- The genes that control the colour of your eyes, or your blood group, or anything else about you, make up only 2 per cent of the total.
- Until recently large amounts of the human genetic code, or genome, were dismissed as "junk" - DNA sequences that had no function.
- The findings show that around 80% of the genetic code is actively involved in keeping life going.
We're going to find out ways of helping us understand disease, avoid disease, prevent disease and perhaps cure disease in different ways from this, but I'm not going to be able to put my finger on this disease or that disease right now.
It's clinical researchers and doctors who are going to be the people who I think will benefit from this. I'm a kind of servant to that community of researchers.
Scientists have discovered that huge parts of our DNA - which were previously thought to have no obvious use - could in fact be essential in controlling genetic diseases.
So-called 'junk' DNA contains millions of 'switches' which can turn genes on or off. That could include controlling genes which lead to a hereditary diseases such as breast cancer or cystic fibrosis.
In the future, scientists hope the findings will lead to a deeper understanding of numerous diseases and help them devise more effective diagnostic tools and treatments.
Dr Geoff Watts, Chairman of the Working Party for Nuffield Council of Bioethics: "Ethically we feel these technologies are acceptable....
"The benefit to them (families affected by mitochondrial diseases) of this technology if it ever came into practice, is that they would with great confidence be able to have children who were disease-free."
A report from an influential think tank could help clear the way to IVF babies being born with DNA from three different people.Read the full story ›
As with IVF and cloning, this mitochondrial technique may well lead to the developmental abnormalities. Creating embryonic children in the laboratory abuses them, by subjecting them to unnatural processes. These techniques are both destructive and dangerous and therefore unethical.
"Scientists should abandon the spurious field of destructive embryo experimentation and instead promote the ethical alternative of adult stem cell research, which is already providing cures and treatments for an increasing number of conditions."
Controversy surrounds attempts to prevent mitochondrial diseases through hi-tech variations of In-Vitro Fertilisation (IVF) treatment.
One technique, pronuclear transfer, involves transferring nuclear DNA out of a day-old embryonic cell containing defective mitochondria.
The DNA is planted into another single-cell embryo whose mitochondria function normally.
The donor embryo's own nuclear DNA is discarded. However, it still contains the normal mitochondria of the woman whose egg was fertilised to create it.
As it grows, the embryo produces a baby with DNA from three sources - nuclear DNA from the original parents, plus a tiny amount of mitochondrial DNA from the woman egg donor.
Although such techniques are banned, they could be voted in by Parliament under existing legislation.
If further research shows these techniques to be sufficiently safe and effective, we think it would be ethical for families to use them if they wished to, provided they receive an appropriate level of information and support.
"They could offer significant health and social benefits to individuals and families, who could potentially live their lives free from what can be very severe and debilitating disorders."
- Around a hundred babies a year are born with genetic defects in what scientists call mitochondrial genes.
- Faulty mitochondrial genes can lead to a wide range of serious disorders including heart malfunction, kidney and liver disease, stroke, dementia, and blindness.
- Around 6,000 adults in the UK are believed to be affected by mitochondrial diseases.
- Children born after 'Three parent IVF' would possess nuclear DNA inherited from their parents plus mitochondrial DNA (mDNA) from a woman donor.