(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)
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
|Mitochondrial myopathies decrease the ability of nerves and muscles. Weakness and uncoordinated movement may result.
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This condition is caused by a mutation in a specific gene.
Having a family member with the mutated gene increases the risk of mitochondrial myopathies.
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
|Kearns-Sayre syndrome (KSS)
||Before age 20
||Salt and pepper pigmentation in eye, eye movement problems, heart and skeletal muscle dysfunction
||Cardiomyopathy, general muscle weakness, and a low white blood cell count
||Infancy—can appear later
||Brain 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 syndrome
||Muscle weakness and liver failure, floppiness, feeding difficulties, and developmental delay
|Mitochondrial encephalomyopathy, lactic acidosis and stroke-like episodes (MELAS)
||Childhood to adulthood
||Stroke-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 adulthood
||Myoclonus (jerky movements), seizures, muscle weakness, uncoordinated muscle movement (ataxia)
|Mitochondrial neurogastrointestinal encephalomyopathy (MNGIE)
||Before age 20
||Eye movement problems (PEO), drooping eyelid, limb weakness, digestive problems, peripheral neuropathy
|Neuropathy, ataxia, and retinitis pigmentosa (NARP)
||Early childhood to adulthood
||Uncoordinated muscle movement (ataxia), degeneration of the retina in the eye leading to loss of vision
||Causes severe anemia and pancreas problems, survivors usually develop KSS
|Progressive external ophthalmoplegia (PEO)
||Adolescence or adulthood
||Eye movement difficulty, and often symptoms of other mitochondrial diseases, but can be an independent syndrome
Other general symptoms include:
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:
- Blood tests
—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
Your nerve function may be tested. This can be done with
There is no specific treatment for these diseases. Instead, treatment will focus on managing the symptoms. Treatment options include the following:
Supplements may help make energy in the cells. These may include:
Therapy may be used to strengthen muscles and improve mobility. Some may need devices like braces,
to help get around.
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 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 may be needed for symptoms such as irregular heartbeat, seizures or pain.
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.
Muscular Dystrophy Association
National Institute of Neurological Disorders and Stroke
Canadian Institutes of Health Research
Muscle Dystrophy Canada
DiMauro S. Pathogenesis and treatment of mitochondrial myopathies: recent advances.
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:
http://www.ninds.nih.gov/disorders/mitochondrial%5Fmyopathy/mitochondrial%5Fmyopathy.htm. 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.