- 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:249900)
- Gait ataxia (HP:0002066): A type of ataxia characterized by the impairment of the ability to coordinate the movements required for normal walking. Gait ataxia is characteirzed by a wide-based staggering gait with a tendency to fall. Evidence: IEA. (OMIM:249900)
- Polyneuropathy (HP:0001271): A generalized disorder of peripheral nerves. Evidence: PCS. Frequency: 1/1. (PMID:10682309)
- 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: PCS. Frequency: 1/1. (PMID:10682309)
- Urinary incontinence (HP:0000020): Loss of the ability to control the urinary bladder leading to involuntary urination. Evidence: IEA. (OMIM:249900)
- Childhood onset (HP:0011463): Onset of disease at the age of between 1 and 5 years. Evidence: PCS. Frequency: 1/1. (PMID:8554069)
- Abnormal periventricular white matter morphology (HP:0002518): A structural abnormality of the myelinated axons (white matter) located near the cerebral ventricles. Evidence: PCS. (OMIM:249900)
- Muscle weakness (HP:0001324): Reduced strength of muscles. Evidence: PCS. Frequency: 1/1. (PMID:10682309)
- Mental deterioration (HP:0001268): Loss of previously present mental abilities, generally in adults. Evidence: TAS. (OMIM:249900)
- CNS demyelination (HP:0007305): A loss of myelin from nerve fibers in the central nervous system. Evidence: PCS. (OMIM:249900)
- Hyperreflexia (HP:0001347): Hyperreflexia is the presence of hyperactive stretch reflexes of the muscles. Evidence: IEA. (OMIM:249900)
- Hyporeflexia (HP:0001265): Reduction of neurologic reflexes such as the knee-jerk reaction. Evidence: IEA. (OMIM:249900)
- Motor deterioration (HP:0002333): Loss of previously present motor (i.e., movement) abilities. Evidence: PCS. Frequency: 1/1. (PMID:10682309)
- Dysphagia (HP:0002015): Difficulty in swallowing. Evidence: IEA. (OMIM:249900)
- 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:249900)
- Developmental regression (HP:0002376): Loss of developmental skills, as manifested by loss of developmental milestones. Evidence: PCS. Frequency: 1/1. (PMID:8554069)
- 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:249900)
- Global developmental delay (HP:0001263): A delay in the achievement of motor or mental milestones in the domains of development of a child, including motor skills, speech and language, cognitive skills, and social and emotional skills. This term should only be used to describe children younger than five years of age. Evidence: PCS. Frequency: 1/1. (PMID:8554069)
- Loss of speech (HP:0002371). Evidence: IEA. (OMIM:249900)
- Spastic tetraparesis (HP:0001285): Spastic weakness affecting all four limbs. Evidence: IEA. (OMIM:249900)
- Peripheral demyelination (HP:0011096): A loss of myelin from the internode regions along myelinated nerve fibers of the peripheral nervous system. Evidence: PCS. Frequency: 2/2. (PMID:8554069;PMID:10682309)
- Peripheral neuropathy (HP:0009830): Peripheral neuropathy is a general term for any disorder of the peripheral nervous system. The main clinical features used to classify peripheral neuropathy are distribution, type (mainly demyelinating versus mainly axonal), duration, and course. Evidence: PCS. Frequency: 1/1. (PMID:8554069)
- 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:8554069)
- Increased CSF protein concentration (HP:0002922): Increased concentration of protein in the cerebrospinal fluid. Evidence: PCS. Frequency: 1/1. (PMID:8554069)
- Loss of ambulation (HP:0002505): Inability to walk in a person who previous had the ability to walk. Evidence: PCS. Frequency: 1/1. (PMID:8554069)
- Decreased nerve conduction velocity (HP:0000762): A reduction in the speed at which electrical signals propagate along the axon of a neuron. Evidence: PCS. Frequency: 2/2. (PMID:8554069;PMID:10682309)
These phenotypes are associated with the disease metachromatic leukodystrophy due to saposin B deficiency (OMIM:249900).