- Dysmetria (HP:0001310): A type of ataxia characterized by the inability to carry out movements with the correct range and motion across the plane of more than one joint related to incorrect estimation of the distances required for targeted movements. Evidence: PCS. Frequency: 1/1. (PMID:17438228)
- Bulbar signs (HP:0002483). Evidence: TAS. (OMIM:203450)
- 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:203450)
- Infantile onset (HP:0003593): Onset of signs or symptoms of disease between 28 days to one year of life. Evidence: PCS. Frequency: 19/21. (PMID:11138011;OMIM:203450)
- 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: PCS. Frequency: 1/1. (PMID:17438228)
- Progressive macrocephaly (HP:0004481): The progressive development of an abnormally large skull. Evidence: IEA. (OMIM:203450)
- Diffuse demyelination of the cerebral white matter (HP:0007162): A diffuse loss of myelin from nerve fibers in the central nervous system. Evidence: IEA. (OMIM:203450)
- Childhood onset (HP:0011463): Onset of disease at the age of between 1 and 5 years. Evidence: PCS. Frequency: 1/11. (PMID:11138011)
- Hydrocephalus (HP:0000238): Hydrocephalus is an active distension of the ventricular system of the brain resulting from inadequate passage of CSF from its point of production within the cerebral ventricles to its point of absorption into the systemic circulation. Evidence: IEA. (OMIM:203450)
- 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: 1/1. (PMID:17438228)
- Death in infancy (HP:0001522): Death within the first 24 months of life. Evidence: PCS. Frequency: 2/11. (PMID:11138011)
- Juvenile onset (HP:0003621): Onset of signs or symptoms of disease between the age of 5 and 15 years. Evidence: PCS. Frequency: 1/11. (PMID:11138011)
- Developmental regression (HP:0002376): Loss of developmental skills, as manifested by loss of developmental milestones. Evidence: TAS. (OMIM:203450)
- 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: 1/1. (PMID:17438228)
- 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: 1/1. (PMID:17438228)
- Death in adolescence (HP:0011421): Death during adolescence, the period between childhood and adulthood (roughly between the ages of 10 and 16 years). Evidence: PCS. Frequency: 5/11. (PMID:11138011)
- Palatal tremor (HP:0010530): Palatal tremor (PT) is an involuntary, rhythmic and oscillatory movement of the soft palate. PT is a rare type of tremor involving the soft palate. It can be unilateral or bilateral. Evidence: PCS. Frequency: 1/1. (PMID:17438228)
- Abnormal dentate nucleus morphology (HP:0100321): An abnormality of the dentate nucleus. Evidence: PCS. Frequency: 1/1. (PMID:17438228)
- Fatigue (HP:0012378): A subjective feeling of tiredness characterized by a lack of energy and motivation. Evidence: PCS. Frequency: 1/1. (PMID:17438228)
- Microcoria (HP:0025492): A small pupil (typically diameter less than 2 mm) that dilates poorly or not at all in response to topically administered mydriatic drugs. Evidence: PCS. Frequency: 1/1. (PMID:17438228)
- Death in childhood (HP:0003819): Death in during childhood, defined here as between the ages of 2 and 10 years. Evidence: PCS. Frequency: 1/11. (PMID:11138011)
- Pendular nystagmus (HP:0012043): Rhythmic, involuntary sinusoidal oscillations of one or both eyes. The waveform of pendular nystagmus may occur in any direction. Evidence: PCS. Frequency: 1/1. (PMID:17438228)
- Increased CSF protein concentration (HP:0002922): Increased concentration of protein in the cerebrospinal fluid. Evidence: IEA. (OMIM:203450)
- Drowsiness (HP:0002329): Abnormal feeling of sleepiness or difficulty staying awake. Evidence: PCS. Frequency: 1/1. (PMID:17438228)
- Apathy (HP:0000741): Apathy is a quantitative reduction of interest, motivation and the initiation and persistence of goal-directed behavior, where often the accompanying emotions, thoughts, and social interactions are also diminished. The individual is typically non-reactive to provocations, positive or negative, and appears to not care. Distinguished from lethargy which involves lack of physical or mental energy. Evidence: PCS. Frequency: 1/1. (PMID:17438228)
- Spasticity (HP:0001257): A motor disorder characterized by a velocity-dependent increase in tonic stretch reflexes with increased muscle tone, exaggerated (hyperexcitable) tendon reflexes. Evidence: IEA. (OMIM:203450)
- 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:11138011)
These phenotypes are associated with the disease Alexander disease (OMIM:203450).