Significance of Mitochondria DNA Mutations in Diseases.

Mitochondria are essential double-membraned cytoplasmic organelles to support aerobic respiration and produce cellular energy by oxidative phosphorylation (OXPHOS). Mitochondrial functions are controlled by mitochondrial (mtDNA) and nuclear genomes (nDNA). Mutations of mtDNA result in mitochondrial dysfunction and multisystem diseases through compromising OXPHOS function directly by a point mutation or a large-scale mtDNA rearrangement. One or more of OXPHOS complexes are impaired and dysfunctional to affect tissues with high energy demands. mtDNA is more susceptible to oxidative damage and has more mutations than nDNA. Unlike diploid nDNA, mtDNA is a multi-copy genome transmitted and maternally inherited through oocyte. The multi-copy nature of mtDNA easily causes the heteroplasmy as a unique aspect of mtDNA, making mitochondrial diseases more complex and heterogeneous. mtDNA-associated mitochondrial dysfunction plays the important role in the development of multisystemic primary mitochondrial disease, neurodegeneration, and cancer. The present article overviews the occurrence of mtDNA mutation, interactions with other factors, and molecular mechanisms of mtDNA-associated diseases.