FIGURE 1: Mitochondrial dysfunctions are related to mutations in mtDNA and defects in nuclear encoded mitochondrial proteins. (I) Overview of mutations within the mtDNA. (II) The majority of mitochondrial defects based on a malfuntion of OXPHOS complexes and mitochondrial translation. (III) Defects in other processes, like mitochondrial fusion and fission or lipid homeostasis, leads to different mitochondrial diseaes. (IV) Different strategies to figth the diverse forms of mitochondrial stress. (a: Leigh Syndrome LS; b: Leber Hereditary Optic Neuropathy LHON; c: Neurogenic Muscle Weakness, Ataxia and Retinitis Pigmentosa NARP; d: Mitochondrial Encephalomyopathy, Lactid Acidosis and Stroke-like Episodes MELAS; e: Myoclonic Epilepsy and Ragged Red Fiber Disease MERRF; f: Sensorineural Hearing Loss SNHL; g: mitochondrial non-syndromic Hearing Loss; D: Kearns Sayre Syndrome KSS).