Mitochondrial DNA, human evolution and the cancer genotype.

Mitochondrial DNA is a small, well characterized chromosome which is transmitted across the generations in the maternal lineage, independently of nuclear DNA. mtDNA acts in effect as a robust, species specific biological clock and tracer which can be used to follow the evolution and spread by geographic migration of populations from their origins. Mutations in mtDNA cause specific maternally hereditable diseases, and can be used for forensic purposes. They are not specifically implicated in neoplasia, but they may provide clues as to the nature and origins of cancer susceptibility in various populations.