Parents with
a family history of a serious or
fatal genetic condition now have
the option of combining IVF and
genetic testing in a technique known
as pre-implantation genetic diagnosis,
or PGD.
Couples using
PGD first need to use IVF procedures
to generate embryos. A single cell
can then be removed from the very
early embryo without damaging it.
This cell can be tested to see if
it carries the genetic defect that
causes the condition. Only embryos
that do not carry the defective
gene are implanted in the mother.
While there has only been limited
use of PGD so far, the potential
applications of PGD are increasing
rapidly as researchers identify
more of the genes associated with
serious genetic conditions.
As with all
IVF procedures, a successful pregnancy
is not guaranteed. However, for
many couples who have experienced
a serious genetic condition or lost
family members, PGD is more acceptable
than using prenatal genetic testing
on a growing baby, or not having
children at all.
Genetic testing
in any context raises many significant
issues for our community, but particularly
when embryos are involved. In general,
PGD is usually only permitted for
serious or life-threatening conditions
and if it leads to an improvement
in the welfare and the interests
of the child being born.
Some families
have used PGD to test their embryos
to ensure they can provide a bone
marrow transplant for a sick sibling.
The bone marrow cells for the sick
sibling are taken from the umbilical
cord blood of the new baby. Using
this process of tissue typing, these
babies are sometimes called ‘saviour
siblings’ as they can literally
save their sick brother or sister’s
life.
Regulations
regarding this use of PGD testing
vary from country to country, and
in Australia some states are regulated
while others are not.
Saviour
sibling
In March
2004 the first 'saviour sibling'
to be born in Australia was reported.
A couple
from Tasmania used PGD with tissue
typing in order to have a second
child who would be free from a particular
genetic condition, Hyper IgM syndrome,
and to also be a matched tissue
donor for the couple's existing
child who is affected by the same
condition.
As a result
of the treatment, carried out at
Sydney IVF, the woman started her
pregnancy knowing that her baby
will be free from Hyper IgM and
a potential tissue donor for her
existing son.
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