Impaired cerebroside sulfate hydrolysis (HP:0034687): Reduced hydrolysis (splitting of a bond and the addition of the hydrogen anion of water) of the sulfuric ester linkage in the molecule of cerebroside sulfate, possibly leading to accumuation of cerebroside sulfate. Evidence: PCS. (PMID:6137805)
- Reduced leukocyte arylsulfatase A activity (HP:0034863): Concentration or activity of the lysosomal enzyme arylsulfatase A (EC 3.1.6.8) as measured in leukocytes is below the limits of normal. Evidence: TAS. (OMIM:250100)
- Cholecystitis (HP:0001082): The presence of inflammatory changes in the gallbladder. Evidence: IEA. (OMIM:250100)
- Peripheral demyelination (HP:0011096): A loss of myelin from the internode regions along myelinated nerve fibers of the peripheral nervous system. Evidence: PCS. (OMIM:250100)
- Progressive peripheral neuropathy (HP:0007133). Evidence: IEA. (OMIM:250100)
- 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: IEA. (OMIM:250100)
- 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: IEA. (OMIM:250100)
- Increased CSF protein concentration (HP:0002922): Increased concentration of protein in the cerebrospinal fluid. Evidence: IEA. (OMIM:250100)
- Delusion (HP:0000746): A delusion is a fixed false belief held despite evidence to the contrary. The term delusion broadly encompasses all false judgments that possess the following external characteristics to a significant, albeit unspecified, extent: (1) they are held with an exceptional level of conviction, accompanied by an unparalleled subjective certainty; (2) there is an inability to consider alternative experiences or compelling counter-arguments; (3) the content of the belief is impossible. Evidence: IEA. (OMIM:250100)
- Decreased nerve conduction velocity (HP:0000762): A reduction in the speed at which electrical signals propagate along the axon of a neuron. Evidence: IEA. (OMIM:250100)
- Abnormal cerebral white matter morphology (HP:0002500): An abnormality of the cerebral white matter. Evidence: IEA. (OMIM:250100)
- Tetraplegia (HP:0002445): Paralysis of all four limbs, and trunk of the body below the level of an associated injury to the spinal cord. The etiology of quadriplegia is similar to that of paraplegia except that the lesion is in the cervical spinal cord rather than in the thoracic or lumbar segments of the spinal cord. Evidence: TAS. (OMIM:250100)
These phenotypes are associated with the disease metachromatic leukodystrophy, juvenile form (OMIM:250100).