Myoclonic epilepsy with ragged red fibers

What causes myoclonic epilepsy with ragged red fibers?

Myoclonic epilepsy with ragged red fibers (MERRF) is caused by mutations in the mitochondrial DNA. Mitochondria are structures present in every cell in our body that produce usable energy from food. Although most of our DNA is located within the nucleus of our cells, mitochondria have a small amount of their own DNA known as mitochondrial or mtDNA. MtDNA contains 37 genes.

Mutations in the MT- TK gene are the most common cause of MERRF. Other genes that might be involved include but are not limited to: MT-TL1, MT- TH , and MT- TS1. Mutations within these genes reduce the ability of the mitochondria to maintain its normal function including building proteins, using oxygen, and producing energy. Organs and tissues with high energy requirements, such as the brain and muscles, are most impacted by these mutations.

Last updated on 05-01-20

How is myoclonic epilepsy with ragged red fibers inherited?

Myoclonic epilepsy with ragged red fibers (MERRF) has mitochondrial or maternal inheritance. It is called maternal inheritance because mitochondrial DNA are inherited from maternally inherited egg cells, but not from paternally inherited sperm cells. If a mother has a mutation in her mitochondrial DNA, all of her children will inherit the mutation and may or may not have symptoms. All of her daughter's children will also inherit the mitochondrial mutation. Her son's children are not at risk of inheriting the mutation.

The mother of an individual with MERRF usually has a mitochondrial mutation and may or may not have apparent symptoms. Rarely, an individual with MERRF may have a mitochondrial mutation that just occurred in them, called a de novo mitochondrial DNA mutation.

Last updated on 05-01-20

What is Myoclonic Epilepsy with Ragged Red Fibers (MERRF)?

Myoclonic epilepsy with ragged red fibers (MERRF) is a multisystem disorder characterized by myoclonus, which is often the first symptom, followed by generalized epilepsy, ataxia, weakness, and dementia. Symptoms usually first appear in childhood or adolescence after normal early development. The features of MERRF vary widely from individual to individual, even within families. Other common findings include hearing loss, short stature, optic atrophy, and cardiomyopathy with Wolff-Parkinson-White (WPW) syndrome. The diagnosis is based on clinical features and a muscle biopsy finding of ragged red fibers (RRF). In over 80% of cases, MERRF is caused by mutations in the mitochondrial gene called MT- TK. Several other mitochondrial genes have also been reported to cause MERRF, but many of the individuals with mutations in these other genes have additional signs and symptoms. Seizures associated with MERRF are generally treated with conventional anticonvulsant therapy. Coenzyme Q10 and L-carnitine are often used with the hope of improving mitochondrial function.

Last updated on 05-01-20

What are mitochondria?

The mitochondria are thought of as the power plant of every cell in our body (except red blood cells). They are rod-shaped or spherical structures located in our cells, and their job is to produce energy for the cell. The mitochondria have their own DNA, called mitochondrial DNA. This DNA is separate from the main DNA found in the nucleus of the cell.

If the mitochondria are not working well, less and less energy is generated within the cell. Cell injury and even cell death can follow. If this process is repeated throughout the body, whole systems begin to fail, and the life of the person in whom this is happening is severely compromised. The onset of mitochondrial diseases is usually during childhood, but symptoms can develop in adulthood. Diseases of the mitochondria appear to cause the most damage to cells of the brain, heart, liver, skeletal muscles, kidney and the endocrine and respiratory systems. Depending on which cells are affected, symptoms may include loss of motor control, muscle weakness and pain, gastro-intestinal disorders and swallowing difficulties, poor growth, cardiac disease, liver disease, diabetes, respiratory complications, seizures, visual/hearing problems, lactic acidosis, developmental delays and susceptibility to infection.

Last updated on 05-01-20

Where can I find treatment information to share with my doctor?

GeneReviews provides current, expert-authored, peer-reviewed, full-text articles describing the application of genetic testing to the diagnosis, management, and genetic counseling of patients with specific inherited conditions.

Last updated on 05-01-20

How might myoclonic epilepsy with ragged red fibers (MERRF) be treated?

While there is no cure for MERRF, there are various medications and therapies that can be helpful in managing symptoms. This includes: Antiseizure medications, levetiracetam for myoclonus, physical therapy, and aerobic exercise. Standard medication is used to treat cardiac symptoms.

Daily use of Coenzyme Q10 and L-carnitine have been of some benefit to individuals. Other supplements that might be utilized include creatinine and lipoic acid.

Last updated on 05-01-20

Name: United Mitochondrial Disease Foundation 8085 Saltsburg Road, Suite 201
Pittsburgh, PA, 15239 , United States
Phone: +1-412-793-8077 Toll Free: 1-888-317-8633 Fax : +1-412-793-6477 Email: Url:
Name: The Mitochondria Research and Medicine Society PO Box 55322
Birmingham, AL,
Phone: 716-907-4349 Fax : 716-845-1047 Email: Url:
Name: MitoAction PO Box 51474
Boston, MA, 02205, United States
Phone: 1-888-MITO-411 (648-6411) for support line Toll Free: 1-888-648-6228 Email: Url:
Name: Muscular Dystrophy Association MDA 222 S Riverside Plaza Suite 1500
Chicago, IL, 60606, United States
Toll Free: 1-833-275-6321 (Helpline) Email: Url:

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