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Example of "ragged red fibers" in MELAS syndrome.
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 Europe, and has varying degrees of expressivity owing to heteroplasmy.
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
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:
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 Edit
- ↑ Gene Reviews- MERRF
- ↑ OMIM 545000
- ↑ Zeviani M, Muntoni F, Savarese N, et al. (1993). A MERRF/MELAS overlap syndrome associated with a new point mutation in the mitochondrial DNA tRNA(Lys) gene. Eur. J. Hum. Genet. 1 (1): 80–7.
- ↑ Melone MA, Tessa A, Petrini S, et al. (February 2004). Revelation of a new mitochondrial DNA mutation (G12147A) in a MELAS/MERFF phenotype. Arch. Neurol. 61 (2): 269–72.
- ↑ Nakamura M, Nakano S, Goto Y, et al. (September 1995). A novel point mutation in the mitochondrial tRNA(Ser(UCN)) gene detected in a family with MERRF/MELAS overlap syndrome. Biochem. Biophys. Res. Commun. 214 (1): 86–93.
- ↑ Mancuso M, Filosto M, Mootha VK, et al. (June 2004). A novel mitochondrial tRNAPhe mutation causes MERRF syndrome. Neurology 62 (11): 2119–21.
- ↑ Gene reviews - MERRF. Management of patients
Seizures and epilepsy (G40–G41, 345)
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