Assessing Genetic Risks Implications for Health and Social Policy (1994) / Chapter Skim
Currently Skimming:
1 Setting the Stage
1 Setting the Stage
Pages 29-58
The Chapter Skim interface presents what we've algorithmically identified as the most significant single chunk of text within every page in the chapter.
Select key terms on the right to highlight them within pages of the chapter.
From page 29... ...
Tests for detecting genetic predispositions to more common, complex disorders are under development. And even when treatments have not yet been developed, genetic tests can nevertheless help people decide about conceiving or bearing children.
|
From page 30... ...
The development and widespread use of genetic tests before safe and effective treatments are available have raised fears about the uses of genetic testing that genetic tests will be imposed while other approaches to alleviating human suffering are neglected. Their use also raises issues about discrimination and privacy that people found to possess certain genetic characteristics will lose opportunities for employment, insurance, and education.
|
From page 31... ...
This allows scientists to find homologous genes in mice, fruit flies, or primates, and to create artificial manifestations in the DNA to mimic the mutation in the human gene. Animal models carrying the actual human gene will permit the study of the normal and abnormal function of the gene in the development of new therapies.
|
From page 32... ...
32 ~3~,~ , ,,,~ ~ > 8 ~ ~ 8 ~ 8 ~ 8 ~ ~ ~ 8 ~ ~ 8 ~ 8 8 ~ ~ oo§1~ ~ il 83- ~ t, by ~ ~ 3'lp~, to x_ 1~8 ~§!
|
From page 34... ...
In the late 1960s, it proved possible to detect some altered gene products in cells obtained from the amniotic fluid by midtrimester amniocentesis, thus making prenatal diagnosis possible (Fuchs, 1966; Steele and Breg, 1966; Jacobson and Barter, 1967; Hahneman and Mohr, 1968; Nadler, 19681. However, effective treatment was not available for most prenatally diagnosable disorders.
|
From page 35... ...
This has greatly increased the opportunity for people in these families to learn their risks of disease or of having children with the disease. In the case of sickle cell anemia and thalassemia (autosomal recessive disorders for which carrier screening was possible by "gene product" techniques)
|
From page 36... ...
New techniques for prenatal diagnosis are also being evaluated involving fetal cells that are usually present in and can be isolated from the maternal circulation in the first trimester of pregnancy. These techniques are still highly experimental (Bianchi et al., 1991; Elias et al., 19921.
|
From page 37... ...
The committee heard testimony that raised its concern about the reliability of interpretation of prenatal ultrasound images and about the consequences of decisions based on such interpretation (see Chapter 21. Limitations of Genetic Testing Genetic tests are seldom perfect predictors of clinical risk.
|
From page 38... ...
cannot usually be predicted by a genetic test, even a test for a specific mutation; however, some specific mutations tend to be associated with specific levels of severity of the disorder. Aside from problems that arise as a result of allelic diversity, incomplete penetrance, and variable expressivity, tests for genes implicated in single-gene disorders have other limitations.
|
From page 39... ...
That NAS report focused on two disorders for which screening programs had recently been developed: the testing of newborns for phenylketonuria (PKU) , which started in the late 1950s; and screening for sickle cell anemia and carriers, which started in 1971.
|
From page 40... ...
Sickle Cell Anemia and Trait A more serious set of errors was made in the establishment of sickle cell screening programs in the African-American community in the early 1970s.
|
From page 41... ...
Nor was prenatal diagnosis available at that time; the only way parents could avoid having affected children was not to have children at all or to avoid mating with another carrier. Since 8 percent of African-Americans are carriers of the sickle cell trait, many carriers were detected in screening programs.
|
From page 42... ...
Similarly, federal support for community-based sickle cell programs included education of providers and consumers, improving the understanding of both groups. It was not until 1978 that sickle cell anemia could be diagnosed in amniotic fluid cells obtained by amniocentesis (Ken and Dozy, 19781.
|
From page 43... ...
Since 1971, screening in the Ashkenazi Jewish populations has led to more than a 90 percent reduction in TaySachs disease in that population in the United States and Canada. By contrast, it is the committee's impression that the incidence of sickle cell anemia among African-Americans has not decreased since screening began.
|
From page 44... ...
When problems such as these were analyzed and worked out in advance, as in Tay-Sachs disease and thalassemia screening, genetic screening programs were developed in a more appropriate way, and implementation raised fewer scientific, ethical, legal, and social issues. UPDATING THE FINDINGS OF THE 1975 NAS COMMITTEE The 1975 NAS committee concluded that it would be useful to elaborate some fundamental principles and rules of procedure for genetic testing.
|
From page 45... ...
. A second is providing reproductive options to people with high probability of having children with severe, untreatable disease, for whom counseling could be helpful and prenatal diagnosis or abortion of interest, with Tay-Sachs disease as the prototypical example.
|
From page 46... ...
Recently, highly experimental genetic tests have become possible prior to fertilization of the ovum and prior to implantation of the fertilized ovum, although not without the stress, cost, and other issues associated with in vitro fertilization. Work is also in progress in genetic testing of fetal cells isolated from the maternal blood-stream early in pregnancy (Bianchi et al., 1991; Elias et al., 19921.
|
From page 47... ...
This will help to hold down the costs per case averted at a time when neither the states nor the federal government is as likely to finance an expansion of genetic testing or screening as they were for PKU and sickle cell anemia. Equal access may also depend on reforms in our health insurance system that will either pay for, or reim
|
From page 48... ...
Such individuals, including geneticists and primary care physicians, may have a business or financial interest in laboratories or companies that provide testing and/or hold patents on genes from which royalties are generated through the testing process. The committee believes that all such holdings should be publicly disclosed and strongly discouraged.
|
From page 49... ...
, and state insurance laws may ensure that charges for genetic tests are reimbursed. But today the concern is no longer that of ensuring that new genetic screening tests will be done, but rather that pretest education and counseling, the offering of tests, their performance, and the counseling and medical interventions that follow positive test results, will be done appropriately.
|
From page 50... ...
Genetic counselors can help in the training of physicians, and in the training of nurses and social workers, who in turn can assist primary care physicians in genetic education and counseling (see Chapters 4 and 63. Standards of Care If testing is to be provided primarily by primary care physicians, how will these providers know when to adopt genetic tests?
|
From page 51... ...
The committee sees a particular need for advisory bodies with grass roots consumer representatives-to guide state health departments or legislatures on such issues as deciding when tests should be added to state-run screening programs and to ensure that the offering, testing, and associated education and counseling are always conducted in accord with the principles suggested in this report. The committee also sees the need for continuing national oversight for the evaluation of existing and new genetic tests, and of pilot projects for the use of such tests, to help states decide what tests to adopt, to advise federal agencies with responsibilities related to genetic testing, and to provide broad policy advice on genetic testing (see Chapter 9 for the committee's recommendations)
|
From page 52... ...
The only possible exception is newborn screening leading to effective treatment "if it were found that nonmandatory screening leaves many babies unscreened because of parental noncooperation or physicians' ignorance or oversight" (NAS, 1975, p.
|
From page 53... ...
If directiveness is accepted for any form of testing for which a safe, effective, and widely accepted treatment is not available, this compromises a critically held tenet: patient autonomy. The decision to support or reimburse genetic tests should be based on how well they meet the criteria and principles stated here and in Chapters 2 and 8, not on economic considerations.
|
From page 54... ...
Such a restriction would undermine individual autonomy as much as the view that people should be urged or forced to use genetic tests and abortion to prevent disabilities. Nevertheless, the concerns of persons with disabilities are critical ones for our society.
|
From page 55... ...
1984. Education, consent, and counseling in sickle cell screening programs: Report of a survey.
|
From page 56... ...
19~71. Synthesis of adult hemoglobin by reticulocytes from the human fetus at midtrimester: Possible applications to prenatal detection of sickle cell anemia and other disor ders.
|
From page 57... ...
1972. Sickle Cell Disease in the Armed Forces.
|
From page 58... ...
American Journal of Human Genetics 36:199S. Virginia Code Annotated.
|
Key Terms
This material may be derived from roughly machine-read images, and so is provided only to facilitate research.
More
information on Chapter Skim is available.