by EBSCO Medical Review Board
(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 that affect the mitochondria. These are tiny structures found in almost all cells. It is their job to provide energy to these cells. These diseases can make it hard for the body to function as it should. The muscles and nerves are most affected.

Muscular and Nervous Systems
Torso muscle and nerves
Mitochondrial myopathies decrease the ability of nerves and muscles. Weakness and uncoordinated movement may result.
Copyright © Nucleus Medical Media, Inc.


This health problem is caused by a mutation in a specific gene.

Risk Factors

The risk of this problem is higher in people who have a family member with the mutated gene.


Muscle fatigue, pain, and weakness are the main symptoms. Other symptoms depend on which cells of the body are affected. Problems can be mild to severe and they vary from person to person.

Some common problems may be:

  • Lack of balance or coordination
  • Vision or hearing problems
  • Trouble controlling eye movement
  • Poor growth and slowed development in children
  • Vomiting
  • Problems with thinking
  • Difficulty learning in children
  • Irregular heartbeat
  • Seizures
Kearns-Sayre syndrome (KSS) Before age 20 Salt and pepper eye color, eye movement problems, and heart and skeletal muscle problems
Barth syndrome Infancy Heart muscle problems and frequent infections
Leigh’s syndrome Infancy—can appear later Changes with how the brain works, seizures, poor vision and hearing, developmental delay, and problems breathing
Mitochondrial DNA depletion syndrome Infancy Liver failure, muscle floppiness, feeding problems, 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, and short stature
Myoclonic epilepsy associated with ragged red fibers (MERRF) Late childhood to adulthood Jerky muscle movements, seizures, muscle weakness, and uncoordinated muscle movements
Mitochondrial neurogastrointestinal encephalomyopathy (MNGIE) Before age 20 Eye movement problems, drooping eyelid, limb weakness, and digestive problems
Neuropathy, ataxia, and retinitis pigmentosa (NARP) Early childhood to adulthood Uncoordinated muscle movement and vision problems
Pearson’s syndrome Infancy Anemia, problems with the pancreas, development of KSS
Progressive external ophthalmoplegia (PEO) Adolescence or adulthood Eye movement problems, and often symptoms of other mitochondrial diseases, but can be an independent syndrome


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

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

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

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


There is no cure. The goal is to manage symptoms. Options are:

Dietary Supplements

Supplements may help the cells make energy. These may be:


Therapy may be:

  • Physical therapy to strengthen muscles, improve movement, and learn how to use devices like braces, walkers, or wheelchairs.
  • Speech therapy to strengthen muscles needed to speak and swallow or to learn to work around any weaknesses.
  • Respiratory therapy to train the muscles needed for breathing. This can also include pressurized air treatment or the use of a ventilator.


Medicines may be needed to manage specific symptoms, such as irregular heartbeat, seizures, or pain.


There are no current guidelines to prevent this health problem.


Muscular Dystrophy Association 

National Institute of Neurological Disorders and Stroke 


Canadian Institutes of Health Research 

Muscle Dystrophy Canada 


Mitochondrial myopathies (MM). Muscular Dystrophy Association website. Available at: Accessed August 19, 2021.

Mitochondrial myopathies information page. National Institute of Neurological Disorders and Stroke website. Available at: Accessed August 19, 2021.

Mitochondrial myopathy. National Organization of Rare Disorders website. Available at: Accessed August 19, 2021.

Overview of metabolic myopathies. EBSCO DynaMed website. Available at: Accessed August 19, 2021.

Revision Information

  • Reviewer: EBSCO Medical Review Board James Cornell, MD
  • Review Date: 07/2021
  • Update Date: 08/19/2021