What are the ethoeconomic issues of gene therapy?

Gene Therapy

Advances in molecular biology and genetics near the end of the last century have presented tantalizing possibilities for new treatment for medical conditions once viewed as incurable. Gene therapy for the treatment of human genetic diseases can take two forms: somatic cell therapy and germ-line therapy. Somatic cell therapy is less controversial, because it modifies only nonreproductive cells, and therefore the changes cannot be passed on to a person’s children. Still, caution is needed, as with any new technology, to be sure that the emerging technologies and techniques are ethically sound. Germ-line therapy is more permanent in that the changes include modification of reproductive cells, and thus the changes can be passed on to a person’s children. This has led to much greater controversy, because all the same cautions apply to this approach as to somatic cell therapy, with the added problem that any defects introduced by the technology could become permanent features of the human population. Because of this, germ-line gene therapy is currently banned in the United States and in much of the rest of the world.

Somatic Cell Therapy

Somatic cell therapy could provide some clear benefits. For example, it could potentially free insulin-dependent diabetics from reliance on external sources of insulin by restoring the ability of the patient’s own body to manufacture it. Scientists have already succeeded in genetically engineering bacteria to grow recombinant insulin, eliminating the need to harvest it from animal pancreatic tissue obtained from slaughterhouses. The next step would seem to be the use of somatic cell therapy to treat individual diabetics.

The ethical concerns about treating a disease like diabetes using somatic cell therapy primarily relate to cost and technological proficiency. Currently, the potential costs of gene therapy put it out of reach for most people. Is it ethical to develop a technological solution to a problem that will be available to only a few? Of course, this same concern could be directed at virtually every expensive medical procedure.

A more basic ethical concern, at present, is whether the technology is safe enough to use on humans. Clinical trials of some somatic cell therapies have been halted due to unforeseen complications, including deaths and the development of cancer in some cases. The most famous of these incidents is the death of Jesse Gelsinger, a teenager with partial ornithine transcarbamylase deficiency, who took part in a 1999 gene therapy experiment at the University of Pennsylvania. His death prompted media attention as well as criticism from the Food and Drug Administration (FDA) and President Bill Clinton. This negative publicity for gene therapy was at the time a major setback for supporters of gene therapy research and remains a touchstone in current ethical debates of gene therapy.

Early clinical failures have led some ethicists to question whether gene therapy trials should be considered at all. Is it fair to expect individuals who are managing their diabetes with conventional methods to accept the unknown risks inherent in such a complex and poorly understood technology? Is so little known at this point that one cannot even adequately assess potential risks? These questions are difficult even for extensively studied monogenic disorders like cystic fibrosis, but many genetic diseases, and certainly most common ones, are not so simple. Disorders like chronic heart disease or schizophrenia, which are believed to have numerous genetic and environmental contributing causes, may or may not be treatable by introducing a single change to a single gene. If more complex series of gene therapies are required for treatment of complex disorders, or if environmental factors play significant roles in disease progression, then it is clear that gene therapies for such disorders will need to clear numerous evaluative hurdles before they can be deemed safe.

Assuming that the technological hurdles can be overcome, somatic cell therapy to cure diabetes mellitus appears to offer a fairly clear-cut candidate for treatment. What about less threatening conditions, such as the insufficient production of growth hormone? A shortage of human growth hormone can result in dwarfism. The use of somatic cell therapy to correct the condition clearly would be beneficial, but growth hormone deficiencies vary, and even otherwise normal children can be shorter than average. In a society in which height is associated with success, wealthy parents have been known to pressure doctors to prescribe human growth hormone to their children who are only slightly smaller than average and not truly suffering from a pituitary gland disorder. If somatic cell gene therapy became widely available for human growth, how many parents would succumb to the temptation to give their children a boost in height? The same potential for abuse is present for any number of perceived defects that might be cured by gene therapy, with only those who are rich being able to afford the technology. When the defect is not life threatening, or even particularly debilitating, do parents have the right to decide that their children receive these treatments?

Germ-Line Therapy

Germ-line gene therapy faces all the same ethical objections as somatic cell therapy, and it introduces what some consider more serious ethical concerns. Germ-line therapy changes the characteristics an organism passes on to its offspring. Humans suffer from a variety of inherited diseases, including hemophilia, Huntington’s disease, and cystic fibrosis, and physicians have long recognized that certain conditions, such as coronary artery disease and diabetes, have genetic components. It is tempting to consider the possibility of eliminating these medical conditions through germ-line therapies: Not only would the person suffering from the disease be cured, but his or her descendants would never have to worry about passing the condition on to their offspring. Eventually, at least in theory, the genes that cause the disease could be eliminated from the general population.

Tempting though it may be to see this as a good thing, ethicists believe that such an approach could be extremely susceptible to abuse. They view discussions of human germ-line therapy as an attempt to resurrect the failed agenda of the eugenics movement of the first half of the twentieth century. If scientists are allowed to manipulate human heredity to eliminate certain characteristics, what is to prevent those same scientists from manipulating the human genome to enhance other characteristics? Would parents be able to request custom-tailored offspring, children who would be tall with predetermined hair and eye color? Questions concerning class divisions and racial biases have also been raised. Would therapies be equally available to all people who requested them, or would such technology lead to a future in which the wealthy custom-tailor their offspring while the poor must rely on conventional biology? Would those poor people whose parents had been unable to afford germ-line therapy then find themselves denied access to medical care or employment based on their “inferior” or “unhealthy” genetic profiles? Others predict that traditional socioeconomic class divisions could be deepened by the availability of effective but expensive gene therapy treatments, leading to increased health disparities between the upper and lower classes.

In addition, many ethicists and scientists raise cautionary notes about putting too much faith in new genetic engineering technologies too soon. Most scientists concede that not enough is known about the interdependency of various genes and the roles they play in overall health and human evolution to begin a program to eliminate so-called bad genes. Genes that in one combination may result in a disabling or life-threatening illness may in another have beneficial effects that are not yet known. Germ-line therapy could eliminate one problem while opening the door to a new and possibly worse condition. Thus, while the economic benefits of genetic engineering and gene therapies can be quite tempting, ethicists remind us that many questions remain unanswered. Some areas of genetic research, particularly germ-line therapy, may simply be best left unexplored until a clearer understanding of both the potential social and biological cost emerges.

Key Terms



germ cells

:

reproductive cells such as eggs and sperm




germ-line gene therapy

:

alteration of germ cells resulting in a permanent genetic change in the organism and succeeding generations





insulin


:

a pancreatic hormone that is essential to metabolize carbohydrates, used in the control of diabetes mellitus




recombinant DNA

:

genetically engineered DNA prepared by cutting up DNA molecules and splicing together specific DNA fragments, often from more than one species of organism




somatic cell therapy

:

treatment of specific tissue with therapeutic genes





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