Mutations

Mutations within mitochondrial DNA appear to be 5 or 10
times more common than mutations in nuclear DNA, and the
accumulation of mitochondrial mutations with time has been
suggested as playing a role in ageing. As the main function of
mitochondria is the synthesis of ATP by oxidative
phosphorylation, disorders of mitochondrial function are most
likely to affect tissues such as the brain, skeletal muscle, cardiac
muscle and eye, which contain abundant mitochondria and rely
on aerobic oxidation and ATP production. Mutations in
mitochondrial DNA have been identified in a number of
diseases, notably Leber hereditary optic neuropathy (LHON),
myoclonic epilepsy with ragged red fibres (MERRF),
mitochondrial myopathy with encephalopathy, lactic acidosis,
and stroke-like episodes (MELAS), and progressive external
ophthalmoplegia including Kaerns–Sayre syndrome.