- Hyporeflexia (HP:0001265): Reduction of neurologic reflexes such as the knee-jerk reaction. Evidence: IEA. (OMIM:500002)
- Elevated circulating creatine kinase activity (HP:0003236): The activity of creatine kinase in the blood circulation is above the upper limit of normal. Evidence: IEA. (OMIM:500002)
- Facial palsy (HP:0010628): Facial nerve palsy is a dysfunction of cranial nerve VII (the facial nerve) that results in inability to control facial muscles on the affected side with weakness of the muscles of facial expression and eye closure. This can either be present in unilateral or bilateral form. Evidence: IEA. (OMIM:500002)
- 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: PCS. Frequency: 1/1. (PMID:7726154)
- 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: PCS. Frequency: 1/1. (PMID:7726154)
- Gait disturbance (HP:0001288): The term gait disturbance can refer to any disruption of the ability to walk. Evidence: PCS. Frequency: 1/1. (PMID:7726154)
- Weakness of orbicularis oculi muscle (HP:0012507): Reduced strength of the orbicularis oculi, the circumorbital muscle in the face that closes the eyelid. Evidence: TAS. (OMIM:500002)
- Dysarthria (HP:0001260): Dysarthric speech is a general description referring to a neurological speech disorder characterized by poor articulation. Depending on the involved neurological structures, dysarthria may be further classified as spastic, flaccid, ataxic, hyperkinetic and hypokinetic, or mixed. Evidence: IEA. (OMIM:500002)
- 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: IEA. (OMIM:500002)
- 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:500002)
- Generalized hypotonia (HP:0001290): Generalized muscular hypotonia (abnormally low muscle tone). Evidence: TAS. (OMIM:500002)
- Limb muscle weakness (HP:0003690): Reduced strength and weakness of the muscles of the arms and legs. Evidence: PCS. Frequency: 1/1. (PMID:7726154)
- Motor delay (HP:0001270): A type of Developmental delay characterized by a delay in acquiring motor skills. Evidence: IEA. (OMIM:500002)
- Mitochondrial inheritance (HP:0001427): A mode of inheritance that is observed for traits related to a gene encoded on the mitochondrial genome. Because the mitochondrial genome is essentially always maternally inherited, a mitochondrial condition can only be transmitted by females, although the condition can affect both sexes. The proportion of mutant mitochondria can vary (heteroplasmy). Evidence: PCS. (PMID:7726154)
- Decreased activity of mitochondrial complex IV (HP:0008347): A reduction in the activity of the mitochondrial respiratory chain complex IV, which is part of the electron transport chain in mitochondria. Evidence: TAS. (OMIM:500002)
- Late young adult onset (HP:0025710): Onset of disease at an age of greater than or equal to 25 to under 40 years. Evidence: PCS. Frequency: 1/1. (PMID:7726154)
- 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. (OMIM:500002)
- Proximal amyotrophy (HP:0007126): Amyotrophy (muscular atrophy) affecting the proximal musculature. Evidence: TAS. (OMIM:500002)
- Proximal muscle weakness (HP:0003701): A lack of strength of the proximal muscles. Evidence: IEA. (OMIM:500002)
- Type II diabetes mellitus (HP:0005978): A type of diabetes mellitus initially characterized by insulin resistance and hyperinsulinemia and subsequently by glucose interolerance and hyperglycemia. Evidence: PCS. Frequency: 1/1. (PMID:7726154)
- Cytochrome C oxidase-negative muscle fibers (HP:0003688): An abnormally reduced activity of the enzyme cytochrome C oxidase in muscle tissue. Evidence: PCS. Frequency: 1/1. (PMID:7726154)
- EMG: myopathic abnormalities (HP:0003458): The presence of abnormal electromyographic patterns indicative of myopathy, such as small-short polyphasic motor unit potentials. Evidence: IEA. (OMIM:500002)
- 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: PCS. Frequency: 1/1. (PMID:7726154)
- Neck muscle weakness (HP:0000467): Decreased strength of the neck musculature. Evidence: PCS. Frequency: 1/1. (PMID:7726154)
These phenotypes are associated with the disease mitochondrial myopathy with diabetes (OMIM:500002).