Ethical Dilemmas in Genetic Testing
Prenatal Genetic Testing
Geneticists are frequently asked to help couples use prenatal diagnosis or assisted reproductive technology to avoid having offspring with a serious hereditary disorder. For some hereditary disorders, prenatal diagnosis remains controversial, particularly when the diagnosis leads to a decision to terminate the pregnancy for a disease that causes various kinds of physical or intellectual disabilities but is not fatal in infancy. Prenatal diagnosis is equally controversial for adult-onset disorders, particularly ones that may be managed or treated. A debate is ongoing in the community of persons who have a physical or intellectual disability and deaf patients and their families (to name only a few examples) about whether prenatal diagnosis and abortion for these disorders are ethically justified. The dilemma lies in attempting to balance, on the one hand, respect for the autonomy of parents’ reproductive decision making about the kind of family they wish to have versus, on the other hand, an assessment of whether aborting a fetus affected with a disability compatible with life is fair to the fetus or to the broader community of persons with a disability or people with hearing impairment.
The dilemma also arises when a couple makes a request for prenatal diagnosis in a pregnancy that is at risk for what most people would not consider a disease or disability at all. Particularly troubling is prenatal diagnosis for selection of sex for reasons other than reducing the risk for sex-limited or X-linked disease. Many genetics professionals are concerned that couples are using assisted reproductive technologies, such as in vitro fertilization and blastomere biopsy, or prenatal sex determination by ultrasonography and abortion, to balance the sexes of the children in their family or to avoid having children of one or the other sex for social and economic reasons prevalent in their societies. There are already clear signs of a falling ratio of female to male infants from 0.95 to less than 0.85 in certain areas of the world where male children are more highly prized.
Other areas of ethical debate include seeking prenatal diagnosis to avoid recurrence of a disorder associated with a mild or cosmetic defect or for putative genetic enhancement, such as genetic variants affecting muscle physiology and therefore athletic prowess. Other examples are the use of prenatal diagnosis and possible pregnancy termination for what is considered by society to be a normal phenotype, such as hearing or typical stature, in a family in which both parents are deaf or have achondroplasia and consider their phenotypes to be important components of their family identity, not disabilities. Such dilemmas have so far been more theoretical than real. Although surveys of couples with deafness or achondroplasia show that the couples are concerned about having children who are not deaf or do not have achondroplasia, the vast majority would not actually use prenatal diagnosis and abortion to avoid having children who do not share their conditions.
In the future, particular alleles and genes that contribute to complex traits, such as intelligence, personality, stature, and other physical characteristics, will likely be identified. Will such nonmedical criteria be viewed as a justifiable basis for prenatal diagnosis? Some might argue that parents are already expending tremendous effort and resources on improving the environmental factors that contribute to healthy, successful children. They might therefore ask why they should not try to improve the genetic factors as well. Others consider prenatal selection for particular desirable genes a dehumanizing step that treats children simply as commodities fashioned for their parents’ benefit. Once again, the ethical dilemma is in attempting to balance respect for the autonomy of parents’ reproductive decision making with an assessment of whether it is just or beneficial to terminate a pregnancy when a fetus has a strictly cosmetic problem or carries what are perceived to be undesirable alleles or is even of the “wrong” sex. Does a health professional have, on the one hand, a responsibility and, on the other hand, the right to decide for a couple when a disorder is not serious enough to warrant prenatal diagnosis and abortion or assisted reproduction?
There is little consensus among geneticists as to where or even whether one can draw the line in deciding what constitutes a trait serious enough to warrant prenatal testing.
Genetic Testing for Predisposition to Disease
Another area of medical genetics and genomics in which ethical dilemmas frequently arise is genetic testing of asymptomatic individuals for diseases that may have an onset in life later than the age at which the molecular testing is to be performed. The ethical principles of respect for individual autonomy and beneficence are central to testing in this context. At one end of the spectrum is testing for late-onset, highly penetrant neurological disorders, such as Huntington disease (see Chapter 12) (Case 24). For such diseases, individuals carrying a mutant allele may be asymptomatic but will almost certainly develop a devastating illness later in life for which there is currently little or no treatment. For these asymptomatic individuals, is knowledge of the test result more beneficial than harmful, or vice versa? There is no simple answer. Studies demonstrate that some individuals at risk for Huntington disease choose not to undergo testing and would rather not know their risk, whereas others choose to undergo testing. Those who choose testing and test positive have been shown to sometimes have a transient period of depression, but with few suffering severe depression, and many report positive benefits in terms of the knowledge provided to make life decisions about marriage and choice of career. Those who choose testing and are found not to carry the trinucleotide expansion allele report positive benefits of relief but can also experience negative emotional responses due to guilt for no longer being at risk for a disease that either affects or threatens to affect many of their close relatives. In any case, the decision to undergo testing is a highly personal one that must be made only after thorough review of the issues with a genetics professional.
The balance for or against testing of unaffected, at-risk individuals shifts when testing indicates a predisposition to a disease for which intervention and early treatment are available. For example, in autosomal dominant hereditary breast cancer, individuals carrying various mutations in BRCA1 or BRCA2 have a 50% to 90% chance of developing breast or ovarian cancer (see Chapter 15) (Case 7). Identification of heterozygous carriers would be of benefit because individuals at risk could choose to undergo more frequent surveillance or have preventive surgery, such as mastectomy, oophorectomy, or both, recognizing that these measures can reduce but not completely eliminate the increased risk for cancer. What if surveillance and preventive measures were more definitive, as they are in familial adenomatous polyposis, for which prophylactic colectomy is a proven preventive measure (see Chapter 15) and (Case 15)? Upon testing for any predisposing gene mutation(s), individuals incur the risk for serious psychological distress, stigmatization in their social lives, and discrimination in insurance and employment (see later). How are respect for a patient’s autonomy, the physician’s duty not to cause harm, and the physician’s desire to prevent illness to be balanced in these different situations?
Geneticists would all agree that the decision to be tested or not to be tested is not one made in a vacuum. The patient must make an informed decision using all available information concerning the risk for and severity of the disease, the effectiveness of preventive and therapeutic measures, and the potential harm that could arise from testing.
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