[Molecular tests of mitochondrial genome]

Mitochondria are considered to have originated from the symbiotic invasion of bacteria with aerobic ATP production into pro-eukaryotic cells about two billion years ago. For this evolutionary reason, mitochondria have maintained their own genome. Mitochondrial DNA is circular and is inherited maternally. Thus, mitochondrial DNA has characteristics different from nuclear DNA. Human mitochondrial DNA is small, about 16.5kbp in length, and encodes only two rRNAs, 22 tRNAs, and 13 proteins. However, the mitochondrial genome is essential for normal integrity of the mitochondrial electron transfer system (or respiratory chain). The electron transfer system is not only responsible for about 90% of cellular ATP production but is also closely linked to the metabolism of fatty acids, amino acids, and nucleic acids. In addition, its lack of integrity can cause overproduction of reactive oxygen species. Therefore, mutations of the mitochondrial genome are currently believed to be involved in many common diseases as well as classical mitochondrial neuromyopathies. Accordingly, more researchers have begun to take an interest in the association of mitochondrial DNA polymorphisms with aging and common diseases such as cancer, diabetes, neurodegeneration, and so on.