Phenotypes associated with the disease Isolated complex I deficiency (ORPHA:2609):
- Decreased activity of mitochondrial complex I (HP:0011923): A reduction in the activity of the mitochondrial respiratory chain complex I, which is part of the electron transport chain in mitochondria. Evidence: TAS. Frequency: Obligate (HP:0040280). (ORPHA:2609)
- Proximal tubulopathy (HP:0000114): Dysfunction of the proximal tubule, which is the portion of the duct system of the nephron of the kidney which leads from Bowman's capsule to the loop of Henle. Evidence: TAS. Frequency: Very frequent (HP:0040281). (ORPHA:2609)
- Sensorineural hearing impairment (HP:0000407): A type of hearing impairment in one or both ears related to an abnormal functionality of the cochlear nerve. Evidence: TAS. Frequency: Very frequent (HP:0040281). (ORPHA:2609)
- 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: Very frequent (HP:0040281). (ORPHA:2609)
- Ptosis (HP:0000508): The upper eyelid margin is positioned 3 mm or more lower than usual and covers the superior portion of the iris (objective); or, the upper lid margin obscures at least part of the pupil (subjective). Evidence: TAS. Frequency: Very frequent (HP:0040281). (ORPHA:2609)
- 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: TAS. Frequency: Very frequent (HP:0040281). (ORPHA:2609)
- Nystagmus (HP:0000639): Rhythmic, involuntary oscillations of one or both eyes related to abnormality in fixation, conjugate gaze, or vestibular mechanisms. Evidence: TAS. Frequency: Very frequent (HP:0040281). (ORPHA:2609)
- Reduced eye contact (HP:0000817): A reduced frequency or duration of eye contact. Evidence: TAS. Frequency: Very frequent (HP:0040281). (ORPHA:2609)
- Optic neuropathy (HP:0001138). Evidence: TAS. Frequency: Very frequent (HP:0040281). (ORPHA:2609)
- Ataxia (HP:0001251): Ataxia refers to impaired coordination of voluntary muscle movement. Cerebellar ataxia refers to ataxia due to dysfunction of the cerebellum. This causes a variety of elementary neurological deficits including asynergy (lack of coordination between muscles, limbs and joints), dysmetria (lack of ability to judge distances that can lead to under- or overshoot in grasping movements), and dysdiadochokinesia (inability to perform rapid movements requiring antagonizing muscle groups to be switched on and off repeatedly). Evidence: TAS. Frequency: Very frequent (HP:0040281). (ORPHA:2609)
- 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: Very frequent (HP:0040281). (ORPHA:2609)
- Lethargy (HP:0001254): A state of fatigue, either physical or mental slowness and sluggishness, with difficulties in initiating or performing simple tasks. Distinguished from apathy which implies indifference and a lack of desire or interest in the task. A person with lethargy may have the desire, but not the energy to engage in personal or socially relevant tasks. Evidence: TAS. Frequency: Very frequent (HP:0040281). (ORPHA:2609)
- 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: TAS. Frequency: Very frequent (HP:0040281). (ORPHA:2609)
- 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: TAS. Frequency: Very frequent (HP:0040281). (ORPHA:2609)
- Muscle weakness (HP:0001324): Reduced strength of muscles. Evidence: TAS. Frequency: Very frequent (HP:0040281). (ORPHA:2609)
- Failure to thrive (HP:0001508): Failure to thrive (FTT) refers to a child whose physical growth is substantially below the norm. Evidence: TAS. Frequency: Very frequent (HP:0040281). (ORPHA:2609)
- Intrauterine growth retardation (HP:0001511): An abnormal restriction of fetal growth with fetal weight below the tenth percentile for gestational age. Evidence: TAS. Frequency: Very frequent (HP:0040281). (ORPHA:2609)
- Hypertrophic cardiomyopathy (HP:0001639): Hypertrophic cardiomyopathy (HCM) is defined by the presence of increased ventricular wall thickness or mass in the absence of loading conditions (hypertension, valve disease) sufficient to cause the observed abnormality. Evidence: TAS. Frequency: Very frequent (HP:0040281). (ORPHA:2609)
- Hypoglycemia (HP:0001943): A decreased concentration of glucose in the blood. Evidence: TAS. Frequency: Very frequent (HP:0040281). (ORPHA:2609)
- Vomiting (HP:0002013): Forceful ejection of the contents of the stomach through the mouth by means of a series of involuntary spasmic contractions. Evidence: TAS. Frequency: Very frequent (HP:0040281). (ORPHA:2609)
- Respiratory insufficiency (HP:0002093). Evidence: TAS. Frequency: Very frequent (HP:0040281). (ORPHA:2609)
- Hepatomegaly (HP:0002240): Abnormally increased size of the liver. Evidence: TAS. Frequency: Very frequent (HP:0040281). (ORPHA:2609)
- Leukoencephalopathy (HP:0002352): This term describes abnormality of the white matter of the cerebrum resulting from damage to the myelin sheaths of nerve cells. Evidence: TAS. Frequency: Very frequent (HP:0040281). (ORPHA:2609)
- Leukodystrophy (HP:0002415): Leukodystrophy refers to deterioration of white matter of the brain resulting from degeneration of myelin sheaths in the CNS. Their basic defect is directly related to the synthesis and maintenance of myelin membranes. Symmetric white matter involvement at MRI is a typical finding in patients with leukodystrophies. Evidence: TAS. Frequency: Very frequent (HP:0040281). (ORPHA:2609)
- 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: TAS. Frequency: Very frequent (HP:0040281). (ORPHA:2609)
- Increased CSF lactate (HP:0002490): Increased concentration of lactate in the cerebrospinal fluid. Evidence: TAS. Frequency: Very frequent (HP:0040281). (ORPHA:2609)
- 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: Very frequent (HP:0040281). (ORPHA:2609)
- Increased circulating pyruvate concentration (HP:0003542): The concentration of pyruvate in the blood circulation is above the upper limit of normal. Evidence: TAS. Frequency: Very frequent (HP:0040281). (ORPHA:2609)
- Mitochondrial myopathy (HP:0003737): A type of myopathy associated with mitochondrial disease and characterized by findings on biopsy such as ragged red muscle fibers. Evidence: TAS. Frequency: Very frequent (HP:0040281). (ORPHA:2609)
- Paroxysmal involuntary eye movements (HP:0007704): Sudden-onset episode of abnormal, involuntary eye movements. Evidence: TAS. Frequency: Very frequent (HP:0040281). (ORPHA:2609)
- Abnormal mitochondria in muscle tissue (HP:0008316): An abnormality of the mitochondria in muscle tissue. Evidence: TAS. Frequency: Very frequent (HP:0040281). (ORPHA:2609)
- Focal T2 hyperintense brainstem lesion (HP:0012748): A lighter than expected T2 signal on magnetic resonance imaging (MRI) of the brainstem. This term refers to a localized hyperintensity affecting a particular region of the brainstem. Evidence: TAS. Frequency: Very frequent (HP:0040281). (ORPHA:2609)
- Microcephaly (HP:0000252): Head circumference below 2 standard deviations below the mean for age and gender. Evidence: TAS. Frequency: Occasional (HP:0040283). (ORPHA:2609)
- Blindness (HP:0000618): Blindness is the condition of lacking visual perception defined as a profound reduction in visual perception. On the 6m visual acuity scale, blindness is defined as less than 3/60. On the 20ft visual acuity scale, blindness is defined as less than 20/400. On the decimal visual acuity scale, blindness is defined as less than 0.05. Blindness is typically characterized by a visual field of no greater than 10 degrees in radius around central fixation. Evidence: TAS. Frequency: Occasional (HP:0040283). (ORPHA:2609)
- Diabetes mellitus (HP:0000819): A group of abnormalities characterized by hyperglycemia and glucose intolerance. Evidence: TAS. Frequency: Occasional (HP:0040283). (ORPHA:2609)
- Feeding difficulties (HP:0011968): Impaired ability to eat related to problems gathering food and getting ready to suck, chew, or swallow it. Evidence: TAS. Frequency: Occasional (HP:0040283). (ORPHA:2609)
- Fetal distress (HP:0025116): An intrauterine state characterized by suboptimal values in the fetal heart rate, oxygenation of fetal blood, or other parameters indicative of compromise of the fetus. Signs of fetal distress include repetitive variable decelerations, fetal tachycardia or bradycardia, late decelerations, or low biophysical profile. Evidence: TAS. Frequency: Occasional (HP:0040283). (ORPHA:2609)