- 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: TAS. Frequency: Very frequent (HP:0040281). (ORPHA:139485)
- Progressive cerebellar ataxia (HP:0002073). Evidence: TAS. Frequency: Very frequent (HP:0040281). (ORPHA:139485)
- 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: TAS. Frequency: Frequent (HP:0040282). (ORPHA:139485)
- Brisk reflexes (HP:0001348): Tendon reflexes that are noticeably more active than usual (conventionally denoted 3+ on clinical examination). Brisk reflexes may or may not indicate a neurological lesion. They are distinguished from hyperreflexia by the fact that hyerreflexia is characterized by hyperactive repeating (clonic) reflexes, which are considered to be always abnormal. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:139485)
- Moderate intellectual disability (HP:0002342): Moderate intellectual disability (ID) is defined as a type of ID characterized by moderately sub-average adaptive functioning and intellectual functioning, with an intelligence quotient (IQ) the range of 35-49. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:139485)
- Developmental regression (HP:0002376): Loss of developmental skills, as manifested by loss of developmental milestones. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:139485)
- Exercise intolerance (HP:0003546): A functional motor deficit where individuals whose responses to the challenges of exercise fail to achieve levels considered normal for their age and gender. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:139485)
- Proximal muscle weakness (HP:0003701): A lack of strength of the proximal muscles. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:139485)
- Talipes cavus equinovarus (HP:0004696). Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:139485)
- Focal T2 hypointense basal ganglia lesion (HP:0012752): A darker than expected T2 signal on magnetic resonance imaging (MRI) of the basal ganglia. This term refers to a localized hypointensity affecting a particular region of the basal ganglia. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:139485)
- 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: TAS. Frequency: Occasional (HP:0040283). (ORPHA:139485)
- 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: TAS. Frequency: Occasional (HP:0040283). (ORPHA:139485)
- Myoclonus (HP:0001336): Very brief, involuntary random muscular contractions occurring at rest, in response to sensory stimuli, or accompanying voluntary movements. Evidence: TAS. Frequency: Occasional (HP:0040283). (ORPHA:139485)
- Tremor (HP:0001337): An unintentional, oscillating to-and-fro muscle movement about a joint axis. Evidence: TAS. Frequency: Occasional (HP:0040283). (ORPHA:139485)
- Hyperreflexia (HP:0001347): Hyperreflexia is the presence of hyperactive stretch reflexes of the muscles. Evidence: TAS. Frequency: Occasional (HP:0040283). (ORPHA:139485)
- Increased circulating lactate concentration (HP:0002151): Abnormally increased level of blood lactate (2-hydroxypropanoic acid). Lactate is produced from pyruvate by lactate dehydrogenase during normal metabolism. The terms lactate and lactic acid are often used interchangeably but lactate (the component measured in blood) is strictly a weak base whereas lactic acid is the corresponding acid. Lactic acidosis is often used clinically to describe elevated lactate but should be reserved for cases where there is a corresponding acidosis (pH below 7.35). Evidence: TAS. Frequency: Occasional (HP:0040283). (ORPHA:139485)
- Increased CSF lactate (HP:0002490): Increased concentration of lactate in the cerebrospinal fluid. Evidence: TAS. Frequency: Occasional (HP:0040283). (ORPHA:139485)
- Lactic acidosis (HP:0003128): An abnormal buildup of lactic acid in the body, leading to acidification of the blood and other bodily fluids. Evidence: TAS. Frequency: Occasional (HP:0040283). (ORPHA:139485)
- EMG abnormality (HP:0003457): Abnormal results of investigations using electromyography (EMG). Evidence: TAS. Frequency: Occasional (HP:0040283). (ORPHA:139485)
- Abnormal pyramidal sign (HP:0007256): Functional neurological abnormalities related to dysfunction of the pyramidal tract. Evidence: TAS. Frequency: Occasional (HP:0040283). (ORPHA:139485)
- Neurodevelopmental delay (HP:0012758): Neurodevelopmental delay (NDD) refers to delays in the maturation of the brain and central nervous system; infants and young children with NDD may experience delays in the development of one or more skills including gross motor abilities, fine-motor coordination, language abilities and ability to solve increasingly complex problems. Evidence: TAS. Frequency: Occasional (HP:0040283). (ORPHA:139485)
- Hearing impairment (HP:0000365): A decreased magnitude of the sensory perception of sound. Evidence: TAS. Frequency: Very rare (HP:0040284). (ORPHA:139485)
- Gynecomastia (HP:0000771): Abnormal development of large mammary glands in males resulting in breast enlargement. Evidence: TAS. Frequency: Very rare (HP:0040284). (ORPHA:139485)
- 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: TAS. Frequency: Very rare (HP:0040284). (ORPHA:139485)
These phenotypes are associated with the disease Autosomal recessive ataxia due to ubiquinone deficiency (ORPHA:139485).