Lori Anderson: Crossing a dangerous genetic line

Three-parent embryos and gender selection could soon become a reality. Picture: TSPL

I will forgive you for thinking that, as I write this, I am clad in an itchy woollen smock of sombre brown, with a linen cap covering my hair, topped off with a tall black felt hat, crying and pointing that I’ve seen “Goody Scientist” playing with the Devil. Now, before you put me in the stocks as a Puritan Luddite par excellence, I would like to implore you to consider that our society is on the verge of a seismic change. The British government is expected to do what no other nation has yet done, which is to endorse and legalise the genetic modification of human embryos.

Previously, a thick line in the sand was drawn when the Human Fertilisation and Embryology Authority (HFEA) banned eggs, sperm or embryos that had alterations made to their nuclear or mitochondrial DNA (mtDNA) from being placed back into a woman’s body. The HFEA also stated that it was illegal for genetically-modified embryos or embryos created by cloning from being implanted into a woman. So what and, more importantly, who has changed its mind?

Are we crossing this bioethical Rubicon for the sake of millions, hundreds of thousands, thousands, or even hundreds of people? No. The beneficiaries will be no more than a dozen or so each year. Are we crossing this bioethical Rubicon to save the lives of people already born? No. We’re crossing this bioethical Rubicon to give a handful of parents not what they need, which is a healthy child, but what they wish, which is a genetic link to that healthy child.

Women who have faulty mtDNA run the risk of giving birth to children liable to suffer neurodegenerative diseases, blindness, muscular dystrophy, diabetes and deafness. Mitochondrial disease affects one in 6,500 babies or about 200 born each year and while some are seriously ill, others can lead productive lives. The options for a woman with faulty mtDNA who wishes to avoid mitochondrial disease are either to adopt or opt for embryo donation or egg donation. With the latter, her male partner would at least have a genetic link to the child, but all three options deny her that profound connection.

Under the new procedure, which has been endorsed by the HFEA, and is expected to be passed by the UK parliament next year and available by the end of 2014, a woman will have the possibility of having a child that is genetically linked to her, but does not have any genetic link to her faulty mtDNA. Instead, the child will have a genetic link to a third person, the woman who donated her egg from which the healthy mtDNA is utilised.

The first child born of this procedure will be unique in human evolution. He or she will have three genetic “parents”. This should not be overblown. The child will have 25,000 genes from its genetic mum and dad through their nuclear DNA and just 13 genes from the donor’s mtDNA – and none of those 13 genes deliver physical traits or personal characteristics. The child will be just 0.2 per cent of “parent three”. Yet, this should also not be underplayed.

The process works as follows: IVF techniques create an embryo using the parents’ sperm and egg. When the embryo is one day old and still a single, undivided cell, the two pronuclei from the parents are removed and the faulty mtDNA, which comes from the cytoplasm in the mother’s egg, is left behind. A second embryo is created using an unrelated donor with healthy mitochondria and the father’s sperm. Again, at the one-day stage, the pronuclei are removed and destroyed, and replaced with the parents’ pronuclei, which can now grow supported by the donor’s healthy mitochondria. The embryo is then implanted into the mother.

A miracle of modern science will allow a mother who may have had a number of children die or be left seriously ill as a consequence of faulty mtDNA will now be able to give birth to a child free from mitochondria disease. How can this possibly be a cause for concern?

It is a cause for concern because a door once locked and bolted has been allowed to creak open. Prior to 2008, the government and the HFEA considered it unconscionable to permit the genetic engineering of human embryos and now, to assist women with faulty mtDNA, they have changed their mind. An exception has been made and, in time, there will be more and more exceptions until, in decades to come, potential parents could screen for height, weight and colour of eyes.

We are also placing a bet for which future generations may be liable. We do not know what the medical consequence of a “three-parent” child will be. There may be none, or there may be unknown side-effects, but what makes this medical treatment unique is that it will be carried on through future generations. If the resultant child is a girl and goes on to have girls, each new generation will carry the mtDNA of the donor.

The UK is the first government to authorise what Stuart Newman of New York Medical College described as “full-scale germline genetic engineering”, so the ripples from the British lab have the potential to carry on for centuries and millennia.

My concerns are not based on any religious beliefs – and they will not concern or interest the mother who eventually benefits and is able to cradle a healthy child – but I do find the idea of severing the link to mitochondrial DNA poignant. Each of us can use our mtDNA to peer back in time to “Eve”, an African woman who lived 190-200,000 years ago to whom every human on earth is related.

The point about drawing lines in the sand is that they will be washed away by the onrushing tide of progress. I’m not trying to tame the sea, just anxious to point out the possible hidden dangers lurking beneath the surface.