Ooplasmic transfer, also known as cytoplasmic transfer, is an experimental fertility technique that
involves injecting a small amount of ooplasm from eggs of
fertile women into eggs of women whose fertility is compromised.
The modified egg is then fertilized with sperm and implanted
in the uterus of the woman attempting to achieve pregnancy.
Children born from this procedure have been reported to possess
cytoplasmic organelles called mitochondria from both their biological
mother and the ooplasmic donor, a condition referred to as mitochondrial
heteroplasmy. Because mitochondria carry their own sets of genes
that are passed on to succeeding generations, the mixing of
parent and cytoplasmic donor mitochondria might be considered
to be a form of germline modification. However, the technique
does not involve modification of particular genes and could
not be used as part of any procedure to create "designer
In 2001, researchers at St. Barnabas Hospital in New Jersey
announced that they had used ooplasmic transfer to enable several
women with impaired fertility to bear children. They described
their work to the press as "the first case of human germline
However, ooplasmic transfer is not germline genetic modification, or
inheritable genetic modification (IGM), in the usual sense.
It cannot be used to modify genes housed in the cell nucleus,
which influence all traits except for those regulated by mitochondrial
genes. But the procedure might be considered a form of IGM in
that the mixed mitochondrial DNA would be passed on to all future
On the other hand, some advocates of IGM have identified ooplasmic transfer as
a technology whose development and use could be used to help
erode popular resistance to IGM.
Following the St. Barnabas announcement, the FDA notified all
US fertility clinics known to be offering the procedure that
further ooplasm transfer protocols could not proceed without
On May 9, 2002, an FDA Advisory Committee held a public meeting
to discuss ooplasm transfer procedures. A statement issued by
the FDA at this meeting reported that at least two dozen births
attributed to ooplasm transfer have been reported by three fertility
clinics since 1998.
The FDA expressed concerns about this "de facto
germ line gene transfer" technique, citing its potential
to alter the germline, the medical risks associated with mitochondrial
heteroplasmy, the high incidence of Turner's syndrome in
fetuses reported in one study (2 of 13 reported pregnancies),
and the paucity of animal studies and other pre-clinical data.
A general consensus was reached at the meeting that more preclinical
data would be necessary before FDA would allow further clinical
trials involving ooplasm transfer to proceed.