ODRA NOELMutations in one or more copies of mitochondrial DNA, known as heteroplasmies, are likely to be much more common in healthy people than previously anticipated. Approximately 90 percent of healthy participants in the 1,000 Genomes Project harbored at least one heteroplasmy, and 20 percent bore mitochondrial genome mutations implicated in diseases, according to the results of a study published today (July 7) in PNAS.
“It’s been known for a long time that lesions in mitochondrial DNA become more prevalent with age,” said metabolic disease specialist Neal Sondheimer of the Children’s Hospital of Philadelphia who was not involved with the work. This study “offers the intriguing possibility that maybe everybody has a little bit of something wrong with their mitochondrial DNA and that might play a role in aging.”
Because a single cell can contain hundreds to thousands of mitochondria, it also carries multiple copies—and, sometimes, variants—of these maternally inherited genomes. Pathogenic mutations can co-exist with healthy mitochondrial DNA (mtDNA) within a cell or group of cells; clinical signs of disease only occur when the frequency of mutations crosses a threshold, which typically ranges from 60 percent to 85 percent ...
