By Doris T. Zallen
An avalanche of genetic information seems to be burying us. Each day brings another dramatic finding. A gene connected with a serious health problem has been identified, a test has been developed that can predict the likely onset of disease in later life. How our historical and cultural values will determine the role of genetic testing for our families and society is unclear.
The first rumblings of this avalanche were heard in 1900, when the work of the nineteenth-century Austrian monk Gregor Mendel was rediscovered and brought to light. Mendel had worked in the garden of his monastery at Brno trying to figure out how certain features of the pea plants he was growing were inherited. He proposed that "elements" were involved in producing the inheritance patterns that he was observing. Based on his work, it became possible to lay out a set of basic rules, now called Mendel's laws, that could be used to predict how traits might be passed from one generation to the next. In 1907, these traits were named "genes."
Over succeeding decades, the study of genes progressed well beyond describing the inheritance patterns of pea plants to explaining the inheritance of all life forms. However, very few studies could be done on humans. The ideal subjects were organisms with a short generation time and which produced large numbers of progeny. Fruit flies, mice, corn, even bacteria, became the workhorses of genetic research.
The situation began to change as genetic study moved from examining observable features of organisms to looking at the genetic material itself. Though it was clear as early as 1902 that genes did not float about individually but were connected together in long ribbon-like structures called chromosomes, there was no way to know what they were made up of or how they functioned.
In 1953 came the discovery of the structure of deoxyribonucleic acid, or DNA, by James Watson and Francis Crick. These findings triggered an extraordinary growth in research and revealed that the way genes act is by directing the synthesis of proteins that are responsible for carrying out all life functions.
Scientists turned their attention to DNA, the genetic molecule itself. DNA could be easily extracted from any cells, including human cells, to study. Suddenly human genetics was no longer a backwater area. Today, the study of human genes is one of the most active in all medical research.
Scientists have developed a cornucopia of different procedures for examining the DNA of a gene. These procedures are revealing a great deal about how changes in the genetic material can lead to various kinds of health problems. Once the relationship between genes and health is understood, genetic tests that look for such changes become possible.
The number of disorders for which DNA tests exist has grown steadily. Testing is now being done to look for the presence of flaws in single genes -- flaws that lead to disorders such as cystic fibrosis, hemophilia, the muscular dystrophies, and spinal muscular atrophy. However, even if we know that a certain mutant gene is present, it may not be possible to predict how that gene will finally be expressed and what the outcome on health will be, either at the time of birth or later on as the individual develops and matures. Different mutations in the same gene can have different effects -- from being virtually unnoticeable to causing severe and devastating health problems.
The newest wave of testing goes beyond single gene disorders and looks for genes that can predispose a person to a disorder. Some of the first susceptibility genes found have been for familial colon cancer, breast cancer, and Alzheimer's disease. These are complex conditions which result from the interaction of several different genes with environmental factors -- diet, exercise, exposure to viruses, or environmental chemicals. The presence of a susceptibility gene can increase the chances that a disorder can develop but it does not mean that it will. And the absence of a susceptibility gene does not mean a person will be spared.
Many more tests are being developed as a result of research conducted by the Human Genome Project. The Human Genome Project is an enormously ambitious project that began in 1989 in the United States. It is a massive effort to find the location of all the human genes on each of the twenty-three chromosome pairs and then to determine the precise chemical arrangement within each gene. More than 16,000 genes, out of an estimated 100,000 human genes, have already been located. By early in the twenty- first century, the entire structural record of human DNA should be known. This structural record should be a valuable tool for working out the precise function of genes and for figuring out how they may go awry. This ultimate gene map will be the starting point for an immense number of genetic tests.
Genetic tests open up many opportunities. Prenatal tests can provide information on whether the fetus has inherited a genetic disorder. Carrier tests can make individuals aware that they have a mutant gene which could, if their partner is also a carrier, cause problems should the gene appear in double dose in their children. Presymptomatic tests can alert individuals that they may have a mutant gene which will bring on a disorder, years before any symptom appears.
Genetic tests provide information that can assist in reproductive planning, in making plans for the future, and in triggering life-style changes that can improve the chances of retaining good health.
Genetic tests can also produce disturbing and difficult consequences. Because genes are shared in families, finding a flawed gene in one family member will mean that other family members may also have inherited it. This feature of genetic testing raises troubling questions. Is there an obligation to share genetic news about oneself with others in the family? Or to share with employers and insurance companies? How should the genetic information that is obtained for one person be transmitted to others? The strains within families can be enormous when information is poorly understood or perceived as threatening. Sometimes a permanent estrangement of one part of the family from another has resulted as people blame each other for mutant genes. Even obtaining test results that show one does not have the mutant gene, rather than producing relief, has led to the distress of survivor guilt.
Though genetic tests can be of real value to some, it is clear that they are not right for everyone. The mere availability of a genetic test does not determine whether it is useful or when it would be useful. Some individuals will decide that they want to know their genetic status; others will postpone that journey or decide never to set out on it. Ultimately, each decision about genetic testing has to be made on the basis of personal values and family realities. It has to fit with one's physical, emotional, and financial strengths and limitations. This is not a scientific or technical decision. It is an intensely personal, humanistic decision.
Although considerable media attention has been given to genetics, it is not reflected in the medical community's dissemination of genetic information to its clients -- information that could help them understand the genetic component of a disorder and, if genetic testing is available, decide whether they wish to have it done. Because genetics has long been a neglected subject in medical education, some physicians lag in their knowledge of the genetic basis of disorders and may not be up to date on the availability of new tests.
In fifty interviews recently done with families affected by a genetic disorder, about one-third had received little or no genetic information after diagnosis of a medical condition. One woman from a large family said she was never told about the genetic basis to Duchenne muscular dystrophy even though she had a brother with the disorder. "When you are in your twenties, you don't think that anything could happen to you," she said. She and a sister have subsequently each had a child with the disorder. She maintains that she would have sought genetic counseling and, perhaps, genetic testing prior to her own pregnancy, had she known more about it.
One-fourth of those interviewed, including individuals who had genetic counseling at a previous point, did not know that a test for the disorder had become available. For one couple whose child was diagnosed to have a serious genetic disorder in 1991, the existence of a genetic test was a complete surprise. Having decided that they could "not go through this again," her husband had recently had a vasectomy. They believe their decision might have been different had they known there was a genetic test.
What haunts the present is the specter of the past, in which genetic information, however incomplete, was used to validate specific institutional and governmental policies. The twentieth century was witness to some of the most extreme human abuses carried out under the banner of eugenic improvement. The medical experiments in Nazi Germany remain a chilling chapter in our history. Earlier in the century, eugenic ideas were also a vogue in the United States. They led to the enactment of state laws permitting the involuntary sterilization of people thought to have unfavorable genes, beginning in 1907 in Indiana and, over the next several decades, in thirty other states. More than 60,000 such sterilizations were carried out.
Eugenic ideas played a role in the enactment of the Immigration Act of 1924: By tying quotas to the makeup of immigrant groups in the United States in the 1890 census, it favored immigrants from Great Britain and northwestern Europe and restricted the admission of people, seen as genetically less sound, coming from eastern and southern Europe.
The policies produced by these beliefs have been abandoned. However, the deluge of genetic knowledge coming from research laboratories there are real concerns that, once again, people might be stigmatized because of their genes. There are fears that the new forms of DNA testing could be used to deny insurance, jobs, educational opportunities, and even government services.
The Health Insurance Portability and Accountability Act, which becomes effective in July 1997, may restrict the use of genetic information in determining eligibility for insurance and in setting premium contributions for some workers. As important as these first steps are, their range is limited and their effects remain to be seen.
Genetics is now a field in which many researchers use highly sophisticated techniques to gain a detailed view of our genetic inheritance. Medicine is being transformed as clinicians are rapidly applying those findings to a host of health problems. The scope of testing could even expand to include genes that may have a bearing on personality traits, behavioral patterns, or sexual preference. On the one hand, it may give rise to greater acceptance of those individual differences, over which people have no control; On the other, it could deepen divisions in society and create new types of intolerance based in beliefs of biological inevitability.
Genetic testing may soon be available on an unprecedented scale, presenting at the same time both powerful opportunities and perplexing decisions. As individuals and citizens, we must be sure that each of us gets the information needed to deal with these decisions and to develop policies that protect people from suffering political consequences from the very makeup of their beings.