Mitochondria in the media

Mitochondria in the media

18 June 2012

By Dr Geoff

Dr Geoff Watts chaired the working group that produced the
Nuffield Council on Bioethics' report, 'Novel techniques for the prevention of
mitochondrial DNA disorders: an ethical review'. Here, he offers some personal
reflections on a few of its key conclusions.

Appeared in BioNews
Consider the plight of a woman who wants children but comes from a
family in which her offspring run the risk of being born with an incurable
mitochondrial inherited disease (MiD). If she's happy to adopt or to undergo IVF
using an egg donated by a woman whose mitochondria are healthy, she can sidestep
the problem. But if the genetic connection is important to her, the options
available to minimise the risk (PGD or prenatal diagnosis) may be unreliable, or
inappropriate, or both.

Small wonder that affected families are keen to
see the advent of another option in which variants of IVF technology would be
used to rehouse the parental genetic material in a donor cell with healthy
mitochondria. The genetic material of the resulting embryo would be 99.9 percent
that of the parents.

Two methods of achieving this end look increasingly
promising, but both raise a number of ethical issues. Our report set out to
examine them and to decide if, following further research on safety and
efficacy, they would be acceptable for clinical use. Subject to a number of
conditions, we believe they would.

These conditions include the need to
provide prospective parents with proper counselling and a full explanation of
what are, after all, novel and complex interventions. We also think that, if
used clinically, the treatments should be provided only by centres that
specialise in MiD. And they should also be carried out as part of a clinical
study extending over several generations. This is because their influence would
be felt not only by the child born through their use, but by the female
descendants of that child. These technologies are not just gene therapies; they
are germline gene therapies. They cross into what is still forbidden

It's with this in mind that I've been reflecting on the media
coverage of our report, in particular on the way that most journalists have
framed the story. As on previous occasions when these technologies have made the
news, most of the focus has been on what now seems doomed to be labelled the
'three parent' issue. As already mentioned, a fraction of one percent of the
child's DNA (37 mitochondrial genes, as opposed to more than 20,000 nuclear
genes) would come not from its mother and father, but from a third

Both legally and biologically our group found no evidence to
suggest that this would cause distress or confusion to a child who learned of
his or her slightly unusual inheritance. The only known function of
mitochondrial genes is to provide the cell with the energy it needs. Vital,
certainly; but of no significance for what is usually regarded as an
individual's sense of identity.

The big ethical development as far as
I'm concerned is that we have endorsed what we choose to describe as a germline
therapy. I say 'choose' because there are those who prefer not to so label these
techniques. Our view is that if you knowingly influence the genetic make up of
generations as yet unborn, you're changing the germline.

Gene therapists
have often emphasised that what they aim to do affects only the person being
treated. They are aware that any attempt to alter our descendants is likely to
induce nervousness and suspicion; it comes with a deal of historical and
emotional baggage. So why did our working party feel able to endorse such a
controversial enterprise? Because our approval was limited to techniques used
only for the prevention of MiD, and only those forms caused by possession of
mutant mitochondrial genes (mitochondrial disease can also be caused by mutant
nuclear genes).

We are, of course, aware that some will see this as a
justification for germline interventions in nuclear genes. It is not. There is a
clear demarcation between the two enterprises, and our endorsement is confined
to mitochondrial genetic material. But we recognise that it does cross a

This, and not the 'three parent' froth, is the deeper significance
of our report. Yet few commentators in the media and elsewhere seem to see it
that way.

This is regrettable. Sooner or later a researcher somewhere is
going to claim to have found a safe way of altering, replacing or otherwise
manipulating a nuclear gene in a human egg or early embryo. This would be orders
of magnitude riskier than anything considered in our report. And even if it
really were safe, would we want to change our descendants in a manner that might
go far beyond the prevention of a debilitating disease?

The debate on
this issue, when it comes, will be far tougher, far more complicated, and with
far more at stake than any issue confronting our working party during the past
six months. It is a pity that our report has, so far, been little used to prompt
that particular discussion. It does however appear to have made a considerable
contribution to supporting a level-headed discussion of mitochondrial

Throughout June, BioNews is running its own poll on the
question 'Should Government allow variations of IVF using genetic material from
three people to prevent children from inheriting mitochondrial diseases?', to
which you can respond here.


techniques for the prevention of mitochondrial DNA disorders: an ethical
Nuffield Council on Bioethics | 12 June 2012