Power plant. A mitochondrion surrounded by cytoplasm.
Credit: U.S. National Institutes of Health
In vitro fertilization (IVF) techniques that could help prevent mitochondrial diseases are ethical, provided the techniques prove to be safe, according to
the Nuffield Council on Bioethics. The council, an independent and influential think tank based in the
United Kingdom, released its report today evaluating various methods that could potentially allow women who have mitochondrial disease to bear healthy,
genetically related children. The techniques would be a form of germline therapy, the report says, because the mitochondrial DNA introduced during the
procedure would potentially be passed on to future generations.
Mitochondria are organelles that provide cells with energy. They carry their own genomes, and mutations in mitochondrial genes can lead to a range of
symptoms, especially those involving organs that require relatively high levels of energy. In the most problematic cases, some patients are blind, others
are deaf, and others have dementia or muscle disorders. The disease is progressive, and there is no cure.
Mitochondria are inherited from only the mother. (Although sperm have mitochondria, they degenerate shortly after fertilization of the egg.) A few research
groups around the world have experimented with ways to transfer the genetic material from an egg with faulty mitochondria into a healthy egg, either before
or just after fertilization. Earlier this year, the Wellcome Trust announced it was funding a new Centre for Mitochondrial Research
at Newcastle University in Newcastle upon Tyne, U.K., where researchers are working on the technique.
The technique raises some ethical questions because any resulting child would carry genetic material—the mitochondrial genome—from the mitochondrial
donor. And any female child would pass the donated mitochondrial genome to her children.
The Nuffield Council said that fact does mean that the technique would be a form of germline therapy. Nevertheless, it said that provided the technique
proves to be safe and effective, it would be ethical for families to use it. They did recommend that the procedure be offered only as part of a research
trial and that families who use the technique should be required to agree to long-term follow-ups of the health of any resulting children.
Although some reports about the technique have said it would produce babies "with three parents," the council says that mitochondrial donation does not
result in a baby having a "second mother." Unlike egg donors, the report says, mitochondrial donors should not have to be identifiable to the adult
children born from their donation.
The techniques are currently not allowed in the United Kingdom. The country's law that governs IVF treatments prohibits any techniques in which sperm or
eggs that have had any of their DNA altered are implanted in a woman's body. Mark Walport, director of the Wellcome Trust, said he hoped the Nuffield
report would prompt the government to take steps toward discussing legislation that would allow the technique. The Human Fertilisation and Embryology
Authority, which oversees IVF treatments, will launch a public consultation on the topic in September.