Genetic Testing and Screening: III. Population Screening

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III. POPULATION SCREENING

One of the sequelae of the Human Genome Project has been a resurgence of interest in using clinical genetic testing tools at the population level to promote public health goals (Khoury, 1996; Coughlin). This resurgence raises a number of bioethical issues for public health policy-makers and the health professionals involved in delivering genetic services: questions about the limits of public health authority in this domain, the justice of population-based genetic interventions, the social costs of such screening, and the ethical allegiances of the clinicians involved. In this entry, these issues will be reviewed through the lens of one problem that seems to animate all the rest: the problem of defining prevention for the purposes of a public health genetics.

Background

Mass genetic screening programs have a relatively long history amongst modern genetic services, starting with the screening of newborns for prophylactic therapy against metabolic disorders in the 1960s and continuing into adult carrier testing programs for recessive genetic diseases such as Tay-Sachs (Kaback; Blitzer and McDowell), sickle cell disease (Bowman; Duster), and the thalassemias (Angastiniotis, Kyriakidou, Hadjiminas) in specific at-risk populations in the 1970s. The early adult screening programs shared two features that warranted, and garnered, significant attention within bioethics and health policy (National Academy of Sciences; President's Commission). First, they targeted specific socially-defined populations, which raised issues of group-specific stigmatization and discrimination (Kenan and Schmidt; Markel). Second, the information about carrier status the screens provided was primarily useful for reproductive rather than therapeutic decision-making, raising issues of parental autonomy, paternalism and procreative choice (Juengst, 1988; Thompson et. al).

The 1980s witnessed a second wave of adult genetic screening programs, aimed at detecting pregnant women at risk for delivering children with genetic birth defects and chromosomal abnormalities (Cunningham and Kizer; Haddow, Palomaki, Knight). These programs are intended to have universal application within populations, and have been routinized into the obstetrical care of pregnant women in many countries, raising issues of voluntariness and informed consent (Press and Browner; Marteau). They have also provoked an outspoken reaction from the community of people with disabilities, who argue that such programs work against attempts to reform social attitudes about disability (Parens and Asch).

Today, these three traditional forms of population genetic screening—newborn screening, risk-group carrier testing, and pregnancy screening—continue to make up the vast bulk of population genetic screening activities that are funded and evaluated as state public health initiatives. At the same time, the disease targets of these screening efforts have changed, as public health programs see rationales for shifting specific tests from one form of testing to another. Thus, many states have added sickle cell testing to their universal newborn screening panels (Olney), and calls have been made for universal screening of pregnant women for maternal PKU (Kaye, et. al) and fetal hemoglobinopathies (Cuckle). Moreover, genetic tests originally reserved for clinical use in families at risk for diseases such as cystic fibrosis or fragile-X syndrome have also begun to be used as population screens, both as part of newborn screening panels and prenatal testing programs (Caskey; Cuckle). In all such shifts, the tests have moved in the direction of earlier and more universal screening.

The new wave of interest in public health genetics generated by advances in genomic science focuses on tests that would have universal application within multi-ethnic populations, like pregnancy testing, but, like newborn screening, would measure the tested individuals' personal risk for disease, with an eye toward prophylactic action. Moreover, in addition to screening for signs of rare genetic diseases, like all the traditional forms of screening, the emphasis is on the detection of molecular markers that confer statistically increased risks for more complex, and more common, chronic diseases of adulthood, like coronary artery disease, cancer, or diabetes (Khoury, Burke, Thompson).

The discussion of using these new tests as public health tools has been dominated by questions of feasibility and utility (Omenn, Holtzman). As one review concludes:

Several issues must be addressed, however, before such tests can be recommended for populationbased prevention programs. These issues include the adequacy of the scientific evidence, the balance of risks and benefits, the need for counseling and informed consent, and the costs and resources required. Ongoing assessment of the screening program and quality assurance of laboratory testing are also needed. (Burke et al., p. 201)

These concerns mirror those expressed in the literature on using predictive genetic risk assessments as a part of medical care in clinical settings (Geller, et. al.). The use of these same tests as population screening tools would place them in the larger context of the existing population genetic screening programs, however, and it is in that context that they become most bioethically challenging. As these tests become integrated into the shifting mix of existing population-based prevention programs, they expose fundamental questions about the goals of the enterprise that have not been so apparent in the past. What should population-based genetic screening strive to accomplish, and by what criteria should one measure success?

Phenotypic and Genotypic Prevention

The ubiquitous answer to these questions in the literature of public health genetics is the prevention of disease, a classic public health goal. This goal is operationalized as the reduction over time in measures of the morbidity and mortality caused by the target disease within the screened population. To flesh out the kinds of interventions that should be counted in those measures, most authors appeal to the public health field's traditional lexically-ordered scheme of primary, secondary and tertiary levels of prevention, and attempt to categorize population genetic screening tests accordingly. Thus, for example, one public health guidance document states:

Primary prevention genetic services are services intended to prevent a birth defect, genetic disorder, or disease before it occurs. Genetic counseling is a form of primary prevention. Genetic counseling provides couples with information about their pregnancy, and reproductive risks and pregnancy options. Secondary prevention genetic services are services intended to prevent the unfavorable sequelae of an existing disorder or genotype. Newborn screening is a classic example of secondary prevention. Tertiary prevention genetic services are services aimed at ameliorating the unfavorable consequences of existing disorders, through enabling services such as parent-to-parent support and empowerment. (Kaye et al.)

Using this scheme provides a logic for shifting tests into the newborn, prenatal and preconception stages, because traditionally "primary prevention" has been considered the ultimate goal of public health interventions.

Unfortunately, this scheme also introduces an important equivocation into public health discourse between two different ways in which genetic screening might be thought to be preventive: genetic screening as a technique for preventing the expression of a genetic disease in an individual and genetic screening as a technique for preventing the inter-generational transmission of disease genes. For convenience, the first kind of prevention may be called phenotypic prevention, since its goal is to prevent the manifestation of a particular clinical phenotype. Similarly, the second sort of prevention may be called genotypic prevention, (or geno-prevention) because its goal is to prevent the birth of people with particular genotypes. Equivocating between these two senses of prevention in discussions of population screening results in the attribution of genotypic preventive goals to public health genetics. That, in turn, generates the deeper questions of public authority, social justice, and professional allegiance that animate bioethical concern in this area.

Phenotypic Prevention

The dominant rhetoric of contemporary public health genetics stresses phenotypic forms of prevention as the primary goal of population genetic screening (Coughlin). This is not surprising. Phenotypic prevention is a straightforward medical pursuit that few would criticize: it is designed to further the health interests of individual patients by allowing them to avoid foreseeable medical problems. Almost all public health efforts outside of population genetic screening employ this concept of prevention, and even within public health genetics there are typical phenotypic prevention efforts at each of the three levels of prevention (Holtzman).

The concept of phenotypic prevention rests on several assumptions, however, which are worth unpacking. First, phenotypic prevention assumes that there are people who survive the intervention to benefit from having their foreseeable health problems forestalled. Thus, for example, proposals to prevent occupational disease by firing all susceptible employees instead of cleaning up the workplace seem inherently wrong-headed. Second, it assumes that diseases are best defined at the level of the actual health problems that they occasion for individual people, rather than in terms of their preclinical etiology. Otherwise, preclinical interventions like dietary changes would be directly curative, not prophylactic. Third, it assumes that diseases are distinct from the people they burden, so that it becomes appropriate to use metaphors of external defense to describe the beneficiaries, as vulnerable to attack by disease without the protection of prevention.

Along with these assumptions, the concept of phenotypic prevention enjoys a high degree of moral authority as an imperative for medicine and society. In fact, the promise of phenotypic preventive measures to "protect the helpless from harm" has been compelling enough in our society to allow both primary and secondary forms of phenotypic prevention to become established in effectively mandatory programs as a matter of public policy (President's Commission).

Of course, if primary prevention is the prevention of the onset of a genetic disease in an at-risk patient, then most of the preconception, preimplantation, and prenatal genetic screening interventions usually classified as primary prevention strategies cannot, in fact, qualify for that status. Neither pre-implantation embryo screening nor selective termination can serve to prevent the onset of a heritable disease in affected patients. At most, they are capable of preventing cases of a disease within a family (or a population), by allowing parents (or a society) to avoid the birth of at-risk individuals.

This conceptual confusion does lead to some cognitive dissonance in the literature. The Centers for Disease Control and Prevention, for example, illustrates the concept of primary prevention in genetics by listing "medical and community-based interventions focused on carrier detection and premarital counseling as ell as on prenatal diagnosis and pregnancy termination," but then adds the confusing parenthetical remark that "(This last may not be considered primary prevention)" (Khoury et al., 1997, p. 1718). It is also telling that one can find carrier screening, intrauterine diagnosis and selective termination classified in the literature as an example of primary prevention (Kaye, et. al.), secondary prevention (Wertz, Fletcher, and Berg), and even tertiary prevention (Porter)! Clearer thinkers: Holtzman (1989) sets carrier screening, amniocentesis and selective termination outside of preventive medicine's traditional trichotomy, by labeling them as a form of genetic disease avoidance. Similarly, the editor of the journal Community Genetics declares that:

Calling termination of pregnancy after prenatal diagnosis "prevention" is a perversion of terminology. I suggest that we should use the term "reproductive choice." By analogy with prevention, one might define different levels of reproductive choice. Primary reproductive choice would then consist of actions to avoid conception of affected offspring, while secondary reproductive choice would bar implantation or birth of affected embryos and fetuses. (ten Kate, p. 87)

In fact, when they incorporate reproductive genetic screening programs into their menu of preventive interventions, public health geneticists have been forced to slip between two very different senses of prevention. They have conflated screening to prevent the phenotypic expression of a genotype in a particular patient (phenotypic prevention) with screening to prevent the birth of individuals with a particular genotype (genotypic prevention). These two visions of screening reflect quite distinct concepts of disease prevention, with different histories within healthcare, different philosophical assumptions, and different degrees of moral authority.

Genotypic Prevention

Genotypic prevention is a pursuit that is much more controversial than phenotypic prevention. That is understandable, for several reasons: First, it is often hard to know what ends genotypic preventive measures are intended to serve. Genotypic preventive measures are usually described as a way of furthering the procreative interests of prospective parents, by allowing them to avoid the birth of individuals with foreseeable health problems (like AID following adult carrier testing for cystic fibrosis mutations, or selective termination following intrauterine diagnosis of Down's syndrome).

At the same time, these same interventions are often evaluated in terms of the economic and public health interests of society, according to their ability to reduce the incidence of genetic disease in a population. Thus, the famous "success stories" of genetic screening (like the Mediterranean carrier screening programs for beta-thalassemia, or Tay-Sachs screening in the Ashkenazi-American population) most often counted as successful in terms of these societal criteria (Rao, et. al.; Blitzer and McDowell). In those stories, in fact, the commitment to channeling screening efforts through the individual's voluntary reproductive choices is itself portrayed as simply a savvy strategy for achieving the profession's underlying goal of reducing society's healthcare costs (Caskey; Palomaki; Chappele, et. al.).

Secondly, whether geno-prevention is pursued in the cause of family planning or the public health (or both), it must make two sets of related assumptions. First, it assumes that the diseases it prevents are best understood at the level of the genotype, rather than through the pathophysiology of their expression, just as AIDS is understood in terms of its causal HIV infection rather than the infection's clinical sequelae. Understanding genetic disease through the lens of the germ theory in this way means that the language of "molecular disease," and "DNA-based diagnosis" seems apt, and it makes sense to contrast preventing the vertical transmission of pathogenic disease genes with palliative or symptomatic interventions like low phenylalanine diets.

Second, proponents of geno-preventive efforts must assume important personal (or social) value judgments about the burden of the cases of disease being prevented. Genes are not, like germs, external infectious agents that can be kept (or cleaned) out of a living person's body. Instead, genotypic prevention has to involve avoiding the birth of individuals conceived with the pathological genotype. The beneficiaries of such an intervention cannot be the individuals whose births are avoided: if the genotypic transmission has been successfully prevented, there can be no such individuals.

That means that to justify geno-prevention someone (parents or society) must make the judgment that the burden of coping with cases of a disease outweighs any other value that individuals with a given genotype might bring to a family or community, and warrants action to exclude individuals with those mutations from the lives of the wild type.

Finally, genotypic prevention already has a bad track record as a social and professional goal. Genotypic prevention has been accepted before as a societal imperative, on the coat-tails of the public health movement's successes with the primary prevention of infectious disease (Allen). The "Eugenics Movement" of the first half of the twentieth century is remembered primarily for the discriminatory immigration restrictions and coercive sterilization laws it produced (Reilly), and the ease with which it was appropriated to support genocide (Muller-Hill). The horrific consequences of ranking genotypic preventive goals over individual interests still effectively undermine any claims to moral authority it might make.

Unfortunately, as its controversial features already suggest, to the extent that population genetic screening becomes associated with a professional allegiance to genotypic prevention, it inherits all the history, assumptions and moral liability of that concept, and the prospects for a well-reasoned public assessment of its merits dim considerably.

Against this background, the professional confusion over the true goals of contemporary genotypic prevention services and the fact that all geno-preventive services require the judgment that some genotypes are predictably burdensome enough to others to outweigh any other potential their bearers might have, makes it easy for critics of new approaches to genotypic prevention to remind the public of the excesses of the historical eugenics movement, and label any new efforts accordingly, with powerful political effect (Hubbard).

Moreover, inviting external political challenges is not the only trouble that endorsing genotypic prevention would create for public health genetics. it would also create substantive philosophical tensions within the field which could threaten the ethical integrity of the field. Since genotypic prevention is also unnecessary as a rationale genetic screening and counseling services, some argue that it is time for public health authorities to explicitly eschew this old eugenic legacy as a professional goal.

Ethical and Social Implications

As a professional ethical matter, accepting genotypic prevention as a proper goal of public health genetics has chilling implications. Expanding the geneticist's preventive goals of genetic medicine to include reducing the incidence of pathological genotypes broadens their responsibilities beyond their presenting patients to the next generation's aggregate population. Since the latter will always be a bigger group, its preventive health needs will always be greater by at least some scores (e.g., disease care costs), and therefore, for some, more compelling. This makes it very easy for genetic medicine to elevate what began as a serendipitous "by-product" of its services—the reduction of disease burden and cost to society—to a central position within its mission, without even noticing when it does so.

Again, such criteria do have a long history in applied human genetics, as basic ingredients in the various programs of "negative eugenics" this century has witnessed. They even continue to be explicitly used by some genetic services programs seeking to justify their public support in economic terms (Chappele, et al; Cuckle). As a result, there is no need to guess at the internal dangers that adopting such ideals would pose for the professional ethics of genetic medicine: the experiment has already been conducted. Experience shows that there are at least four important hazards for the profession:

1. First, the field would have to decide where within the spectrum of human genetic variation to define the pathological genotypes it would seek to prevent (Juengst, 1988). Most of the proponents of preventive genetic screening programs skirt this problem by stipulating that they are only talking about "severe congenital abnormalities" that produce "serious handicaps." (Cuckle). These caveats address this line-drawing problem in a time-honored way, by appealing to common sense notions of severity. In doing so, the proponents of geno-preventive germ-line intervention are following the footsteps of authors like Dr. Nathan Fasten, when he wrote in 1935 that:

Here one must pause to comment that it is difficult to define clearly the standards of desirability or the standards of perfection in the human family. Even so, most normal persons would agree that the hopeless cases of physical and mental defectives, those that are incapable of care for themselves, particularly where it is certain that such defects are the results of hereditary factors, are no asset to society and should be eliminated as quickly as possible. (p. 354)

So far, Dr. Fasten appears to be anticipating the modern argument. However, Dr. Fasten's own list of what "most normal persons" should include in the class of "hopeless cases" is telling:

Here are included the feeble-minded, the insane, the paupers, the confirmed criminals, and the grave sex offenders. This group, in general, is a tremendous burden on society. Genetic evidence has been accumulating to reveal that most of these defects are due to heredity. Social workers also have discovered that from this stock the largest percentage of the dependent individuals originate. Geneticists and social workers, therefore, believe that nothing but good can come from efforts in the direction of the rapid elimination of this branch of society. (p. 355)

Of course, it would be unfair and anachronistic to insinuate that the contemporary advocates of genetic screening subscribe to eugenic ideologies like Fasten's: they clearly do not. The point in resurrecting him is simply to illustrate that it is often hard to know, in the thick of things, how much one's professional assessments of pathology are influenced by larger cultural ideologies and social values.

If genetic medicine is to prevent its practitioners from being lured away into other social agendas, it still must address the challenge of defining its domain. As the intensity of the debates over the prenatal sex selection as a professional practice already demonstrates (Warren), drawing these boundaries will involve just as difficult a set of value judgments as attempts to use genetic technologies to enhance specific human traits. As Dr. Fasten reminds us, without more operational definitions, rhetorical appeals to "severity" and the intuitions of the "reasonable person" will not help brighten any of the lines that will need to be drawn across the spectrum of human traits as genetic medicine's power matures.

2. Moreover, it is increasingly clear that preventing the birth of a particular "pathological" genotype will not always mean preventing a clinical health problem. The more we learn about human genetics at the molecular level, the more complicated the story becomes. One increasingly prominent feature of that story over the last few years has been the deterioration of the theory of specific causation within genetics (Strohman). Not only are most health problems "polygenic" to some degree, but even the traditional "single gene disorders" are turning out to be molecularly heterogeneous (Holtzman). As the number and variety of different specific mutations that can all cause the same disease increases, so does the challenge of detecting and correcting them all in a patient. Worse yet, the causal complexity works in both ways: even the paradigmatic examples of clean Mendelian "singe gene" disorders, like "recessive" cystic fibrosis and "dominant" Huntington's disease are turning out to be multifactoral enough that carrying one of their (multiple) pathognomic genotypes no longer guarantees that one will experience a problematic clinical syndrome (cf. Tsui; Benjamin).

In other words, genotypes are not turning out to function very well as germs. The complexity of their expression as health problems undermines the confidence with which a clinician can predict the occurrence of severe health problems from a DNA diagnosis. Since genotypic prevention is conceptually committed to a deterministic etiology of specific causation, geno-preventive measures risk making (and acting on) both false negative and false positive prognoses. This means that they also risk intervening unnecessarily in cases that the environmental forces of expression and penetrance would have naturally mitigated.

3. Thirdly, as a consequence of its deterministic assumptions, genotypic prevention cannot help stigmatizing genotypes, and (since they are inseparable) the people whom they mark, as undesirable or pathological in themselves (Markel, Parens, and Asch). This kind of reductionism, reducing personal identities to disvalued health problems and disvalued health problems to one stigmatizing sign, is at the root of much of the social discrimination that people with disabilities must already overcome (Fine and Asch). To have public health authorities endorse genotypic prevention as a goal can only exacerbate these challenges, because it provides a medical sanction for exclusionary attitudes.(Saxton; Kaplan; Faden). The concern is that, if a given genotype carries such a disvalue for health professionals, it would not seem unreasonable for the public to chastise those who avoid screening as "irresponsible reproducers" and hold them accountable for their recklessness by denying them opportunities or services, like medical care for affected offspring (Thompson, et. al).

4. Finally, the ways in which genotypic preventive goals tend to overshadow individual interests also endangers the therapeutic relationship within genetic medicine. To the extent that genetic services programs are evaluated in terms of their success to reducing the incidence of particular genotypes, genetic service providers will inevitably have an stake in seeing that their clients make the "right" reproductive decisions: i.e., decisions not to bear children at risk for genetic disease. This is a pressure that is already creating tension within medical genetics, as the field attempts to accommodate itself to healthcare delivery systems that are managed with societal healthcare costs in mind. For example, there has been a lively debate in the British medical literature about how genetic services should interpret the societal expectation that they will "pay their own way" within the national health budget (Chappelle; Clarke). Genotypic prevention, in other words, imports a professional goal that encourages practitioners to influence the reproductive decisions their clients make, despite their professed respect for the reproductive autonomy of those they serve.

Fortunately, all of these professional ethical risks—the subordination of professional integrity to social ideology, the inappropriate reliance on simplistic science, the professional disvaluing of human minorities, and the willingness to invade the sphere of reproductive privacy on behalf of society's economic interests—are dangers which human geneticists have succumbed to and overcome before (Kevles; Allen). Moreover, they are also the dangers in response to which the contemporary client-centered professional ethic of medical genetics has largely been shaped. In contemplating the future of germ-line gene therapy, it may be helpful to recall how this existing moral tradition handles the question of genotypic prevention, and consider its relevance for public health genetics. Doing so shows that genotypic prevention is not only a dangerous goal for genetic medicine to espouse, it is also completely unnecessary.

The Existing Tradition

One of the reasons it is easy to slip between the phenotypic and genotypic senses of prevention in discussing genetic medicine's goals is that the desire to bear children free from specific genetic diseases can and often does provide a rationale for prospective parents' interest in the specialty's services. But that does not pose a professional ethical problem for clinical geneticists: whether the intervention is genetic counseling, adult carrier screening, intrauterine diagnosis, pre-implantation screening, providers of genetic services can help parents achieve their geno-preventive goal in good conscience, because it falls within the sphere of reproductive choices which parents are free to make in a tolerant society. Even the sharpest critics of genotypic prevention as a professional and public policy will agree that individual decisions about these interventions are inseparable enough from core personal values and beliefs to warrant the same respect we give to other fundamental freedoms (of religion, for example)(Saxton; Fine and Asch).

However, it is not necessary to conflate the patients' goals with the professional goals of genetic medicine in order to display respect for reproductive autonomy. In doing so, advocates of increased screening blur a distinction that clinical geneticists providing more traditional genetic service have worked hard to clarify: the distinction between the profession's mission in providing its services and the personal interests of their clients (Botkin).

Clinical geneticists argue that their professional goals in offering reproductive genetic testing and counseling services have little to do with the content of the autonomous reproductive choices that their clients make. Their mission is to treat a special class of reproductive health problems their clients face as prospective parents: the reproductive planning problems posed by their risk of having a child with a genetic disease (NSGC; Bartels). The advocates of this ethos assert that "the fundamental value of genetic screening and counseling is their ability to enhance the opportunities for individuals to obtain information about their personal health and child-bearing risks and to make autonomous and noncoerced choices based on that information," not the elimination of genetic disease (President's Commission). From this perspective, the geneticists' goals are not so much "preventive" as directly therapeutic: the reproductive planning problems they address are already fulminant when their clients engage their services, and their treatment consists of giving them the information, counseling, and options they need to address their problems in terms of their own values and beliefs (Kessler).

This approach to defining the mission of reproductive clinical genetics has several important features for our purposes. The first is its emphasis on the practitioner's primary professional obligations to his or her presenting clients—usually prospective parents—rather than with the next generation. Thus, practitioners are warned that:

Counselors may find themselves pulled by an allegiance to the unborn child—whose well-being is, after all, the ultimate object of their concern as well as the motivating interest of the parents. As understandable as this concern may be, in the end it must give way to the duty owed to the counselee—the parents (Capron, p. 334).

Secondly, since in practice reproductive health largely boils down to the ability to fulfill one's procreative ambitions, the geneticists' treatment goals can only really be accomplished within the context of their patients' own life plans and beliefs. Because the content and consequences of the reproductive decisions that the geneticist helps facilitate reflect personal moral judgments made within the sphere of the patients' procreative liberty, they are understood to be beyond the geneticists' professional domain of concern. As a consequence, geneticists are expected to be strictly nondirective in the counseling they provide, and to help their clients to make their own value judgments about the relative burden of the disease their children may inherit. The practical result of this orientation is a strongly client-centered ethos that, historically, anticipated the rise of patient autonomy in the ethics of other medical specialties by twenty years.

In part, this tradition has historical roots in the reaction of postwar medical geneticists to the excesses of their eugenic predecessors. However, it also reflects an important strategy for dealing with the predictive and moral uncertainties of the reproductive decisions that geneticists' help their clients make (Juengst, 1989). The tradition is often inaccurately accused of prescribing "value-neutrality" and criticized accordingly (Caplan), but it would be more accurate to label it as "value-sensitive," since it instructs clinical geneticists to discern and work with their clients' values, rather than be blind to them.

The consequence of this client-centered, non-directive ethos is that genetic medicine has no need to adopt geno-preventive goals in order to explain or justify the interventions it performs on behalf of its clients. In fact, it is free to repudiate "public policy intended to change the genetic makeup of the populations" (Council of Regional Genetics Networks), and thereby to distance itself from the liabilities that the geno-preventive concept brings to the profession. One recent statement of this ethos is worth citing at length, because of the ways it clearly displays its roots in the field's concern with the hazards of espousing geno-preventive goals for their services:

Reproductive genetic services must ultimately serve personal—not public—interests, in improving the overall reproductive lives of women. Whatever societal gains might be realized through the eugenic use of reproductive genetic services should be heavily outweighed by the personal needs of women and their families. The ideals of self-determination in family matters and respect for individual differences, ideal that lie behind the client-centered view of reproductive genetic services, are jeopardized whenever the primary goal of these services becomes the prevention of the birth of individuals with a disorder or a disability. To the extent that voluntary reproductive genetic services are evaluated even indirectly in eugenic terms, societal pressures have the potential to threaten the important interests of individual women and their families. (Thomson et al., p. 1161)

Of course, there are still plenty of ethical tensions within this model of genetic medicine (e.g. cf. Bartels). For example, as more can be done to address the phenotypic problems associated with fetal genotypes identified through genetic testing, it becomes harder to interpret prenatal testing as solely aimed at addressing a parental reproductive health problem. In these cases, the fetus emerges as a presenting patient for the medical geneticist, with its own claims to professional allegiance. Similarly, to the extent to which the profession fails to distinquish between their commitment to a non-directive counseling style and their professional obligation to establish the limits of their services, concerns about a laissez faire, commercialized, "consumer eugenics" will remain. Genetic medicine also has to grapple with the fact that, unless the profession is willing to use genotypic preventive measures of success, it may find its reproductive testing and counseling services excluded from cost-conscious healthcare coverage plans as relative luxuries.

Moreover, despite its prominence in the rhetoric of the field, it is also true that this client-centered ethos does not command universal allegiance amongst human geneticists: in fact, 59% of geneticists surveyed do still endorse the "reduction in the number of carriers of genetic disorders" as a professional goal for their field (Wertz and Fletcher). Nevertheless, on the whole, rejecting genotypic prevention in favor of focusing on the interests of the presenting patient serves its advocates well in clinical genetics. By keeping the specialty's loyalties with the particular patients at hand, and its professional prescriptions within the context of those patients' own values and goals, it inoculates the field against infection by the dangerous agendas of negative eugenics.

The bad news for proponents of population genetic screening, of course, is that returning to the client-centered ethos of medical genetics does mean that they will have to forego their appeals to genotypic prevention in making their case. Whether or not genetic screening has any promise for "purifying the human gene pool" should remain totally irrelevant to its acceptance as a public health tool. Given the political, professional and social dangers of going down the eugenic road, any short-term benefits of doing so could carry a very heavy price for all concerned.

Conclusion

Genetic medicine is quickly leaving the stage in its history when it only has information and solace to provide its patients. As it becomes increasingly incorporated into public health, it will be important not to forget the moral tradition that sustains it. Affirming the traditional commitment of geneticists to the physical health and reproductive autonomy of their clients and patients means relinquishing genotypic prevention as a formal goal for the profession. In contemporary political argot, public health genetics should continue to be an empowering, not an exclusionary science: it should continue to be about helping living people address their individual health problems, and not about protecting the gene pool or society from those people, as some form of expensive pollution. Speaking clearly about the place of prevention in public health genetics is one way the pioneers of the new era can reaffirm this fundamental conviction.

eric t. juengst

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