Mitochondrial myopathy

Simplified structure of a typical mitochondrion

Mitochondrial myopathies are types of myopathies associated with mitochondrial disease.[1] 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.

## Contents

* 1 Signs and symptoms
* 2 Cause
* 3 Diagnosis
* 4 Treatment
* 5 See also
* 6 References
* 7 External links

## Signs and symptoms[edit | edit source]

Mitochondrial disease symptoms (and skeletal muscle biopsies)[2]

Signs and symptoms include (for each of the following causes):

* Mitochondrial encephalomyopathy, lactic acidosis, and stroke-like syndrome (MELAS)
* Varying degrees of cognitive impairment and dementia
* Lactic acidosis
* Strokes
* Transient ischemic attacks
* Hearing loss
* Weight loss
* 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)
* External ophthalmoplegia
* Cardiac conduction defects
* Sensorineural hearing loss
* Chronic progressive external ophthalmoplegia (CPEO)
* Progressive ophthalmoparesis
* Symptomatic overlap with other mitochondrial myopathies

## Cause[edit | edit source]

Mitochondrial myopathy literally means mitochondrial muscle weakness, muscle weakness caused by mitochondrial dysfunction. The mitochondrion is the powerhouse of the cell. Every muscle cell has mitochondria, and if the muscle cell’s mitochondria have problems by which there is not enough energy to function or perform its duties, problems occur. The cause may be genetic, such as a variation within the POLG (polymerase gamma) gene, which causes mitochondrial DNA (mtDNA) to become damaged and lose function.

## Diagnosis[edit | edit source]

Muscle biopsy: ragged red fibers in Gömöri trichrome stain.

* a-d)Abnormalities on skeletal muscle biopsy in mitochondrial myopathy

* Very high magnification micrograph showing ragged red fibres in a mitochondrial myopathy. Gömöi trichrome stain.

## Treatment[edit | edit source]

Although no cure currently exists, there is hope in treatment for this class of hereditary diseases with the use of an embryonic mitochondrial transplant.[3]

## See also[edit | edit source]

* Metabolic Myopathies

## References[edit | edit source]

1. ↑ "Mitochondrial Myopathy Information Page | National Institute of Neurological Disorders and Stroke". www.ninds.nih.gov. Archived from the original on 2017-02-28. Retrieved 2017-02-28.
2. ↑ Ahmed, Syeda T.; Craven, Lyndsey; Russell, Oliver M.; Turnbull, Doug M.; Vincent, Amy E. (1 October 2018). "Diagnosis and Treatment of Mitochondrial Myopathies". Neurotherapeutics. 15 (4): 943–953. doi:10.1007/s13311-018-00674-4. ISSN 1878-7479.
3. ↑ "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. Archived from the original on 2021-04-04. Retrieved 2008-02-08.

## External links[edit | edit source]

Classification|

* ICD-10: G71.3
* MeSH: D017240

|

External resources|

* Orphanet: 206966

* v
* t
* e

Diseases of muscle, neuromuscular junction, and neuromuscular disease

Neuromuscular-
junction disease|

* autoimmune
* Myasthenia gravis
* Lambert–Eaton myasthenic syndrome
* Neuromyotonia

Myopathy|

| Muscular dystrophy
(DAPC)|

| AD|

* Limb-girdle muscular dystrophy 1
* Oculopharyngeal
* Facioscapulohumeral
* Myotonic
* Distal (most)

|

AR|

* Calpainopathy
* Limb-girdle muscular dystrophy 2
* Congenital
* Fukuyama
* Ullrich
* Walker–Warburg

XR|

* dystrophin
* Becker's
* Duchenne
* Emery–Dreifuss

Other structural|

* collagen disease
* Bethlem myopathy
* PTP disease
* X-linked MTM
* adaptor protein disease
* BIN1-linked centronuclear myopathy
* cytoskeleton disease
* Nemaline myopathy
* Zaspopathy

Channelopathy|

| Myotonia|

* Myotonia congenita
* Thomsen disease
* Neuromyotonia/Isaacs syndrome
* Paramyotonia congenita

|

Periodic paralysis|

* Hypokalemic
* Thyrotoxic
* Hyperkalemic

Other|

* Central core disease

Mitochondrial myopathy|

* MELAS
* MERRF
* KSS
* PEO

General|

* Inflammatory myopathy
* Congenital myopathy

* v
* t
* e

Mitochondrial diseases

Carbohydrate metabolism|

* PCD
* PDHA

Primarily nervous system|

* Leigh disease
* LHON
* NARP

Myopathies|

* KSS
* Mitochondrial encephalomyopathy
* MELAS
* MERRF
* PEO

No primary system|

* DAD
* MNGIE
* Pearson syndrome

Chromosomal|

* OPA1
* Kjer's optic neuropathy
* SARS2
* HUPRA syndrome
* TIMM8A
* Mohr–Tranebjærg syndrome

see also mitochondrial proteins

* v
* t
* e

Disorders of citric acid cycle and electron transport chain

Citric acid cycle|

* Pyruvate dehydrogenase deficiency
* Fumarase deficiency

Electron transport chain|

* Coenzyme Q10 deficiency
* Björnstad syndrome
* GRACILE syndrome
* Leigh disease

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