From the Revd Dr David de Pomerai
Sir, - For once the House of Commons has got it right, and the
Church of England has got it sadly wrong. My duties are currently
split between ordained parish ministry and an academic position at
the University of Nottingham, teaching biology students about
bioethics, as well as genetics and animal development. Knowing this
field in some detail, I believe that medical science can offer a
real prospect of relief from the otherwise untreatable suffering
for that small number of children whose mothers carry mitochondrial
genetic diseases.
Without the approval of the Human Fertilisation and Embryology
Authority, and a change to the law (the HFE Act 2008), this
technique cannot enter clinical trials in humans. Numerous animal
trials have already proved successful, even when using macaques in
Oregon a few years ago. All the evidence so far suggests that the
technique is safe - insofar as any kind of human transplantation
technique is safe. We won't really know till we try on human
patients. Paradoxically, it is impossible to do a standard
phase-one trial of this treatment in healthy humans. No mother
would volunteer for such an untried procedure - of replacing her
own egg mitochondria with those from a donor egg - unless her own
egg mitochondria were defective and very likely to result in a
child condemned to a life of illness and early death.
Could there be long-term adverse consequences? Much has been
said about so-called mitochondrial incompatibility, although the
evidence for this is inconclusive at best. It is true that many of
the energy-producing functions of the mitochondria are dependent on
nuclear genes, working in co- operation with the very small set of
genes encoded in the mitochondrial (mt) DNA; it is only genetic
malfunctions involving these mtDNA genes which will be addressed by
mitochondrial replacement. But any set of mtDNA genes seems to work
satisfactorily in collaboration with pretty well any set of
paternal genes, since we all get our mitochondria from mum but not
from dad (maternal inheritance).
Remember that all of dad's nuclear genes were used to working
with a different set of mitochondrial genes (maternal grandma's);
so those genes have to get used to working with mum's mitochondrial
genes in each and every one of us. By and large, that doesn't seem
to cause serious problems - although, of course, as a scientist, I
am bound to add the caveat that we can never be 100 per cent sure.
But it is probably well into the high-90-plus-per-cent-probability
range.
Could mitochondrial replacement lead to genetic engineering of
humans, either for therapeutic purposes (a permanent cure for a
range of genetic diseases affecting nuclear genes) or for
"improvement" (off-the-shelf sets of genes designed to maximise IQ,
sporting, or musical ability)? The short answer is "No," and for a
reason that is self-evident to any practising animal geneticist.
Mitochondria are little semi-autonomous genetic entities: the
functions that are not encoded by the mitochondrial genes
themselves are simply imported from the rest of the cell.
If the fault lies within the mtDNA, then replacing the faulty
set of mitochondria with non-faulty ones should work in the vast
majority of cases. And, even if problems did arise, they are very
unlikely to be as severe as those caused by leaving the faulty
mitochondria in place -which is the alternative on offer.
But putting new genes into the nucleus of a cell is much
riskier, with remarkably low success rates (usually below ten per
cent), even though this technique has been around since Richard
Palmiter's giant mice in the early 1980s.
I have engineered genetically nematode worms - most recently as
a model for Parkinson's disease - and there's still a moment of
joyous discovery when you find one line out of dozens which
actually expresses the inserted gene properly. There are no
guarantees of success in these "transgenic" techniques, and it
therefore follows that no one will want to try such methods out on
humans. A 90-per-cent failure rate means that the doctors and
scientists involved will be sued for failing to deliver the goods
in nine cases out of ten.
Whatever our views on litigation in medical cases, in this
instance it serves to protect us against a technique that would be
genuinely risky and unpredictable in outcome. Those who understand
even a little of the science can see not merely clear blue water,
but a veritable ocean separating mitochondrial replacement from
germ-line gene therapy or designer babies.
If Jesus calls us to join him in healing the sick, we in this
Church should not be seen to side with hand-wringing and delay,
trying to block what looks like a promising treatment for genetic
diseases that have caused one woman to lose seven babies in early
childhood. The key point about mitochondria is that they are
self-contained functional genetic packages, and therein lies the
best possible guarantee that they will work appropriately.
David de Pomerai
Associate Minister, and Science Adviser in the diocese
of Derby; Associate Professor in the School of Life
Sciences at Nottingham University
74 Woodville Road, Hartshorne
Swadlincote DE11 7ET
From the Revd Dr Michael Perry
Sir, - When the Revd Dr Brendan McCarthy releases a statement
using the collective "we" for the Church of England, it would be
helpful to know what the collective process is for "us" to arrive
at this conclusion. Certainly, in regard to mitochondrial
replacement therapy (MRT), as a parish priest and former biochemist
with research experience in developmental biochemistry, I would
echo Bishop Lee Rayfield reported regret about the Church's
communication of its position.
I would also urge us to be informed when raising questions of
safety. Your otherwise excellent report (News,
7 February) cites a New Scientist editorial concerning
suggestions that mitochondria may have a "greater influence" in
cells. New Scientist articles are often speculative. In
this case, that piece needs to be read alongside the devastating
counter-critique by Dr Robin Lovell-Badge FRS the following
month.
I welcome the vote in favour of MRT, and believe that the
dedicated and inspired scientific research that makes this now a
possibility, together with the years of careful ethical reflection,
should be welcomed by the Church at large.
Michael Perry
The Vicarage
Middle Woodford
Salisbury SP4 6NR