Preimplantation Genetic Diagnosis - A Questionable Procedure
IMEW Briefing, No. 3, January 2003
Preimplantation genetic diagnosis (PGD) is genetic testing of embryos created by in vitro fertilisation (IVF). In Germany PGD is prohibited by the Embryo Protection Act. In many other countries it is allowed.
From the medical point of view PGD is a stressful procedure which is time-consuming and expensive, has a low success rate and carries a high risk.
Couples who wish to use PGD need to undergo in vitro fertilisation (IVF). The woman is treated with hormones so that several egg cells mature. Approximately 12 egg cells are required for PGD. These are collected and fertilised in the laboratory. After three days one to two cells are removed from the embryos and genetically tested. Only embryos not affected by the genetic disorder in question are transferred to the woman's womb.
The success rate of PGD is low. According to an international survey, only 14 % of the couples undergoing PGD treatment gave birth to children after several attempts (ESHRE 2001). On the other hand the risks of IVF are considerable. Many women have severe side-effects as a result of the hormone treatment. In addition there are the operative risks and probably an increased risk of cancer. As several embryos are usually implanted, multiple pregnancies (27 %) and premature births are common. Moreover, the reliability of genetic testing of individual cells is limited. Prenatal diagnosis (PND) is therefore usually performed for confirmation. According to the study mentioned above, four of 279 children were born sick or disabled and four pregnancies were terminated after PND (ESHRE 2001).
Initially PGD was introduced as an alternative to PND for couples with a high risk of giving birth to a child with a genetic disorder or disability. This indication is also being discussed in Germany. Internationally, PGD is now used just as often to improve the prospects of success of IVF by avoiding implanting embryos which are likely to lead to a non-viable pregnancy. In individual cases it is used for gender selection for social reasons or to create a child which is suitable as blood or bone marrow donor for a sick sibling.
Rights of affected couples versus embryo protection?
The central argument in support of legalising PGD here in Germany is that termination of pregnancy after PND could be avoided. With PGD, couples with a family history of genetic disease could fulfil their desire to have children without having to go through a trial pregnancy. Some people are even of the opinion that affected couples have a right to this.
Naturally no-one should be prevented from starting a family through social or state constraints. However, this does not mean that couples automatically have a right to medical assistance to achieve this end. While the desire of affected couples to have children must be taken seriously, this does not imply an inalienable right to PGD if there are strong arguments against the procedure.
As PGD involves the rejection of unsuitable embryos, the destruction of these embryos is part of the procedure. It can therefore be argued that legalisation of PGD contravenes the fundamental principle of protection of unborn human life.
Nevertheless, the "moral status" of the embryo is one of the most controversial issues in our society. For many people the fertilised egg already has a right to life because it has the potential to become a human being. Other people see the early developmental stages as nothing more than a collection of cells which is not worthy of protection. However, restriction of the need for protection on the basis of the stage of development would require the specification of generally valid criteria. Criteria defining when human life begins, such as nidation, development of the brain or birth, are more or less arbitrary and leave questions about their ethical quality unanswered. Ethically relevant criteria for human life worthy of protection, such as the ability to feel pain, the ability to have a concept of self or the ability to value one's existence, are always applicable to born individuals too.
It is often argued that it is illogical to effectively tolerate abortion while providing comprehensive protection for embryos created in the laboratory. This disregards the fact that pregnancy is not comparable with any other life situation. An unwanted pregnancy inevitably affects a woman's entire physical and mental integrity. Protection of the life of the fetus against the will of the mother would only be possible at the cost of violating the mother's rights. Legislators have refrained from doing this, for good reason. A woman who decides to use PGD is not pregnant. There is no unavoidable conflict between the woman's rights and protection of the embryo. This conflict would be deliberately brought about through the use of in vitro fertilisation with the aim of selecting only the "healthy" embryos.
Social consequences of PGD
Almost all people in favour of PGD want to restrict the procedure to serious disorders. However, this is not possible. Experience with PND has shown that a general clause which makes the expected burden on the mother the criterion would not provide effective limitation. Review of each individual case by a central ethics committee, as has been suggested by representatives of the medical profession, would constitute a scarcely justifiable invasion of the autonomy of the couples concerned (Bundesärztekammer 2000). Who apart from the couple itself can presume to judge whether having a child with a particular disorder would be a "reasonable burden"? A list of specific serious disorders for which PGD is considered acceptable would imply discrimination against people living with these disorders.
It is to be feared that social constraints will make a truly self-determined decision for PGD impossible in many cases. Sociological studies have shown that decisions for PND are often made in response to indirect or even direct pressure from the social environment. While it is highly unlikely that women with a "normal" risk of giving birth to a sick or disabled child will voluntarily submit to the stresses of IVF and PGD such constraints could operate in the case of high-risk couples or couples undergoing IVF treatment anyway.
PGD is often said to have a discriminatory character with regard to people with disabilities. It would be going too far to maintain that the decision of an individual couple to use PGD constituted discrimination against the group of people with disabilities. However, what can justifiably be seen as discrimination would be the social establishment of a procedure the explicit goal of which is to prevent the existence of sick and disabled people. That this would be the expression of a value judgment of society about people with disabilities can scarcely be disputed.
It is also to be feared that PGD will pave the way for further procedures such as embryo research and germ line engineering. Although this could be prevented by restrictive legislation it can be assumed that the legalisation of PGD would lower the moral threshold for legalisation of other procedures. If PGD were to become legal, "supernumerary" embryos would be created for the first time in Germany. This could precipitate other desires. Moreover, international developments suggest that the extension of PGD, for example to routine screening in IVF and positive selection of desired traits, is likely.
(Translation by Hilary Coleman)
Bundesärztekammer: Diskussionsentwurf zu einer Richtlinie zur Präimplantationsdiagnostik, Februar 2000.
Bundesministerium für Gesundheit (ed.): Fortpflanzungsmedizin in Deutschland, Schriftenreihe des Bundesministeriums für Gesundheit Band 132, Nomos, Baden Baden 2000.
Deutsches IVF Register, Jahrbuch 2001.
Düwell, Marcus und Mieth, Dietmar (guest ed.): Von der Pädiktiven zur Präventiven Medizin - Ethische Aspekte der Präimplantationsdiagnostik. Ethik in der Medizin 11, Supplement 1, 1999.
Düwell, Marcus und Mieth, Dietmar (ed.): Ethik in der Humangenetik. Die neueren Entwicklungen der genetischen Frühdiagnostik aus ethischer Perspektive. Francke, Tübingen 2000 (2nd ed.).
ESHRE 2001: Preimplantation Genetic Diagnosis (PGD) Consortium: data collection III. Human Reproduction 15/12.
Geyer, Christian (ed.): Biopolitik. Die Positionen. Suhrkamp, Frankfurt 2001.
Graumann, Sigrid (ed.): Die Genkontroverse. Wohin die Reise geht - Grundpositionen. Herder, Freiburg, 2001.
Kollek, Regine: Präimplantationsdiagnostik, weibliche Autonomie und Recht. Tübingen 2002 (2nd ed.).
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