Researchers have discovered a new type of mitochondrial DNA damage that accumulates significantly more than nuclear DNA damage. This damage disrupts energy production in cells and triggers stress responses. Simulations show that damaged mtDNA becomes more rigid, likely marking it for removal. This mechanism may explain the link between mtDNA damage and diseases such as diabetes, inflammatory conditions and neurodegenerative diseases. The findings offer new insights into the origin and development of these diseases. Damage to mtDNA is thus a possible missing link between ageing, inflammation and disease.