- Juvenile onset (HP:0003621): Onset of signs or symptoms of disease between the age of 5 and 15 years. Evidence: PCS. Frequency: 1/2. (PMID:28386624)
- Bradykinesia (HP:0002067): Bradykinesia literally means slow movement, and is used clinically to denote a slowness in the execution of movement (in contrast to hypokinesia, which is used to refer to slowness in the initiation of movement). Evidence: PCS. Frequency: 2/2. (PMID:28386624)
- Hypokinesia (HP:0002375): Abnormally diminished motor activity. In contrast to paralysis, hypokinesia is not characterized by a lack of motor strength, but rather by a poverty of movement. The typical habitual movements (e.g., folding the arms, crossing the legs) are reduced in frequency. Evidence: PCS. Frequency: 2/2. (PMID:28386624)
- Protein-losing enteropathy (HP:0002243): Abnormal loss of protein from the digestive tract related to excessive leakage of plasma proteins into the lumen of the gastrointestinal tract. Evidence: PCS. Frequency: 1/2. (PMID:28386624)
- 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: 2/2. (PMID:28386624)
- Developmental regression (HP:0002376): Loss of developmental skills, as manifested by loss of developmental milestones. Evidence: PCS. Frequency: 2/2. Onset: Juvenile onset (HP:0003621). (PMID:28386624)
- Hyperglycinemia (HP:0002154): An elevated concentration of glycine in the blood. Evidence: PCS. Frequency: 3/4. (PMID:28386624)
- 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:28386624)
- Increased CSF lactate (HP:0002490): Increased concentration of lactate in the cerebrospinal fluid. Evidence: PCS. Frequency: 1/1. (PMID:28386624)
- Motor delay (HP:0001270): A type of Developmental delay characterized by a delay in acquiring motor skills. Evidence: PCS. Frequency: 2/2. (PMID:28386624)
- Increased mitochondrial number (HP:0040014). Evidence: PCS. Frequency: 2/2. (PMID:28386624)
- Childhood onset (HP:0011463): Onset of disease at the age of between 1 and 5 years. Evidence: PCS. Frequency: 1/2. (PMID:28386624)
- 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:28386624)
- Decreased activity of mitochondrial complex IV (HP:0008347): A reduction in the activity of the mitochondrial respiratory chain complex IV, which is part of the electron transport chain in mitochondria. Evidence: PCS. Frequency: 2/2. (PMID:28386624)
- Lacticaciduria (HP:0003648): An increased concentration of lactic acid in the urine. Evidence: PCS. (PMID:28386624)
- Recurrent respiratory infections (HP:0002205): An increased susceptibility to respiratory infections as manifested by a history of recurrent respiratory infections. Evidence: PCS. Frequency: 1/2. (PMID:28386624)
- Increased CSF alanine concentration (HP:0500233): Abnormally increased levels of alanine in cerebrospinal fluid. Evidence: PCS. Frequency: 1/1. (PMID:28386624)
These phenotypes are associated with the disease mitochondrial complex IV deficiency, nuclear type 19 (OMIM:619063).