- Peripheral axonal neuropathy (HP:0003477): An abnormality characterized by disruption of the normal functioning of peripheral axons. Evidence: PCS. Frequency: 1/1. (PMID:39233737)
- Hyperkinetic movements (HP:0002487): Motor hyperactivity with excessive movement of muscles of the body as a whole. Evidence: PCS. Frequency: 2/2. (PMID:39233737)
- Poor head control (HP:0002421): Difficulty to maintain correct position of the head while standing or sitting. Infant head lag is observed when the head seems to flop around or lags posteriorly behind the trunk. Several articles have maintained that head lag should be absent by age 3 to 4 months. Evidence: PCS. Frequency: 1/1. (PMID:39233737)
- Encephalopathy (HP:0001298): Encephalopathy is a term that means brain disease, damage, or malfunction. In general, encephalopathy is manifested by an altered mental state. Evidence: PCS. Frequency: 1/1. (PMID:39233737)
- Respiratory acidosis (HP:0005972): Acidosis because of respiratory retention of carbon dioxide. Evidence: PCS. Frequency: 1/1. (PMID:39233737)
- 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:39233737)
- 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: 2/2. (PMID:39233737)
- Infantile onset (HP:0003593): Onset of signs or symptoms of disease between 28 days to one year of life. Evidence: PCS. Frequency: 1/2. (PMID:39233737)
- Lower limb spasticity (HP:0002061): Spasticity (velocity-dependent increase in tonic stretch reflexes with increased muscle tone and hyperexcitable tendon reflexes) in the muscles of the lower limbs, hips, and pelvis. Evidence: PCS. Frequency: 1/1. (PMID:39233737)
- Nystagmus (HP:0000639): Rhythmic, involuntary oscillations of one or both eyes related to abnormality in fixation, conjugate gaze, or vestibular mechanisms. Evidence: PCS. Frequency: 1/2. (PMID:39233737)
- Fetal onset (HP:0011461): Onset prior to birth but after 8 weeks of embryonic development (corresponding to a gestational age of 10 weeks). Evidence: PCS. Frequency: 1/2. (PMID:39233737)
- Esodeviation (HP:0020045): A manifest or latent ocular deviation in which one or both eyes tends to deviate nasally. Evidence: PCS. Frequency: 1/2. (PMID:39233737)
- Delayed ability to sit (HP:0025336): A failure to achieve the ability to sit at an appropriate developmental stage. Most children sit with support at 6 months of age and sit steadily without support at 9 months of age. Evidence: PCS. Frequency: 2/2. (PMID:39233737)
- Cytochrome C oxidase-negative muscle fibers (HP:0003688): An abnormally reduced activity of the enzyme cytochrome C oxidase in muscle tissue. Evidence: PCS. Frequency: 0/1. (PMID:39233737)
- Dysphagia (HP:0002015): Difficulty in swallowing. Evidence: PCS. Frequency: 1/2. (PMID:39233737)
- 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: PCS. Frequency: 0/1. (PMID:39233737)
- 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: 1/2. (PMID:39233737)
- 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:39233737)
- Spastic tetraparesis (HP:0001285): Spastic weakness affecting all four limbs. Evidence: PCS. Frequency: 2/2. (PMID:39233737)
- 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:39233737)
- Increased CSF lactate (HP:0002490): Increased concentration of lactate in the cerebrospinal fluid. Evidence: PCS. Frequency: 1/1. (PMID:39233737)
- Dyspnea (HP:0002094): Difficult or labored breathing. Dyspnea is a subjective feeling only the patient can rate, e.g., on a Borg scale. Evidence: PCS. Frequency: 1/1. (PMID:39233737)
- EEG with burst suppression (HP:0010851): The burst suppression pattern in electroencephalography refers to a characteristic periodic pattern of low voltage (<10 microvolts) suppressed background and a relatively shorter pattern of higher amplitude slow, sharp, and spiking complexes. Evidence: PCS. Frequency: 1/1. (PMID:39233737)
- Myoclonic status epilepticus (HP:0032667): A type of motor status epilepticus with repeating bilateral sudden brief (less than 100 ms) involuntary single or multiple contraction of muscles or muscle groups of variable topography. Evidence: PCS. Frequency: 1/1. (PMID:39233737)
- Motor regression (HP:0033044): Loss of previously achieved motor skills, as manifested by loss of developmental motor milestones. Evidence: PCS. Frequency: 1/1. (PMID:39233737)
- Visual fixation instability (HP:0025405): A deficit in the ability to fixate eye movements in order to stabilize images on the retina. Evidence: PCS. Frequency: 1/1. (PMID:39233737)
- Intrauterine growth retardation (HP:0001511): An abnormal restriction of fetal growth with fetal weight below the tenth percentile for gestational age. Evidence: PCS. Frequency: 1/1. (PMID:39233737)
- Optic disc pallor (HP:0000543): A pale yellow discoloration of the optic disc (the area of the optic nerve head in the retina). The optic disc normally has a pinkish hue with a central yellowish depression. Evidence: PCS. Frequency: 1/2. (PMID:39233737)
- Autosomal dominant inheritance (HP:0000006): 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 heterozygotes. In the context of medical genetics, an autosomal dominant disorder is caused when a single copy of the mutant allele is present. Males and females are affected equally, and can both transmit the disorder with a risk of 50% for each child of inheriting the mutant allele. Evidence: PCS. (PMID:39233737)
These phenotypes are associated with the disease mitochondrial dna depletion syndrome 14A (encephalomyopathic type) (OMIM:621481).