CGS-authored

"In a country nervous about genetically modified crops, we are making the foolhardy move to genetically modified babies." So said MP Jacob Rees-Mogg in a UK Parliamentary debate on draft regulations to allow trials of controversial techniques that might allow women with mitochondrial disease to have healthy babies.

If approved, the regulations would, for the first time, allow human germ-line modification – in which DNA is changed and the change remains inheritable.

The technique at the heart of the debate is mitochondrial transfer. Mitochondria are the energy generators of cells and have their own DNA, which is separate from DNA in the nucleus. Mitochondrial DNA is inherited via the maternal line, from mother to child. So to prevent a woman with faulty, disease-causing mitochondria from passing on her condition, a female donor supplies healthy mitochondria.

However, the phrase mitochondrial transfer does not fully describe what is involved: the manipulation of an entire human egg. In reality, the nucleus is removed from an egg or single-celled embryo from a woman who has mitochondrial disease and is then transferred into a donor...