Mitochondrial Disease

*Mitochondiral myopathies facts medical author: Charles Patrick Davis, MD, PhD

• Mitochondrial disease includes a group of neuromuscular diseases caused by damage to intracellular structures that produce energy, the mitochondria; disease symptoms usually involve muscle contractions that are weak or spontaneous.
• There is no specific treatment for mitochondrial diseases (myopathies).
• The prognosis varies according to the disease type; in general, these diseases are progressive and can cause death.
• Research into treatments and other disease aspects is ongoing; there are several organizations devoted to understanding and treating these relatively rare disorders.

Mitochondrial myopathies are a group of neuromuscular diseases caused by damage to the mitochondria—small, energy-producing structures that serve as the cells' "power plants." Nerve cells in the brain and muscles require a great deal of energy, and thus appear to be particularly damaged when mitochondrial dysfunction occurs. Some of the more common mitochondrial myopathies include Kearns-Sayre syndrome, myoclonus epilepsy with ragged-red fibers, and mitochondrial encephalomyopathy with lactic acidosis and stroke-like episodes.

The symptoms of mitochondrial myopathies include muscle weakness or exercise intolerance, heart failure or rhythm disturbances, dementia, movement disorders, stroke-like episodes, deafness, blindness, droopy eyelids, limited mobility of the eyes, vomiting, and seizures. The prognosis for these disorders ranges in severity from progressive weakness to death. Most mitochondrial myopathies occur before the age of 20, and often begin with exercise intolerance or muscle weakness. During physical activity, muscles may become easily fatigued or weak. Muscle cramping is rare, but may occur. Nausea, headache, and breathlessness are also associated with these disorders.

Although there is no specific treatment for any of the mitochondrial myopathies, physical therapy may extend the range of movement of muscles and improve dexterity. Vitamin therapies such as riboflavin, coenzyme Q, and carnitine (a specialized amino acid) may provide subjective improvement in fatigue and energy levels in some patients.

The prognosis for patients with mitochondrial myopathies varies greatly, depending largely on the type of disease and the degree of involvement of various organs. These disorders cause progressive weakness and can lead to death.

The NINDS conducts and supports research on mitochondrial myopathies. The goals of this research are to increase scientific understanding of these disorders and to find ways to effectively treat, prevent, or potentially cure them.

Muscular Dystrophy Association
3300 East Sunrise Drive
Tucson, AZ 85718-3208
mda@mdausa.org
http://www.mda.org
Tel: 520-529-2000
800-572-1717
Fax: 520-529-5300

United Mitochondrial Disease Foundation
8085 Saltsburg Road Suite 201
Pittsburgh, PA 15239
info@umdf.org
http://www.umdf.org
Tel: 412-793-8077
888-317-UMDF (8633)
Fax: 412-793-6477

National Organization for Rare Disorders (NORD)
55 Kenosia Avenue
Danbury, CT 06810
orphan@rarediseases.org
http://www.rarediseases.org
Tel: 203-744-0100
Voice Mail 800-999-NORD (6673)
Fax: 203-798-2291

MitoAction
P.O. Box 51474
Boston, MA 02205
info@mitoaction.org
http://www.mitoaction.org
Tel: 888-648-6228