We are living at the beginning of an exciting era, when we are rapidly discovering the genetic bases of many human illnesses. As we discover the defective genes associated with these diseases and learn the nature and function of the proteins they encode, we are greatly improving our ability to understand and therefore to treat many of these diseases. Once we have learned the basis of a given disease, there are a number of possible approaches that we may take by means of genetic engineering and other molecular techniques to treat it. For example, the gene for insulin has been inserted into a bacterial genome, so that the bacterium can produce large quantities of human insulin, increasing its availability and functional quality. Antibodies are being developed that will target specific cells or cell surface marker molecules associated with diseases such as arthritis or cancer, Within a few years, it may be possible to introduce a functional copy of a gene into the cells of a person who has a defective gene.

However, there is a negative side to this technology. Many people are concerned that the introduction of foreign genes into bacteria and human cells may have unexpected side effects. Many genes have multiple functions, and there is a danger that we may begin using gene therapy before we know all the ramifications. There is also a great concern as to how far genetic engineering should be allowed to go. What range of "genetic defects" should a person be allowed to change, or should there be no limit? For example, when we discover the genes involved in controlling human height, should parents be allowed to use gene therapy to increase a child's height so that he or she can be better at basketball? An even more immediate concern is to what extent should a person's genetic code be made public. For example, should a medical insurance company or employer be allowed to see a person's genetic profile in order to set insurance premiums or make employment judgments? If a person is shown to have a gene for muscular dystrophy, should the person's insurance company be given that information? Also of current concern is whether a person or company should be able to patent and thus to own a human gene.