Inside the cells in our body are lots of tiny mitochondria. These organelles produce energy for the cell, but the unique properties of their DNA mean they can also do so much more.
Every mitochondria contains multiple copies of its own circular DNA. Far simpler than the nuclear genome, this mitochondrial DNA (mtDNA) becomes mutated when the cells are put under stress by diseases such as cancer. And because there are so many copies of the DNA within the mitochondria, it doesn’t need to repair the mutated copies, leaving behind a unique, disease-specific biomarker like a real-time indicator of disease status.