Human Gene Therapy

Keyna Billman

Copyright 1996

What is human gene therapy? Human gene therapy is a procedure that is being used in an attempt to treat genetic and other diseases. Many ethical, social and safety concerns are being raised on the use of human genetic engineering. Gene therapy techniques will introduce copies of a "healthy" gene into cells of the body. The disease will be controlled if the introduced genes work normally. This is called somatic gene therapy because it introduces the gene into a somatic or body cell. Any cells that could divide to form sperms or eggs will not have genes introduced into them through somatic gene therapy. The insertion of a single gene into the somatic cells of an individual with a life threatening genetic disease is the somatic cell gene therapy. This type of therapy is intended solely to eliminate the clinical consequences of the disease. Future generations shouldn't have any problems because the inserted gene is not passed down to them.

Germ line gene therapy, involves the insertions of a healthy gene into the fertilized egg of an animal that has a specific genetic defect. This has been performed successfully in several animal studies. The new gene is obtained in every cell in the body including reproductive cells. There are three overwhelming technical problems that are preventing consideration of this technique for the use in human beings. "The first is that scientists have no way of diagnosing genetic disorders in the fertilized egg. Secondly, the procedure is most often used to insert genes into fertilized eggs - injection with a microscopically guided glass needle - has a high failure rate and thirdly, the problem is lack of control over where the gene is inserted into the embryo's genetic machinery (Nichols E.K., 1988)."

Gene therapy techniques will introduce copies of the "healthy" gene into those cells (called target cells) in the body that are affected by the faulty gene. These healthy genes that are inserted should not be accepted into other cells in the body. There have been a number of proposed methods for inserting human genes into target cells. When scientists discovers a gene that is faulty, the research begins. Scientists compare the faulty gene to the healthy functional gene. This could tell scientists a lot about the faulty gene and how it affects the chemical reactions within a cell. This may lead to the development of new drugs to control the condition. Human suffering, due to inherited diseases, have been reduced more by the use of genetic diagnosis than any other medical technology. The identity of a gene responsible for a genetic disease must be known before scientists can begin to consider gene therapy.

The task of picking one defective gene out of the approximately 100,000 genes that constitutes the human genome may seem overwhelming, but recent advances in molecular biology have made the process relatively straight forward. Scientists need to know the identity of the abnormal gene's protein product before any choice of technique can be selected.

Gene therapy techniques effectiveness depends upon the life span of the target cells. The whole gene therapy process will have to be repeated regularly if the target cells only survive for a few weeks. "It would be much more effective if the therapy genes could be directed into those stem cells which regularly divide to produce new target cells, especially if all of the new cells produced contained functional therapy genes. Much research is being concentrated on gene transfer into haematopoietic stem cells which divide to form white blood cells (NRI 1995)."

In only a short time, human gene therapy has progressed from speculation to reality. "The first clinical gene transfer (albeit only a marker gene) in an approved protocol took place on 22 May 1989, the first federally approved gene therapy protocol, for correction of adenosine deaminase (ADA) deficiency (Anderson W.F. 1992)." In the early 1980's, retroviral-mediated gene transfer was developed in animal models. This technology is the principal procedures used today. There has been many recent reviews on retroviral vector development, packaging cell lines and alternate gene delivery techniques as well as on gene transfer and expression in cell cultures and in animal models. It also addresses the technical issues upon which human gene therapy relies.

There are many controversial issues about human gene therapy. In the 1980's , neither government agencies nor committees addressed the many issues regarding human gene therapy. These included ethical and moral issues. There is a wide range of popular views on gene therapy. Some people view human gene therapy as a great weapon to fight against every genetic disease known. Other people worry that one step into the arena of gene therapy will turn the human species into a technologically designed product and will reduce the human race as we know it. "Gene therapy will be limited to a smaller number of inherited disorders that result from the absence or inactivity of a single gene product. The ethical and social implication of somatic cell gene therapy have been discussed, and there is now a general consensus that somatic cell gene therapy for the purpose of treating a serious disease is an ethical therapeutic option (Anderson W.F., 1992)."

Germ line gene therapy is a different matter because it constitutes a departure from previous medical interventions. Future generations would not have the ability to choose to have the gene therapy or not because these genetic changes would be passed on the them anyway. The only way this procedure will be accepted is to resolve all the complex ethical issues. One concern is that future generations would be damaged if genetic manipulation took place in the germline. As of now, altering genetic information in patients cells may result in long-term side effects that are unpredictable. "LeRoy Walters, director of the center of Bioethics at Georgetown University, explains that there would be two basic rationales for using germ line gene therapy to treat genetic diseases. The first that would arise is some genetic diseases were found resistant to somatic cell gene therapy the second use for germ line gene therapy, would be one of efficiency (Nichols E.K., 1988)."

"Ethical arguments against the use of germ line gene therapy to treat genetic diseases falls into two categories. The first relates to the potential risks of gene therapy: for example, is it ethical to use a technique in which unanticipated problems or mistakes could be passed on to future generations? The second category consists of broader concerns about changes to the gene pool - the genetic inheritance of the human population (Nichols E.K., 1988)." The main underlying concern is that people will use the human gene therapy to alter genetic traits in normal' healthy individuals. This is one type of human gene therapy that people object strongly to. The prospect of parents turning to genetic engineering as a way of producing "perfect" children is extremely disturbing. Many concerns that arise from the use of human gene therapy are philosophical, ethical and theological in nature. For instance, do infants have the right to inherit an unmanipulated genome, does the concept of informed consent have any validity for patients who do not yet exist, and at what point do we cross the line into "playing God? Researchers are exploring the possibility of using somatic cell gene therapy in cancer treatment. If somatic cell gene therapy is found to be useful in the treatment of severe diseases of childhood, there will be a strong incentive to develop techniques for gene therapy in fetuses. There would be great economic benefits for patients who would otherwise require long-term institutional care. Researchers will have to prove or demonstrate that the potential benefits out way the potential risks in the use of human gene therapy before clinical trials will begin. Therapies known to be effective will not be withheld for purposes of conducting the trials. The process of selecting patients must be fair among everyone needing the treatment. Also parents or guardians must be informed fully about the whole procedure and what types of aspects could be expected. They also should know what types of side effects that could arise and maybe irreversible.

There are many issues about human gene therapy and my opinion varies on certain issues. I think somatic cell gene therapy will have great benefits for some of the diseases that human beings suffer. I also feel if they can get the germ cell gene therapy to work on humans and decrease the failure rate and guarantee where the new gene will go, then I think this type of gene therapy should be used also. There are many diseases that are ailing humans and there is no cure or treatment for some of them. If gene therapy could help by eliminating cancers, Alzheimer disease, AIDS, and many other diseases it would end the needless suffering. If curing the disease means changing a bad gene for a good, gene then I feel that it should be done.

I do feel that changing healthy genes to make enhancements like increasing IQ, increasing height and any other non related diseases just to improve a person is morally wrong. I think diseases that are life-threatening and incurable should be cured if possible by using human gene therapy. I don't believe in altering normal human beings; especially by those people who would want to create "perfect" children. I feel what you are born with is what you get. Insurance agencies should not be allowed to use any information from genetic testing to increase rates or deny any person of health insurance.

I feel that any person regardless of age, sex, wealth and so on should have the opportunity to have the human gene therapy techniques performed. I also feel that the cost of the procedure of human gene therapy should be in the price range of anyone needing the procedure. Human gene therapy should not be available to only an elite group. Human gene therapy should be used in fetuses if the disease is recognized and if that fetus is in danger of dying. I feel human gene therapy will have a good impact on our society. More funding should be allowed for human gene therapy so more research can be done to improve the techniques for this procedure.


Anderson, W.F., Science, vol 256 pp 808-813, May 8, 1992 . Human Gene Therapy.

Nichols, E.K., Human Gene Therapy , Harvard University Press, Cambridge, Massachusetts (1988) PP 1-251.

NRI. Somatic Gene Therapy. Obtained from the WWW:

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