Mitochondrial DNA deletion mutations increase exponentially with age in human skeletal muscle.

The exponential increase in mtDNA deletion frequency is concomitant with the known muscle fiber loss and accelerating mortality that occurs with age. The improved assay permits the accurate and sensitive quantification of deletion mutations from DNA samples and is sufficient to measure changes in mtDNA deletion mutation frequency in healthy individuals across the lifespan and, therefore, patients with suspected mitochondrial diseases.