- 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:1349)
- 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:1349)
- Gait disturbance (HP:0001288): The term gait disturbance can refer to any disruption of the ability to walk. Evidence: TAS. Frequency: Very frequent (HP:0040281). (ORPHA:1349)
- Muscle weakness (HP:0001324): Reduced strength of muscles. Evidence: TAS. Frequency: Very frequent (HP:0040281). (ORPHA:1349)
- Slurred speech (HP:0001350): Abnormal coordination of muscles involved in speech. Evidence: TAS. Frequency: Very frequent (HP:0040281). (ORPHA:1349)
- 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:1349)
- Mild global developmental delay (HP:0011342): A mild delay in the achievement of motor or mental milestones in the domains of development of a child. Evidence: TAS. Frequency: Very frequent (HP:0040281). (ORPHA:1349)
- Progressive external ophthalmoplegia (HP:0000590): Initial bilateral ptosis followed by limitation of eye movements in all directions and slowing of saccades. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:1349)
- Ophthalmoparesis (HP:0000597): Ophthalmoplegia is a paralysis or weakness of one or more of the muscles that control eye movement. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:1349)
- Mental deterioration (HP:0001268): Loss of previously present mental abilities, generally in adults. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:1349)
- 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: Frequent (HP:0040282). (ORPHA:1349)
- Congestive heart failure (HP:0001635): The presence of an abnormality of cardiac function that is responsible for the failure of the heart to pump blood at a rate that is commensurate with the needs of the tissues or a state in which abnormally elevated filling pressures are required for the heart to do so. Heart failure is frequently related to a defect in myocardial contraction. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:1349)
- 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. Frequency: Frequent (HP:0040282). (ORPHA:1349)
- Dyspnea (HP:0002094): Difficult or labored breathing. Dyspnea is a subjective feeling only the patient can rate, e.g., on a Borg scale. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:1349)
- 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: TAS. Frequency: Frequent (HP:0040282). (ORPHA:1349)
- 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: TAS. Frequency: Frequent (HP:0040282). (ORPHA:1349)
- EMG abnormality (HP:0003457): Abnormal results of investigations using electromyography (EMG). Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:1349)
- Increased circulating pyruvate concentration (HP:0003542): The concentration of pyruvate in the blood circulation is above the upper limit of normal. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:1349)
- 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: TAS. Frequency: Frequent (HP:0040282). (ORPHA:1349)
- Lower limb pain (HP:0012514): An unpleasant sensation characterized by physical discomfort (such as pricking, throbbing, or aching) localized to the leg. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:1349)
- Abnormal cardiovascular system morphology (HP:0030680): Any structural anomaly of the heart and blood vessels. Evidence: TAS. Frequency: Frequent (HP:0040282). (ORPHA:1349)
- Hypertension (HP:0000822): The presence of chronic increased pressure in the systemic arterial system. Evidence: TAS. Frequency: Occasional (HP:0040283). (ORPHA:1349)
- Multiple lipomas (HP:0001012): The presence of multiple lipomas (a type of benign tissue made of fatty tissue). Evidence: TAS. Frequency: Occasional (HP:0040283). (ORPHA:1349)
- Hyperreflexia (HP:0001347): Hyperreflexia is the presence of hyperactive stretch reflexes of the muscles. Evidence: TAS. Frequency: Occasional (HP:0040283). (ORPHA:1349)
- Febrile seizure (within the age range of 3 months to 6 years) (HP:0002373): A febrile seizure is any type of seizure (most often a generalized tonic-clonic seizure) occurring with fever (at least 38 degrees Celsius) but in the absence of central nervous system infection, severe metabolic disturbance or other alternative precipitant in children between the ages of 3 months and 6 years. Evidence: TAS. Frequency: Occasional (HP:0040283). (ORPHA:1349)
- Myalgia (HP:0003326): Pain in muscle. Evidence: TAS. Frequency: Occasional (HP:0040283). (ORPHA:1349)
- Increased adipose tissue (HP:0009126): An increase in adipose tissue mass by hyperplastic growth (increase in the number of adipocytes) or by hypertrophic growth (increase in the size of adipocytes occurring primarily by lipid accumulation within the cell). Evidence: TAS. Frequency: Occasional (HP:0040283). (ORPHA:1349)
- Peripheral neuropathy (HP:0009830): Peripheral neuropathy is a general term for any disorder of the peripheral nervous system. The main clinical features used to classify peripheral neuropathy are distribution, type (mainly demyelinating versus mainly axonal), duration, and course. Evidence: TAS. Frequency: Occasional (HP:0040283). (ORPHA:1349)
- Fatigue (HP:0012378): A subjective feeling of tiredness characterized by a lack of energy and motivation. Evidence: TAS. Frequency: Occasional (HP:0040283). (ORPHA:1349)
- Chest pain (HP:0100749): An unpleasant sensation characterized by physical discomfort (such as pricking, throbbing, or aching) localized to the chest. Evidence: TAS. Frequency: Occasional (HP:0040283). (ORPHA:1349)
These phenotypes are associated with the disease Mitochondrial DNA-related cardiomyopathy and hearing loss (ORPHA:1349).