Mitochondrial Myopathy

Mitochondrial myopathies are a group of diseases. Each disease has different symptoms. Some may be mild while others are life threatening. However, the diseases are all caused by a problem with the mitochondria. Mitochondria are tiny structures found in almost all cells. It is their job to provide energy to these cells. Mitochondrial myopathies can interfere with many different bodily functions. It tends to have the greatest impact on structures that are active such as the muscles and nerves.

  • Causes

    This condition is caused by a mutation in a specific gene.

  • Definition

    Mitochondrial myopathies are a group of diseases. Each disease has different symptoms. Some may be mild while others are life threatening. However, the diseases are all caused by a problem with the mitochondria.

    Mitochondria are tiny structures found in almost all cells. It is their job to provide energy to these cells. Mitochondrial myopathies can interfere with many different bodily functions. It tends to have the greatest impact on structures that are active such as the muscles and nerves.

    Muscular and Nervous Systems
    Torso muscle and nerves
    Mitochondrial myopathies decrease the ability of nerves and muscles. Weakness and uncoordinated movement may result.
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  • Diagnosis

    Your doctor will ask about your symptoms and medical history. A physical exam will be done. You will also be asked about any family history of the disease. An eye exam may also be done.

    Your bodily fluids and tissues may be tested. This can be done with:


    • Muscle
      biopsy
    • Blood tests
    • Lumbar puncture—also known as a spinal tap

    Your heart activity may be tested. This can be done with an electrocardiogram.


    Your nerve function may be tested. This can be done with
    electromyography
    (EMG).

  • Prevention

    There are no known guidelines to prevent this condition.

  • Risk Factors

    Having a family member with the mutated gene increases the risk of mitochondrial myopathies.

  • Symptoms

    Mitochondrial myopathies can cause a range of symptoms. Symptoms by specific condition include:

    NAME OF CONDITIONAGE OF ONSETDEFINING SYMPTOMS
    Kearns-Sayre syndrome (KSS)Before age 20Salt and pepper pigmentation in eye, eye movement problems (PEO), heart and skeletal muscle dysfunction
    Leigh’s syndromeInfancy—can appear laterBrain abnormalities that lead to muscle problems, seizures, uncoordinated muscle movement (ataxia), impaired vision and hearing, developmental delay, and poor control over breathing
    Mitochondrial DNA depletion syndromeInfancyMuscle weakness and liver failure, floppiness, feeding difficulties, and developmental delay
    Mitochondrial encephalomyopathy, lactic acidosis and stroke-like episodes (MELAS)Childhood to adulthoodStroke-like episodes, migraine headaches, vomiting and seizures, muscle weakness, exercise intolerance, hearing loss, diabetes, short stature
    Myoclonic epilepsy associated with ragged red fibers (MERRF)Late childhood to adulthoodMyoclonus (jerky movements), seizures, muscle weakness, uncoordinated muscle movement (ataxia)
    Mitochondrial neurogastrointestinal encephalomyopathy (MNGIE)Before age 20Eye movement problems (PEO), drooping eyelid, limb weakness, digestive problems, peripheral neuropathy
    Neuropathy, ataxia, and retinitis pigmentosa (NARP)Early childhood to adulthoodUncoordinated muscle movement (ataxia), degeneration of the retina in the eye leading to loss of vision
    Pearson’s syndromeInfancyCauses severe anemia and pancreas problems, survivors usually develop KSS
    Progressive external ophthalmoplegia (PEO)AdulthoodEye movement difficulty, and often symptoms of other mitochondrial diseases, but can be an independent syndrome

    Other general symptoms include:

    • Muscle weakness or exercise intolerance
    • Lack of balance or coordination

    • Arryhthmias of the heart or
      heart failure
    • Problems with eye movements—either problems with control or inability to move them
    • Seizures
    • Stroke-like episodes
    • Vomiting
    • Cognitive or learning deficits
    • Dementia

  • Treatment

    There is no specific treatment for these diseases. Instead, treatment will focus on managing the symptoms. Treatment options include the following: