(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)
Definition
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 SystemsMitochondrial myopathies decrease the ability of nerves and muscles. Weakness and uncoordinated movement may result.
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Causes
Causes
This condition is caused by a mutation in a specific gene.
Risk Factors
Risk Factors
Having a family member with the mutated gene increases the risk of mitochondrial myopathies.
Symptoms
Symptoms
Mitochondrial myopathies can cause a range of symptoms. Symptoms by specific condition include:
| NAME OF CONDITION | AGE OF ONSET | DEFINING SYMPTOMS |
| Kearns-Sayre syndrome (KSS) | Before age 20 | Salt and pepper pigmentation in eye, eye movement problems (PEO), heart and skeletal muscle dysfunction |
| Leigh’s syndrome | 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 | Infancy | 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 |
| Pearson’s syndrome | Infancy | Causes severe anemia and pancreas problems, survivors usually develop KSS |
| Progressive external ophthalmoplegia (PEO) | Adulthood | Eye 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
- Heart arryhthmias 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
Diagnosis
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—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
Treatment
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:
Your doctor will work with you on the proper doses of these supplements.
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
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
Respiratory therapy will help make sure you are breathing properly. It may involve some training techniques for respiratory muscles. It can include pressurized air treatment or the use of a ventilator.
Medications
Medications may be needed for symptoms such as seizures or pain.
Prevention
Prevention
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:
National Institute of Neurological Disorders and Stroke http://www.ninds.nih.gov
CANADIAN RESOURCES:
Muscle Dystrophy Canada http://www.muscle.ca
References:
Facts about mitochondrial myopathies. Muscular Dystrophy Association website. Available at:
http://www.mda.org/publications/mitochondrial_myopathies.html
Published December 2009. Accessed August 10, 2015.
Jacobs L, Wert GD, Geraedts JP, et al. The transmission of OXPHOS disease and methods to prevent this. Hum Reprod Update. 2006;12(2):119-136.
Mitochondrial myopathies. EBSCO DynaMed website. Available at:
http://www.ebscohost.com/dynamed
Updated December 2, 2013. Accessed August 20, 2014.
NINDS mitochondrial myopathy information page. National Institute of Neurological Disorders and Stroke website. Available at:
http://www.ninds.nih.gov/disorders/mitochondrial_myopathy/mitochondrial_myopathy.htm
Updated Jul 8, 2015. Accessed August 10, 2015.
Last Updated: 5/11/2013