Mothers can influence children’s height and disease risk ‘in unexpected way’

Mothers can influence their children’s height, lifespan and disease risk in unexpected ways, new research has suggested.

Mitochondria –  the powerhouse of the cell – play a surprising role in common diseases such as type 2 diabetes and multiple sclerosis, according to a new study.

Scientists found that genetic variants in the DNA of mitochondria could increase the risk of developing these conditions, as well as influencing characteristics such as height and lifespan.

In the study published in Nature Genetics there was also a suggestion that some changes in mitochondrial DNA were more common in people with Scottish, Welsh or Northumbrian genetic ancestry.

Researchers say this implies that mitochondrial DNA and nuclear DNA – which accounts for 99.9% of our genetic make-up – interact with each other.

While errors in mitochondrial DNA can lead to so-called mitochondrial diseases, which can be severely disabling, until now there has been little evidence these variants can influence more common diseases.

Several small-scale studies have indicated this is possible but scientists have been unable to replicate their findings.

Now, a team at the University of Cambridge has developed a new technique to study mitochondrial DNA and its relation to human diseases and characteristics in samples taken from 358,000 volunteers as part of UK Biobank, a large-scale biomedical database and research resource.

Dr Joanna Howson, who carried out the work while at the Department of Public Health and Primary Care at the University of Cambridge, said: “Aside from mitochondrial diseases, 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 as well as a number of common characteristics.”

The factors found to be influenced by mitochondrial DNA include type 2 diabetes, multiple sclerosis, liver and kidney function, blood count parameters, life span and height.

The research suggests that while some of the effects are seen more extremely in patients with rare inherited mitochondrial diseases, the effect in healthy individuals tends to be much subtler, likely accounting for just a few millimetres’ height difference, for example.

Professor Patrick Chinnery, from the MRC mitochondrial biology unit at Cambridge, 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.”

Unlike nuclear DNA, which is passed down from both the mother and the father, mitochondria DNA is inherited exclusively from the mother.

This suggests the two systems are inherited independently and hence there should be no association between an individual’s nuclear and mitochondrial DNA – however, this was not what the team found.

The researchers found that certain nuclear genetic backgrounds are associated preferentially with certain mitochondrial genetic backgrounds, particularly in Scotland, Wales and Northumbria.

They say this indicates our nuclear and mitochondrial genomes have evolved – and continue to evolve – side-by-side and interact with each other.