Prevention is the Best Therapy: The Geneticist's Approach.

Abstract During the last two decades prenatal genetic screening and diagnosis has become the cornerstone of medical care for family planning to prevent genetic disease. Carrier screening programs for genetic disorders that are prevalent in various populations identify couples and pregnancies at risk of having an affected child. These couples can proceed with a choice of invasive prenatal diagnosis tests of the fetus (chorionic villous sampling and amniocentesis), or non-invasive prenatal testing of free fetal DNA circulation in the maternal blood which has emerged within the last few years and is currently available for fetal sexing for X Linked disorders. Despite the advances in prenatal diagnosis, couples found to have a fetus affected with a genetic disorder may need to face the dilemma of pregnancy termination. Preimplantation genetic diagnosis (PGD) is an alternative to preempt risk of having a child affected with a life-altering genetic disorder. This technique allows biopsy and genetic diagnosis of embryos obtained from in vitro fertilization by analysis of the genetic material from one or a few embryonic cells. Only unaffected embryos are returned to the mother to establish the pregnancy. We present our experience using PGD for four Lysosomal storage disorders: Tay Sachs, Gaucher type 1, Hunter and Fabry disease with some of the couples being carriers of more than one genetic disorder. PGD is applicable to most disorders for which the gene and the familial mutation are known and should be presented to couples as an alternative to invasive prenatal testing.

Germ-line gene modification and disease prevention: some medical and ethical perspectives.

There has been considerable debate about the ethics of human germ-line gene modification. As a result of recent advances in the micromanipulation of embryos and the laboratory development of transgenic mice, a lively discussion has begun concerning both the technical feasibility and the ethical acceptability of human germ-line modification for the prevention of serious disease. This article summarizes some of the recent research on germ-line gene modification in animal models. Certain monogenic deficiency diseases that ultimately might be candidates for correction by germ-line intervention are identified. Several of the most frequently considered ethical issues relative to human germ-line gene modification are considered in the context of professional ethics, parental responsibility, and public policy. Finally, it is suggested that there is merit in continuing the discussion about human germ-line intervention, so that this technique can be carefully compared with alternative strategies for preventing genetic disease.

Population screening for reproductive risk for single gene disorders in Australia: now and the future.

Abstract As the results of the Human Genome Project are realized, it has become technically possible to identify carriers of numerous autosomal and X-linked recessive disorders. Couples at risk of having a child with one of these conditions have a number of reproductive options to avoid having a child with the condition should they wish. In Australia the haemoglobinopathies are the only group of conditions for which population screening is widely offered and which is government funded. In some Australian states there are also population screening programs for cystic fibrosis and autosomal recessive conditions more common in Ashkenazi Jewish individuals which are generally offered on a user pays basis. It is predicted that as consumer demand increases and testing becomes cheaper, that many people planning or in the early stages of pregnancy will have carrier screening for multiple genetic conditions. This will have significant implications for genetic counseling, laboratory and prenatal testing resources. In addition such screening raises a number of ethical issues including the value of lives of those born with genetic conditions for which screening is available.

Heterozygote carrier testing in high schools abroad: what are the lessons for the U.S.?

The main value of carrier detection in the general population is to determine reproductive risks. In this manuscript I examine the practice of providing carrier screening programs in the school setting. While the data show that high school screening programs can achieve high uptake, I argue that this may reflect a lack of full understanding about risks, benefits, and alternatives, and the right not to know. It may also reflect the inherent coercion in group testing, particularly for adolescents who are prone to peer pressure. The problem of carrier screening in the schools is compounded when the condition has a predilection for certain groups based on race, ethnicity or religion. I examine programs around the world that seek to test high school students for Tay Sachs and Cystic Fibrosis carrier status. I argue that carrier programs should be designed so as to minimize stigma and to allow individuals to refuse. The mandatory school environment cannot achieve this. Rather, I conclude that screening programs should be designed to attract young adults and not adolescents to participate in a more voluntary venue.

Screening for carriers of Tay-Sachs disease in the ultraorthodox Ashkenazi Jewish community in Israel.

A screening program for the detection of Tay-Sachs disease (TSD) carriers in the ultra Orthodox community of Ashkenazi Jews has operated in Israel since 1986. The purpose of this program is the prevention of marriages of 2 heterozygotes. The screened individuals are mostly couples in the engagement process or students in religious high schools. Two mandatory requirements guide this program. First, anonymity of the tested individuals who are identified only by code numbers; second completion of the test results of couples in the engagement process within a few days. The screening program is performed by the determination of hexosaminidase A (Hex A) activity in serum which is repeated in serum and leukocyte extracts in couples where both partners were found in the heterozygote range in the initial tests. The minimal carrier frequency was estimated to be 1:26 or higher, which is higher then in the general Jewish Ashkenazi population. This higher carrier frequency apparently stems from the fact that most members of this community originate from central Europe where the TSD carrier frequency was previously reported to be the highest in the Ashkenazi population. Since the beginning of the screening program no TSD child has been born to newlywed couples of this community in Israel.

A private view of heterozygosity: eight-year follow-up study on carriers of the Tay-Sachs gene detected by high school screening in Montreal.

We surveyed 264 persons (132 carriers, 132 matched noncarriers) screened for Tay-Sachs heterozygosity during 1974-76 in a program directed at senior high school students in Montreal. Among 198 who apparently received the questionnaire in 1982, the response rate was 42% (38 carriers, 45 noncarriers; age range 21-26 yr). Respondents and nonrespondents had no apparent demographic differences. Of eight unable to remember their genotype only one was a carrier (these persons were excluded from the study). The subjects were: single (75%), married (20%), engaged (3%), divorced (1%); 32% of carriers were engaged or married vs 16% of noncarriers. (There were no carrier couples in our sample, but one such couple, who married after being screened in the high school program, requested amniocentesis in 1981.) Only three of the 12 spouses or fiancé(s) of carriers have not been tested (vs 3 of 6 noncarrier partners). Only 19% of carriers now attach any "worry" to heterozygosity (vs 46% at the earlier time of test disclosure, P = 0.001); carriers with spouses or fiancé(e)s are less "worried" than unattached carriers. Only 3% of carriers claim they would change marriage plans if their fiancé(e) was also a carrier. Carriers and noncarriers uniformly approve (96%) genetic screening for themselves and for other mutant genotypes; 92% of carriers and 95% of noncarriers approve being screened in high school. These findings indicate that Canadians screened in high school: 1) have largely positive attitudes toward genetic screening long after the experience, and 2) are making appropriate use of the test result.

A cost-benefit analysis of the Quebec Network of Genetic Medicine.

Certain serious diseases, including several major genetic disorders, cannot be treated effectively unless they are detected before symptoms appear. In such cases, only systematic population screening can ensure that the necessary preventive treatment can be administered to affected individuals. The question of whether to establish such screening programs, which may be relatively costly, is a pressing problem for many public administrations. This study of the costs and benefits of the Quebec Network of Genetic Medicine has as its main objective the development of an analytical framework which can be generally applied to such problems. In this article, we attempt to evaluate the profitability of the Network to society. For the evaluation of the less tangible costs and benefits, we adopted the minimum profitability principle, which essentially involves establishing a lower bound on the value of the profitability of the Network. The net benefits assessed by this study, although certainly underestimated, are still very significant. Since the Network is administered by a team of researchers, the study also throws some light on the links existing between research and development activities on the one hand and public services on the other, and hence on the general question of the socioeconomic profitability of biomedical research.

KIE: The Quebec Network of Genetic Medicine was established in 1969 by a group of researchers concerned with the systematic early detection of congenital disorders in neonates. The authors performed a cost-benefit analysis of the profitability of the Network during the period 1969-1980. They quantified the costs and benefits of detecting phenylketonuria and hypothyroidism and found significant savings to society. In the cases of Tay Sachs disease and tyrosinemia, for which there are no curative treatments, a quantitative analysis was not performed but costs were calculated and potential benefits considered. Overall, the Network was found to be both socially advantageous and financially profitable, at least partly because it has been managed by active researchers.

Screening Jews and genes: a consideration of the ethics of genetic screening within the Jewish community: challenges and responses.

Screening for genetic disorders, particularly Tay-Sachs Disease, has been traditionally welcome by the Jewish community. I review the history of genetic screening among Jews and the views from the Jewish tradition on the subject, and then discuss ethical challenges of screening and the impact of historical memories upon future acceptance of screening programs. Some rational principles to guide future design of genetic screening programs among Jews are proposed.

Tay-Sachs disease carrier screening: a model for prevention of genetic disease.

Tay-Sachs disease (TSD) is an autosomal-recessive, progressive, and ultimately fatal neurodegenerative disorder. Within the last 30 years, the discovery of the enzymatic basis of the disease, namely deficiency of the enzyme hexosaminidase A, made possible both enzymatic diagnosis of TSD and heterozygote identification. In the last decade, the cloning of the HEXA gene and the identification of more than 80 associated TSD-causing mutations has permitted molecular diagnosis in many instances. TSD was the first genetic condition for which community-based screening for carrier detection was implemented. As such, the TSD experience can be viewed as a prototypic effort for public education, carrier testing, and reproductive counseling for avoiding fatal childhood disease. More importantly, the outcome of TSD screening over the last 28 years offers convincing evidence that such an effort can dramatically reduce incidence of the disease.

Discovery of children's carrier status for recessive genetic disease: some ethical issues.

Knowledge of one's carrier status for recessive genetic diseases is useful primarily in making marital and reproductive decisions. These decisions are peculiarly the private domain of the young adults who are dating, mating, and forming new families. The privacy of these decisions may be compromised when parents know the carrier status of their children. Thus, the practice of sharing that information with the parents of fetuses, babies, and minor children ought to be discouraged, out of respect for the autonomy and privacy of these children when they become adults.

Economic considerations in technology assessment: the case of genetic disease.

This paper describes economic issues pertinent to health care technology assessment. Of interest are the allocation of resources between health and other sectors of the economy, between alternative services within the health sectors, and the costs of producing the services that are selected. These issues are discussed and then illustrated by reference to a specific area of health care technology: screening for and intervention against genetic diseases. It is concluded that investments in screening programs for Tay Sachs disease and Down Syndrome are allocatively efficient. Indications are that such investments are also efficient for interventions against Neural Tube Defects; however, there are complex ethical issues involved. There are many genetic diseases for which screening tests have yet to be developed. As such tests become available, each will have to be evaluated on its own merits relative to alternative health sector investments.

The ovrselling of genetic anxiety.

KIE: Mass screening programs to detect carriers of Tay Sachs disease in the American Jewish population are described and criticized from an ethical standpoint. Educational programs promoting screening often trigger long-lasting anxiety among members of the target population. Other ethical problem areas include the co-opting of community resources and the dangers of stigmatization of carriers. In addition, cost-benefit analyses have been narrowly construed and have failed to demonstrate any clearcut advantage to mass screening. Finally, alternative approaches have been proposed to achieve the goal of preventing Tay Sachs births through individual counseling of high-risk couples.^ieng

Genetic screening of prospective parents and of workers: some scientific and social issues.

Genetic screening programs are based on assumptions and values that reflect the history of racial and social eugenics in the United States and Europe. They stigmatize individuals by shifting the focus from social, economic, and political decisions that affect the health of prospective parents, newborns, and workers to "bad genes," that is, intrapersonal factors that are given the status of "causes" of disease. Prenatal screening, at best, can help the relatively few individuals who know that their future children are at risk for a particular inherited disease or disability; it has little positive value for the average person. Workplace genetic screening has not been shown to reduce occupational disease, but it has led to employment discrimination and has drawn attention away from controlling exposures to toxic chemicals in the workplace.

Assessing ethnicity in preconception counseling: genetics--what nurse practitioners need to know.

PURPOSE: To define and discuss five genetic disorders--Tay-Sachs, sickle cell anemia, Canavan's disease, thalassemia, and cystic fibrosis (CF)--and to explain the importance of the nurse practitioner's (NP's) assessment of clients' ethnicity during preconception counseling, which should address these genetic conditions. DATA SOURCES: Review of literature from professional journals, professional organizations' Web sites, guidelines from the American College of Obstetricians and Gynecologists, the National Institute of Health Consensus Statement, and the authors' professional clinical experience. CONCLUSIONS: The goal of preconception counseling is to identify potential or actual medical, psychological, or social conditions that may affect the mother or fetus. NPs are often the health care providers that initiate preconception counseling to women in varied primary care settings. NPs must be familiar with ethnicity-related inheritable conditions in order to provide appropriate client information and education and to implement testing and, when needed, referral for genetic counseling to individuals and families at risk for genetic disorders such as Tay-Sachs, Canavan's disease, CF, sickle cell anemia, and thalassemia. IMPLICATIONS FOR PRACTICE: NPs providing health care to women of child-bearing age should assess the client's use of contraception and intent for future pregnancy. Preconception counseling when indicated should be initiated to all women to increase their potential for healthy pregnancy outcomes. Although a comprehensive personal, family, medical, and psychosocial history and initiation of folic acid are the mainstays of preconception counseling, assessment for risk of ethnicity-related genetic conditions must also be included in prepregnancy health care.