MERRF syndrome

MERRF syndrome
Example of "ragged red fibers" in MELAS syndrome.
Classification and external resources
Specialty
ICD-10	G31.8
ICD-9-CM	277.87
OMIM	545000
DiseasesDB	30794
Patient UK	MERRF syndrome
MeSH	D017243
GeneReviews	MERRF

MERRF syndrome (or Myoclonic Epilepsy with Ragged Red Fibers) is a mitochondrial disease. It is extremely rare, with an estimated prevalence of 1/400,000 in Northern Europe, and has varying degrees of expressivity owing to heteroplasmy.

Presentation

It involves the following characteristics:

• progressive myoclonic epilepsy
• "Ragged Red Fibers" - clumps of diseased mitochondria accumulate in the subsarcolemmal region of the muscle fiber and appear as "Ragged Red Fibers" when muscle is stained with modified Gömöri trichrome stain
• short stature
• hearing loss
• lactic acidosis
• exercise intolerance
• poor night vision

Causes

The MERRF syndrome is caused by a maternally-inherited mutation at position 8344 in the mitochondrial genome in over 80% of cases. This point mutation disrupts the mitochondrial gene for tRNA-Lys and so disrupts synthesis of proteins essential for oxidative phosphorylation.

Many genes are involved. These include:

• MT-TK
• MT-TL1
• MT-TH
• MT-TS1
• MT-TS2
• MT-TF

Treatment

Like many mitochondrial diseases, there is no cure for MERRF and treatment is primarily symptomatic. High doses of Coenzyme Q10 and L-Carnitine have been tried with little success as therapies in hopes of improving mitochondrial function.

See also

• Epilepsy
• Myoclonus

External links

• MERRF Syndrome at the US National Library of Medicine Medical Subject Headings (MeSH)
• -214630359 at GPnotebook
• merrf at NIH/UW GeneTests