Mitochondrial DNA encodes the genes of oxidative phosphorylation for complexes I-IV. Mitochondriae are the place of implementation of the electron transport chain and therefore are the main producers of reactive oxygen species (ROS), with most of them being formed with participation of complexes I and III (NADH-coenzyme Q oxidoreductase and Q-cytochrome c oxidoreductase).
Increased oxidative stress has a negative effect on bone metabolism, bone-forming osteoblasts as well as osteoclasts degrading the bone tissue, and may lead to the development of osteoporosis and other bone diseases. Mitochondrial gene mutations and lowered mitochondrial DNA copy numbers are associated with the development of osteoporosis and other bone diseases.
Epigenetics of mitochondrial DNA has been a subject of research since 2011 when methylation of mitochondrial DNA as well as the presence of DNA methyltransferases in mitochondria were first discovered. Currently, the effects of these changes and associations with other diseases are investigated.