Mitochondrial myopathy
Pronunciation: my-toe-CON-dree-al my-AH-pa-thee
Muscle disorders caused by defects in mitochondrial function, characterized by exercise intolerance, weakness, and often multisystem involvement including neurological features.
Full Definition
Mitochondrial myopathy encompasses a group of disorders caused by defects in mitochondrial DNA or nuclear genes affecting mitochondrial function, resulting in impaired cellular energy production. These conditions typically present with exercise intolerance, proximal muscle weakness, and fatigue, often accompanied by multisystem features such as neurological deficits, cardiomyopathy, diabetes, or hearing loss. Diagnostic hallmarks include ragged red fibers on muscle biopsy (indicating abnormal mitochondrial proliferation), elevated lactate levels, and characteristic findings on genetic testing. Common syndromes include MELAS (mitochondrial encephalomyopathy with lactic acidosis and stroke-like episodes) and MERRF (myoclonic epilepsy with ragged red fibers). Treatment is largely supportive, focusing on symptom management and avoiding mitochondrial toxins.
Usage
Usage note: Document systemic features as these conditions are multisystem. Consider family history pattern (maternal inheritance for mtDNA mutations).
In Context
- "Muscle biopsy revealed ragged red fibers and cytochrome c oxidase-negative fibers, confirming mitochondrial myopathy." — Pathology report
- "The patient's combination of exercise intolerance, diabetes, and sensorineural hearing loss raised suspicion for mitochondrial myopathy." — Metabolic neurology consultation