- Hearing impairment (HP:0000365): A decreased magnitude of the sensory perception of sound. Evidence: TAS. Frequency: Occasional (HP:0040283). (OMIM:614946)
- Aminoaciduria (HP:0003355): An increased concentration of an amino acid in the urine. Evidence: TAS. Frequency: Occasional (HP:0040283). (OMIM:614946)
- 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: PCS. Frequency: 2/2. (PMID:22833457)
- Cerebral cortical atrophy (HP:0002120): Atrophy of the cortex of the cerebrum. Evidence: PCS. Frequency: 1/1. (PMID:22833457)
- 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:22833457)
- 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. (OMIM:614946)
- Elevated brain lactate level by MRS (HP:0012707): An increase in the level of lactate in the brain identified by magnetic resonance spectroscopy (MRS). Evidence: PCS. Frequency: 1/1. (PMID:22833457)
- Copper accumulation in liver (HP:0025321): An anomalous build up of copper (Cu) in the liver. Evidence: PCS. Frequency: 1/1. (PMID:22833457)
- Myoclonic seizure (HP:0032794): A myoclonic seizure is a type of motor seizure characterized by sudden, brief (<100 ms) involuntary single or multiple contraction of muscles or muscle groups of variable topography (axial, proximal limb, distal). Myoclonus is less regularly repetitive and less sustained than is clonus. Evidence: PCS. Frequency: 2/2. (PMID:22833457)
- Anemia (HP:0001903): A reduction in erythrocytes volume or hemoglobin concentration. Evidence: TAS. Frequency: Occasional (HP:0040283). (OMIM:614946)
- Atrophy/Degeneration affecting the brainstem (HP:0007366). Evidence: PCS. Frequency: 1/1. (PMID:22833457)
- Ventriculomegaly (HP:0002119): An increase in size of the ventricular system of the brain. Evidence: TAS. (OMIM:614946)
- Death in infancy (HP:0001522): Death within the first 24 months of life. Evidence: PCS. Frequency: 1/2. (PMID:22833457)
- Neonatal onset (HP:0003623): Onset of signs or symptoms of disease within the first 28 days of life. Evidence: PCS. Frequency: 2/2. (PMID:22833457)
- Lactic acidosis (HP:0003128): An abnormal buildup of lactic acid in the body, leading to acidification of the blood and other bodily fluids. Evidence: PCS. Frequency: 2/2. (PMID:22833457)
- Basal ganglia gliosis (HP:0006999): Focal proliferation of glial cells in the basal ganglia. Evidence: PCS. Frequency: 1/1. (PMID:22833457)
- Microcephaly (HP:0000252): Head circumference below 2 standard deviations below the mean for age and gender. Evidence: PCS. Frequency: 2/2. (PMID:22833457)
- Cerebral atrophy (HP:0002059): Atrophy (wasting, decrease in size of cells or tissue) affecting the cerebrum. Evidence: PCS. Frequency: 1/1. (PMID:22833457)
- EEG abnormality (HP:0002353): Abnormality observed by electroencephalogram (EEG), which is used to record of the brain's spontaneous electrical activity from multiple electrodes placed on the scalp. Evidence: TAS. (OMIM:614946)
- Elevated brain N-acetyl aspartate level by MRS (HP:0025053): An increase in the level of N-acetyl aspartate in the brain identified by magnetic resonance spectroscopy (MRS). Evidence: PCS. Frequency: 1/1. (PMID:22833457)
- Feeding difficulties (HP:0011968): Impaired ability to eat related to problems gathering food and getting ready to suck, chew, or swallow it. Evidence: PCS. Frequency: 2/2. (PMID:22833457)
- 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: PCS. Frequency: 2/2. (PMID:22833457)
- Increased CSF lactate (HP:0002490): Increased concentration of lactate in the cerebrospinal fluid. Evidence: PCS. Frequency: 1/2. (PMID:22833457)
- Gliosis (HP:0002171): Gliosis is the focal proliferation of glial cells in the central nervous system. Evidence: TAS. (OMIM:614946)
- Profound global developmental delay (HP:0012736): A profound delay in the achievement of motor or mental milestones in the domains of development of a child. Evidence: PCS. Frequency: 2/2. (PMID:22833457)
- Elevated hepatic iron concentration (HP:0012465): An increased level of iron in liver tissues. Evidence: PCS. Frequency: 1/1. (PMID:22833457)
- Death in childhood (HP:0003819): Death in during childhood, defined here as between the ages of 2 and 10 years. Evidence: PCS. Frequency: 1/2. (PMID:22833457)
- Diffuse cerebral atrophy (HP:0002506): Diffuse unlocalised atrophy affecting the cerebrum. Evidence: PCS. Frequency: 1/1. (PMID:22833457)
- 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:22833457)
- Visual impairment (HP:0000505): Visual impairment (or vision impairment) is vision loss (of a person) to such a degree as to qualify as an additional support need through a significant limitation of visual capability resulting from either disease, trauma, or congenital or degenerative conditions that cannot be corrected by conventional means, such as refractive correction, medication, or surgery. Evidence: TAS. Frequency: Occasional (HP:0040283). (OMIM:614946)
- Thrombocytopenia (HP:0001873): A reduction in the number of circulating thrombocytes. Evidence: TAS. Frequency: Occasional (HP:0040283). (OMIM:614946)
- Growth delay (HP:0001510): A deficiency or slowing down of growth pre- and postnatally. Evidence: TAS. (OMIM:614946)
- Increased hepatic glycogen content (HP:0006568): An increase in the amount of glycogen stored in hepatocytes compared to normal. Evidence: PCS. Frequency: 1/2. (PMID:22833457)
- Myoclonus (HP:0001336): Very brief, involuntary random muscular contractions occurring at rest, in response to sensory stimuli, or accompanying voluntary movements. Evidence: PCS. Frequency: 2/2. (PMID:22833457)
These phenotypes are associated with the disease combined oxidative phosphorylation defect type 14 (OMIM:614946).