Genetic Testing

Genetic Testing

PRENATAL DIAGNOSTIC TESTING

PREDICTIVE GENETIC TESTING

BIBLIOGRAPHY

The term genetic testing refers to the molecular analysis of DNA for genetic markers associated with particular genetic conditions, to tests for enzymes or proteins related to gene function, and to chromosomal analysis. Social science studies of genetic testing practices and their social and cultural implications involve, for example, considerations of community, family, kinship, and health and address issues such as informed consent, intellectual property rights, and privacy. Critical assessments of screening and testing practices and of the interpretations of genetic information illuminate the normative effects and premises, past and present, that occur both in institutional settings and in everyday life and are reflected in policy.

PRENATAL DIAGNOSTIC TESTING

One of the earliest and most enduring areas of social science research on genetic testing concerns the social implications of prenatal diagnostic testing (PND). PND involves genetic testing during pregnancy for genetic conditions and chromosomal anomalies in the developing fetus using practices such as chorionic villus sampling (testing placental blood cells) and amniocentesis (testing fetal cells from amniotic fluid). Studies of prenatal diagnostic testing have illustrated the influence it has on experiences of pregnancy, conceptualizations of disability, mediations of genetic information, and knowledge and performances of parental and civil responsibility. Barbara Katz Rothman’s The Tentative Pregnancy: How Amniocentesis Changes the Experience of Motherhood (1986) was among the first studies following the introduction of amniocentesis (at that time done between sixteen and twenty weeks) to illustrate the complexity of women’s experiences of mediating the possibility of undergoing the test, abortion, and/or results indicating a possible disability during the first four to five months of pregnancy. By the late 1990s, amniocentesis had become a routine testing possibility during pregnancy, concurrent with the emergence of an understanding of the fetus as patient (Casper 1998). Published in 1999, Rayna Rapp’s book Testing Women, Testing the Fetus speaks to the duality of women and fetuses as the subjects of prenatal testing. Employing a multi-sited approach, including research with lab technicians, genetic counselors, and pregnant women, Rapp explores the meanings of amniocentesis within this shifting context. Critical decisions stemming from the availability of PND involve the interpretation of genetic information and embodied experience by medical practitioners, genetic counselors, lab technicians, and prospective parents.

In 1989 the first child born as a result of the application of preimplantation genetic diagnosis (PGD), involving the molecular analysis of one or two cells taken from an embryo created by in vitro fertilization prior to transferring the embryo to a woman’s uterus, was reported. In most cases, PGD involves tests for specific genetic mutations, which are offered on the basis of an understanding that one or both potential parents (or egg or sperm donor) is a carrier of a genetically inheritable condition or has a prior history of having a child with a genetic condition. In common parlance and media coverage, children born following PGD have been called designer babies, a term referring to the growing potential to influence the genetic make-up of one’s child and reflecting concerns over the procedure’s implications for social perceptions of normalcy and disability. Aneuploidy screening, generally testing embryos for chromosomal anomalies rather than for specific genetic mutations, is referred to as preimplantation genetic screening (PGS), rather than PGD.

In 2000 Adam Nash became the first child reported to be born as a result of the use of PGD not only for the purpose of selecting out embryos with a particular genetic marker, but also for selecting in embryos whose HLA tissue type directly matches that of an already existing sibling, rendering the child-to-be a compatible stem cell donor. In the media, such children have been referred to as savior siblings, invoking associations with sacrifice as well as life-saving. The use of PGD, or PID as it is sometimes called, is banned in many countries (for example, Germany) and restricted to use in relation to particular genetic conditions in others (for example, the United Kingdom).

Preimplantation genetic diagnosis is also applied to test embryos for late-onset disorders and genetic susceptibility to particular conditions, including Huntington’s disease, breast cancer, and hereditary colon cancer. Debates in this area highlight the perceptions and cultural management of “genetic risk status” in relation to disorders with variable degrees of penetrance (or the degree to which the genetic mutation corresponds to the manifestation of the condition) and for which preventative measures or treatment may be available. For example, the genetic mutation associated with Huntington’s disease is highly penetrant, corresponding to an expected certainty of developing the disease over the course of a lifetime. In contrast, the mutations on the BRCA 1 and BRCA 2 genes, associated with hereditary forms of breast cancer (accounting for 5 to 10 percent of breast cancer cases), have a penetrance level of approximately 80 percent. This means that not everyone who carries the BRCA 1 and BRCA 2 gene mutations will develop breast cancer in their lifetime and that the likelihood of developing this form of breast cancer increases with age.

PREDICTIVE GENETIC TESTING

The term predictive genetic testing (PGT) refers to testing that occurs prior to the appearance of symptoms. It is used in situations where there is a known history of a perceived genetic condition among genetically related individuals. While issues involving the individual are often the focus of studies of genetic testing—for example, the autonomy of the individual to make an informed decision regarding a test and follow-up actions or the specificity and uniqueness of an individual’s “genetic code”—social science research on PGT provides critical data and insight into the construction and experience of hereditary risk and the familial and social context of genetic testing. In the case of testing for genetically inherited mutations, testing may require the prior or parallel testing of a family member and the communication of their potential genetic risk status. Results of genetic tests for one family member may implicate the “risk” status of other genetically related family members, who may or may not choose to undergo genetic testing.

The Human Genome Project, which ran from 1991 to 2003, resulted in the identification of increasing numbers of specific genes and genetic mutations implicated in genetic conditions, as well as the function of enzymes and proteins. There is increasing emphasis placed on the use of predictive genetic testing among a broader population with no prior awareness or familial history of specific genetic conditions. This form of predictive testing is proposed with respect to the implementation of preventative measures and personalized medicine. Routine genetic screening, for example of newborns for cystic fibrosis, raises additional questions regarding the disclosure and use of information about the gene carrier status of individuals, as well as about potential implications for individuals who did not consent to genetic testing. While in many cultural contexts, predictive testing of children is advised against, research demonstrates that testing occurs and, in the name of preventative medicine, is promoted. The availability of genetic tests and their use on a broader scale raises concerns regarding genetic discrimination, specifically in the areas of health insurance and employment.

The field of pharmocogenomics (sometimes referred to as personalized medicine ) focuses on the development of medical and preventative care tailored to an individual’s genetic makeup. In 2005 the U.S. Food and Drug Agency approved the use of BiDil, a post-heart-attack drug treatment marketed by NitroMed, for black individuals following a clinical trial exclusively involving self-identifying black patients. Because women of Ashkenazi Jewish descent are seen to have a significantly higher percentage of mutations at particular points along the BRCA 1 and BRCA 2 genes, in some jurisdictions they may be given access to breast cancer gene testing without the involvement of another living family member with breast cancer, which is often otherwise required. This relationship between genetic testing and ethnic identification has manifested differently in Europe, where in 2005 Myriad Genetics won the right to a patent on a particular mutation associated with the Ashkenazi Jewish population, requiring physicians to ask breast cancer gene test candidates whether they are of Ashkenazi Jewish descent. While variations in the manifestation, management, and recognition of various conditions have been recognized in comparative and cross-cultural studies of health, reducing these variations to genetic difference runs the risk of reifying and geneticizing concepts such as race and ethnicity and obscuring social determinants of health.

The turn toward genomics, the study of the interaction between genes and the environment, has resulted in the implementation of biobanks, or population genetic databases, as genetic research resource centers. Members of communities and nation-states are requested to donate blood (DNA) samples for research purposes. When genetic testing is conducted within the framework and for the purpose of health care, there is a normative expectation that individuals are aware of the tests being carried out and also of how resulting genetic information will be managed. Studies of biobanking reveal, however, that research participants (those who donated DNA samples) do not have a clear idea of what will be done with the sample or the information derived from it and are not aware of whom it could be distributed to or for how long it will be retained (see Hoeyer 2003). Children are also being included as participants in larger genomic studies, enrolled at birth via the donation of umbilical cord blood by consenting parents.

The advent of genetic testing in the form of PND, PGD, predictive testing, and population-based genetic research is captured by the phrase new genetics, within which is embedded a distinction from eugenics and other previous uses and abuses of genetics. Whereas eugenics is depicted as the imposition on individuals of decisions made by states or other authorities, the new genetics is associated with choice, information, knowledge, autonomy, and responsibility. Social science research and analysis of the new genetics is needed in order to address, for example, how concepts of normalcy are mobilized in new ways, how new forms of genetic information may lead to present and future discrimination, and how concepts such as reproductive choice and civil responsibility are experienced in the context of increasing emphasis on the significance of genetic information, genetic health, and genetic research.

SEE ALSO Bioethics; Eugenics; Genomics

BIBLIOGRAPHY

Casper, Monica. 1998. The Making of the Unborn Patient. A Social Anatomy of Fetal Surgery. New Brunswick, NJ: Rutgers University Press.

Cox, Susan M., and William H. McKellin. 1999. “There’s This Thing in Our Family”: Predictive Testing and the Social Construction of Risk for Huntington Disease. Sociology of Health and Illness 21 (5): 622–646.

Hoeyer, Klaus. 2003. “Science Is Really Needed—That’s All I Know”: Informed Consent and the Non-Verbal Practices of Collecting Blood for Genetic Research in Northern Sweden. New Genetics and Society 22 (3): 229–244.

Koch, Lene. 2004. The Meaning of Eugenics: Reflections on the Government of Genetic Knowledge in the Past and the Present. Science in Context 17 (3): 315–331.

Rapp, Rayna. 1999. Testing Women, Testing the Fetus: The Social Impact of Amniocentesis in America. New York: Routledge.

Rothman, Barbara Katz. 1986. The Tentative Pregnancy: How Amniocentesis Changes the Experience of Motherhood. New York: Viking.

Jacquelyne Marie Luce