Early genetic testing puts more slip in slope

How would you respond to a patient or couple who requests preimplantation genetic diagnosis to achieve desired or preferred characteristics in their offspring? Would you offer your help or referral if the purpose were to create a savior sibling for an older child with medical problems?

Reply:

These questions bring to mind a scene from the 1997 movie "Gattaca." A geneticist is meeting with a couple as their eight-cell embryos float on a video screen overhead. The geneticist explains: "Your extracted eggs, Maria, have been fertilized with Antonio's sperm and we have performed an analysis of the resulting pre-embryos. After screening, we are left with two healthy boys and two healthy girls. Naturally, no critical predispositions to any of the major inheritable diseases. ... You have already specified blue eyes, dark hair and fair skin."

Science fiction gives us an estimate of what technical capabilities might emerge, as well as a guess as to how people will respond to new opportunities and powers. Since nothing is more important to most parents than their children, grappling with the potential for technical control over the nature of our children will remain enormously controversial ground.

The technical ability to detect fetuses with serious malformations and heritable conditions has expanded rapidly since its beginnings in the 1960s, now including a host of testing and imaging capabilities.

Traditionally, prenatal diagnostic technology has been used as a form of negative selection, that is, the ability to detect an abnormal fetus and terminate the pregnancy prior to fetal viability. Newer technology, preimplantation genetic diagnosis (PGD), offers the ability to perform positive selections, that is, the ability to select an embryo for desirable traits, as well as to discard those embryos with genetic abnormalities. This evolution is an example of a technology being developed for a readily justifiable purpose, but then applied to new arenas and, perhaps, across ethical boundaries.

PGD involves an embryo (or polar body) "biopsy" and genetic analysis of a single cell. Embryos destined to be affected with an unwanted condition are discarded or frozen while embryos free of the trait are selected for transfer to a woman's uterus.

In 2000, geneticist Ricki Lewis estimated that PGD was offered in more than 50 centers around the world for more than 100 genetic conditions.

The obvious advantage of PGD for some at-risk couples is the ability to start a pregnancy without the prospect of a termination decision four to five months down the road.

A newer application of PGD involves embryo selection for a specific HLA type (human leukocyte antigen) so that the child will be a match for a sibling who needs a bone marrow transplantation.

This approach was successful for a newsworthy case involving Fanconi anemia several years ago. More recently, a series of cases was reported in which HLA-matched donors were born following PGD. Other controversial applications are embryo selection against adult-onset conditions like Huntington's disease, gender selection, and selection against conditions like deafness. Gattaca-like capabilities are still beyond reach, but to the extent that traits like intelligence and athletic ability and body characteristics have significant genetic foundations, such traits may be predictable for a future child with greater or lesser degrees of accuracy.

While several professional societies discourage the use of prenatal diagnosis for gender selection or other nonmedical conditions, there are no formal standards for the use of PGD that delineate its ethical applications. For the most part, physicians, scientists, and prospective parents are free to develop and use this technology as they see fit.

To address the ethical issues raised by this emerging technology, we need to consider the basic justification for preimplantation genetic diagnosis, or any form of prenatal diagnosis for that matter. One approach to ethical analysis asks the deceptively simple question of whether the benefits of technology use exceed the harms. Some suggest that prospective children benefit from prenatal diagnosis. Parents often say that they are interested in prenatal diagnosis for the benefit of the future child.

These issues have been addressed legally and philosophically through "wrongful life" lawsuits that have been brought on behalf of affected children against physicians who provided inaccurate or insufficient genetic information to their parents. The children claim that, but for the negligence of the physician, their lives of suffering would have been prevented.

The majority of these suits have not been successful for basic philosophical reasons. It simply strains logic and common experience to claim that the majority of individuals with heritable conditions do not benefit from their lives. There may be a few conditions that could cause individuals with the disease to say, "I wish I had never been born!" But these are not many.

Similarly, proposing social benefits for preventing individuals with heritable (and expensive) conditions pulls society onto very thin ice.

Preventing the social burdens of disease by eliminating those with diseases is otherwise not an acceptable strategy. In this case, "those with diseases" are embryos or fetuses, so this strategy may be more acceptable for the many who do not think embryos or fetuses have full moral status. Yet most people believe that embryos and fetuses have some moral status, so the ethical balancing of benefits and harms is not eliminated.

Many benefits to society flow from the existence and contributions of people who happen to have disabilities, including the benefit of diversity itself, so it is simply a false economy to claim that social welfare will be improved by preventing people with less-than-desirable traits.

The most compelling justification for prenatal diagnosis is to assist prospective parents in avoiding the difficulties of raising a child with serious impairments. This justification is not founded on a simple philosophy of parental autonomy.

Prospective parents have strong negative rights to be left alone with their reproductive decisions, but they do not necessarily have positive rights to obtain any or all prenatal diagnostic services for any purpose they wish. This is simply because these diagnostic services are developed, provided, and funded by moral agents -- doctors, nurses, counselors, etc. As moral agents, professionals have the prerogative of deciding the scope of their services based on personal and professional values. Therefore a parent's desire to use prenatal diagnosis does not, in and of itself, create a duty for physician participation.

For negative selections, that is, selections against an undesirable trait, there is the weighty ethical concern of the destruction of prenatal life. Again, one need not believe that embryos or fetuses have full moral status to be concerned about such destruction for less-than-compelling reasons. One can take a stand against "trivial" uses of prenatal diagnosis both because of the destruction of prenatal life and the use of scarce resources for marginal interests (although the definition of "trivial" remains a problem).

A more subtle and speculative harm associated with positive selections is harm to the children who are selected. Selection of children by parents for their own purposes in life may pose a threat to the child's autonomy as he or she charts a course in life. Selection for traits that normally would be beneficial could be seen as a burden by the child as parents bear down to achieve their goals and to make their investments worthwhile. Uninhibited selection of children may threaten the very core of the parent-child relationship, that is, unconditional love.

What are the implications of this argument for PGD for HLA type? In this situation, the parents want to select a child not for the qualities she would have as a person, but for her HLA-matched cells. Once the cells are harvested for transplant, any special expectations for the child would cease. The child is being used for her cells, but presumably she is not used only for her cells. That is, she remains a new baby in the family. So the deeper problems inherent in the positive selection of children do not pertain to this application.

PGD for the HLA selection looks like a win-win scenario -- a new life is created and a threatened life can be saved. But does accepting this type of positive selection place our society on a slippery slope to other kinds of dangerous selections? Possibly, but only if we continue to use this powerful technology without a thorough analysis of its ethical justification and without professional standards that clearly embody a strong set of moral values.

Jeffrey R. Botkin, MD, MPH, Professor of Pediatrics and Medical Ethics, associate vice president for Research Integrity at the University of Utah