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|Simplified structure of a typical mitochondrion|
Mitochondrial myopathies are types of myopathies associated with mitochondrial disease. On biopsy, the muscle tissue of patients with these diseases usually demonstrate "ragged red" muscle fibers. These ragged-red fibers contain mild accumulations of glycogen and neutral lipids, and may show an increased reactivity for succinate dehydrogenase and a decreased reactivity for cytochrome c oxidase. Inheritance was believed to be maternal (non-Mendelian extranuclear). It is now known that certain nuclear DNA deletions can also cause mitochondrial myopathy such as the OPA1 gene deletion. There are several subcategories of mitochondrial myopathies.
Signs and symptoms
Signs and symptoms include (for each of the following causes):
- Mitochondrial encephalomyopathy, lactic acidosis, and stroke-like syndrome (MELAS)
- Myoclonic epilepsy and ragged-red fibers (MERRF)
- Progressive myoclonic epilepsy
- Clumps of diseased mitochondria accumulate in muscle fibers and appear as "ragged-red fibers" when muscle is stained with modified Gömöri trichrome stain
- Short stature
- Kearns–Sayre syndrome (KSS)
- Chronic progressive external ophthalmoplegia (CPEO)
- Progressive ophthalmoparesis
- Symptomatic overlap with other mitochondrial myopathies
Zidovudine, an HIV medication can cause red ragged fiber myopathy.
Muscle biopsy: ragged red fibers in Gömöri trichrome stain.
- "Mitochondrial Myopathy Information Page | National Institute of Neurological Disorders and Stroke". www.ninds.nih.gov. Retrieved 2017-02-28.
- "Three-parent embryo formed in lab" (web). Scientists believe they have made a potential breakthrough in the treatment of serious disease by creating a human embryo with three separate parents. BBC News. 5 February 2008. Retrieved 2008-02-08.