MERRF Syndrome

National Organization for Rare Disorders, Inc.

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 syndrome (Myoclonus Epilepsy Associated with Ragged-Red Fibers) is one of a group of rare muscular disorders that are called mitochondrial encephalomyopathies. Mitochondrial encephalomyopathies are disorders in which a defect in the genetic material arises from a part of the cell structure that releases energy (mitochondria). This can cause a dysfunction of the brain and muscles (encephalomyopathies). The mitochondrial defect as well as "ragged-red fibers" (an abnormality of tissue when viewed under a microscope) are always present. The most characteristic symptom of MERRF syndrome is myoclonic seizures that are usually sudden, brief, jerking, spasms that can affect the limbs or the entire body. Impairment of the ability to coordinate movements (ataxia), as well as an abnormal accumulation of lactic acid in the blood (lactic acidosis) may also be present in affected individuals. Difficulty speaking (dysarthria), optic atrophy, short stature, hearing loss, dementia, and involuntary jerking of the eyes (nystagmus) may also occur.


CLIMB (Children Living with Inherited Metabolic Diseases)
Climb Building
176 Nantwich Road
Crewe, Intl CW2 6BG
United Kingdom
Tel: +44 870 7700 325
Fax: +44 870 7700 327

United Mitochondrial Disease Foundation (UMDF)
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
Tel: (301)459-3700
Fax: (301)577-2684
Tel: (800)332-1000
TDD: (800)332-2070

Muscular Dystrophy Association
3300 E. Sunrise Dr
Tucson, AZ 85718
Tel: (520)529-2000
Fax: (520)529-5300
Tel: (800)572-1717

Johns, Donald R., M.D.
Johns Hopkins Hospital
600 North Wolfe Street
Baltimore, MD 21205

National Institute of Neurological Disorders and Stroke (NINDS)
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
Zwolle, 8000 AR
The Netherlands
Tel: 31384661497
Fax: 31384661497

Children's European Mitochondrial Disease Network
Mayfield House
30 Heber Walk
Chester Way
Northwich, Intl CW9 5JB
United Kingdom
Tel: 44 0 1606 43946
Fax: 44 0 1606 43946

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

For a Complete Report

For a Complete Report

This is an abstract of a report from the National Organization for Rare Disorders, Inc. ® (NORD). A copy of the complete report can be obtained for a small fee by visiting the NORD website. The complete report contains additional information including symptoms, causes, affected population, related disorders, standard and investigational treatments (if available), and references from medical literature. For a full-text version of this topic, see

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