Preimplanation
Genetic Diagnosis
Preimplanation Genetic Diagnosis
(PGD) is the cellular and molecular screening which determines if the In-vitro
fertilized embryo will be used in the uterus.
PGD is available since the early
90es and since then PGD was performed on more than 15000 children. It is mostly
used to identify
hereditary diseases and
anomalies. Also the gender can be determined by this
diagnosis.
Before making the decision to undergo
such procedures parents are advised to get a genetic screening to evaluate the
risk of transferring the genetic disease to their offspring.
When parents make the decision to
use PGD they will have to go through an In-Vitro fertilization, which means that
an egg cell will be taken and fertilized outside of the body.
After that the egg will be kept
under certain conditions so that the embryo will develop in to the cleavage
stage embryo. At the third day a single blasphomere is removed from the cells
for the genetic diagnosis. At this point it will be ascertained which embryo
will be used.
The embryos which does not show any
abnormalities will then be planted in to the uterus. (Molina B Dayal)
The conditions which are diagnosed
by PGD are Sex linked diagnosis, which accrues when the mother is a carrier of
the disease and could transfer the disease over the X-chromosome to a male
offspring. There is also a 50% chance that if the embryo turns out to be female
that this child also will be carrying on the disease.
Another condition which is
diagnosed by PGD are single gene defects. Under this are falling diseases which
are transmitted over only one gene.
The last condition is chromosomal
disorder which is a chromosomal rearrangement or translocation which leads for
example to miscarriage.
People who benefit from it are for
example woman in advanced maternal age because the risk of having an
abnormality is rising with age.
Also couples with a history of
miscarries benefit from PGD. However PGD does not improve the pregnancy rate
but increases the likelihood of pregnancy at term.
Another group which profits from
PGD are man with infertility. The risk of chromosomal abnormalities rises with
the condition of sever infertility. (Molina B Dayal)
Objectors however argue that all
the fertilized eggs could develop into a baby under the right conditions and
that it is unethically that the unsuitable egg cells will be destroyed.
One main argument that religious
people bring up is that life starts at conception and destroying the unwanted
egg cells is equal to murder.
Others argue that the disorder will
not develop by 100% chance and that most diseases will develop at an older age
and that at that time a cure might be found.
Others again are afraid that PGD
could develop into producing babies which will be used as spare parts. (B.A. Robinson )
Even though that I think that some
of the concerns are justified I still think that the advantages outweigh the
disadvantages.
For example, nowadays the most
common procedure used to check for abnormalities is prenatal diagnosis. First
this procedure itself can cause harm to the unborn child and secondly if at
this point of time an abnormality is diagnosed, the parents are left with the
struggle to choose if they want to abort the child. So at this point I do not
understand the objectors because aborting a child at this developing stage is
worse than checking beforehand, because at this point of time there is already
a developed baby present and the screening itself could already harm the baby.
Also I think parents want to give
their child the best starting conditions, so how does someone wants to refuse
this wish to the parents?
In my opinion an additional
argument to that is that if parents already know about their condition, does
someone want to force them to leave their child into their fate?
As well one of the biggest
advantages is that some of the recent diseases could be extinct with a regular
practice of PGD. Some people might say that it is against nature but no one
ever had an accurate definition of nature. So is using medication and changing
life so nowadays people can reach the age of 80 also against nature?
And do we really have to put people
thru the struggle to live with this kind of abnormality to “protect” nature?
Also the argument of killing a
human being when destroying the unsuitable embryos is not valid in my opinion.
People might argue with this because of their religious believe but the start
of live needs a scientific definition. So in my opinion there could be two
starting points of live, the heart beat which starts after the third week after
fertilization or the brain activity which accrues at first at the brain stem at
the 54 day.
So by this definition there is no
live after fertilization so thereby there is no dead by disposing the
unsuitable egg cells.
I do agree that humanity has to be
careful about choosing the right path and how we will use this procedure in the
future. But at this point of time the preimplanation genetic diagnosis is the
best alternative which is available.
Molina B Dayal, „Preimplantation
Genetic Diagnosis“, December 30, 2015,
http://emedicine.medscape.com/article/273415-overview
B.A.
Robinson , „Pre-implantation genetic diagnosis (PGD) &
haplotyping (PGH)Current status; Objections; Advantages“ , September 20, 2007,
http://www.religioustolerance.org/abo_pgd2.htm
