Cover Story
Three-person IVF:
groundbreaking
fertility treatment
or dicey gamble?
Though the young technique has already led to the birth of a few babies,
its efficacy, safety, and morality remain uncertain
A
The aim of the
procedure,
dubbed
nuclear
genome
transfer, is to
minimise the
chances of
transmitting
mitochondrial
disease, a
collection
of genetic
disorders
passed on
from parents
to children
that affect the
mitochondria
50
MARCH 2020
novel cutting-edge fertility procedure that
mixes the DNA of three different people has
shown promising results in helping women
conceive without passing down debilitating or fatal
genetic conditions. Its future is uncertain, however, as
the potentially serious health risks and the inevitable
modifications to the human genome entailed in the
process have also created a storm of controversy.
The aim of the procedure, dubbed nuclear genome
transfer, is to minimise the chances of transmitting
mitochondrial disease, a collection of genetic
disorders passed on from parents to children that
affect the mitochondria, the so-called energy factories
in the cells. These disorders can lead to a wide range
of problems, including fatigue, weakness, seizures,
vision loss, and heart problems, as well as mental
delay and disability in children.
In some instances, mitochondrial disease can be
fatal and there’s no definitive cure for it.
Although disease-causing defects are often passed
through the DNA in the cells’ nucleus, where about
99.9 percent of human genome is stored in the form
of chromosomes, a minor subset of mitochondrial
diseases are caused by mutations in the mitochondrial
DNA (mtDNA) itself, a cluster of 37 genes found
outside the cellular nucleus that babies inherit only
from their mothers.
This is where nuclear genome transfer comes in.
The technique is a form of assisted reproductive
technology involving the use of donated healthy
mitochondria to replace the mother’s faulty ones and
can be performed in two ways.
In spindle transfer, the mother’s nuclear DNA, also
known as spindle, is inserted into a donor’s egg whose
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