The following information may help to address your question:
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
, 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
In over 80% of cases, MERRF is caused by mutations in the mitochondrial gene
. 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
are often used with the hope of improving mitochondrial function.
Last updated: 3/16/2016
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: 5/17/2016
What are the symptoms of myoclonic epilepsy association with ragged red fibers (MERRF)?
Because muscle cells and nerve cells have especially high energy needs, muscular and neurological problems are common features of diseases that affect the mitochondria. MERRF is a progressive multi-system syndrome with symptoms that begin during childhood, but onset may occur in adulthood. The rate of progression varies widely. Onset and extent of symptoms can differ widely from individual to individual and among affected siblings.
The classic features of MERRF include:
- Myoclonus (brief, sudden, twitching muscle spasms) – the most characteristic symptom
- Epileptic seizures
- Ataxia (impaired coordination)
- Ragged-red fibers (a characteristic microscopic abnormality observed in muscle biopsy of patients with MERRF and other mitochondrial disorders)
Additional symptoms may include: hearing loss, lactic acidosis (elevated lactic acid level in the blood), short stature, exercise intolerance, dementia, cardiac defects, eye abnormalities, and speech impairment.
Last updated: 5/17/2016
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
have been of some benefit to individuals. Other supplements that might be utilized include creatinine and lipoic acid.
Last updated: 6/23/2016
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
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
, 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: 5/16/2016
How can I find a genetics professional in my area?
Last updated: 7/15/2016
Where can I find treatment information to share with my doctor?
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: 6/23/2016
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