We know that these devastating mitochondrial mutations can pop up in families without any previous history, but previously we didn’t know how that happened. We were surprised to find that egg cells in healthy females all carry a few defects in their mitochondrial DNA
- Patrick Chinnery
Mitochondrial diseases caused by mutations in mitochondrial DNA are rare, affecting approximately 1 in 10,000 births, but can cause severe conditions. For example, Leigh Syndrome is a severe brain disorder causing progressive loss of mental and movement abilities, which usually becomes apparent in the first year of life and typically results in death within two to three years.
Mitochondria are the powerhouses inside our cells, producing energy and carrying their own DNA instructions (separate from the DNA in the nucleus of every cell). Mitochondria are inherited from a person’s mother via the egg.
In the study, published in Nature Cell Biology, the researchers isolated mouse and human female embryonic germ cells – the cells that will go on to be egg cells in an adult woman – and tested their mitochondrial DNA.
They found that a variety of mutations were present in the mitochondrial DNA in the developing egg cells of all 12 of the human embryos studied, showing that low levels of mitochondrial DNA mutations are carried by healthy humans.
Image: Three mitochondria surrounded by cytoplasm
Credit: Dr David Furness (Wellcome Collection)
Reproduced courtesy of the University of Cambridge