Phenotypes associated with the disease mitochondrial complex II deficiency, nuclear type 1 (OMIM:252011):
- Dystonia (HP:0001332): An abnormally increased muscular tone that causes fixed abnormal postures. There is a slow, intermittent twisting motion that leads to exaggerated turning and posture of the extremities and trunk. Evidence: IEA. (OMIM:252011)
- Short stature (HP:0004322): A height below that which is expected according to age and gender norms. Although there is no universally accepted definition of short stature, many refer to "short stature" as height more than 2 standard deviations below the mean for age and gender (or below the 3rd percentile for age and gender dependent norms). Evidence: IEA. (OMIM:252011)
- Flexion contracture (HP:0001371): A flexion contracture is a bent (flexed) joint that cannot be straightened actively or passively. It is thus a chronic loss of joint motion due to structural changes in muscle, tendons, ligaments, or skin that prevents normal movement of joints. Evidence: TAS. (OMIM:252011)
- 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: IEA. (OMIM:252011)
- 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: IEA. (OMIM:252011)
- Infantile onset (HP:0003593): Onset of signs or symptoms of disease between 28 days to one year of life. Evidence: PCS. Frequency: 1/1. (PMID:10746566)
- Pigmentary retinopathy (HP:0000580): An abnormality of the retina characterized by pigment deposition. It is typically associated with migration and proliferation of macrophages or retinal pigment epithelial cells into the retina; melanin from these cells causes the pigmentary changes. Pigmentary retinopathy is a common final pathway of many retinal conditions and is often associated with visual loss. Evidence: TAS. (OMIM:252011)
- Elevated lactate:pyruvate ratio (HP:0032653): An abnormal increase in the molar ratio of lactate to pyruvate in the blood circulation. Evidence: PCS. Frequency: 1/1. (PMID:10746566)
- Cognitive impairment (HP:0100543): Abnormal cognition is characterized by deficits in thinking, reasoning, or remembering. Evidence: TAS. (OMIM:252011)
- Nystagmus (HP:0000639): Rhythmic, involuntary oscillations of one or both eyes related to abnormality in fixation, conjugate gaze, or vestibular mechanisms. Evidence: TAS. (OMIM:252011)
- Decreased activity of mitochondrial complex II (HP:0008314): A reduction in the activity of the mitochondrial respiratory chain complex II, which is part of the electron transport chain in mitochondria. Evidence: PCS. Frequency: 3/3. (PMID:7550341;PMID:10746566)
- Abnormal mitochondria in muscle tissue (HP:0008316): An abnormality of the mitochondria in muscle tissue. Evidence: IEA. (OMIM:252011)
- Muscle weakness (HP:0001324): Reduced strength of muscles. Evidence: IEA. (OMIM:252011)
- Dilated cardiomyopathy (HP:0001644): Dilated cardiomyopathy (DCM) is defined by the presence of left ventricular dilatation and left ventricular systolic dysfunction in the absence of abnormal loading conditions (hypertension, valve disease) or coronary artery disease sufficient to cause global systolic impairment. Right ventricular dilation and dysfunction may be present but are not necessary for the diagnosis. Evidence: TAS. (OMIM:252011)
- Exercise intolerance (HP:0003546): A functional motor deficit where individuals whose responses to the challenges of exercise fail to achieve levels considered normal for their age and gender. Evidence: IEA. (OMIM:252011)
- Hyperreflexia (HP:0001347): Hyperreflexia is the presence of hyperactive stretch reflexes of the muscles. Evidence: IEA. (OMIM:252011)
- Stress/infection-induced lactic acidosis (HP:0004897): A form of lactic acidemia that occurs in relation to stress or infection. Evidence: IEA. (OMIM:252011)
- Ragged-red muscle fibers (HP:0003200): An abnormal appearance of muscle fibers observed on muscle biopsy. Ragged red fibers can be visualized with Gomori trichrome staining as irregular and intensely red subsarcolemmal zones, whereas the normal myofibrils are green. The margins of affect fibers appear red and ragged. The ragged-red is due to the accumulation of abnormal mitochondria below the plasma membrane of the muscle fiber, leading to the appearance of a red rim and speckled sarcoplasm. Evidence: IEA. (OMIM:252011)
- Truncal ataxia (HP:0002078): Truncal ataxia is a sign of ataxia characterized by instability of the trunk. It usually occurs during sitting. Evidence: PCS. Frequency: 1/1. (PMID:10746566)
- 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: IEA. (OMIM:252011)
- Developmental regression (HP:0002376): Loss of developmental skills, as manifested by loss of developmental milestones. Evidence: PCS. Frequency: 1/1. (PMID:10746566)
- 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. (OMIM:252011)
- 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:10746566)
- 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:10746566)
- Left ventricular noncompaction (HP:0030682): Left ventricular noncompaction (LVNC) is defined by 3 markers: prominent left ventricular (LV) trabeculae, deep intertrabecular recesses, and the thin compacted layer. Evidence: TAS. (OMIM:252011)
- 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: IEA. (OMIM:252011)
- Increased intramyocellular lipid droplets (HP:0012240): An abnormal increase in intracellular lipid droplets In a muscle. The number and size of these drops can increase with somd disorders of lipid metabolism affecting muscle. See PMID 20691590 for histological images. Evidence: TAS. (OMIM:252011)
- 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. (OMIM:252011)
- Ophthalmoplegia (HP:0000602): Paralysis of one or more extraocular muscles that are responsible for eye movements. Evidence: TAS. (OMIM:252011)
- Progressive leukoencephalopathy (HP:0006980): Leukoencephalopathy that gets more severe with time. Evidence: TAS. (OMIM:252011)
- 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:7550341)
- Neonatal hypotonia (HP:0001319): Muscular hypotonia (abnormally low muscle tone) manifesting in the neonatal period. Evidence: IEA. (OMIM:252011)
- Optic atrophy (HP:0000648): Atrophy of the optic nerve. Optic atrophy results from the death of the retinal ganglion cell axons that comprise the optic nerve and manifesting as a pale optic nerve on fundoscopy. Evidence: TAS. (OMIM:252011)
- 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. (OMIM:252011)
- Spasticity (HP:0001257): A motor disorder characterized by a velocity-dependent increase in tonic stretch reflexes with increased muscle tone, exaggerated (hyperexcitable) tendon reflexes. Evidence: IEA. (OMIM:252011)
- Myoclonus (HP:0001336): Very brief, involuntary random muscular contractions occurring at rest, in response to sensory stimuli, or accompanying voluntary movements. Evidence: IEA. (OMIM:252011)