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Epilepsy Health Center

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MERRF Syndrome

It is possible that the main title of the report MERRF Syndrome is not the name you expected. Please check the synonyms listing to find the alternate name(s) and disorder subdivision(s) covered by this report.


  • Fukuhara syndrome
  • myoclonus epilepsy associated with ragged red fibers
  • myoencephalopathy ragged-red fiber disease

Disorder Subdivisions

  • None

General Discussion

MERRF (Myoclonus Epilepsy with Ragged-Red Fibers) syndrome is an extremely rare disorder that begins in childhood and affects the nervous system and skeletal muscle as well as other body systems. The distinguishing feature in MERRF is myoclonus, consisting of sudden, brief, jerking spasms that can affect the arms and legs or the entire body. In addition, individuals with MERRF syndrome may have muscle weakness (myopathy), an impaired ability to coordinate movements (ataxia), seizures, and a slow deterioration of intellectual function (dementia). Short stature, degeneration of the optic nerve (optic atrophy), hearing loss, cardiomyopathy and abnormal sensation from nerve damage (peripheral neuropathy) are also common symptoms. Abnormal muscle cells are present and appear as ragged red fibers (RRF) when stained with the modified Gomori trichrome and viewed microscopically. MERRF is caused by mutations in mitochondrial DNA (mtDNA).


CLIMB (Children Living with Inherited Metabolic Diseases)
Climb Building
176 Nantwich Road
Crewe, CW2 6BG
United Kingdom
Tel: 4408452412173
Fax: 4408452412174

United Mitochondrial Disease Foundation
8085 Saltsburg Road Suite 201
Pittsburgh, PA 15239
United States
Tel: (412)793-8077
Fax: (412)793-6477
Tel: (888)317-8633

Lactic Acidosis Support Trust
1A Whitley Close
Cheshire, CW10 0NQ
United Kingdom
Tel: 0160683719
Fax: 01606837198

Epilepsy Foundation
8301 Professional Place
Landover, MD 20785-7223
Tel: (866)330-2718
Fax: (877)687-4878
Tel: (800)332-1000
TDD: (800)332-2070

Muscular Dystrophy Association
3300 East Sunrise Drive
Tucson, AZ 85718-3208
Tel: (520)529-2000
Fax: (520)529-5300
Tel: (800)572-1717

NIH/National Institute of Neurological Disorders and Stroke
P.O. Box 5801
Bethesda, MD 20824
Tel: (301)496-5751
Fax: (301)402-2186
Tel: (800)352-9424
TDD: (301)468-5981

Mitochondrial Disease Support Group Online
5022 Michigan Avenue
West Palm Beach, FL 33415
Tel: (407)641-4712

Vereniging voor Kinder met Stofwisselingsziekten
P.O. Box 664
Bloemendalstraat 11
Zwolle, 8000 AR
The Netherlands
Tel: 0384201764
Fax: 0384201447

Children's Mitochondrial Disease Network
Mayfield House
30 Heber Walk
Chester Way
England, CW9 5JB
United Kingdom
Tel: 440160643946
Fax: 440160643946

Madisons Foundation
PO Box 241956
Los Angeles, CA 90024
Tel: (310)264-0826
Fax: (310)264-4766

14 Pembroke Street
Medford, MA 02155
Tel: (888)648-6228
Fax: (888)648-6228

For a Complete Report:

This is an abstract of a report from the National Organization for Rare Disorders (NORD). A copy of the complete report can be downloaded free from the NORD website for registered users. The complete report contains additional information including symptoms, causes, affected population, related disorders, standard and investigational therapies (if available), and references from medical literature. For a full-text version of this topic, go to and click on Rare Disease Database under "Rare Disease Information".

The information provided in this report is not intended for diagnostic purposes. It is provided for informational purposes only. NORD recommends that affected individuals seek the advice or counsel of their own personal physicians.

It is possible that the title of this topic is not the name you selected. Please check the Synonyms listing to find the alternate name(s) and Disorder Subdivision(s) covered by this report

This disease entry is based upon medical information available through the date at the end of the topic. Since NORD's resources are limited, it is not possible to keep every entry in the Rare Disease Database completely current and accurate. Please check with the agencies listed in the Resources section for the most current information about this disorder.

For additional information and assistance about rare disorders, please contact the National Organization for Rare Disorders at P.O. Box 1968, Danbury, CT 06813-1968; phone (203) 744-0100; web site or email

Last Updated: 9/30/2010
Copyright 1993, 1996, 1998, 1999, 2000, 2001, 2010 National Organization for Rare Disorders, Inc.

WebMD Medical Reference from the National Organization for Rare Disorders

Last Updated: May 28, 2015
This information is not intended to replace the advice of a doctor. Healthwise disclaims any liability for the decisions you make based on this information.

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