A disorder that happens when structures inside cells that make energy don't work properly.

In mitochondrial disease, the mitochondria can't do their job of burning food and oxygen to make the energy all cells need to work. This group of diseases most often affects the heart, brain, eyes, ears, liver and muscles. These diseases often are passed through families.

Symptoms depend on what parts of the body are affected. Symptoms can include poor growth and delays in development, muscle weakness, not being able to exercise, heart disease, seizures, balance issues, diabetes, and vision or hearing loss.

There's no cure. Treatment depends on the type of disease and what parts of the body are affected.