Scientists are to investigate “three parent IVF” for preventing mitochondrial diseases

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Cite this as: BMJ 2012;344:e540

by Aniket Tavare

A pioneering research laboratory has been awarded £4.4m (€5.3m; $6.8m)
to look into the role of a modified type of in vitro fertilisation
(IVF) involving three adults to prevent the inheritance of
mitochondrial diseases.

Mark Walport, director of the Wellcome Trust, which made the grant,
said that “mitochondrial diseases can be devastating for sufferers and
their families.” He added that although science had made great
progress in uncovering the nature of these diseases, “treatment hasn’t
kept pace.”

If approved for use in the United Kingdom—which would require a change
in the law—the procedure could help the estimated 12 000 people who
have a mitochondrial disease to have a healthy baby. About 100 babies
are born each year with a severe form of the diseases, many of whom
die in infancy.

Mitochondria, present in almost all human cells, generate energy for
cells to function. Mitochondrial diseases occur when the DNA contained
within mitochondria, distinct from that of the rest of the cell, gets
damaged. Mitochondrial DNA is inherited solely through the maternal
line, as are the diseases, which affect energy hungry organs such as
the heart, muscles, and brain but often vary in severity.

Current options to prevent mothers passing on the diseases to their
children, such as preimplantation genetic diagnosis, only reduce the
risk of transmission. Doug Turnbull, who will direct the new Centre
for Mitochondrial Research at the University of Newcastle, said that
the new technique, which has been successful in rodent and primate
models, “offers the possibility of stopping these diseases entirely.”
If successful, the technique may be able to eradicate these incurable
diseases “within the next generation,” he said.

The technique, pioneered by the Newcastle team, involves removing the
DNA from the nucleus of an affected woman’s egg and implanting it into
a recently fertilised donor egg (from which the nuclear DNA has been
removed) from a woman with normal mitochondria. Known as three parent
IVF, the procedure can also be performed in unfertilised eggs. A baby
born as a result of one of these techniques would have the genetic
characteristics mainly of its mother and father but also some from the
mitochondria of the egg donor.

Although the technique has been successful in the laboratory, the
Human Fertilisation and Embryology Authority (HFEA) has asked for
further research into the safety of the technique before it can be
considered for use in patients.

“We hope to demonstrate to the HFEA and to the public that these
techniques, which are based on existing IVF techniques, are safe and
effective,” said Professor Turnbull.

Donor embryos will be sourced from women undergoing IVF and from
altruistic donors.

However, work involving embryos and the transfer of genetic material
remains controversial. The Department of Health for England has asked
the HFEA to embark on a public consultation over the scientific,
ethical, social, and regulatory issues posed by such novel techniques.
Professor Walport believes that the parallel consideration of science,
regulation, and public debate is a “good model.” The findings of the
dialogue will be fed back to the secretary of state for health, who
will decide the need for further parliamentary discussion.

David Willetts, minister for universities and science, said,
“Scientists have made an important and potentially lifesaving
discovery in the prevention of mitochondrial disease. However, as with
all developments in cutting edge science, it is vital that we listen
to the public’s views before we consider any change in the law
allowing it to be used.”