Feb. 15 (HealthDay News) -- A single change in the DNA of mitochondria -- the cellular power plants that generate energy in all human cells -- has been found to cause degenerative heart and muscle disease in mice, a new study says.

Mice harboring the mutation appeared normal early in life, but after a year, they developed marked muscle and heart disease, similar to what can develop in humans, according to University of California, Irvine, researchers. Their findings are published in the Feb. 15 issue of Science.

The study provides further proof that the mitochondria play a central role in human health, the researchers wrote.

"Consequently, mitochondrial DNA mutations and their related energy defects are sufficient to cause age-related disease," study author Douglas Wallace, director of the Center for Molecular and Mitochondrial Medicine and Genetics at the university, said in a prepared statement. "Therefore, mitochondrial energy deficiency may be a common factor in these diseases."

The mice in the study inherited a relatively mild mitochondrial DNA mutation that reduced a key enzyme of mitochondrial energy production by 50 percent. This was done by researchers creating mice from genetically altered female mouse embryonic stem cells.

Mitochondria exist in all human cells and have their own DNA. It is inherited exclusively from the mother and is present in thousands of copies per cell.

As the mitochondrial DNA of cells accumulates damage with age, the blueprints required to sustain energy production are lost, the body's equivalent of a brownout. The resulting age-related decline in cellular energy production ultimately leads to tissue and organ failure and the development of disease.

SOURCE: University of California, Irvine, news release, Feb. 14, 2008