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 is maternal (non-Mendelian extranuclear). There are several subcategories of mitochondrial myopathies.