- Hepatic steatosis (HP:0001397): Steatosis is a term used to denote lipid accumulation within hepatocytes. Evidence: TAS. (OMIM:615918)
- Axial hypotonia (HP:0008936): Muscular hypotonia (abnormally low muscle tone) affecting the musculature of the trunk. Evidence: PCS. Frequency: 2/2. Onset: Neonatal onset (HP:0003623). (PMID:24827421)
- Cerebral atrophy (HP:0002059): Atrophy (wasting, decrease in size of cells or tissue) affecting the cerebrum. Evidence: PCS. Frequency: 1/1. (PMID:33153448)
- Congenital onset (HP:0003577): A phenotypic abnormality that is present at birth. Evidence: PCS. Frequency: 2/2. (PMID:24827421)
- Hypoplasia of the corpus callosum (HP:0002079): Underdevelopment of the corpus callosum. Evidence: PCS. Frequency: 1/1. (PMID:24827421)
- 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: 1/1. (PMID:33153448)
- 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:33153448)
- 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. Onset: Neonatal onset (HP:0003623). (PMID:24827421)
- 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: 1/1. (PMID:33153448)
- Infantile onset (HP:0003593): Onset of signs or symptoms of disease between 28 days to one year of life. Evidence: IEA. Frequency: 1/1. (PMID:33153448)
- Increased cerebral lipofuscin (HP:0011813): Lipofuscin (age pigment) is a brown-yellow, electron-dense, autofluorescent material that accumulates progressively over time in lysosomes of postmitotic cells, such as neurons and cardiac myocytes. This term pertains if there is an increase in the accumulation of lipofuscin (also known as autofluorescent lipoprotein) more than expected for the age of the patient. Evidence: IEA. Frequency: 1/1. (PMID:24827421)
- Reduced eye contact (HP:0000817): A reduced frequency or duration of eye contact. Evidence: PCS. Frequency: 1/1. (PMID:33153448)
- Limb hypertonia (HP:0002509). Evidence: PCS. Frequency: 2/2. Onset: Neonatal onset (HP:0003623). (PMID:24827421)
- Limb hypertonia (HP:0002509). Evidence: PCS. Frequency: 1/1. (PMID:33153448)
- 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:24827421)
- Hyperprolinemia (HP:0008358): The concentration of proline in the blood circulation is above the upper limit of normal. Evidence: PCS. Frequency: 1/1. (PMID:33153448)
- Neonatal death (HP:0003811): Death within the first 28 days of life. Evidence: PCS. Frequency: 2/2. (PMID:24827421)
- Hyperalaninemia (HP:0003348): An increased concentration of alanine in the blood. Evidence: PCS. Frequency: 1/1. (PMID:33153448)
These phenotypes are associated with the disease combined oxidative phosphorylation defect type 21 (OMIM:615918).