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However,
many women
are reluctant
to opt for
egg donation
because the
resulting baby
would have a
closer genetic
relationship
with the donor
than the
mother
Darnovsky and Dr Keefe both believe the risks
posed by nuclear genome transfer outweigh its
benefits, mostly because there are safer alternatives
for conceiving healthy babies through assisted
reproductive technologies. For example, there’s some
evidence that pre-implantation genetic testing could
help select embryos that are going to grow free of
mitochondrial disease.
“In general, the technology is good enough to
find embryos with low levels of mitochondrial DNA
mutation that are thought to be safe,” explained Dr
Falk. “However, nobody can ever be sure because
it’s not clear that any level couldn’t potentially change
between the measurement you pick in an embryo
and the one you pick a trillion cell divisions later in a
person when that embryo becomes a human.”
Dr Keefe acknowledges the test is not perfect
but says the same applies to nuclear genome
transfer. “There’s some carry over when you pull the
nucleus out of the mother’s egg as some mutated
mitochondria may remain attached to it,” he explained.
Because of this carry over of the mutation from the
mother, Dr Falk says it’s still unclear whether nuclear
genome transfer is 100 percent effective at preventing
the disease, though the procedure seems quite
effective. “Typically, the mutation level carried over
from the mother is less than two percent, which seems
reassuring,” she said.
Another alternative to nuclear genome transfer,
one that has an established safety record and would
eliminate any risk of transmitting mitochondrial
disease, is egg donation, or the practice of fertilising
a donor’s egg in the lab and then implanting it into the
mother’s uterus.
“Egg donation is very effective and safe,” said Dr
Keefe. “If I were told: ‘You can either do egg donation,
which we know how it works, or an experimental
therapy that might cause permanent neuorpsychiatric
conditions, autoimmune diseases, and sterility,’ I
wouldn’t take the risk.”
However, many women are reluctant to opt for
egg donation because the resulting baby would have
a closer genetic relationship with the donor than the
mother. According to Curtis of The Lily Foundation,
egg donation is an approach that suits many families
but, unlike mitochondrial donation, it doesn’t allow you
to have a genetically-related child.
Dr Keefe, however, believes this notion is
Cell Structure
54
MARCH 2020
GlobalHealthAndTravel.com