- Lower limb hypertonia (HP:0006895). Evidence: TAS. Frequency: Occasional (HP:0040283). (ORPHA:3208)
- Feeding difficulties in infancy (HP:0008872): Impaired feeding performance of an infant as manifested by difficulties such as weak and ineffective sucking, brief bursts of sucking, and falling asleep during sucking. There may be difficulties with chewing or maintaining attention. Evidence: TAS. Frequency: Occasional (HP:0040283). (ORPHA:3208)
- Focal myoclonic seizure (HP:0011166): A type of focal motor seizure characterized by sudden, brief (<100 ms) involuntary single or multiple contraction(s) of muscles(s) or muscle groups of variable topography (axial, proximal limb, distal). Myoclonus is less regularly repetitive and less sustained than is clonus. Evidence: TAS. Frequency: Occasional (HP:0040283). (ORPHA:3208)
- Moderate global developmental delay (HP:0011343): A moderate delay in the achievement of motor or mental milestones in the domains of development of a child. Evidence: TAS. Frequency: Occasional (HP:0040283). (ORPHA:3208)
- Noncompaction cardiomyopathy (HP:0012817): A type of cardiomyopathy characterized anatomically by deep trabeculations in the ventricular wall, which define recesses communicating with the main ventricular chamber. Evidence: TAS. Frequency: Occasional (HP:0040283). (ORPHA:3208)
- Mild microcephaly (HP:0040196): Decreased occipito-frontal (head) circumference (OFC). For the microcephaly OFC must be between -3 SD and -2 SD compared to appropriate, age matched, normal standards (i.e. -3 SD <= OFC < -2 SD). Evidence: TAS. Frequency: Occasional (HP:0040283). (ORPHA:3208)
- Vesicoureteral reflux (HP:0000076): Abnormal (retrograde) movement of urine from the bladder into ureters or kidneys related to inadequacy of the valvular mechanism at the ureterovesicular junction or other causes. Evidence: TAS. Frequency: Very rare (HP:0040284). (ORPHA:3208)
- External ophthalmoplegia (HP:0000544): Paralysis of the external ocular muscles. Evidence: TAS. Frequency: Very rare (HP:0040284). (ORPHA:3208)
- 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. Frequency: Very rare (HP:0040284). (ORPHA:3208)
- 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: Very rare (HP:0040284). (ORPHA:3208)
- 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 rare (HP:0040284). (ORPHA:3208)
- Dementia (HP:0000726): A loss of global cognitive ability of sufficient amount to interfere with normal social or occupational function. Dementia represents a loss of previously present cognitive abilities, generally in adults, and can affect memory, thinking, language, judgment, and behavior. Evidence: TAS. Frequency: Very rare (HP:0040284). (ORPHA:3208)
- 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 rare (HP:0040284). (ORPHA:3208)
- Loss of ambulation (HP:0002505): Inability to walk in a person who previous had the ability to walk. Evidence: TAS. Frequency: Very rare (HP:0040284). (ORPHA:3208)
- Abnormality of the eye (HP:0000478): Any abnormality of the eye, including location, spacing, and intraocular abnormalities. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:3208)
- 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: TAS. Frequency: Frequent (HP:0040282). (ORPHA:3208)
- Motor delay (HP:0001270): A type of Developmental delay characterized by a delay in acquiring motor skills. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:3208)
- Abnormality of the cardiovascular system (HP:0001626): Any abnormality of the cardiovascular system. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:3208)
- 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: Frequent (HP:0040282). (ORPHA:3208)
- Left ventricular hypertrophy (HP:0001712): Enlargement or increased size of the heart left ventricle. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:3208)
- Weight loss (HP:0001824): Reduction of total body weight. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:3208)
- Generalized myoclonic seizure (HP:0002123): A generalized myoclonic seizure is a type of generalized motor seizure characterized by bilateral, sudden, brief (<100 ms) involuntary single or multiple contraction of muscles or muscle groups of variable topography (axial, proximal limb, distal). Myoclonus is less regularly repetitive and less sustained than is clonus. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:3208)
- Motor deterioration (HP:0002333): Loss of previously present motor (i.e., movement) abilities. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:3208)
- Developmental regression (HP:0002376): Loss of developmental skills, as manifested by loss of developmental milestones. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:3208)
- Generalized muscle weakness (HP:0003324): Generalized weakness or decreased strength of the muscles, affecting both distal and proximal musculature. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:3208)
- Easy fatigability (HP:0003388): Increased susceptibility to fatigue. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:3208)
- 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: TAS. Frequency: Frequent (HP:0040282). (ORPHA:3208)
- Proportionate short stature (HP:0003508): A kind of short stature in which different regions of the body are shortened to a comparable extent. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:3208)
- Severe short stature (HP:0003510): A severe degree of short stature, more than -4 SD from the mean corrected for age and sex. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:3208)
- Distal amyotrophy (HP:0003693): Muscular atrophy affecting muscles in the distal portions of the extremities. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:3208)
- Proximal muscle weakness (HP:0003701): A lack of strength of the proximal muscles. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:3208)
- Skeletal myopathy (HP:0003756). Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:3208)
- Abnormal left ventricular function (HP:0005162): Inability of the left ventricle to perform its normal physiologic function. Failure is either due to an inability to contract the left ventricle or the inability to relax completely and fill with blood during diastole. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:3208)
- Hyperactive deep tendon reflexes (HP:0006801). Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:3208)
- Hyperactive patellar reflex (HP:0007083). Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:3208)
- Progressive psychomotor deterioration (HP:0007272). Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:3208)
- Upper limb hyperreflexia (HP:0007350): Increased intensity of the a reflex in the arm. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:3208)
- Reduced visual acuity (HP:0007663). Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:3208)
- Irritability (HP:0000737): An emotional state characterized by negative feelings of heightened frustration, annoyance, or feeling upset, often triggered by internal factors (e.g., fatigue, hunger, unfulfilled desires) or external factors (e.g., social or environmental challenges). Irritability may be unpredictable, and is accompanied by a lowered threshold for emotional reactivity and observable features (speech, facial expressions, or psychomotor activity). Evidence: TAS. Frequency: Occasional (HP:0040283). (ORPHA:3208)
- 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: TAS. Frequency: Occasional (HP:0040283). (ORPHA:3208)
- 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: Occasional (HP:0040283). (ORPHA:3208)
- Spastic tetraparesis (HP:0001285): Spastic weakness affecting all four limbs. Evidence: TAS. Frequency: Occasional (HP:0040283). (ORPHA:3208)
- Generalized hypotonia (HP:0001290): Generalized muscular hypotonia (abnormally low muscle tone). Evidence: TAS. Frequency: Occasional (HP:0040283). (ORPHA:3208)
- Intrauterine growth retardation (HP:0001511): An abnormal restriction of fetal growth with fetal weight below the tenth percentile for gestational age. Evidence: TAS. Frequency: Occasional (HP:0040283). (ORPHA:3208)
- Spastic paraparesis (HP:0002313): Partial loss of the ability to move the lower limbs accompanied by spasticity of the lower limbs. Evidence: TAS. Frequency: Occasional (HP:0040283). (ORPHA:3208)
- Frequent falls (HP:0002359). Evidence: TAS. Frequency: Occasional (HP:0040283). (ORPHA:3208)
- Expressive language delay (HP:0002474): A delay in the acquisition of the ability to use language to communicate needs, wishes, or thoughts. Evidence: TAS. Frequency: Occasional (HP:0040283). (ORPHA:3208)
- Skeletal muscle atrophy (HP:0003202): The presence of skeletal muscular atrophy (which is also known as amyotrophy). Evidence: TAS. Frequency: Occasional (HP:0040283). (ORPHA:3208)
- Abnormal atrioventricular conduction (HP:0005150): An impairment of the electrical continuity between the atria and ventricles. Evidence: TAS. Frequency: Occasional (HP:0040283). (ORPHA:3208)
- Knee flexion contracture (HP:0006380): A type of knee joint contracture in which the knee is in a fixed bent (flexed) configuration such that it cannot be straightened actively or passively. Evidence: TAS. Frequency: Occasional (HP:0040283). (ORPHA:3208)
These phenotypes are associated with the disease Isolated succinate-CoQ reductase deficiency (ORPHA:3208).