Mitochondrial myopathies

**Definition:** Mitochondrial myopathies are heterogeneous group of disorders caused by dysfunction of mitochondrial oxidative phosphorylation and can be classified according to the associated biochemical, genetic defects (in the mitochondrial DNA or in nuclear encoded proteins) or clinical phenotype. Exclude: defects of mitochondrial respiratory chain, Kearns-Sayre syndrome, myoclonic epilepsy with ragged red fibres (MERRF)