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Mitochondrial Myopathy

(Kearns-Sayre Syndrome; Leigh’s Syndrome; Mitochondrial DNA Depletion Syndrome; Mitochondrial Encephalomyopathy, Lactic Acidosis and Strokelike Episodes; Myoclonic Epilepsy Associated With Ragged Red Fibers; Mitochondrial Neurogastrointestinal Encephalopathy; Neuropathy, Ataxia, and Retinitis Pigmentosa; Pearson’s Syndrome; Progressive External Ophthalmoplegia)

Pronounced: My–toe-con-dree-al My-op-a-thee

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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Causes    TOP

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

Risk Factors    TOP

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

Symptoms    TOP

Mitochondrial myopathies can cause a range of symptoms, but usually include muscle fatigue, weakness, and exercise intolerance. Symptoms by specific condition include:

NAME OF CONDITION AGE OF ONSET DEFINING SYMPTOMS
Kearns-Sayre syndrome (KSS)Before age 20Salt and pepper pigmentation in eye, eye movement problems, heart and skeletal muscle dysfunction
Barth syndromeInfancyCardiomyopathy, general muscle weakness, and a low white blood cell count
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)Adolescence or adulthoodEye movement difficulty, and often symptoms of other mitochondrial diseases, but can be an independent syndrome

Other general symptoms include:

Diagnosis    TOP

You will be asked 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—to evaluate the cerebrospinal fluid that protects the brain and spinal cord

Your heart's electrical activity may be tested. This can be done with an electrocardiogram (EKG).

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

Treatment    TOP

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

Dietary Supplements

Supplements may help make energy in the cells. These may include:

Physical Therapy

Therapy may be used to strengthen muscles and improve mobility. Some may need devices like braces, walkers, or wheelchairs to help get around.

Speech Therapy    TOP

Muscle weakness in the throat may make talking or swallowing difficult. Speech therapy may help strengthen the muscles or work around the weakness.

Respiratory Therapy    TOP

Respiratory therapy will help make sure breathing is normal. It may involve some training techniques for respiratory muscles. It can include pressurized air treatment or the use of a ventilator.

Medications    TOP

Medications may be needed for symptoms such as irregular heartbeat, seizures or pain.

Prevention    TOP

There are no current guidelines to prevent mitochondrial myopathies. If you have a family history of the disorder, you can talk to a genetic counselor when deciding whether to have children.

RESOURCES:

Muscular Dystrophy Association
http://www.mda.org
National Institute of Neurological Disorders and Stroke
http://www.ninds.nih.gov

CANADIAN RESOURCES:

Canadian Institutes of Health Research
http://www.cihr-irsc.gc.ca
Muscle Dystrophy Canada
http://www.muscle.ca

References:

DiMauro S. Pathogenesis and treatment of mitochondrial myopathies: recent advances. Acta Myol. 2010;29(2):333-338.
Mitochondrial myopathies. Muscular Dystrophy Association website. Available at: https://www.mda.org/disease/mitochondrial-myopathies. Accessed September 18, 2017.
Mitochondrial Myopathy. National Organization of Rare Disorders website. Available at: https://rarediseases.org/physician-guide/mitochondrial-myopathy/. Published 2008. Accessed August 24, 2017.
Mitochondrial Myopathy Fact Sheet. National Institute of Neurological Disorders and Stroke website. Available at:
...(Click grey area to select URL)
Accessed September 18, 2017.
Mitochondrial Myopathy. Online Mendelian Inheritance in Man website. Available at: https://www.omim.org/entry/251900?search=Mitochondrial%20Myopathy&highlight=myopathic%20mitochondrial%20myopathy. Updated May 11, 2010. Accessed August 24, 2017.
Last reviewed September 2017 by EBSCO Medical Review Board Michael Woods, MD, FAAP
Last Updated: 8/24/2017

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