A child with Down’s Syndrome showing white spots on the iris known as Brushfield’s Spots. Tests can screen for a predisposition to the syndrome. Source: Wikimedia Commons.
Will a genetic test change your life for the better? Predictive Genetic Testing (PGT) is the use of a genetic test to predict future risk of disease. Although PGT is relatively new, arising from the mapping of the human genome, it has rapidly emerged as a technology that carries many benefits, but many risks, as well. Considerable debate surrounds the moral and ethical issues regarding persons who have undergone predictive genetic testing.
PGT is utilized commonly in the following circumstances:
- carrier testing1, which identifies persons with a genetic mutation for a disorder inherited in an autosomal recessive2 or X-linked recessive manner3;
- prenatal diagnosis, in which testing determines whether a fetus is affected with a particular disorder4; and
- predictive testing, which is offered to asymptomatic persons who, based on their family history, are at risk for developing a disorder.
Each one of these circumstances carries a particular set of ethical, legal, or social implications, depending on the reasoning behind the testing. For example:
- For medical purposes, is the testing diagnostic, or predictive with a treatment?
- Are you having the testing done for personal decision-making reasons? That is, predictive without a treatment, carrier, or prenatal?
In any circumstance, privacy and confidentiality are critical because the genetic results are directly related to an individual’s identity.5 Not only is confidentiality an issue for health care, but to prevent genetic discrimination in insurance coverage and employment, as well. Information from a genetic test can affect an entire family. If the disorder is either genetically dominant or carried by an individual, that person’s parents, children, brothers, sisters, and even extended family may also be affected. Questions that arise may be:
- Should family members be informed of the test results?
- Should the individual diagnosed with a genetic disorder inform his/her family they may be at risk?
- Alternatively, should the physician who has diagnosed the patient inform the family of the disorder and recommend testing?
Furthermore, a person may make life-altering decisions based on the results of a genetic test.6
Disclosure of genetic test results can be critical in all aspects of an individual’s life. When a person is identified through family history as being at risk for an inherited condition, a genetic test may be available to clarify their chances of their developing that disease; in addition, the genetic test results may also reveal information regarding risk for disease of other biological family members.
Marybeth: a case study
At age 37, Marybeth is pregnant with her second child, in her first trimester. She discloses to her family physician that she had a severely mentally and physically handicapped younger brother who died shortly before she was born. Ashamed, Marybeth’s mother told her that her younger brother’s death was caused due to injuries resulting from a loss of oxygen when he was born. Marybeth has a healthy four-year-old daughter.
Marybeth pursues genetic testing, and she is found to be the carrier of fragile X-gene mutation (a genetic mutation associated with mental retardation and developmental disabilities). She decides to have chorionic villus sampling (CVS), and the results show that her fetus is a boy who has not inherited the fragile X gene mutation. At her follow-up visit, she tells the clinician that she understands that it is likely that her mother is a carrier of this condition, and that her first cousin, Jillian may be a carrier.
In this situation, identifying Marybeth as a carrier for the fragile X-gene mutation means that other maternal family members, such as her mother, sister, maternal aunts/uncles, and maternal cousins, may also be carriers of this gene mutation, as well as her own daughter. This raises the issue who should counsel the patient and/or family, and how the patient and/or family should be counseled. Even though, Marybeth’s physician may be knowledgeable about Marybeth, her family, their socioeconomic background, and personal attitudes, he/she may not be the best person to provide genetic counseling. Family physicians often choose to refer patients to a genetics professional because of the time needed to become familiar with the relevant aspects of the disorder, testing, management, and disease-specific psychosocial support services.
Additionally, Marybeth has indicated she would like her four-year-old daughter tested, which raises the issue of whether or not children should be tested for carrier status. Ethicists argue that carrier testing has the potential to affect the future reproductive prospects of a child. Therefore, the decision should be made by the child when he/she reaches reproductive age.7 This view is based on the basic ethical principle of informed consent, which states an individual can freely and voluntarily give their consent to be tested —without external pressure. That is after being informed of the benefits, risks, procedures, and other pertinent information relating to the carrier test.
In addition, it is argued that carrier testing performed during childhood also denies the child of confidentiality, as well—a right he/she would receive if tested as an adult. On the other hand, in a study done in the United States, most parents of individuals with Fragile X-syndrome were very concerned that their children knew the genetic risk before becoming sexually active, and/or should be able to marry informed of their carrier status. They also argued that carrier testing in childhood might help the child to adapt to the knowledge of being a carrier slowly, while receiving the information later could be more shocking.8
What were Marybeth’s choices?
- Marybeth chose to have CVS, which is a form of genetic prenatal testing. If Marybeth’s fetus had been diagnosed with the Fragile X mutation, Marybeth may have chosen to terminate the pregnancy. However, if Marybeth were opposed to abortion, this would have created an ethical dilemma.
- Now that Marybeth knows that she is a carrier of the Fragile X-gene mutation, she may choose to undergo preimplantation genetic diagnosis (PGD), the earliest form of prenatal diagnosis.
PGD: testing early-stage embryos
Preimplantation genetic diagnosis (PGD) tests early-stage embryos produced through in vitro fertilization (IVF) for the presence of a variety of conditions. One cell is extracted from the embryo in its eight-cell stage (which does not harm the embryo) and genetically analyzed. PGD allows couples at risk of passing on a serious genetic disease to reduce the risk of selecting an embryo that would have a serious genetic disease to be implanted in a woman’s uterus and be allowed to gestate and develop into a newborn child. PGD cannot ensure that an embryo is free of any genetic disorders; it can only look at those genetic disorders of which we are currently aware.
PGD is not without controversy, however. Those who oppose the destruction of human embryos in general are necessarily opposed to PGD; however, for some, PGD is preferable to terminating a pregnancy already underway. Other criticisms of PGD include that it can be considered a eugenic technology; that PGD will be used to select a child of a preferred sex, or to select a future child’s aesthetic or behavioral traits, or worse, to help create a ‘super-race’. Some groups have advocated restrictions for PGD, such as:
- Limiting genetic testing of embryos to those conditions that result in early and painful death of children, such as anencephaly, Tay Sachs, Lech Nyan’s Disease.
- Prohibiting negative eugenics in the case of all other genetic conditions.
- Prohibit the use of PGD for selecting for non-disease characteristics such as height, weight, intelligence, personality traits, behavior, or gender.
Such restrictions are inevitably intertwined with the issues of personal choice, however, and autonomy over one’s body and one’s offspring. Should these issues remain choices of the individual? Alternatively, do they rise to the level of requiring governmental interference or regulation for the sake of the greater good of society? For example, if a therapy is developed that could prevent cystic fibrosis, would it be reasonable to require pregnant women with a family history of CF undergo genetic testing? Because the right to bear children is one that has been protected legally by the United States Constitution, any testing is governmentally mandated could be seen as an impingement upon procreative liberty and imposing an unfair burden upon women. Mandatory screening would require individuals to learn things about themselves they may have no wish to know and potentially threaten their economic security by putting them at risk of social stigmatization as well as employment and insurance discrimination. Such a mandate, in the end, could have a chilling effect on the exercise of the right to procreate.9
However, mandatory education about basic genetics and the available of voluntary screening services, could offer a means promoting healthy births without sacrificing personal liberty, while at the same time giving informed choice and serving governmental objectives.10
Other predictive testing
In the case of testing asymptomatic individuals, the benefits of some predictive genetic tests can be substantial. Two examples:
- First, the screening of healthy appearing newborns with sickle cell anemia permits the administration of prophylactic antibiotics, which significantly reduces infant mortality.
- Second, by screening asymptomatic infants for phenylketonuria, they can be placed on a low-phenylalanine diet, which prevents mental retardation. In these examples, the technical accuracy of the tests is fairly certain and treatment can be administered or preventive action can be taken to prevent harm.11
Potential harm from genetic testing
However, because relatively few interventions have yet been devised to improve the outcome of most genetic disorders, the potential harm can be substantial. Some genetic tests are imperfect predictors of future disease. As a result, some people may choose to forego testing; others undergo testing despite the uncertainty of the results. Others who are tested may not foresee the impact on them of getting a positive test result for a currently untreatable condition, such as Huntington’s chorea. Others who receive a negative result for a common complex disease (e.g., familial adenomatous polyposis, a particular form of colon cancer) may not appreciate that they still are at risk for the disease. The American Academy of Family Physicians has recommended specific guidelines when discussing and obtaining informed consent for predictive genetic testing, including:
Obtaining an accurate family history and confirming diagnoses before testing.
Providing information about the natural history of the condition and the purpose of the test.
Discussing the predictive value of the test, the technical accuracy of the test and the meaning of a positive or negative test.
Exploring the patient’s motives for undergoing the test, the potential impact of testing on relatives and the risk of passing a mutation on to children.
Discussing the potential risk of psychosocial distress to the patient and family, even if no mutation is found.
Discussing issues involving confidentiality and the risk of unemployment and insurance discrimination.12
The enactment of the Health Insurance Portability and Accountability Act of 1996 (HIPAA) has helped in that it explicitly states that a presymptomatic genetic diagnosis does not qualify as a preexisting condition, thereby offering a degree of protection to some patients seeking presymptomatic testing. However, HIPAA does not prohibit other discriminatory practices, such as mandatory testing, disclosure of genetic information to third parties, and raising premiums or setting caps on insurance if these conditions are equally applied to all persons enrolled in the plan.13
As for employment, currently the United States does not have a national law prohibiting the use of genetic testing to determine employment eligibility, but a patchwork of federal laws and state-based laws have created some protection for genetic information about employees.14 Today most states have enacted legislation that prohibits genetic discrimination in the workplace and in obtaining health insurance coverage. There is legislation pending in the United States Congress, which proposes the protection of workers in all industries from discrimination based on genetic information; the legislation would limit how employers and organizations, (such as unions and labor committees) could use genetic information in hiring and other employment decisions.15
As the technical accuracy of predictive genetic testing improves and the tests become more widely available, recognition of the limitations of predictive genetic testing, as well as ethical concerns regarding use and misuse of this technology, need to be considered by patients, clinicians, and policy makers.
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