Monday, May 31, 2004
The Genetics and Public Policy Center at Johns Hopkins University has prepared a report on PGD, entitled Preimplantation Genetic Diagnosis: A Discussion of Challenges, Concerns, and Preliminary Policy Options Related to the Genetic Testing of Human Embryos. The also did a survey, Genetic Testing of Embryos (144KB PDF) which shows that 61% of the US public thinks that it is OK to use PGD to produce a savior baby, but 57% disapprove of its use for gender selection.
When PGD is done, unfertilized egg cells are removed from a woman, then mixed with sperm cells. Early embryos develop from this process of in vitro fertilization. The embryos are then tested until one (or more) is found that meets selection criteria. In the case of gender selection, the criteria would include the presence or absence of a Y chromosome. Unlike sperm sorting, this method results in near-perfect reliability of gender selection.
Their PGD report summarizes the most important and potentially contentious ethical issue as follows:
Other ethical issues are:
- Potential for changing the attitudes of the parents toward the child who was born via PGD
- Potential for changing the attitude of the child who was born via PGD
- Potential for changing the family dynamics between the child born via PGD, and any other children of the couple who were born without PGD.
- Potential for erroneously selecting the wrong gender -- which could invoke any or all of the three items above
- Potential for emotional dehumanization or loss of dignity to the species as a whole, arising from out efforts to intervene in what previously was left solely to nature (or a supreme being)
- Potential for producing a child who develops abnormally as a result of the procedure.
- Potential for producing a child with some defect not related to the procedure, and that was not screened out by the PGD
Presumably, the fist four risks in the list are similar to those facing anyone who is pregnant. There are many factors that can influence people's attitudes, or family dynamics. The magnitude of these risks probably is not great, given that they are the kind of thing that any family can struggle with, even without having used PGD. The risk of item #4 is a risk that is inherent in any technology. Presumably, the couple will have been informed of the risk of human error, and will be prepared to accept that risk.
Item #5 is a tricky one. It is an intangible risk that will bother some people and not others.
The BrothersJudd weblog has a post entitled Man as Meat, which, as the title suggests, indicates that the brothers are concerned about the dehumanization of humanity through the use of biotechnology. They link to a long review of a book, Our Posthuman Future, by Francis Fukuyama. In it, they say:
Related to this is the concern that, somehow, preselecting the gender of a child is encroaching upon territory that is the sole purview of a supreme being; or, for the more secularly-minded folks, it could be phrased as an incursion into something best left to nature. Until recently, the uncertainty about the gender of the child has been an universal part of the experience of pregnancy and delivery. Even now, with the more commonplace techniques of ultrasound, amniocentesis, and chorionic villus sampling, parents do not know the gender of the child until well into the pregnancy. Some parents chose to be told; others choose to wait. But in all cases, there is a prolonged period of uncertainty. Is it dehumanizing to remove this uncertainty? It seems to me that some people might believe so, but personally, I do not. Direct intervention into one aspect of pregnancy still leaves much mystery and inspiration of awe, and does not make the process so clinical as to be inhuman.
Item #6 is something that has been addressed, although only in retrospective studies. Probably the only way to get a definitive answer would be to select a random sample of the population, offer them no choice as to whether to get pregnant, and divide them into two groups. One group gets PGD, the other gets no intervention. Obviously, such a study would be unethical to perform, so it will not be done. The existing information (link requires free registration) suggests that there is a higher risk of malformations in offspring who result from in vitro fertilization. The baseline risk for a natural pregnancy is about 4.2%. The risk for IVF children is 9%. Because this is based upon a retrospective study, it is not possible to draw firm conclusions. Also, it may not be applicable to PGD when used for gender selection. Couples using IVF because of infertility may be at a higher risk than those who use PGD for bender selection. Another factor to consider is that a large number of embryos never implant, or they abort spontaneously. Some of these fail to progress to term because of genetic problems. Use of assisted reproduction technology might sidestep some of the screening that takes place naturally. By this I mean that nature has screening mechanisms that reduce the risk of carrying an abnormal fetus to term; it is possible that human intervention could reduce the effectiveness of this process.
Item #7 is another risk that is inherent in any pregnancy, related to #6. Using PGD for gender selection, any embryos that look funny will not be implanted in the uterus. This will screen out some, but not all, defects. Therefore, it is possible for a woman to have PGD done, and still have an abnormal child. The difference between this and a natural pregnancy is that the parents could have an unrealistically optimistic expectation for delivery of the exact baby they want, and they might not get it.
I don't see risks 1-7 as reasons to ban or to regulate the procedure, other than to make sure that the risks are explained in the informed consent process. This leaves us with the first issue, specifically, that some of the embryos created in the process will be destroyed. To some, this is ethically equivalent to murder; to others, it is a replication of something that happens all the time anyway, and is not a matter of concern. in the process of normal procreation, as many as half of all fertilized eggs either never implant, or spontaneously abort. In the case of nonimplantation, the woman never even knows about it. In the case of spontaneous abortion (miscarriage) this may or may not be known to the woman, depending on how far the gestation goes.
The ethical problem here often is boiled down to the question: when does life begin? The idea here is that, if we can define the moment that life begins, we can use that moment as the dividing line between permissible intervention, and those interventions than are not permissible. One could argue that an individual sperm or egg cell is alive, in the sense that a single-cell organism is alive; or, one could argue that life begins at conception; or, one could argue that life begins when the embryo is capable of survival outside of the uterus. Still others would argue that life begins at birth.
There are problems with all of these arguments. Ununited sperm and egg cells have only half of the genetic material needed to produce a fully-grown human, but using cloning technology, even an unfertilized egg could potentially give rise to a human. Defining life as beginning at conception raises problems, because often there is no way to know when a conception has occurred, and the product of the conception is not capable of independent life for many weeks. Likewise, there are problems in using the time of the capability of independent life. There is no clear-cut divider. As the fetus develops, past a certain point, the probability of independent survival progresses from zero to something approaching -- but never attaining -- 100%. Using the time of birth has problems, too. Whether you define the the time of birth as the moment any part of the fetus emerges from the birth canal, or the moment when the last part emerges, there will be people who argue that a fetus of 38 or 39 weeks gestation should be accorded the same rights as a person already walking around.
So far, no one has been able to resolve this question in a way that satisfies everyone. Personally, I do not think that the problem can be resolve using the "when does life begin?" approach. I also do not find it satisfactory to argue that it is permissible to destroy an early embryo just because it is something that happens all the time anyway. Everyone dies eventually; this does not mean that murder is OK.
Thus, we are left with the question: at what point in the process, from the generation of gametes (eggs and sperm cells), through conception, implantation, gestation, and delivery, does it become unethical for us to stop the process? If the answer cannot be reached using science (When does life begin?) it must be reached using some other means. For some, the usual legal process is satisfactory: take the case to the supreme court, and see what they say. Others will turn to religious, philosophical, or sociological means. The fact is, the public is deeply divided on this issue, and we cannot wait for a consensus to emerge. These issues are with us today. As a result, we are left with the legal process to decide the issue. So far, there is no law that specifically refers to gender selection via PGD, so people who wish to use this method are free to do so.
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