Britain’s Human Fertility and Embryology Authority (HFEA) has today launched a public consultation over new IVF techniques that produce embryos which carry DNA from three people.
The techniques are designed to prevent mitochondrial diseases being passed down the maternal line. They involve transferring nuclear DNA, which contains our genetic make-up, from a female donor to the egg of a woman suffering from such a disease.
Mitochondria have been described as the ‘batteries’ that power the cells in our bodies. When these fail, patients can develop devastating diseases that typically affect the tissues that need the most energy – the heart, muscles and brain.
There are currently two techniques under development by Professor Doug Turnbull and his colleagues at the Wellcome Trust Centre for Mitochondrial Research at Newcastle University: pro-nuclear transfer and maternal spindle transfer.
Immediately after fertilisation, an embryo has two pro-nuclei, the parts of the egg and sperm that hold the nuclear DNA. Pro-nuclear transfer (PNT) involves removing pro-nuclei from an embryo with unhealthy mitochondria immediately after fertilisation, and then transferring them into a donated embryo. This donor embryo contains healthy mitochondria, but has had its own pro-nuclei removed.
An alternative approach incvolves the maternal spindle, a structure within a woman’s egg that contains the mother’s half of a child’s nuclear DNA.
Maternal spindle transfer (MST) involves removing the spindle from the mother’s egg before it’s fertilised by the father’s sperm. The spindle is then placed into a healthy donor egg with healthy mitochondria, from which the donor’s spindle, and therefore the nuclear DNA, has been removed.
Both techniques have already been shown to work in the lab, but in a review of the scientific evidence, the HFEA last year requested further experiments to assess their safety. Meanwhile, the HFEA is consulting the public about its views.
“The work of Professor Turnbull and colleagues holds great promise for preventing previously incurable diseases and giving families affected by these diseases the chance to have healthy children, something most of us take for granted,” says Sir Mark Walport, director of the Wellcome Trust.
“The HFEA consultation provides an important opportunity for us to discuss with the public why we believe this technique is essential and to listen to any concerns they may have.”