Analysis of Mitochondrial DNA Mutations

Human mitochondrial DNA (mtDNA) is a closed circular genome of 16,569 bp (1 ), encoding 13 subunits of four enzyme complexes (Complexes I, III, IV, and V) in the oxidative phosphorylation system (2 ). Mutations of mtDNA have been demonstrated to be associated with various neuromuscular diseases. Point mutations of mtDNA are reported in MELAS syndrome (mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes) (3 ,4 ), MERRF syndrome (myoclonus epilepsy associated with ragged-red fibers) (5 ,6 ), Leber’s disease (hereditary optic neuropathy) (7 ), a type of encephalomyopathy (8 ), and fatal infantile cardiomyopathy (9 ). Deletions of mtDNA are observed in Kearns-Sayre syndrome and chronic progres sive external ophthalmoplegia (CPEO) (10 ). It is also proposed that accumulation of mtDNA mutations is an important contributor to several degenerative diseases and the aging process (11 ). Evidence supporting this hypothesis has been presented in Parkinson’s disease (12 ,13 ), cardiomyopathy (14 ,15 ), and presbycardia (16 ). Therefore, the analysis of mtDNA mutations seem to be increasing their importance both in clinical neurology and in the basic neurological science.