- Congenital onset (HP:0003577): A phenotypic abnormality that is present at birth. Evidence: PCS. Frequency: 2/2. (PMID:15981765)
- Mild intellectual disability (HP:0001256): Mild intellectual disability (ID) is defined as a type of ID characterized by mildly sub-average adaptive functioning and intellectual functioning, with an intelligence quotient (IQ) the range of 50-69. Evidence: PCS. Frequency: 1/1. (PMID:27016154)
- Strabismus (HP:0000486): A misalignment of the eyes so that the visual axes deviate from bifoveal fixation. The classification of strabismus may be based on a number of features including the relative position of the eyes, whether the deviation is latent or manifest, intermittent or constant, concomitant or otherwise and according to the age of onset and the relevance of any associated refractive error. Evidence: PCS. Frequency: 1/1. (PMID:26197978)
- 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: 4/4. (PMID:26197978;PMID:27016154;PMID:15981765)
- 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: PCS. Frequency: 1/1. (PMID:26197978)
- Cerebellar atrophy (HP:0001272): Cerebellar atrophy is defined as a cerebellum with initially normal structures, in a posterior fossa with normal size, which displays enlarged fissures (interfolial spaces) in comparison to the foliae secondary to loss of tissue. Cerebellar atrophy implies irreversible loss of tissue and result from an ongoing progressive disease until a final stage is reached or a single injury, e.g. an intoxication or infectious event. Evidence: PCS. Frequency: 1/1. (PMID:27016154)
- 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: PCS. Frequency: 1/1. (PMID:27016154)
- 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: 3/3. (PMID:26197978;PMID:25361784)
- 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:27016154)
- Infantile onset (HP:0003593): Onset of signs or symptoms of disease between 28 days to one year of life. Evidence: PCS. Frequency: 1/1. (PMID:27016154)
- Appendicular hypotonia (HP:0012389): Muscular hypotonia of one or more limbs. Evidence: PCS. Frequency: 2/2. Onset: Juvenile onset (HP:0003621). (PMID:15981765)
- Intention tremor (HP:0002080): A type of kinetic tremor that occurs during target directed movement is called intention tremor. That is, an oscillatory cerebellar ataxia that tends to be absent when the limbs are inactive and during the first part of voluntary movement but worsening as the movement continues and greater precision is required (e.g., in touching a target such as the patient's nose or a physician's finger). Evidence: PCS. Frequency: 2/2. (PMID:26197978;PMID:27016154)
- Childhood onset (HP:0011463): Onset of disease at the age of between 1 and 5 years. Evidence: PCS. Frequency: 1/1. (PMID:26197978)
- Oculomotor apraxia (HP:0000657): Ocular motor apraxia is a deficiency in voluntary, horizontal, lateral, fast eye movements (saccades) with retention of slow pursuit movements. The inability to follow objects visually is often compensated by head movements. There may be decreased smooth pursuit, and cancelation of the vestibulo-ocular reflex. Evidence: PCS. Frequency: 1/1. (PMID:26197978)
- Unsteady gait (HP:0002317). Evidence: PCS. Frequency: 3/3. (PMID:27016154;PMID:15981765)
- Frequent falls (HP:0002359). Evidence: PCS. Frequency: 2/2. (PMID:15981765)
- 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: PCS. Frequency: 2/2. (PMID:25361784)
- Hyperreflexia (HP:0001347): Hyperreflexia is the presence of hyperactive stretch reflexes of the muscles. Evidence: PCS. Frequency: 2/2. (PMID:15981765)
- Cerebellar vermis hypoplasia (HP:0001320): Underdevelopment of the vermis of cerebellum. Evidence: PCS. Frequency: 3/3. (PMID:26197978;PMID:25361784)
- Broad-based gait (HP:0002136): An abnormal gait pattern in which persons stand and walk with their feet spaced widely apart. This is often a component of cerebellar ataxia. Evidence: PCS. Frequency: 1/1. (PMID:26197978)
- Clumsiness (HP:0002312): Lack of physical coordination resulting in an abnormal tendency to drop items or bump into objects. Evidence: PCS. Frequency: 1/1. (PMID:26197978)
- Delayed speech and language development (HP:0000750): A degree of language development that is significantly below the norm for a child of a specified age. Evidence: PCS. Frequency: 1/1. (PMID:27016154)
- Thick eyebrow (HP:0000574): Increased density/number and/or increased diameter of eyebrow hairs. Evidence: PCS. Frequency: 1/1. (PMID:27016154)
- Truncal ataxia (HP:0002078): Truncal ataxia is a sign of ataxia characterized by instability of the trunk. It usually occurs during sitting. Evidence: PCS. Frequency: 2/2. (PMID:25361784)
- Cerebellar hypoplasia (HP:0001321): Cerebellar hypoplasia is a descriptive term implying a cerebellum with a reduced volume, but a normal shape and is stable over time. Evidence: PCS. Frequency: 3/3. (PMID:26197978;PMID:25361784)
- Easy fatigability (HP:0003388): Increased susceptibility to fatigue. Evidence: PCS. Frequency: 1/1. (PMID:26197978)
- 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: 4/4. (PMID:26197978;PMID:27016154;PMID:15981765)
- 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: 2/2. (PMID:25361784)
- Limb ataxia (HP:0002070): A kind of ataxia that affects movements of the extremities. Evidence: PCS. Frequency: 2/2. (PMID:25361784)
- Mild microcephaly (HP:0040196): Decreased occipito-frontal (head) circumference (OFC). For the microcephaly OFC must be between -3 SD and -2 SD compared to appropriate, age matched, normal standards (i.e. -3 SD <= OFC < -2 SD). Evidence: PCS. Frequency: 1/1. (PMID:27016154)
- 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:25361784)
- Synophrys (HP:0000664): Meeting of the medial eyebrows in the midline. Evidence: PCS. Frequency: 1/1. (PMID:27016154)
- Slowly progressive (HP:0003677): Applies to a disease manifestation that only slowly increases in scope or severity over the course of time. Evidence: PCS. (PMID:27016154)
These phenotypes are associated with the disease autosomal recessive spinocerebellar ataxia 17 (OMIM:616127).