Pre-implantation genetic diagnosis (PGD) & haplotyping (PGH)
Alternative uses for PGD;
PGH; Recent developments
One alternative use for PGD:
Some people are seriously ill or dying, but can be treated or cured with
a transplant from a suitable donor. For example, people who suffer from
leukemia, aplastic anemia and other potentially life-threatening blood
diseases can often be cured with a bone marrow transplant (BMT) from a
compatible donor. Too often, sick people die because a matching donor cannot
PGD offers an alternative way of finding a compatible donor -- by
creating one. The patient's mother can go through a standard IVF procedure,
have many ova harvested, have the ova fertilized by the father's sperm, and
have the resulted embryos go through a PGD procedure. If any embryos are
found to contain DNA that is an appropriate match to the patient, they can
be implanted in the mother's uterus. With luck, a pregnancy will develop and
an infant will be born. That infant may then be able to supply needed stem
cells from his/her umbilical cord or some other body component to their
sibling and save their life.
To some parents, this option is literally a life saver. Instead of
watching their child waste away and die, they can have the possibility of a
cure. Also, another child will be added to their family. The first family to
go through this process was the Nash family in Colorado. Their child:
was born with Fanconi anemia, a rare genetic disease that causes many
problems, the most serious of which is inadequate bone marrow
production....her poor bone marrow production meant that she would develop
leukemia and die, possibly within a few years."
The Nashes wanted a
second child anyway. IVF and PGD procedures assured that their second child
would be disease free and would be a compatible donor to their sister. A
month after Adam was born Molly was treated with radiation and chemotherapy
to completely destroy her bone marrow. She was then given a transfusion of
Adam's umbilical cord blood. Her chances of survival increased from 42% with
cord blood transplant from an unrelated marrow donor to 85% with a
transplant from a matched sibling. There was no danger at all to Adam. 1
There are some negative aspects to the use of IVF and PGD to create a
child to treat her or his sibling:
||Some diseases develop too quickly to allow time for a pregnancy and
perhaps maturity of the infant to the point where they can donate.
||Some people raise ethical questions about the creation of what they
call "designer babies" in order to treat a sibling.
||Others object to the discarding of unused embryos. They generally
feel that human personhood starts at the instant
of fertilization. They view the killing of diseased embryos or
embryos with poorly matched DNA is equivalent to murder.
||Some fear that IVF and PGD is the first step down a slippery slope
that will lead to babies being created to be used for spare parts.
Another alternative use for PGD:
Advanced Cell Technology
(ACT) in Worcester, MA conduct world-class research with stem cells. They
suggest that when fertility clinics perform human PGD to detect genetic
diseases, they could:
||Remove the single cell as usual.
||Allow it to divide into two cells.
||Use one of the cells to test for genetic problems.
||Use the other cell to establish a stem cell line. 2
Lines of stem cells would then
be created as a byproduct of existing PGD testing. No embryo would be killed
in the process. The scientists hope, perhaps naively, that this technique
might be acceptable to the pro-life community.
Pre-implantation Genetic Haplotyping (PGH):
In 2004,Ali al-Hellani, a Saudi Arabian fertility specialist, pioneered a
more advanced technique called PGH. Pamela Renwick at Guy's hospital
genetics centre and Prof Braude, who runs a fertility center at Kings
College, London further refined the method. 3
"It is more accurate, highly reliable and available for a whole range
of disorders. It opens the doors to all sorts of conditions." 4
PGH overcomes the main deficiency of PGD: it can only be used when the
physicians is looking for one of the 200 or so diseases that have already been
procedure involves taking blood samples from the couple, and from their
child or another relative who is affected by a disease, They fertilize several ova,
allow them to develop normally for three days, and then remove a single cell from each. This cell is grown overnight in the
laboratory, using multiple displacement amplification to produce a large DNA sample.
The doctors can compare the DNA from relatives who are affected by the disease with
the DNA from other relatives that are disease free. They can identify the
region of a chromosome that causes the disease. They can then determine
whether a given embryo is unaffected by the disease, or is a carrier of the
disease, or is destined to develop the disease. 3
The Daily Mail reported:
"From this the scientists can spot if the embryo is carrying the
problem chromosome or a disease-free version. Only the healthy ones are
then implanted." 4
The Guardian reported that almost 6,000
diseases and disorders can be sensed with this technique, including
Duchenne's muscular dystrophy (DMD), fragile-x syndrome and some forms of
cystic fibrosis. Stuart Lavery, a fertility expert at Hammersmith
hospital, London, said that
"The idea of a universal tool that can be applied regardless of what
the mutation is means many more patients will have access to this." 3
Some recent developments:
||1999-NOV-15: UK: Public views sought: According to the
Guardian UK News:
"The human fertilisation and embryology
authority, which regulates all such work in the UK, and the advisory
committee on genetic testing (ACGT) yesterday published a consultation
paper in print and on the internet. They claim this is the first such
public consultation in the world. "
"They want to know whether the public finds it acceptable for genetic
technology to be used to screen embryos to eliminate those that would be
born with distressing inherited diseases, such as cystic fibrosis. If such
screening is acceptable, the two bodies are asking, then how far should it
go? What sort of severity of disease should the labs be allowed to screen
for? If it becomes possible to detect a genetic mutation that will lead to
a non-life threatening disability such as deafness, what should be done?
||2005-APR-28: UK: Court of Appeal ruling
upheld: The country's highest appeal court ruled that couples can
create embryos through in-vitro fertilization in order to help cure sick
siblings: According to the Toronto Star:
"The Law Lords backed a 2003 Court of Appeal ruling that
some couples undergoing the fertility treatment could have their embryos
screened to find tissue matches for seriously ill children, Advocates
say the procedure will help save desperately ill children. Opponents
fear it could lead to the creation of babies for spare parts." 7
The following information sources were used to prepare and update the above
essay. The hyperlinks are not necessarily still active today.
"The Nash family: miracle baby," University of Minnesota Cancer
Malcolm Ritter, "Studies
show new ways to get stem cells," Associated Press, 2005-OCT-16, at:
Ian Sample, "New embryo test to screen for 6,000 diseases," The
Guardian, 2006-JUN-19, at:
Julie Wheldon, "Ethical row erupts over designer babies breakthrough,"
Daily Mail, 2006-JUN-19, at:
Sarah Boseley, "Public views on embryo genetic testing sought,"
"Consultation document on preimplantation genetic diagnosis," The
Human Fertilisation and Embryology Authority, at:
"Court lets couples create babies to cure ill siblings," The
Toronto Star, 2005-APR-29, Page A16.
Copyright © 1999 to 2007 by Ontario
Consultants on Religious Tolerance
Latest update: 2007-SEP-20
Author: B.A. Robinson