Mitochondria are tiny structures in all cells. They provide energy. Mitochondrial myopathies are a group of diseases that affect them. The diseases affect the nerves and muscles, among other systems. The severity of these diseases can vary greatly. Some produce mild symptoms and others have life-threatening conditions. Mitochondrial myopathies include:

Kearns-Sayre Syndrome (KSS)Before age 20Salt and pepper pigmentation in eye, eye movement problems (PEO), heart and skeletal muscle dysfunction
Leigh’s SyndromeInfancyBrain 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 Strokelike Episodes (MELAS)Childhood to adulthoodStrokelike 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

If you suspect you have this condition, contact your doctor.

Muscular and Nervous Systems

Torso muscle and nerves
Mitochondrial myopathies decreases the abilities of nerves and muscles. This causes symptoms like weakness and uncoordinated movement.
© 2009 Nucleus Medical Art, Inc.


This condition is caused by mutation in the genes.

Risk Factors

Having a family member with the gene.


Mitochondrial myopathies can cause a range of symptoms. Some people experience very few symptoms. Others may experience the full range. If you have any of these symptoms, do not assume it is due to this condition, as these symptoms may be caused by a number of conditions.

Tell your doctor if you have any of these:

  • Muscle weakness
  • Exercise intolerance
  • Loss of hearing
  • Seizures
  • Lack of balance or coordination
  • Progressive weakness
  • Inability to move eyes
  • Heart failure
  • Learning deficits
  • Fatigue
  • Blindness
  • Strokelike episodes
  • Droopy eyelids
  • Vomiting
  • Breathlessness
  • Headache
  • Nausea
  • Dementia
  • Diabetes
  • Muscle wasting


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.

Tests may include the following:

  • Muscle biopsy—test that involves removing a small piece of muscle to look for abnormal levels of mitochondria or the presence of certain proteins and enzymes
  • Blood test—a blood test that looks for abnormal levels of certain enzymes and other substances
  • Genetic test—a blood test or muscle biopsy that tests for the presence of genetic mutations


Talk with your doctor about the best plan for you. There is no specific treatment for these diseases. Symptoms can be treated. 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 people may need devices like braces, walkers , or wheelchairs .

Speech Therapy

Muscle weakness in the throat may require speech therapy.

Respiratory Therapy

In some cases, this therapy may be needed. It can include pressurized air treatment or the use of a ventilator.


Medications are used to treat specific symptoms such as:

  • Seizures
  • Pain
  • Diabetes


There are no known guidelines to prevent this condition.