Mitochondria influence not only our energy levels but also our risk of certain diseases.
The nuclei of our cells contain 99.9 percent of our DNA, with only 0.1 percent located in our mitochondria. Therefore, most genetic studies focus on the effect of nuclear DNA on our susceptibility to disease. However, a study by researchers at the University of Cambridge has revealed that mitochondrial DNA also strongly influences disease risk.
'We don't generally associate mitochondrial DNA variants with common diseases. But what we've shown is that mitochondrial DNA – which we inherit from our mother – influences the risk of some diseases such as type 2 diabetes and MS [multiple sclerosis] as well as a number of common characteristics,' said Dr Joanna Howson, who co-led the study.
The research team investigated 358,000 volunteers from the UK Biobank, a nationwide biomedical database. Using a novel technique, they evaluated associations of mitochondrial DNA with individuals' geographical location as well as their specific traits and disease status.
Publishing their research in Nature Genetics, they found that certain mitochondrial DNA variants were associated with regions of the UK, specifically those with Scottish, Northumbrian, or Welsh ancestry. This suggested that nuclear and mitochondrial DNA have evolved together and interact with each other. This was surprising as, unlike nuclear DNA, which is passed down from both mothers and fathers, mitochondrial DNA is strictly maternally inherited.
The team also found that mitochondrial DNA was associated with factors such as height and longevity. Moreover, liver and kidney function, blood cell count, and the risk of diseases such as type 2 diabetes and multiple sclerosis were associated with mitochondrial DNA. This could be due to mitochondrial DNA altering our cells' ability to produce energy, but is likely to be a result of complex biological processes.
Professor Patrick Chinnery, who co-led the study, said, 'If you want a complete picture of common diseases, then clearly you're going to need to factor in the influence of mitochondrial DNA. The ultimate aim of studies of our DNA is to understand the mechanisms that underlie these diseases and find new ways to treat them. Our work could help identify potential new drug targets.'