Mitochondrial diseases: a review

Mitochondria are organelles responsible for production of mostenergy through oxidative phosphorylation process (OXPHOS). Itcontains a double strand DNA (mitDNA) of about 16,500 bp encodingtwo ribosomal RNAs and 37 mitochondrial proteins. Mutation inmitDNA may result in multisystem syndromes known asmitochondrial diseases, affecting predominantly tissues thatrequire high levels of ATP such as skeletal muscle (mitochondrialmyopathies), brain (e.g. MELAS, MERRF, LHON e NARP), liver,kidney (Fanconi syndrome), heart and endocrine glands (Pearsonsyndrome). A case of mitochondrial disease was first reported in1962 and correlation of such disease with mutations in mitDNAgained scientific importance in late 1980’s. There are 150 alterationsreported in mitDNA capable of producing metabolic dysfunctionsof clinical relevance. To date, no standard protocol for diagnosis ofmitochondrial diseases has been established, partially due to thewide amplitude of clinical manifestation generally observed. Acombined analysis of clinical data, biochemical, morphologicaland laboratory tests must be performed to evaluate mitochondrialrespiratory chain activity and integrity of nuclear and mitochondrialgenomes. Currently, there are no effective treatments availablefor mitochondrial diseases, but only palliative therapeutics usingconventional strategies to relieve symptoms. Thus, gene therapyemerges as potential therapeutic strategy for more efficienttreatment of mitochondrial diseases