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)

How to Say It: My–toe-con-dree-al My-op-a-thee

by Cynthia M. Johnson, MA

Definition

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

Mitochondrial myopathies decrease the ability of nerves and muscles. Weakness and uncoordinated movement may result.

Causes

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.

Symptoms

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

NAME OF DISEASE	WHEN IT STARTS	SYMPTOMS
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

Diagnosis

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:

Blood tests
Muscle biopsy
Lumbar puncture to test the fluid that protects the brain and spinal cord

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).

Treatment

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

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.

Medications

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

Prevention

There are no current guidelines to prevent this health problem.

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:

Mitochondrial myopathies (MM). Muscular Dystrophy Association website. Available at: https://www.mda.org/disease/mitochondrial-myopathies. Accessed August 19, 2021.

Mitochondrial myopathies information page. National Institute of Neurological Disorders and Stroke website. Available at: https://www.ninds.nih.gov/Disorders/All-Disorders/Mitochondrial-Myopathy-Information-Page. Accessed August 19, 2021.

Mitochondrial myopathy. National Organization of Rare Disorders website. Available at: https://rarediseases.org/physician-guide/mitochondrial-myopathy. Accessed August 19, 2021.

Overview of metabolic myopathies. EBSCO DynaMed website. Available at: https://www.dynamed.com/condition/overview-of-metabolic-myopathies. Accessed August 19, 2021.

Last reviewed July 2021 by EBSCO Medical Review Board James Cornell, MD
Last Updated: 8/19/2021